Mikuni MX60 problems
Frank Auffret
Last October (2004) I fitted a Mikuni MX60 CH unit to my boat NB
Midnight). The main reason for choosing it was the claim that I could
use the Danfoss TP5 timer/stat which seemed ideal for keeping the boat
frost free during the winter weekdays when nobody is around to keep
the stove going.
So far the unit has broken down 4 times, once caused by a burnt out
glow plug, but mainly through a problem in the buring chamber which
seems to produce a large clinker of burnt carbon which in turn
prevents the flame detector seeing the flame.
The usual sign of impending failure is when the unit runs several
aborted cycles (fires for about 5 seconds then goes in shutdown mode),
before it starts up and runs. This eventually leads to complete
failure.
I have read somewhere that this can be caused if the TP5 calls for
heat again during the shutdown routine.
I can't fault Mikuni on their after sales service and although they
did suggest setting the TP5 at 25 degrees instead of using the default
or frost stat settings, stopped short of condeming it. Not surprising
really as they do supply this unit - and even include the TP5 option
in their wiring diagram.
Has anyone experienced similar a problem and managed to overcome it
using an alternative to the TP5?
Frank Auffret
nb Midnight
http://www.friendsafloat.co.uk
Julian
message news:4378fbcb...@news.btopenworld.com...
> Hi all
>
> I have read somewhere that this can be caused if the TP5 calls for
> heat again during the shutdown routine.
This could well be the problem....
The golden rule for these heaters is NEVER use a thermostat.
The only way to run them is on a timer with thermostatic radiator valves.
If the stat calls for heat during the shutdown phase it will give you the
above problems.
Mine is set to run on a timer with the thermostat set at 30degC so that it
never switches off when in use.
The lower temp on the stat is set at 5degC and so far this has not been a
problem as the temp in the boat never goes that low.
Sugest you get some type of timer that is tripped when the heater goes into
shutdown and locks out the stat for 20minutes this should cure the problem
or just run it with the stat disabled.
J
mickspangle
Julian I tried setting the thermostat to either 5 or 30 degrees.
Since then it's been fine for the last 6 months, although I suppose
winter is going to be the real test!
At least it doesn't keep starting up and shutting down all the time
now.
Gibbo
I have an MX40 with same Danfoss fitted. I had the same problem.
Clinkers appearing in the glow plug and the burning chamber. I don't
use the danfoss anymore. I switch it on and off manually or use a time
switch.
The other main problem that causes clinkers in these things is the vent
hole at the top of the glow plug housing. If this becomes blocked the
glowplug clogs up with carbon and eventually (about 30 start ups)
wrecks the glow plug.
It just looks like a small hole but it's actually force fed with air
from the air motor which swirls the fuel round the gauze.
Since I discovered this (and regularly unblock the hole), and stopped
using the thermostat I haven't had a single problem with the unit.
Gibbo
Frank Auffret
Thanks everyone for your help.
I am now convinced the Danfoss TP5 isn't compatible with the Mikuni.
>I have experienced the same problems with a Mikuni MX40, and like
>Julian I tried setting the thermostat to either 5 or 30 degrees.
I can see this option would work most of the time but if we had a
prolonged cold spell with temperaures below 5 degrees wouldn't the TP5
in effect act like a frost guard and wouldn't the same problem ocurr -
just at lower temperatures?
I rang Danfoss to see if they offer an alternative time switch only
controller, but they only have 240volt versions.
They did suggest the Danfoss TP5000 which can be set to 30 degrees at
the top end and OFF at the lower end but on checking with a local
supplier it's over Ł100.
Does anyone know of a sensibly priced 12volt time switch which has
similar programme option as the TP5?
Les Esling
>> Midnight). The main reason for choosing it was the claim that I could
>> use the Danfoss TP5 timer/stat which seemed ideal for keeping the boat
>> frost free during the winter weekdays when nobody is around to keep
>> the stove going.
>>
>> So far the unit has broken down 4 times, once caused by a burnt out
>> glow plug, but mainly through a problem in the buring chamber which
>> seems to produce a large clinker of burnt carbon which in turn
>> prevents the flame detector seeing the flame.
>>
>> The usual sign of impending failure is when the unit runs several
>> aborted cycles (fires for about 5 seconds then goes in shutdown mode),
>> before it starts up and runs. This eventually leads to complete
>> failure.
I had the identical problem when my boat was first launched from new. Also
before delivery the glow plug burnt out when testing the system in the
factory.
The Mikuni rep came out and when I explained all this to him he said that it
was caused by running the unit on batteries that were not properly charged.
He cleaned the flame failure detection device and it worked perfectly. It
has now done so through 3 winters without the need for any maintenance on my
part. I went away for a month last Feb (the coldest part of last winter) and
left the boat with fully charged batteries and the Danfoss set to the frost
5 degrees position. The unit performed perfectly whilst I was away and the
batteries were down to 58% when I got back.
I have never experienced any problems due to the Danfoss unit and at times
have increased the temperature setting when it is closing down without any
adverse effect whatsoever. The unit just carries on going through its shut
down cycle.
Les
Les Esling
>
> I am now convinced the Danfoss TP5 isn't compatible with the Mikuni.
>
See my earlier posting on this topic. I use a Danfoss unit that was supplied
with my Mikuni and it works 100% all of the time and it gets used a lot
through the winter as I do not winterise my nb because I like to use it
occasionally throughout the winter.
The problem you experienced is probably caused by low charge on your
batteries according to the Mikuni rep who sorted out an identical problem on
my nb. Do you have a battery capacity meter fitted? And do you have a
Sterling or adverc type of battery manager?
I would strongly advise that you speak to Mikuni. They came out to my boat
within 3-4 hours of a phone call and fixed the unit within an hour as well
as explaining the cause of the problem to avoid a repeat. That was nearly 3
years ago and since then it has worked perfectly - touch wood!!
Les
Frank Auffret
<esl...@netspinners.co.uk> wrote:
>I had the identical problem when my boat was first launched from new. Also
>before delivery the glow plug burnt out when testing the system in the
>factory.
>The Mikuni rep came out and when I explained all this to him he said that it
>was caused by running the unit on batteries that were not properly charged.
>He cleaned the flame failure detection device and it worked perfectly. It
>has now done so through 3 winters without the need for any maintenance on my
>part. I went away for a month last Feb (the coldest part of last winter) and
>left the boat with fully charged batteries and the Danfoss set to the frost
>5 degrees position. The unit performed perfectly whilst I was away and the
>batteries were down to 58% when I got back.
>I have never experienced any problems due to the Danfoss unit and at times
>have increased the temperature setting when it is closing down without any
>adverse effect whatsoever. The unit just carries on going through its shut
>down cycle.
Hi Les
Thanks it's good to know these things do work well in some
circumstances - I know of other boaters with similar long term
satisfaction using the TP5 default settings. Regrettably for me not so
- yet!
I have done a lot of technical research this week with various
companies and it seems there may well be a compatibility issue with
the Danfoss TP5, due to the lengthy shutdown routine on the Mikuni.
Having said that ithe TP5 is fine for most situations especially if
it's set as advised by Julian.
The positioning of the TP5 in my own boat may be part of the problem.
On several occasions I have heard the 'click' as unit calls for heat a
few minutes after switching down.
The Danfoss TP5000 is a slightly better option for new installations
as it has a true OFF setting. A 12volt battery operated programmable
timer would be the ideal solution but so far I haven't been able to
source a suitable one.
As Julian suggested, another alternative is a mod for the TP5 system
which will prevent the unit being switched on within 10 minutes or so
of being switched off. A colleague of mine is and electrical whizzo
and he is currently making such a device for me to try.
In all of this I have to say Mikuni Heating in Southampton have been
excellent. They have been very helpful and willing to service the
unit again but in the end I found it quite simple to strip it down and
remove the offending clinker. They have even promised to find a
suitable timer for me to try.
BTW
My understanding is that at least 12 volts are required for the MX60
or else the unit won't start at all. In my case I had some initial
teething troubles with voltage drop because I mistakenly wired the
unit throught the switch panel - the voltage reading was 11.7 volts -
it was cured by taking the lead direct to the battery + terminal.
Frank Auffret
>The problem you experienced is probably caused by low charge on your
>batteries according to the Mikuni rep who sorted out an identical problem on
>my nb. Do you have a battery capacity meter fitted? And do you have a
>Sterling or adverc type of battery manager?
Pretty sure this isn't the problem here - see my previous reply (must
have crossed in the mail) .
The two 250AH Elecsol batteries are usually 100% charged when
'Midnight' is in the marina. I fitted a Mastervolt system, Mass
charger, Mastervolt 95amp alternator with battery management system
included, Invertor and MICC. The latter is so intelligent when it
comes to providing electrical information it could probably pass A
levels.
Les Esling
> The two 250AH Elecsol batteries are usually 100% charged when
> 'Midnight' is in the marina. I fitted a Mastervolt system, Mass
> charger, Mastervolt 95amp alternator with battery management system
> included, Invertor and MICC. The latter is so intelligent when it
> comes to providing electrical information it could probably pass A
> levels.
>
One thought - how old are your batteries?
I was out for 2 months this summer and one morning when the batteries were
down to just over 50% according to the MICC I put the electric kettle on and
the Mastervolt inverter tripped on low voltage.
I realised then that my batteries were just about flat and that they had
lost about half of their capacity. I have since replaced them.
As I see it the MICC is just a "bean counter" when it comes to battery
capacity. It subtracts what you take out and adds back what you put in and
expresses the running total as a percentage against the Amp-Hrs figure that
you have told it is installed on your nb. So if the battery capacity
decreases as it must do with time then the remaining percentage will be
wrong as I found out!
Les
pound...@blueyonder.co.uk
Take a look at www.smartgauge.co.uk Your experience justifies the
comments therin!
Richard
Nb "Pound Eater" Parkend G+S
Frank Auffret
<esl...@netspinners.co.uk> wrote:
>One thought - how old are your batteries?
Just over 2 years old, but this problem has been ongoing since I
installed the MX60 over a year ago.
The MICC is certainly too sopisticated for me to understand - what's
the usual way to check batteries?
Les Esling
>
> Just over 2 years old, but this problem has been ongoing since I
> installed the MX60 over a year ago.
>
a lot of replies criticising Elecsol batteries for being unreliable.
A friend of mine bought 3 110AH units for his boat recently and 1 failed
within a week and a second one within a further month. Worse still about 3
months later he has still not managed to get replacements out of Elecsol who
seem to be "avoiding" the issue.
I opted for the standard HD batteries in the end at about a quarter of the
price.
I doubt that you can have lived with battery(s) that have suffered a
catastrophic failure for such a long period but it might be worth
disconnecting them and checking the terminal voltages just to be sure.
You'll soon see if a cell has gone. If you also check the SG of the
electrolyte I think that will give an indication of capacity if you make
sure that the batteries are fully charged first.
My hydrometer is coloured Red, White, Green for discharged, not full and
full and latterly my last set of batteries never got above the white zone
even when supposedly fully charged. The new ones do!
Les
Les Esling
> The MICC is certainly too sopisticated for me to understand - what's
> the usual way to check batteries?
>
>
>
> Frank Auffret
> nb Midnight
> http://www.friendsafloat.co.uk
I think the normal way would be to carry out a calibrated load test
measuring SG of the electrolyte and voltage to check if the calculated load
has caused the correct decrease in remaining capacity.
Perhaps someone with more knowledge than me could answer this in more
detail.
I'd be interested in keeping a better eye on my battery capacity from now
on.
Les
Les Esling
> Take a look at www.smartgauge.co.uk Your experience justifies the
> comments therin!
>
> Richard
>
> Nb "Pound Eater" Parkend G+S
mmm - having looked at that I wonder if I am not being fair to the MICC
panel. It does have a lot of the properties described therein. I'll read the
manual in more detail when I get time (might have to get a PHd first tho'!!)
Les
Tony Brooks
"Les Esling" <esl...@netspinners.co.uk> wrote in message
news:dln0sk$8pf$2...@nwrdmz01.dmz.ncs.ea.ibs-infra.bt.com...
>>>One thought - how old are your batteries?
Snip
If you also check the SG of the
> electrolyte I think that will give an indication of capacity if you make
> sure that the batteries are fully charged first.
> My hydrometer is coloured Red, White, Green for discharged, not full and
> full and latterly my last set of batteries never got above the white zone
> even when supposedly fully charged. The new ones do!
>
> Les
>
Watch this one on the big yellow jobbies. Elecsol state that they use a
lower specific gravity acid than standard so the hydrometer should always
give a lower reading than the actual battery charge.
I am afraid I can not remember what SG they say they used, so its probably
best to phone and (probably) insist they tell you the SAG for half and
--
Tony Brooks
www.TB-Training.co.uk
fully charged. This should allow a mental recalibration of the hydrometer.
Tony Brooks
In my view a straight forward SG test is probably the simplest and most
reliable way for the amateur to test their batteries. List the SG of each
cell and remember to insert a decimal point after the first number one (1).
All cells should give an SG with no larger variation of 0.03 (I say 0.05)
between any two cells on a battery. If they do, take to a specialist to test
with electronic equipment.
The problem with using voltage is that large battery banks can give spurious
reading caused by surface charge and such like and that confuses both the
owner and I suspect a good many "magic gauges".
Ideally you would have a proper ammeter and voltmeter fitted so you can
continuously monitor what is going on and thus see the first signs of
battery degradation - lower than expected voltage first thing in the morning
with no discernable reason. This is a very empirical load test.
--
Tony Brooks
www.TB-Training.co.uk
pound...@blueyonder.co.uk
frank_auffret_r...@yahoo.co.uk (Frank Auffret) wrote:
>Hi all
>
>Last October (2004) I fitted a Mikuni MX60 CH unit to my boat NB
>Midnight). The main reason for choosing it was the claim that I could
>use the Danfoss TP5 timer/stat which seemed ideal for keeping the boat
>frost free during the winter weekdays when nobody is around to keep
>the stove going.
Snip
I question the control philosophy on the Mikuni if it faults with a
restart during shutdown. If it cannot restart during shutdown then
IMHO It should ignore restart, finish shutdown and then restart as
normal.
Given your problem one option may be to increase the differential on
the stat. This should increase the time before a restart is requested.
Whilst I totally agree that the best way to run a heater is with
TRV's on the rads, this is not a good option in a frost control
scenario, far too expensive on fuel.
I could not find the wiring diagram on the Mikuni site, are you
absolutely sure that it is wired correctly? The fact that some others
do not have the same problem is of concern.
Gibbo
It's not often appreciated that the SG reading will *not* tell you the
state of charge of a battery!
Scoff you may, but it's a fact.
Let's assume you have a brand new battery with a fully charged SG of
1.285 and a flat SG of 1.180
After 12 months use the fully charged SG of that battery might be
around 1.240 and no matter how long you leave your charger connected
that is as high as it will ever go. So the battery is fully charged,
but according to the SG it half flat. This loss of maximum SG is a
result of reduced capacity due to ageing (mainly but not entirely
sulphation).
SG will tell you the *condition* (state of health) of the battery if
you know what the state of charge is *and* you know how to relate these
two parameters.
SG will tell you the state of charge of the battery if you know what
the *condition* is.
An SG reading of say 1.20 could be an old tired battery that is at 100%
state of charge. It could also be a brand new battery almost completely
flat.
So you can see that an SG reading isn't all it's crakced up to be. It
certainly won't tell you how charged your batteries are.
Also note that the SG versus state of charge graph for each battery
type is different. Elecsols have a *very* low SG compared to other
batteries and using a normal hydrometer will show these batteries to be
almost permanently flat (actually they probably are flat as they are
c&*p :-).
Gibbo
Gibbo
Les Esling wrote:
> I also have a Mastervolt system with an MICC panel.
> One thought - how old are your batteries?
> I was out for 2 months this summer and one morning when the batteries were
> down to just over 50% according to the MICC I put the electric kettle on and
> the Mastervolt inverter tripped on low voltage.
> I realised then that my batteries were just about flat and that they had
> lost about half of their capacity. I have since replaced them.
> As I see it the MICC is just a "bean counter" when it comes to battery
> capacity. It subtracts what you take out and adds back what you put in and
> expresses the running total as a percentage against the Amp-Hrs figure that
> you have told it is installed on your nb. So if the battery capacity
> decreases as it must do with time then the remaining percentage will be
> wrong as I found out!
>
Music to my ears
Gibbo
Pete C
.
>It's not often appreciated that the SG reading will *not* tell you the
>state of charge of a battery!
>
>Scoff you may, but it's a fact.
>
>Let's assume you have a brand new battery with a fully charged SG of
>1.285 and a flat SG of 1.180
>
>After 12 months use the fully charged SG of that battery might be
>around 1.240 and no matter how long you leave your charger connected
>that is as high as it will ever go. So the battery is fully charged,
>but according to the SG it half flat. This loss of maximum SG is a
>result of reduced capacity due to ageing (mainly but not entirely
>sulphation).
Hi,
Would this be the case if the capacity was 57% (0.06/0.105) of
original due to aging/sulphation?
cheers,
Pete.
Gibbo
Pete C wrote:
I'm not sure I understand the question.
What's the 0.06/0.105?
Gibbo
Pete C
Sorry, it's
((1.240 - 1.180)/(1.2805 - 1.180)) * 100%
ie taking the difference between flat and fully charged SG and
comparing this difference between the battery after a year to when it
was new and expressing it as a percentage.
So after a year the SG difference between flat and fully charged is
57% of what it was when the battery was new.
cheers,
Pete.
Gibbo
Pete C wrote:
Ah right I'm with you now!
Correct. Except the lower SG reading won't change. Think about it.
*totally* flat is an SG reading of 1.000 It can't get any lower. And if
it is any higher, then there is still some power in the battery. So
you'll have to decide for yourself what the "flat" SG reading is.
But if you just take the upper SG reading when fully charged you'll get
a good idea of the condition of the battery.
A confusing part is that the voltage of the battery isn't related to
the SG (go figure)
Gibbo
Frank Auffret
>I question the control philosophy on the Mikuni if it faults with a
>restart during shutdown. If it cannot restart during shutdown then
>IMHO It should ignore restart, finish shutdown and then restart as
>normal.
I agree I did rather expect the Mikuni MX60 contol box (which based on
it's size seems to hold more goodies than the much smaller MX40
control box) would be able to detect when the unit is in shutdown and
not try to restart.
When I asked Mikuni about this they told me the unit should function
ok with the TP5 but to use the same differential settings you suggest
and never use the frost stat setting. When I pointed out that this
was, at the lower end, the same as frost stat and that the TP5 doesn't
have an 'off' they seemed quite surprised. They seem quite eager to
help solve this problem and promised to get back to me soon.
This weekend I did change my TP5 settings to 30 / 5 but if the outside
temperature stays lower than 5 for more than a few days I don't see
how the restart problem can be avoided.
Basically the TP5 switches off at the set temperature and back on when
the temperature falls below that set temperature. It's the same
process whether the setting is 5 or 30.
It all really depends how quickly the temperature inside the boat
falls below the set temperature and if that happens while the shutdown
phase is still in progress - same carbon build up just a lower boat
temperature.
It's only when the outside temperature is above 5 degrees that the 30
/ 5 differential will work i.e. it's unlikely the boat temperature
will ever reach 30 so the TP5 doesn't call for shutdown on the higher
setting times and the boat won't get colder than 5 so the unit won't
call for heat when at the lower setting times. During a mild winter
it's easy to see why this wouldn't cause probelms.
>I could not find the wiring diagram on the Mikuni site, are you
>absolutely sure that it is wired correctly? The fact that some others
>do not have the same problem is of concern.
Yes I had the wiring checked by the Mikuni field engineer.
There was a mistake in the wiring digram supplied with the unit
(according to the 3 pin plug connections for the switch loom, live
connects to neutral). I didn't spot that immediately but corrected it
when I was working through the initial voltage drop problem.
Today I have spoken to 2 boaters who have used the TP5 on default
setting with no problems - one for over 2 years. In both case they
were using the MX40 - I wonder if the MX40 control box is able to
detect the shutdown phase and not try to restart? I have assumed that
all the contributors to this thread are using the MX60?
Gibbo
Frank Auffret wrote:
[snip]
>
> Today I have spoken to 2 boaters who have used the TP5 on default
> setting with no problems - one for over 2 years. In both case they
> were using the MX40 - I wonder if the MX40 control box is able to
> detect the shutdown phase and not try to restart? I have assumed that
> all the contributors to this thread are using the MX60?
>
Mine is an MX40 and it will quite happily restart during the shut down
phase and carbon itself up.
Gibbo
pound...@blueyonder.co.uk
frank_auffret_r...@yahoo.co.uk (Frank Auffret) wrote:
snip
>This weekend I did change my TP5 settings to 30 / 5 but if the outside
>temperature stays lower than 5 for more than a few days I don't see
>how the restart problem can be avoided.
>
>Basically the TP5 switches off at the set temperature and back on when
>the temperature falls below that set temperature. It's the same
>process whether the setting is 5 or 30.
>
>It all really depends how quickly the temperature inside the boat
>falls below the set temperature and if that happens while the shutdown
>phase is still in progress - same carbon build up just a lower boat
>temperature.
>
>It's only when the outside temperature is above 5 degrees that the 30
>/ 5 differential will work i.e. it's unlikely the boat temperature
>will ever reach 30 so the TP5 doesn't call for shutdown on the higher
>setting times and the boat won't get colder than 5 so the unit won't
>call for heat when at the lower setting times. During a mild winter
>it's easy to see why this wouldn't cause probelms.
snip
As I said in my previous post I am not au fait with the mikuni.
I cannot relate to this 30/5 business what do you mean by it.
When I talk differential I am discussing the difference between the
switch on temp and the switch off temp at any temperature settring.
Typically the switch on temp may be 5deg and the switch off may be
5.5deg the same differential at 20deg setting - 20deg and 20.5deg. If
this differential can be adjusted then the time to another start will
be lengthened.
If there is an accelerator resistor in the stat then disconnecting
that would have some effect again increasing the differential
Just my 2pennorth.
Pete C
>As I said in my previous post I am not au fait with the mikuni.
>I cannot relate to this 30/5 business what do you mean by it.
>When I talk differential I am discussing the difference between the
>switch on temp and the switch off temp at any temperature settring.
>Typically the switch on temp may be 5deg and the switch off may be
>5.5deg the same differential at 20deg setting - 20deg and 20.5deg. If
>this differential can be adjusted then the time to another start will
>be lengthened.
>If there is an accelerator resistor in the stat then disconnecting
>that would have some effect again increasing the differential
>Just my 2pennorth.
Hi,
If you want longer on/off times then adding thermal mass to the
accelerator resistor would do it, maybe use the same value with a
higher wattage. Also a higher value would reduce the accelerator
effect. Though sometimes there is some sleeving over it which
presumably slows the response down.
IME they're often too small and too low a value, giving more rapid
switching at the expense of basic accuracy. Maybe they're designed for
220V instead of 240V.
cheers,
Pete.
Frank Auffret
>As I said in my previous post I am not au fait with the mikuni.
>I cannot relate to this 30/5 business what do you mean by it.
The Danfoss TP5 sets the 'switch-off' temperature between 5 & 30
degrees for six set times during a 24 hour period - there's no real
'off' setting.
>When I talk differential I am discussing the difference between the
>switch on temp and the switch off temp at any temperature settring.
>Typically the switch on temp may be 5deg and the switch off may be
>5.5deg the same differential at 20deg setting - 20deg and 20.5deg. If
>this differential can be adjusted then the time to another start will
>be lengthened.
There's no user option to set the differential between the switch off
& switch on temperature - the system is quite basic e.g. if the
temperature reaches the setting of say 25 degrees it switches off when
it drops to 24 degrees it switches back on. Like I said this depends
on how quickly the boat cools.
If anyone can suggest a simple DIY mod to the internal gubbings of the
TP5 I would be very interested.
Gibbo
Frank Auffret wrote:
>
> If anyone can suggest a simple DIY mod to the internal gubbings of the
> TP5 I would be very interested.
>
I would imagine the TP5 is entirely microprocessor controlled and
therefore a modification to change the temperature on and off points
would be major work.
However, I've just looked at the wiring diagram for an MX40 and there
is a way to prevent the Mikuni from firing up during the cool down
phase using 2 relays and a couple of diodes. It involves using the
water pump feed on the Mikuni to lock out the signal from the TP5
If I get a chance this coming weekend I'll draw up a circuit diagram.
Gibbo
Frank Auffret
>However, I've just looked at the wiring diagram for an MX40 and there
>is a way to prevent the Mikuni from firing up during the cool down
>phase using 2 relays and a couple of diodes. It involves using the
>water pump feed on the Mikuni to lock out the signal from the TP5
>
>If I get a chance this coming weekend I'll draw up a circuit diagram.
Brill Gibbo!
My MX60 installation guide is down at the marina but if I remember
rightly they include wiring diagrams for both models I will try to get
down mid week and check if there's any significant differences.
Gibbo
Frank Auffret wrote:
Right, me supper wasn't ready so I've done it.
I have had to make the assumption that the water pump stays on during
the cool down phase on an MX60 (it does on my MX40). If it doesn't,
we'll have to find another signal to tap into. Not a major problem
I moved from using diodes to using a double pole relay.
You will need 2 double pole, double throw relays. 12 volt coil (or 24
volt of the system is 24 volt). Actually only one needs to be double
pole but it's easier to buy two the same. The contact ratings only need
to be 2 amps or more.
The diagram is here...
http://www.smartgauge.co.uk/bits/mx40.bmp
Here's how it's wired up......
"blue/yellow" is the feed directly from the boiler control panel. It is
normally interrupted via the TP5 relay contacts before going on to the
normal switch.
"boiler on/off" replaces this so it now interrupts the feed to the
on/off switch.
"water pump" is taken directly from the water pump connections.
"tp switch" goes to the contact terminals on the TP5
And here's how it works.....
Assume the boiler is off and the TP5 is off.
When the TP5 tries to switch the boiler on, there is a 12 volt feed
from "blue/yellow" up through the closed contacts of K1 to the relay
contacts in the TP5. The TP5 contact is closed (as it wants to switch
the boiler on) and this therefore energises K2. The left hand contacts
of K2 therefore close and this switches the boiler on.
Once the boiler is running, the water pump will come on, this will
remove the 12 volt feed to the TP5 conacts, but as K2 is now energised,
the TP5 contacts will still have a 12 volt feed from here.
When the TP5 switches off (which will switch the boiler off), K2
switches off, there is now no feed to TP5 either from K2 or K1. If TP5
tries to switch the boiler back on, it cannot as it has no power feed,
until the water pump switches off (at the end of the cool down phase).
Once the cool down phase is complete, K1 will switch off again and thus
there will, once again, be a 12 volt feed to TP5 so it can, once again,
switch the boiler on.
This of course will completely prevent the TP5 from trying to switch
the boiler back on during the cool down phase.
Gibbo
pound...@blueyonder.co.uk
snip
>http://www.smartgauge.co.uk/bits/mx40.bmp
snip
>Gibbo
I thought that you said you were busy!!!!
Gibbo
pound...@blueyonder.co.uk wrote:
> On 21 Nov 2005 14:56:41 -0800, "Gibbo" <gi...@smartgauge.co.uk> wrote:
>
> snip
>
> >http://www.smartgauge.co.uk/bits/mx40.bmp
> snip
> >Gibbo
>
>
> I thought that you said you were busy!!!!
>
15 minutes while waiting for Alex to make supper.
Gibbo
Allan Jones
<pound...@blueyonder.co.uk> wrote in message
news:abb5o1hef2vucgbar...@4ax.com...
There's an old saying "If you want something done, ask a busy man"
--
Allan Jones - N/B 'Keeping Up'
http://www.keeping-up.co.uk
Frank Auffret
>Right, me supper wasn't ready so I've done it.
>
>I have had to make the assumption that the water pump stays on during
>the cool down phase on an MX60 (it does on my MX40). If it doesn't,
>we'll have to find another signal to tap into. Not a major problem
>
>I moved from using diodes to using a double pole relay.
>
>You will need 2 double pole, double throw relays. 12 volt coil (or 24
>volt of the system is 24 volt). Actually only one needs to be double
>pole but it's easier to buy two the same. The contact ratings only need
>to be 2 amps or more.
>
>The diagram is here...
>
>http://www.smartgauge.co.uk/bits/mx40.bmp
Thanks Gibbo I will get down to my local Maplins at the weekend and
get the relays. The wiring diagram and explanation are new ground for
me but I think I can see what's required. I will let you know when
it's installed.