Cold radiators - air lock?
JoeJoe
cold. They are the two furthest away from the (combi) boiler - upstairs,
boiler downstairs.
The inlet and outlet pipes into both of then are also cold.
I noticed that the last two radiators before the two offending ones are hot
near the top, but much colder near the bottom.
I bled all the radiators in the house, however, there was no sign (sound) or
air in any. Radiators are still cold after that.
Any idea what do to next?
PS: Not sure if this is related, but you may recall from my messages of
several weeks ago that I had a problem with my expansion vessel causing the
pressure to drop very rapidly. This has now been re-pressurised and
everything seemed to be working OK since.
harry
Probably your expansion vessel is faulty & needs replacing. Check
your system pressure.
JoeJoe
"harry" <harol...@aol.com> wrote in message
news:321ef6cb-dabf-4edd...@37g2000prx.googlegroups.com...
Why would you think that? The pressure has remained stable ever since the
vessel has been re-pressurised.
Dave Liquorice
>> I bled all the radiators in the house,
>
> Probably your expansion vessel is faulty & needs replacing. Check
> your system pressure.
>
> Why would you think that? The pressure has remained stable ever since
> the vessel has been re-pressurised.
Even after you bled the radiators? I'd expect some small drop. Jammed
in the off state thermostatic valves is another possibilty.
--
Cheers
Dave.
JoeJoe
"Dave Liquorice" <allsortsn...@howhill.com> wrote in message
news:nyyfbegfubjuvyypb...@srv1.howhill.co.uk...
> On Wed, 8 Dec 2010 07:56:55 -0000, JoeJoe wrote:
>
>>> I bled all the radiators in the house,
>>
>> Probably your expansion vessel is faulty & needs replacing. Check
>> your system pressure.
>>
>> Why would you think that? The pressure has remained stable ever since
>> the vessel has been re-pressurised.
>
> Even after you bled the radiators? I'd expect some small drop.
It is -14c outside at the moment, so can't really leave the system turned
off for long enough to check... But it seems as if the pressure is stilll
stable.
> Jammed in the off state thermostatic valves is another possibilty.
Is that possible for all 3 (just noticed that it was in fact the last 3 and
not two radiators that were cold) valves were jammed at the same time?
I tried to "play" with te valves of the offending radiators, but no luck...
Ronald Raygun
> "Dave Liquorice" <allsortsn...@howhill.com> wrote in message
> news:nyyfbegfubjuvyypb...@srv1.howhill.co.uk...
>>
>> Jammed in the off state thermostatic valves is another possibilty.
>
> Is that possible for all 3 (just noticed that it was in fact the last 3
> and not two radiators that were cold) valves were jammed at the same time?
>
> I tried to "play" with te valves of the offending radiators, but no
> luck...
It does seem too much of a coincidence for 2-3 TRVs to stick as if by
conspiracy. But it's still worth checking. "Playing" with them is not
very likely to free them up (I take it you mean just turning the knob
back and forth several times). You need to take the valve head off.
This is a simple job. They're generally held on either with a knurled
ring nut or with a collar clamp secured with a single screw. Undo this
and the head just pulls off, exposing the pin which actuates the valve.
Grab hold of the pin with pliers and give it a bit of a tug, then you
should hear the water rushing through.
However, the symptom you described, of nearby radiators being hot on top
and cold on the bottom, suggests a different problem. If there is air in
them you would expect the reverse, i.e. hot below and cold on top, and
bleeding would fix this. I suspect there is a build up of sludge causing
a blockage.
You might be able to shift the blockage by turning off all the good
radiators in the hope that this might give bit of extra push through the
bad ones. Otherwise you're probably looking at having to power flush.
Andrew Gabriel
"JoeJoe" <n...@mail.com> writes:
> Woke up this morning to find out that two of our 17 radiators are stone
> cold. They are the two furthest away from the (combi) boiler - upstairs,
> boiler downstairs.
>
> The inlet and outlet pipes into both of then are also cold.
>
> I noticed that the last two radiators before the two offending ones are hot
> near the top, but much colder near the bottom.
Two possibilities.
Flow too low - inlet pipe will be hot, outlet pipe cold.
Radiator silted up - both inlet and outlet pipes will be hot.
> I bled all the radiators in the house, however, there was no sign (sound) or
> air in any. Radiators are still cold after that.
>
> Any idea what do to next?
Try turning off all the ones which are working, and see what happens
with the others. If it's an air-lock, that might force it out, but
be careful of it forcing the airlock just to the pump and then the
circulation stopping and boiler overheating - be ready to turn off
the boiler if it suddenly starts sounding like a boiling kettle.
> PS: Not sure if this is related, but you may recall from my messages of
> several weeks ago that I had a problem with my expansion vessel causing the
> pressure to drop very rapidly. This has now been re-pressurised and
> everything seemed to be working OK since.
Could be related depending on exactly what happened.
Another thought - do the pipes run somewhere where they might have
frozen?
--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]
Dave Liquorice
>> Jammed in the off state thermostatic valves is another possibilty.
>
> Is that possible ...
Everything is possible.
> ... for all 3 (just noticed that it was in fact the last 3 and not two
> radiators that were cold) valves were jammed at the same time?
But some things are not very probable. B-)
Jammed valves are normally found straight after the summer after they
have been forced off for long periods. Depends on room use and
exterior temp how long it is before one is noticed. I only found one
last week when digging out the Christmas stuff from an unused
room....
Try turning off all your radiators but the cold one nearest the
boiler put the pump up to max and fire up the heating. That might
shift an airlock.
--
Cheers
Dave.
JoeJoe
"Ronald Raygun" <no....@localhost.localdomain> wrote in message
news:UmJLo.41296$lZ5....@newsfe16.ams2...
Just had a look at it again:
Both pipes on the last warm radiator are hot. From it the pipes run for
around 5m under the floor boards and along the external wall to the first of
the cold radiators (and then to the other two cold ones). I cannot remember
100%, but I have a feeling that these pipes are copper and uninsulated, and
that there is a very large vent to the eaves - i.e. very exposed to the
outside.
Although I am certain that the radiators were working last night, is it
possible the pipes leading to them simply froze overnight, causing a
blockage?
Sludge accumulation is a possibility. However I have had to top the system
on a daily basis for weeks before it was finally fixed a few weeks ago, and
also the water here is as good as mineral water (i.e. soft - we've been
using the same kettle for the last ten years...). So I assume sludge it less
likely?
JoeJoe
"Andrew Gabriel" <and...@cucumber.demon.co.uk> wrote in message
news:idno3h$ucf$1...@news.eternal-september.org...
You took the words out of my mouth! See my reply above.
Assuming that:
- the pipes leading to the cold rads froze, and that;
- access to them is not easy (+ school closed so kid around), and;
- temperature tomorrow is supposed to be ~10c warmer than the last few days,
Can I simply ignore it (we have "enough" useable rooms) and hope that
everything will be back to normal once pipes defrost?
Mark
>Woke up this morning to find out that two of our 17 radiators are stone
>cold. They are the two furthest away from the (combi) boiler - upstairs,
>boiler downstairs.
Do these normally work? Have they gradually or suddenly stopped
heating up?
>The inlet and outlet pipes into both of then are also cold.
>
>I noticed that the last two radiators before the two offending ones are hot
>near the top, but much colder near the bottom.
Radiators which are cold at the bottom and hot at the top are often
this way because they are partly full of sludge. It may be worth
removing them and flushing them out.
--
(\__/) M.
(='.'=) Due to the amount of spam posted via googlegroups and
(")_(") their inaction to the problem. I am blocking some articles
posted from there. If you wish your postings to be seen by
everyone you will need use a different method of posting.
newshound
>
> Sludge accumulation is a possibility. However I have had to top the system
> on a daily basis for weeks before it was finally fixed a few weeks ago,
> and also the water here is as good as mineral water (i.e. soft - we've
> been using the same kettle for the last ten years...). So I assume sludge
> it less likely?
>
>
air so the steel radiators can rust a bit more, especially as you are
diluting your inhibitor (if you still have any left). The sludge is iron
oxide, not the calcium and other limescale products which come from hard
water.
The Natural Philosopher
partial drain down.
shutdown, on the isolators if necessary, all hot rads, and see if that
pumps the air around. Then bleed any rads with cold tops and hot
bottoms. Use max pump speed if its adjustable.
Be paitent, It took me several hours to get partial clearance and
several more MONTHS of bleeding to get all the gas out, especially if
its fresh pipework with a bit of flux left in.
Re pressurise as required, and remember the new water will also have
dissolved gases in it that will need to be bled..
The Natural Philosopher
It is, but I hope not.
I had a porch once. With rad in it. I never used it in winter. I turned
the rad off. It froze. I burst the rad. I patched it with CAR BODY
FILLER enough to be able to run the CH till the landlord could get a
plumber in.
> Sludge accumulation is a possibility. However I have had to top the system
> on a daily basis for weeks before it was finally fixed a few weeks ago, and
> also the water here is as good as mineral water (i.e. soft - we've been
> using the same kettle for the last ten years...). So I assume sludge it less
> likely?
>
scale yes, not sure about sludge.
>
The Natural Philosopher
> Assuming that:
> - the pipes leading to the cold rads froze, and that;
> - access to them is not easy (+ school closed so kid around), and;
> - temperature tomorrow is supposed to be ~10c warmer than the last few days,
>
> Can I simply ignore it (we have "enough" useable rooms) and hope that
> everything will be back to normal once pipes defrost?
>
You can hope. See my earlier reply.. I had water gushing out of a split
rad..instead.
>
Mike Lane
> Sludge accumulation is a possibility. However I have had to top the system
> on a daily basis for weeks before it was finally fixed a few weeks ago, and
> also the water here is as good as mineral water (i.e. soft - we've been
> using the same kettle for the last ten years...). So I assume sludge it less
> likely?
I live in a very soft-water area (3 degrees Clarke according to the local
water company). My microbore CH pipes clogged up last year so that nothing
would clear them; I had to get most of the piping replaced.
--
Mike Lane
UK North Yorkshire
mike_lane at mac dot com
Mark
Beware -- An empty house a few doors from me have had their ceilings
down and lots of problems from their pipes freezing. I'd turn the
water off if it's not a sealed system and in anycase check all the
pipes.
JoeJoe
"The Natural Philosopher" <t...@invalid.invalid> wrote in message
news:idomks$ois$1...@news.albasani.net...
> JoeJoe wrote:
>> Woke up this morning to find out that two of our 17 radiators are stone
>> cold. They are the two furthest away from the (combi) boiler - upstairs,
>> boiler downstairs.
>>
>> The inlet and outlet pipes into both of then are also cold.
>>
>> I noticed that the last two radiators before the two offending ones are
>> hot near the top, but much colder near the bottom.
>>
>> I bled all the radiators in the house, however, there was no sign (sound)
>> or air in any. Radiators are still cold after that.
>>
>> Any idea what do to next?
>>
>> PS: Not sure if this is related, but you may recall from my messages of
>> several weeks ago that I had a problem with my expansion vessel causing
>> the pressure to drop very rapidly. This has now been re-pressurised and
>> everything seemed to be working OK since.
> airlock is always possible after any work on CH that requires even partial
> drain down.
I am pretty clueless about these things - just looking for an explanation
that sounds rational and makes sense before I look into it. So please bear
with me a little longer...
What I cannot understand is how it is possible for all 3 radiators to
suddenly turned cold (worked at 11pm, didn't come to life at 6am the next
morning), and also, why only the three rads that are the furthest from the
boiler?
As the pipes leading to them could potentially freeze overnight this is why
that possibility seemed most likely to my ignorant mind...
BTW, apart from the problem with the expansion vessel that we have had for
the last year+ and required us to top the system up regularly, we have never
had any problem otherwise (i.e. air in the system, radiators not uniformly
warm, etc). I just cannot understand why suddenly three rads will die at
once...
Weather predicted to warm up a little in the next few days - it has not been
above -8c for the last week, so maybe that will eliminate the freezing
option?
Dave Liquorice
> What I cannot understand is how it is possible for all 3 radiators to
> suddenly turned cold (worked at 11pm, didn't come to life at 6am the
> next morning),
Simplistically radiators are connected in paralle if you get a
blockage in the flow or return any raditors after that point won't
work:
Flow >---+-----+-----+--X--+-----+
| | | | |
R1 R2 R3 R4 R5
| | | | |
Return <---+-----+--Y--+-----+-----+
A blockage at X would stop R4 and R5 heating up.
A blockage at Y would stop R3, R4 and R5 heating up.
A blockage at X and Y would stop R3, R4 and R5 heating up. Unblocking
Y would only bring R3 back as X is still stopping circulation through
R4 and R5.
--
Cheers
Dave.
JoeJoe
"Dave Liquorice" <allsortsn...@howhill.com> wrote in message
news:nyyfbegfubjuvyypb...@srv1.howhill.co.uk...
Thanks Dave - that makes sense!
I was, for some reason, under the impressoion that air locks only occur
inside a radiator and not in the pipework.
BartC
"JoeJoe" <n...@mail.com> wrote in message
news:lO6dnaQgtcSOPp3Q...@brightview.co.uk...
> As the pipes leading to them could potentially freeze overnight this is
> why that possibility seemed most likely to my ignorant mind...
I've only had frozen pipes when I've been away with the heating off, and the
temperature well below freezing for days on end. Or when the pipe runs
outside.
For a CH pipe (which had been hot a few hours earlier) to freeze overnight
and stay frozen (with heat from the rest of the house permeating through)
sounds unlikely. Do the pipes actually run through an area where the
temperature is currently below freezing?
--
Bartc
JoeJoe
"BartC" <b...@freeuk.com> wrote in message
news:idqdkt$tj8$1...@news.eternal-september.org...
The space under the floor boards exactly where the pipes run is completely
open to the outside (well, to the space under the eaves that is the same
temperature as the outside). It is a long story, but during the first winter
after the builders who did our extension had left a couple of years ago I
realised that they forgot to insulate the wall under the eaves (floor to
about a metre high). I have spent many hours crawling there to put the
insulation in place and was (wrongly) under the impression that the gap
under the wall (space under the floor boards, so immediately under the wall)
was left open intentionally to allow air flow (silly, I know). I should
have fixed it, but never did...
I put a very simply diagram of the situation here:
http://tinypic.com/r/dq43gw/7
The temperature outside over night was -16c, so I suspect that freezing is
still a possibility?
As to having an air lock:
It is very cold outside, and is likely to stay that way for a while. Apart
from the three cold radiators both heating and hot water seem to be working
fine, and we can comfortably leave the situation as it is for a while if
needed.
I would rather not do anything that may result in loss of hot water supply
and/or heating for the rest of the house.
My questions therefore are:
- what is the potential downsides of trying to remove the airlock by closing
all the working radiators and after a while trying to bleed all the
radiators (and possibly having to re-balance the system)? I really don't
want to be left without heating/hot water in this weather...
- What is the downside of doing nothing for a while? Can it damage anything
(boiler,pump,pipework, etc)?
Many thanks in advance for all the very useful advice so far.
Weatherlawyer
> "Ronald Raygun" <no.s...@localhost.localdomain> wrote in message
>
> news:UmJLo.41296$lZ5....@newsfe16.ams2...
>
>
>
>
>
> > JoeJoe wrote:
>
> >> "Dave Liquorice" <allsortsnotthis...@howhill.com> wrote in message
It sounds like you don't have enough water pressure. Though you say
you have. I take it there is a scale in the control panel somewhere?
What is it reading?
JoeJoe
"Weatherlawyer" <weathe...@gmail.com> wrote in message
news:cc1c2ad7-06dc-4b1d...@a28g2000prb.googlegroups.com...
What is it reading?
There is a digital display that says 1.1 bar -
BartC
Hmm, it's not the clearest of diagrams... Is it some sort of isometric
drawing?
The space between ceiling and floorboards above, while it might be vented to
the outside, should be nowhere near the outside temperature, providing the
house is heated. (And if it really can get that cold, then the pipes might
need insulation, even if just to preserve the heat.)
But still, -16°C is about the same as the inside of my freezer... And even
if it's 10° warmer in that space, -6° over a matter of hours might possibly
have an effect.
If that pipe has really frozen, then it should fix itself when the
temperature gets above freezing, unless the pipe has burst, then you will
know because the pressure will drop (and you might notice some water
around).
> As to having an air lock:
>
> It is very cold outside, and is likely to stay that way for a while. Apart
> from the three cold radiators both heating and hot water seem to be
> working fine, and we can comfortably leave the situation as it is for a
> while if needed.
>
> I would rather not do anything that may result in loss of hot water supply
> and/or heating for the rest of the house.
>
> My questions therefore are:
> - what is the potential downsides of trying to remove the airlock by
> closing all the working radiators and after a while trying to bleed all
> the radiators (and possibly having to re-balance the system)?
I did that once with one stubborn radiator, closing off all the others, so
the water *had* to flow through that one. Although that wasn't a pressurised
system. So perhaps leave one other radiator open (I think some combis have a
bypass pipe inside, but I wouldn't rely on that).
With your particular problem, I might try and trace the pipes (feeling along
them to see where they stop being hot), but that requires access.
(If I was feeling adventurous, I might even try loosening the pipe to the
first cold radiator (after closing the valves on the cold ones) to see what
sort of pressure there was. Or perhaps just try bleeding them (letting some
water out) should result in a small loss of system pressure, if at least one
pipe has some flow. With some ingenuity (closing one side of rads then the
other), you might be able to test both outward and return pipes.)
> I really don't want to be left without heating/hot water in this
> weather...
> - What is the downside of doing nothing for a while? Can it damage
> anything (boiler,pump,pipework, etc)?
If the other rads are working, then I don't see a problem. (But I'm not an
expert, I just have bad luck with heating systems..)
--
Bartc