inverter powered central heating
Stephen
A few weeks ago I was asking here about powering my boiler from an
inverter during a power cut. I have given it a go and here are my
experiences and questions:
The boiler was fed by a fused connection unit. A poster, sorry I can't
remember who, suggested that I replace the FCU with an unswitched
socket and plug. He said that this fulfilled the requirements for
isolation because the plug could be pulled out of the socket to
isolate the boiler. Is the "unswitched" part important? I ask because
I didn't have a spare unswitched socket so used a switched one, but I
can easily go and buy an unswitched socket if regulations dictate. I'm
trying to think of reasons why a switched socket might not be allowed.
Does the switch only switch the live or is it a double pole switch? If
single pole, I guess the switch cannot be used to isolate if it only
switches one side but then a switched socket would still allow the
plug to be removed for full isolation.
The boiler is oil-fired; does that makes a difference? An oil-fired
boiler uses a pump to suck the oil. Does a gas boiler have a pump or
does it just use the pressure in the supply pipe? The boiler
manufacturer (Grant) said that the boiler could be used with *any*
type of inverter. The boiler is connected to a Horstamn programmer and
Horstman valves, as advertised in the Screwfix catalogue. I did
contact Horstamn about using inverters with their products but never
got a reply. The CH has a Wilo pump and sadly, Wilo did not reply to
my questions either.
When connected to the modified sine wave inverter I had two problems:
1. the controller has a back light dot-matrix LCD. When the inverter
was used the back light and the LCD flickered. Also some vertical
lines appeared on the LCD. Clearly the display did not like the
waveform from the inverter but this seemed to be just cosmetic; the
switching functions worked as intended.
2. the boiler buzzed a lot. I think it was the boiler rather than the
circulating pump but I will double check. I thought it was the oil
pump or fan (or both). Whereas (1) was cosmetic and did not alarm me,
I'm not so sure about this noise. Is it anything to worry about? Is it
causing increased wear on whatever is making the noise? It will be
only for occasional use but even so, should I upgrade to a pure sine
wave inverter? The problem is these cost ten times as much!
I did also try to use lights powered by the inverter and both
traditional filament and CFL bulbs seemed to work without any
noticeable problems. One old CFL buzzed but new ones did not.
Thanks,
Stephen.
Dave Osborne
> Hello,
>
> A few weeks ago I was asking here about powering my boiler from an
> inverter during a power cut. I have given it a go and here are my
> experiences and questions:
>
> The boiler was fed by a fused connection unit. A poster, sorry I can't
> remember who, suggested that I replace the FCU with an unswitched
> socket and plug. He said that this fulfilled the requirements for
> isolation because the plug could be pulled out of the socket to
> isolate the boiler. Is the "unswitched" part important?
No, I think the OP might have been concerned that you could accidentally
switch the switch off and not notice (apart, I suppose from it being
cold and there being no hot water).
>
> The boiler is oil-fired; does that makes a difference? An oil-fired
> boiler uses a pump to suck the oil. Does a gas boiler have a pump or
> does it just use the pressure in the supply pipe?
No pump in a gas boiler.
The boiler
> manufacturer (Grant) said that the boiler could be used with *any*
> type of inverter. The boiler is connected to a Horstamn programmer and
> Horstman valves, as advertised in the Screwfix catalogue. I did
> contact Horstamn about using inverters with their products but never
> got a reply. The CH has a Wilo pump and sadly, Wilo did not reply to
> my questions either.
>
> When connected to the modified sine wave inverter I had two problems:
> 1. the controller has a back light dot-matrix LCD. When the inverter
> was used the back light and the LCD flickered. Also some vertical
> lines appeared on the LCD. Clearly the display did not like the
> waveform from the inverter but this seemed to be just cosmetic; the
> switching functions worked as intended.
The controller does not have a mains transformer in it. This would
normally act as a low-pass filter for the mains and takes out some of
the high frequency crap you get with an inverter.
As it is, the controller itself takes very little power and this power
is derived directly from the mains in a very crude arrangement. If you
want to eliminate the display problems, then you need to insert an
isolating transformer between the inverter and the controller. This
should do the trick:
http://uk.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=0504307
( http://preview.tinyurl.com/djl8e3 )
>
> 2. the boiler buzzed a lot. I think it was the boiler rather than the
> circulating pump but I will double check. I thought it was the oil
> pump or fan (or both). Whereas (1) was cosmetic and did not alarm me,
> I'm not so sure about this noise. Is it anything to worry about? Is it
> causing increased wear on whatever is making the noise? It will be
> only for occasional use but even so, should I upgrade to a pure sine
> wave inverter? The problem is these cost ten times as much!
>
Buy a bigger isolating trandformer and power the whole heating system
via the transformer! You'll need to get a fix on the total current
demand (i.e. boiler on, oil pump running, valves operating all at the
same time) in order to get a transformer of a suitable size. Don't buy a
transformer too big, cos the inverter might not be able to handle the
inrush.
Dave Liquorice
> He said that this fulfilled the requirements for isolation because the
> plug could be pulled out of the socket to isolate the boiler. Is the
> "unswitched" part important?
Only to prevent "accidental" switching off or mistaken use as an isolation
switch. You are obviously aware of what is required for that. I think you
can get double pole switched sockets but that doesn't avoid the
"accidental" switch off by the phantom switch twidler.
> The boiler is oil-fired; does that makes a difference?
More power required for an oil boiler than gas. I think our oil boiler
wants about 150W for the pump/blower the circulation pumps about 30W each,
controller I'd not worry about in power terms. So you are looking at an
invertor that can provide at least 300W continusly but with a fair bit of
"reserve" to start the pump/blower motor.
Things are obviously not overly happy on the invertor you have. Does it
have a high enough power rating? Is it a "quality" brand or a something
something cheapy from China?
--
Cheers
Dave.
Stephen
<rum...@nospam.invalid> wrote:
>>Is the "unswitched" part important?
>
>No, I think the OP might have been concerned that you could accidentally
>switch the switch off and not notice (apart, I suppose from it being
>cold and there being no hot water).
Thanks for the fast reply!
>No pump in a gas boiler.
I thought so.
>The controller does not have a mains transformer in it. This would
>normally act as a low-pass filter for the mains and takes out some of
>the high frequency crap you get with an inverter.
>
>As it is, the controller itself takes very little power and this power
>is derived directly from the mains in a very crude arrangement. If you
>want to eliminate the display problems, then you need to insert an
>isolating transformer between the inverter and the controller.
I was going to ask whether I could fit something to smooth out the
wave but then I thought that if a solution existed, surely the
manufacturer would have built that in; obviously not.
I hadn't realised that an isolating transformer would be the solution.
I have always thought of them as being for bathroom shaver sockets,
not as filters. Is it something to do with inductance?
> 2. the boiler buzzed a lot. I think it was the boiler rather than the
>> circulating pump but I will double check.
>Buy a bigger isolating trandformer and power the whole heating system
>via the transformer! You'll need to get a fix on the total current
>demand (i.e. boiler on, oil pump running, valves operating all at the
>same time) in order to get a transformer of a suitable size. Don't buy a
>transformer too big, cos the inverter might not be able to handle the
>inrush.
I have had another go and with the boiler switched off and the
circulating pump on there is a very faint hum from the pump; quieter
than the hum from a fridge for example. You really have to put your
ear near to the pump to hear it. The louder buzz comes from the boiler
once that is switched on. It's hard to describe how loud that is. It's
like the buzz from a failing fluorescent tube. It's loud enough to
notice when you walk in the room, louder than a fridge or freezer.
Whilst I can live with the display, it would be nice to quieten the
hum. My worry was whether the hum was causing either damage to the
pump or causing it to pump less efficiently. I ran it for a few
minutes and the rads have got warm.
I think we worked out that the inverter needed to be rated about 200W
continuous with 1kW surge. What is inrush? Is that similar to the
start-up surge current in a motor? How would I calculate the inrush of
a transformer?
Thanks,
Stephen.
meow...@care2.com
> Hello,
>
> A few weeks ago I was asking here about powering my boiler from an
> inverter during a power cut. I have given it a go and here are my
> experiences and questions:
>
> The boiler was fed by a fused connection unit. A poster, sorry I can't
> remember who, suggested that I replace the FCU with an unswitched
> socket and plug. He said that this fulfilled the requirements for
> isolation because the plug could be pulled out of the socket to
> isolate the boiler. Is the "unswitched" part important? I ask because
> I didn't have a spare unswitched socket so used a switched one, but I
> can easily go and buy an unswitched socket if regulations dictate. I'm
> trying to think of reasons why a switched socket might not be allowed.
> Does the switch only switch the live or is it a double pole switch? If
> single pole, I guess the switch cannot be used to isolate if it only
> switches one side but then a switched socket would still allow the
> plug to be removed for full isolation.
someone needs to chill
> The boiler is oil-fired; does that makes a difference? An oil-fired
> boiler uses a pump to suck the oil. Does a gas boiler have a pump or
no
> does it just use the pressure in the supply pipe? The boiler
> manufacturer (Grant) said that the boiler could be used with *any*
> type of inverter. The boiler is connected to a Horstamn programmer and
> Horstman valves, as advertised in the Screwfix catalogue. I did
> contact Horstamn about using inverters with their products but never
> got a reply. The CH has a Wilo pump and sadly, Wilo did not reply to
> my questions either.
both those devices will have issues with MSW. The programmer likely
uses a CR supply, and these tend to die on MSW waveforms as the
resistor grossly overheats. Pumps run hotter and less efficienctly on
MSW, but they do run.
> When connected to the modified sine wave inverter I had two problems:
> 1. the controller has a back light dot-matrix LCD. When the inverter
> was used the back light and the LCD flickered. Also some vertical
> lines appeared on the LCD. Clearly the display did not like the
> waveform from the inverter but this seemed to be just cosmetic; the
> switching functions worked as intended.
trivial
> 2. the boiler buzzed a lot. I think it was the boiler rather than the
> circulating pump but I will double check. I thought it was the oil
> pump or fan (or both). Whereas (1) was cosmetic and did not alarm me,
> I'm not so sure about this noise. Is it anything to worry about? Is it
> causing increased wear on whatever is making the noise? It will be
> only for occasional use but even so, should I upgrade to a pure sine
> wave inverter? The problem is these cost ten times as much!
MSW waveforms contain lots of harmonics, so anything prone to hum or
buzz will buzz many times louder. That's life.
> I did also try to use lights powered by the inverter and both
> traditional filament and CFL bulbs seemed to work without any
> noticeable problems. One old CFL buzzed but new ones did not.
>
> Thanks,
> Stephen.
The suggestion to use an iso tf as a filter strikes me as odd. These
would only filter out frequencies so high that the inverter probably
filters them out already. And if it doesnt, they wont really have a
significant effect.
For low power items like the programmer, just a series resistor would
help to reduce the crap and reduce the power diss of the inbuilt
resistor in the CR supply.
For things like pumps, fans etc, I wouldnt worry about them. They'll
just run a bit noisy. If youre as panicky as you seem you want want to
check theyre not running frying hot (ie faulty but still operating) ,
if they were the MSW just might tip them over the edge.
NT
Dave Osborne
>
> I have had another go and with the boiler switched off and the
> circulating pump on there is a very faint hum from the pump; quieter
> than the hum from a fridge for example. You really have to put your
> ear near to the pump to hear it. The louder buzz comes from the boiler
> once that is switched on. It's hard to describe how loud that is. It's
> like the buzz from a failing fluorescent tube. It's loud enough to
> notice when you walk in the room, louder than a fridge or freezer.
>
> Whilst I can live with the display, it would be nice to quieten the
> hum. My worry was whether the hum was causing either damage to the
> pump or causing it to pump less efficiently. I ran it for a few
> minutes and the rads have got warm.
>
> I think we worked out that the inverter needed to be rated about 200W
> continuous with 1kW surge. What is inrush? Is that similar to the
> start-up surge current in a motor?
Yes, just like a start-up surge current in a motor.
How would I calculate the inrush of
> a transformer?
You don't need to work out the inrush of the transformer. Rather, you
need to work out the load which your heating system places on the
inverter and specify the smallest suitable transformer (e.g. 200-300VA
by the sound of it).
One of the things you could do to test the theory is to get two yellow
110V site transformers and wire them back-to-back to make a 230V
double-isolating transformer. You can also get 230V isolating
transformers (usually in a blue box, rather than yellow). However, such
transformers will be between 750VA and 3kVA and your inverter might not
be happy with the inrush.
Stephen
<allsortsn...@howhill.com> wrote:
>Things are obviously not overly happy on the invertor you have. Does it
>have a high enough power rating? Is it a "quality" brand or a something
>something cheapy from China?
300W continuous, 1kW peak. No brand name but when I looked, I couldn't
find anyone selling branded inverters. Do they exist and what are good
names? I think the inverter is ok, it's just that the modified sine
wave is not suitable.
Andrew Gabriel
Stephen <inv...@invalid.org> writes:
> Hello,
>
> A few weeks ago I was asking here about powering my boiler from an
> inverter during a power cut. I have given it a go and here are my
> experiences and questions:
>
> The boiler was fed by a fused connection unit. A poster, sorry I can't
> remember who, suggested that I replace the FCU with an unswitched
> socket and plug. He said that this fulfilled the requirements for
> isolation because the plug could be pulled out of the socket to
> isolate the boiler. Is the "unswitched" part important? I ask because
> I didn't have a spare unswitched socket so used a switched one, but I
> can easily go and buy an unswitched socket if regulations dictate. I'm
> trying to think of reasons why a switched socket might not be allowed.
> Does the switch only switch the live or is it a double pole switch? If
> single pole, I guess the switch cannot be used to isolate if it only
> switches one side but then a switched socket would still allow the
> plug to be removed for full isolation.
It's not in the wiring regs, but I believe it's a requirment
CORGI (as was) imposed on gas installers, and it was so they
were not tempted to treat the switch as valid isolation for
servicing/maintenance. Yes, you can get double pole switched
sockets, but there's no way to know that's what's been fitted.
> The boiler is oil-fired; does that makes a difference? An oil-fired
> boiler uses a pump to suck the oil. Does a gas boiler have a pump or
> does it just use the pressure in the supply pipe? The boiler
> manufacturer (Grant) said that the boiler could be used with *any*
> type of inverter. The boiler is connected to a Horstamn programmer and
> Horstman valves, as advertised in the Screwfix catalogue. I did
> contact Horstamn about using inverters with their products but never
> got a reply. The CH has a Wilo pump and sadly, Wilo did not reply to
> my questions either.
>
> When connected to the modified sine wave inverter I had two problems:
> 1. the controller has a back light dot-matrix LCD. When the inverter
> was used the back light and the LCD flickered. Also some vertical
> lines appeared on the LCD. Clearly the display did not like the
> waveform from the inverter but this seemed to be just cosmetic; the
> switching functions worked as intended.
>
> 2. the boiler buzzed a lot. I think it was the boiler rather than the
> circulating pump but I will double check. I thought it was the oil
> pump or fan (or both). Whereas (1) was cosmetic and did not alarm me,
> I'm not so sure about this noise. Is it anything to worry about? Is it
> causing increased wear on whatever is making the noise? It will be
> only for occasional use but even so, should I upgrade to a pure sine
> wave inverter? The problem is these cost ten times as much!
I've done this. The pump makes more noise due to harmonic components.
These will also result in more magnetic losses, but as the pump is
well cooled by the hot water (strange though this may sound), I didn't
worry about the extra heat.
This might be more of a concern with some other components, where
the higher power dissipation might not be so well handled. In my gas
boiler, that's just the gas valve.
--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]
Stephen
>someone needs to chill
I wasn't in a panic, I just wanted to be sure that I was following
the regs and to understand why the regs required what they do.
>both those devices will have issues with MSW. The programmer likely
>uses a CR supply, and these tend to die on MSW waveforms as the
>resistor grossly overheats. Pumps run hotter and less efficienctly on
>MSW, but they do run.
Sorry, I'm not sure what CR is short for? I was thinking something
regulation but since you mention resistors is it just
resistor-capacitor?
>> Clearly the display did not like the
>> waveform from the inverter but this seemed to be just cosmetic
>trivial
That's what I thought at first. I can live with it flickering a bit
but if you are telling me that the controller power supply will fail
on the MSW then it ceases to be trivial as controllers aren't cheap!
>MSW waveforms contain lots of harmonics, so anything prone to hum or
>buzz will buzz many times louder. That's life.
I can live with the noise but, like you said above, I wonder about the
reduced efficiency. The power wasted on humming is power that should
be spent pumping. Will it have a noticeable effect?
>For low power items like the programmer, just a series resistor would
>help to reduce the crap and reduce the power diss of the inbuilt
>resistor in the CR supply.
Any suggestions on what resistor I should use? It's a shame Horstmann
never replied.
>For things like pumps, fans etc, I wouldnt worry about them. They'll
>just run a bit noisy. If youre as panicky as you seem you want want to
>check theyre not running frying hot (ie faulty but still operating) ,
>if they were the MSW just might tip them over the edge.
Not panicky; just curious. I can't tell if the pump is running hot as
it's always hot, it's pumping hot water ;)
I'm happy for the pump to run noisy as long as it is not causing
premature wear and not loosing too much efficiency. OTOH I don't want
to spend a hundred pounds on a new controller.
Thanks,
Stephen.
Stephen
<rum...@nospam.invalid> wrote:
>You don't need to work out the inrush of the transformer. Rather, you
>need to work out the load which your heating system places on the
>inverter and specify the smallest suitable transformer (e.g. 200-300VA
>by the sound of it).
It looks like the jury's out about the isolating transformer. I was
going to ask about power factors. If its 200-300VA and if that is
roughly equivalent to 200-300W then it sounds fine. Would it be able
to cope with any start up surge? The RS web site said something about
testing 4kV for 6s, so I should think so.
Thanks again,
Stephen.
Dave Osborne
> On Fri, 27 Mar 2009 11:57:15 +0000, Dave Osborne
> <rum...@nospam.invalid> wrote:
>
>> You don't need to work out the inrush of the transformer. Rather, you
>> need to work out the load which your heating system places on the
>> inverter and specify the smallest suitable transformer (e.g. 200-300VA
>> by the sound of it).
>
> It looks like the jury's out about the isolating transformer.
Ok, your call.
I was
> going to ask about power factors. If its 200-300VA and if that is
> roughly equivalent to 200-300W then it sounds fine. Would it be able
> to cope with any start up surge? The RS web site said something about
> testing 4kV for 6s, so I should think so.
Ah, you're confusing voltage and current. The 4kV for 6 seconds thing is
about proofing the insulation resistance of the transformer and has
nothing to do with current surge. The transformer will absolutely cope
with the current surge.
Transformers are not 100% efficient. Generally speaking the larger they
are, the more efficient they are. Different types are more or less
efficient (toroidal more efficient than laminated for example). A
200-300VA toroidal transofrmer is going to be 95% efficient. Power
factor is not a significant issue. I would go with "200-300W is
roughtly equivalent to 200-300VA" as a no-brainer in this situation.
HTH, Rumble
Dave Osborne
> In article <h08ps4h1pmm5n3n5c...@4ax.com>,
> Stephen <inv...@invalid.org> writes:
>> Hello,
>>
>> A few weeks ago I was asking here about powering my boiler from an
>> inverter during a power cut. I have given it a go and here are my
>> experiences and questions:
>>
>> The boiler was fed by a fused connection unit. A poster, sorry I can't
>> remember who, suggested that I replace the FCU with an unswitched
>> socket and plug. He said that this fulfilled the requirements for
>> isolation because the plug could be pulled out of the socket to
>> isolate the boiler. Is the "unswitched" part important? I ask because
>> I didn't have a spare unswitched socket so used a switched one, but I
>> can easily go and buy an unswitched socket if regulations dictate. I'm
>> trying to think of reasons why a switched socket might not be allowed.
>> Does the switch only switch the live or is it a double pole switch? If
>> single pole, I guess the switch cannot be used to isolate if it only
>> switches one side but then a switched socket would still allow the
>> plug to be removed for full isolation.
>
> It's not in the wiring regs, but I believe it's a requirment
> CORGI (as was) imposed on gas installers, and it was so they
> were not tempted to treat the switch as valid isolation for
> servicing/maintenance. Yes, you can get double pole switched
> sockets, but there's no way to know that's what's been fitted.
>
Good call. Nanny state at work, then ;-)
Steve Firth
> 300W continuous, 1kW peak. No brand name but when I looked, I couldn't
> find anyone selling branded inverters. Do they exist and what are good
> names?
Nikkai is a decent brand.
> I think the inverter is ok, it's just that the modified sine
> wave is not suitable.
Yes, I use a square wave inverter (calling it MSW is a bad joke, it's a
square wave with lumps) in a barn to provide lighting from solar
panels/batteries. I've tried it with various electronic items and it
killed a Targus PSU in seconds. I really wouldn't use one with any sort
of switched mode PSU.
Besides true sinewave inverters and generators with sine-wave output can
be had for reasonable prices. I'd suggest getting hold of a two-stroke
600W generator for about £50. It will keep your CH running until power
is restored. Or if you want to do a decent job of it get a diesel
generator and run it on the CH oil.
You'll get a 600! pure sine wave inverter for £50 if you look around
(eBay).
meow...@care2.com
> On Fri, 27 Mar 2009 04:43:38 -0700 (PDT), meow...@care2.com wrote:
> >someone needs to chill
>
> I wasn't in a panic, I just wanted to be sure that I was following
> the regs and to understand why the regs required what they do.
>
> >both those devices will have issues with MSW. The programmer likely
> >uses a CR supply, and these tend to die on MSW waveforms as the
> >resistor grossly overheats. Pumps run hotter and less efficienctly on
> >MSW, but they do run.
>
> Sorry, I'm not sure what CR is short for? I was thinking something
> regulation but since you mention resistors is it just
> resistor-capacitor?
Yes. The capacitor acts as a dropper, with the resistor used to limit
peak currents. MSW waveforms contain way more hf content, making the
current such a supply draws very peaky. This causes the power diss in
resistors in such supplies to go way up, they regularly die quickly.
> >> Clearly the display did not like the
> >> waveform from the inverter but this seemed to be just cosmetic
>
> >trivial
>
> That's what I thought at first. I can live with it flickering a bit
> but if you are telling me that the controller power supply will fail
> on the MSW then it ceases to be trivial as controllers aren't cheap!
>
> >MSW waveforms contain lots of harmonics, so anything prone to hum or
> >buzz will buzz many times louder. That's life.
>
> I can live with the noise but, like you said above, I wonder about the
> reduced efficiency. The power wasted on humming is power that should
> be spent pumping. Will it have a noticeable effect?
relax. Its not worth spending £50+ improving the efficiency of a small
load thats rarely used.
> >For low power items like the programmer, just a series resistor would
> >help to reduce the crap and reduce the power diss of the inbuilt
> >resistor in the CR supply.
>
> Any suggestions on what resistor I should use? It's a shame Horstmann
> never replied.
I dont know the power rating of the thing, if its LCD lets guess at
3VA.
i= 3/240 = 12mA
New products will cope fine with a 20v drop. 20v 12mA = 1.7k
So a 1.5k resistor would be good. Make it a 3 watter.
If your controller ratings are different...
NT
meow...@care2.com
> Stephen <inv...@invalid.org> wrote:
> > I think the inverter is ok, it's just that the modified sine
> > wave is not suitable.
>
> Yes, I use a square wave inverter (calling it MSW is a bad joke, it's a
> square wave with lumps) in a barn to provide lighting from solar
> panels/batteries. I've tried it with various electronic items and it
> killed a Targus PSU in seconds. I really wouldn't use one with any sort
> of switched mode PSU.
SMPSUs are inherently suited to MSW, as the smpsu input contains a
rectifier and reservoir capacitor(s). However some have a resistor in
the way to limit peak current, and this will generally fry on MSW. The
solution is to fit a much more powerful resistor in its place and it
should all run fine. More like 10w instead of 0.5w.
NT
meow...@care2.com
> Stephen wrote:
> > On Fri, 27 Mar 2009 11:57:15 +0000, Dave Osborne
> > <rum...@nospam.invalid> wrote:
> One of the things you could do to test the theory is to get two yellow
> 110V site transformers and wire them back-to-back to make a 230V
> double-isolating transformer.
That would get you 5-10% less than 240v, which would work, but it
wouldnt achieve anything. Mains tranformers wont filter anything out
below 1kHz, which is a frequency above the bulk of the harmonics
causing the issues. You could make it work by adding a capacitor
across the tf secondary, forming an RC filter with the transformer's
copper resistance and the cap, but its an inefficienct and overcostly/
bulky solution.
NT
Dave Osborne
You may well be right, but then again, RF Crap coming from the inverter
may be affecting the microcontroller in the CH controller and this would
be filtered out by a tranny. I'm no expert on the frequency response of
50Hz transformers or the waveform(s) of various types of inverters, so
I'm not going to argue against your point, but under the circumstances,
I would be in favour of galvanic isolation and if it were me I *would*
cobble something together and see if made any difference.
Cheers, Rumble
Steve Firth
Yes, as usual from you that's an authoritative sounding answer that's
useless. Perhaps you can explain how one opens a typical SMPS supplied
for laptop (or in the case of the Targus general) use in order to fit a
"more powerful resistor"? The Targus unit in question was about 4mm
thick and ultrasonically welded.
tony sayer
<rum...@nospam.invalid> scribeth thus
Might he be better off getting a better inverter?..
tony sayer
<rum...@nospam.invalid> scribeth thus
--
Tony Sayer
meow...@care2.com
> meow...@care2.com wrote:
> > Dave Osborne wrote:
> >> Stephen wrote:
> >>> On Fri, 27 Mar 2009 11:57:15 +0000, Dave Osborne
> >>> <rum...@nospam.invalid> wrote:
> >
> >> One of the things you could do to test the theory is to get two yellow
> >> 110V site transformers and wire them back-to-back to make a 230V
> >> double-isolating transformer.
> >
> > That would get you 5-10% less than 240v, which would work, but it
> > wouldnt achieve anything. Mains tranformers wont filter anything out
> > below 1kHz, which is a frequency above the bulk of the harmonics
> > causing the issues. You could make it work by adding a capacitor
> > across the tf secondary, forming an RC filter with the transformer's
> > copper resistance and the cap, but its an inefficienct and overcostly/
> > bulky solution.
> >
>
> You may well be right, but then again, RF Crap coming from the inverter
> may be affecting the microcontroller in the CH controller
Most unlikely. The power supply in the controller will be very
effective at wiping that out, as it inevitably contains a reservoir
cap, and typically other things that also add to the low pass
filtering function..
> and this would
> be filtered out by a tranny. I'm no expert on the frequency response of
> 50Hz transformers
they cover most of the audio spectrum, they've seen use at times as
cost cutting audio transformers.
> or the waveform(s) of various types of inverters, so
MSW invertors normally have a filter to remove harmonics a long way
above the fundamental. Its not impossible for a cost cutting no name
reputable invertor to leave out any filtering and use phoney product
certification, but even if it does the load appliances will still
handle the rf.
> I'm not going to argue against your point, but under the circumstances,
> I would be in favour of galvanic isolation
why?
> and if it were me I *would*
> cobble something together and see if made any difference.
>
> Cheers, Rumble
NT
meow...@care2.com
If you cant open it, the resistor goes in series with the supply input
and you can locate the R externally if you prefer. If you do it that
way you'll need a higher value R to relieve the dissipation on the
internal R, since that's still in circuit. Fortunately smpsus can
handle wide variations in mains V so you can arrange the external R to
drop 10v. Its value isnt a trivial calculation though.
How you arrange it physically depends on what you've got there, and
makes no difference to the fact that what I proposed is electrically a
sound solution. A few options spring to mind, your choices being
limited by the amount of power dissipation.
No-one claimed you could implement trivially it in every case,
obviously there exists equipment thats hard to work on for one reason
or another. And the design and calculation is, like a lot of
electronic design, not trivial in every case. I'm not sure theres much
mileage in whining that electronics isnt a simpler subject, or that I
didnt write you an essay on details you hadnt asked about.
NT
Clint Sharp
<to...@bancom.co.uk> writes
>
>Might he be better off getting a better inverter?..
>
Some big units can be had for buttons on eBay because the batteries have
died and the shipping isn't cheap.
--
Clint Sharp
Steve Firth
> No-one claimed you could implement trivially it in every case,
Yes you did. You jumped in with your stupid ill-thought out suggestion.
> obviously there exists equipment thats hard to work on for one reason
> or another. And the design and calculation is, like a lot of
> electronic design, not trivial in every case.
Aww bless, I'm sorry to hear that you find selecting a resistor hard to
do.
> I'm not sure theres much mileage in whining that electronics isnt a
> simpler subject, or that I didnt write you an essay on details you hadnt
> asked about.
No one was whining, or at least not until you started. And I don't give
a flying fuck for your worthless opinions.
Ed Sirett
No one has (AFAICT) mentioned that some boiler models are sensitive to
the polarity of the supply.
You may have to make sure that the Earth and the supply conductor that
goes to the Neutral input are joined.
Some boilers probably don't mind, but...
--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html
meow...@care2.com
welcome to the filter
NT
Dave Liquorice
> No one has (AFAICT) mentioned that some boiler models are sensitive to
> the polarity of the supply.
Isn't that gas boilers and the flame failure device reliant on ionised
bits?
This is an oil boiler far simpler, big fan, high pressure pump, a jet and
powerful spark to ignite the atomised oil spray from the jet. Flame
detection is optical.
--
Cheers
Dave.
Steve Firth
> welcome to the filter
Please set it so that your worthless drivel goes away. You and the rest
of the meow fuckwits.
geoff
<e...@makewrite.demon.co.uk> writes
I have done in the past
maybe we need a wiki / FAQ entry Ed ...
>
>You may have to make sure that the Earth and the supply conductor that
>goes to the Neutral input are joined.
>
>Some boilers probably don't mind, but...
>
>
Only the ver ver old ones which rely on thermocouples or those which use
infrared sensing IWHT
--
geoff
Stephen
Gabriel) wrote:
>I've done this. The pump makes more noise due to harmonic components.
>These will also result in more magnetic losses, but as the pump is
>well cooled by the hot water (strange though this may sound), I didn't
>worry about the extra heat.
The water pump does not make that much noise when on the inverter, it
is the boiler that makes the loud hum.
Stephen
<rum...@nospam.invalid> wrote:
>> It looks like the jury's out about the isolating transformer.
>
>Ok, your call.
I don't know enough (anything) about transformers so I am unable to
know whether using one would help. All I know is that there's no
consensus within the group. If I had one lying about, I would
certainly try it but the advice seems to be that money spent on a
transformer would be better spent on a new inverter.
Stephen
wrote:
>Yes, I use a square wave inverter (calling it MSW is a bad joke, it's a
>square wave with lumps) in a barn to provide lighting from solar
>panels/batteries.
That sounds interesting: what panels, lights, and batteries do you
use?
>Besides true sinewave inverters and generators with sine-wave output can
>be had for reasonable prices. I'd suggest getting hold of a two-stroke
>600W generator for about £50. It will keep your CH running until power
>is restored. Or if you want to do a decent job of it get a diesel
>generator and run it on the CH oil.
Can you get a diesel generator for less than a thousand pounds? The
cheap ones all seem to be petrol and they are noisy. At least an
inverter is silent.
>You'll get a 600! pure sine wave inverter for £50 if you look around
>(eBay).
I never thought to look there. Are they reputable makes sol by
reputable sellers? The ones I had seen were several hundred pounds. I
thought that if something was too good top be true (e.g. 50UKP on
ebay) it probably is.
Dave Liquorice
> Can you get a diesel generator for less than a thousand pounds?
Yes, they are generally a hundred quid more than similar rated petrol.
> The cheap ones all seem to be petrol and they are noisy.
My diesel is even noisier but who cares when you can have few lights,
heating, and maintain the fridges/freezers. And being diesel will run on
red at 40p/l rather than road fuel at nearer a quid.
> At least an inverter is silent.
Apart from the fans that a 2kW jobbie will have and then you have the
problem of a massive battery bank to supply the energy. Petrol/diesel
generators have a lot going for them in term of energy density of the fuel
and decent power availabilty. B-)
Of course a few hundred watts just for the heating is less of a problem.
But say 200W from the battery @ 12v is 16A, 5 hours for an 80Ahr battery
to dead as a Dodo.
--
Cheers
Dave.
Stephen
<allsortsn...@howhill.com> wrote:
>Yes, they are generally a hundred quid more than similar rated petrol.
I'll have to look more closely then, the shops I have seen seem to
sell petrol for small models and only introduce diesel once the
machines get big and expensive.
>My diesel is even noisier but who cares when you can have few lights,
>heating, and maintain the fridges/freezers. And being diesel will run on
>red at 40p/l rather than road fuel at nearer a quid.
How do you get hold of red diesel? Ask a farmer? Is it legal to use
red in a generator? I wasn't sure whether the noise would be an issue
late at night/early in the morning, or it might alert neighbours that
you have power and they'd all come asking to watch the telly ;)
I suppose an inverter could be kept indoors but a genny could be
stolen from outside?
>Apart from the fans that a 2kW jobbie will have
I imagine that a 2kW inverter costs as much as a genny? I was only
looking at inverters for lights and boiler.
> and then you have the
>problem of a massive battery bank to supply the energy.
Agreed.
> Petrol/diesel
>generators have a lot going for them in term of energy density of the fuel
>and decent power availabilty. B-)
I think they run for 16 hours on a tank? And you can have a jerry can
on standby. Do you have to add a preservative to the petrol though?
Ed Sirett
There are probably some other models where the flame sense is done with
two unearthed electrodes.
Dave Liquorice
> How do you get hold of red diesel?
Take jerry can down to local garage and get it filled from the red diesel
pump. Then sign the book with name adress and what I want it for.
> Ask a farmer?
I would if the local garage didn't sell it.
> Is it legal to use red in a generator?
Yes. I suspect if one wanted to jump through the hoops you could probably
claim back the duty (10p/l I think) and the difference between 15 and 5%
VAT. Provided you could prove to HMR&C that the fuel was used only for
domestic energy purposes.
> I wasn't sure whether the noise would be an issue late at night/early in
> the morning, or it might alert neighbours
Ours is noisey but it's not *that* noisey but then all our neighbours are
some distance away and have lumpy bits of ground between us and them...
> I suppose an inverter could be kept indoors but a genny could be
> stolen from outside?
Could be but you'd notice the noise stop and it weighs quite a bit. Two
blokes couldn't run very fast or far with it. Could heave it into the back
of van PDQ though. Not many tea leaves around here...
> I think they run for 16 hours on a tank? And you can have a jerry can
> on standby.
Something like that with a big tank on the frame, the small engine mounted
tanks only manage a few hours.
> Do you have to add a preservative to the petrol though?
I never have for the petrol I have for the lawn mower or strimmer, that is
often kept over winter. "Preservatives" seems to be an American thing, I
think their petrol must be different to ours...
--
Cheers
Dave.
Steve Firth
> On Fri, 27 Mar 2009 14:12:49 +0000, %steve%@malloc.co.uk (Steve Firth)
> wrote:
>
> >Yes, I use a square wave inverter (calling it MSW is a bad joke, it's a
> >square wave with lumps) in a barn to provide lighting from solar
> >panels/batteries.
>
> That sounds interesting: what panels, lights, and batteries do you
> use?
I use LC Solar monocrystalline panels, which I bought from a company in
Bristol. However I don't think they are in business anymore - I'd like
to increase the number of panels and I can't get a reply from them. The
batteries were bought S/H when a company near Vauxhall got rid of
several hundred 110AH Chloride batteries. They were all in good
conditions and continue to work well for me, five years after I bought
them. I have no idea how long they will last for, I bought 10 and use
them in rotation - next job is to come up with a controller to manage
the charge/discharge cycle. The lights are normal incandescent light
bulbs.
> >Besides true sinewave inverters and generators with sine-wave output can
> >be had for reasonable prices. I'd suggest getting hold of a two-stroke
> >600W generator for about £50. It will keep your CH running until power
> >is restored. Or if you want to do a decent job of it get a diesel
> >generator and run it on the CH oil.
>
> Can you get a diesel generator for less than a thousand pounds? The
> cheap ones all seem to be petrol and they are noisy. At least an
> inverter is silent.
Yes, if you shop around. A 6KVA diesel generator can be had for about
£800 and they're not the noisy "site" generators.
> >You'll get a 600! pure sine wave inverter for £50 if you look around
> >(eBay).
>
> I never thought to look there. Are they reputable makes sol by
> reputable sellers? The ones I had seen were several hundred pounds. I
> thought that if something was too good top be true (e.g. 50UKP on
> ebay) it probably is.
Yes, good makes and no problems in my experience. There are both
inverters and inverter-chargers if you're thinking of a small
installation with wind/solar charging.
Stephen
wrote:
>I use LC Solar monocrystalline panels, which I bought from a company in
>Bristol. However I don't think they are in business anymore - I'd like
>to increase the number of panels and I can't get a reply from them. The
>batteries were bought S/H when a company near Vauxhall got rid of
>several hundred 110AH Chloride batteries. They were all in good
>conditions and continue to work well for me, five years after I bought
>them. I have no idea how long they will last for, I bought 10 and use
>them in rotation - next job is to come up with a controller to manage
>the charge/discharge cycle. The lights are normal incandescent light
>bulbs.
Thanks. What output do the solar panels produce? Can you top up in one
day what you use in one night? What is the total load of the
incandescent lights?
>Yes, if you shop around. A 6KVA diesel generator can be had for about
>£800 and they're not the noisy "site" generators.
What shops and which makes? That could be useful if you wanted to
power a whole house during frequent power cuts but for now I think I
should just get a smaller, cheaper generator as per your earlier
email.
>> >You'll get a 600! pure sine wave inverter for £50 if you look around
>> >(eBay).
I've been looking but can only see a 300W continuous (600W peak) pure
sine and that's £50 to buy with another £30 for postage. I would like
something nearer 600W cont. 1kW peak.
Thanks again.
Steve Firth
> On Wed, 1 Apr 2009 12:14:14 +0100, %steve%@malloc.co.uk (Steve Firth)
> wrote:
>
> >I use LC Solar monocrystalline panels, which I bought from a company in
> >Bristol. However I don't think they are in business anymore - I'd like
> >to increase the number of panels and I can't get a reply from them. The
> >batteries were bought S/H when a company near Vauxhall got rid of
> >several hundred 110AH Chloride batteries. They were all in good
> >conditions and continue to work well for me, five years after I bought
> >them. I have no idea how long they will last for, I bought 10 and use
> >them in rotation - next job is to come up with a controller to manage
> >the charge/discharge cycle. The lights are normal incandescent light
> >bulbs.
>
>
> Thanks. What output do the solar panels produce? Can you top up in one
> day what you use in one night? What is the total load of the
> incandescent lights?
The panels produce 625W which is more than I need at present - they
actually generate a maximum of 50A charging current which is sufficient
to charge one 110AH battery per day. The ultimate aim is to have more
panels as I get to afford them and to have a working wind generator.
I've had a homebrew one working producing 600W but it's more a toy than
a serious source of power at the moment and I daren't leave it running
unattended.
The lights add up to about 300W, but I tend to use no more than 100W at
a time.
> >Yes, if you shop around. A 6KVA diesel generator can be had for about
> >£800 and they're not the noisy "site" generators.
>
> What shops and which makes? That could be useful if you wanted to
> power a whole house during frequent power cuts but for now I think I
> should just get a smaller, cheaper generator as per your earlier
> email.
http://stores.ebay.co.uk/The-Discount-Generator-Store
is one, there are several others. The place I bought from (Peak
Generators, Matlock) appears to have gone bust.
Makes include Kipor, Suntom, Hitachi, Kawasaki and several others. The
Kipor generators have a decent reputation and appear to produce clean
sinewave output. Some makes have remote start capabilities which can be
damned useful.
It looks like prices have come down since I bought one and you can now
get a 6KVA generator under £600.
If you want to research types enter "silent diesel generator", without
the quotes, as a search term in eBay. Where you buy is up to you, but
that search will throw up typical gensets then you can choose if your
shop or go search on Google for better deals.
> >> >You'll get a 600! pure sine wave inverter for £50 if you look around
> >> >(eBay).
>
> I've been looking but can only see a 300W continuous (600W peak) pure
> sine and that's £50 to buy with another £30 for postage. I would like
> something nearer 600W cont. 1kW peak.
I can still see sine wave inverters on eBay at that price. I have no
idea what you're doing. And of course you have to pay postage. There are
600W PSW inverters for £50 + £22 P&P.
You do seem to want the moon on a plate for £0.025.
Stephen
wrote:
>The panels produce 625W which is more than I need at present - they
>actually generate a maximum of 50A charging current which is sufficient
>to charge one 110AH battery per day. The ultimate aim is to have more
>panels as I get to afford them and to have a working wind generator.
>I've had a homebrew one working producing 600W but it's more a toy than
>a serious source of power at the moment and I daren't leave it running
>unattended.
>
>The lights add up to about 300W, but I tend to use no more than 100W at
>a time.
>
It's interesting that you are self-sufficient in lights. I envy your
set-up being able to recharge each day what you use at night. I know
lighting accounts for a very small fraction of my electricity bill but
even so, it would be nice to think I was not paying the electricity
co. for lighting. I appreciate that I would be paying other people for
the equipment and that payback would be long etc.
I don't need a generator yet but I'll keep the useful information
about those for reference so thanks for that too.
>> I've been looking but can only see a 300W continuous (600W peak) pure
>> sine and that's £50 to buy with another £30 for postage. I would like
>> something nearer 600W cont. 1kW peak.
>
>I can still see sine wave inverters on eBay at that price. I have no
>idea what you're doing. And of course you have to pay postage. There are
>600W PSW inverters for £50 + £22 P&P.
>
>You do seem to want the moon on a plate for £0.025.
This is where I got upset. I never said that I wanted to spend £0.025.
I simply do not want to spend hundreds of pounds on >kilowatt rated
inverters. There are a lot of modified sine wave inverters listed on
ebay.co.uk but I've got one of those already. I would like a pure sine
wave inverter, and excluding the high rated, high priced ones, the
only one I have seen lately is the 300W continuous, 600W peak, which I
think is the same one you have seen. Your original post said you could
get 600W inverters for £50. The points I was trying to make were: (i)
this one is 600W peak not 600W continuous and (ii) although the list
price may be £50, you have to pay an additional £30, so in reality
this is not a 600w inverter for £50, it is a 300W inverter for £80.
I am not saying that you are wrong. I am sure you are right and it's
just that this week no-one is listing what I am looking for. Perhaps I
should look at the .com web site for greater choice?
Steve Firth
> This is where I got upset. I never said that I wanted to spend �0.025.
> I simply do not want to spend hundreds of pounds on >kilowatt rated
> inverters. There are a lot of modified sine wave inverters listed on
> ebay.co.uk but I've got one of those already. I would like a pure sine
> wave inverter, and excluding the high rated, high priced ones, the
> only one I have seen lately is the 300W continuous, 600W peak, which I
> think is the same one you have seen. Your original post said you could
> get 600W inverters for �50. The points I was trying to make were: (i)
> this one is 600W peak not 600W continuous and (ii) although the list
> price may be �50, you have to pay an additional �30, so in reality
> this is not a 600w inverter for �50, it is a 300W inverter for �80.
Where's the point in getting upset? Last time I looked there were a
couple of places doing sine-wave inverters for under �50, this week you
can't find them, next week they may be back.
If you don't want to pay postage go and look for the product in a local
shop.
You might want to work out how much 2.5p is before getting all hissy
fit.