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could be scaled up. boilwer only fires for few minutes therefore heat is lost before radiator. it seems that as the return is hot and the flow is not, the valves could be the wrong way round... and causing restriction. either that or the pressure on the return is greater than the flow so it cant push round.
 
Ok guys.
I can't believe so many people are willing to think this thru and offer advice!!
Just to be clear; all rads have new valves, some are TRVs and others wheelhead.
I have fitted a brand new pump.
I have drained down twice in 48 hours and the water coming out of the system is lovely and clean.
Before fitting the new rad I fixed a hose from the o/side tap ( off the mains ) to both valves + blasted thru to try and clear air or blockages.
The pipework to + from the rad is in the 1st floor void between ceiling + floor.
It is a long horizontal run I'm sure + it could be an air lock. It doesn't "feel" like air though, because it doesn't splutter when I drain some water from the return pipe + air doesn't collect in the rad, which I would expect if it was being shifted by the hot coming thru.
It could be a blockage but I'm puzzled as to how the hot water can get thru + continue to work for 2/3 days.
I have taken a board up to reveal the pipework + turned the heating on, in the hope of feeling hot water in the flow pipe and establishing where, exactly, there may be an air lock or blockage.
However, I can only access about 4 feet of pipe, then it goes over a wall. The pipe is cold for as far as I can feel.
I'm convinced that the problem is
a) a long pipe run including having to go over the wall,
b) a tee joint that the hot water is by-passing ( but which I can't get access to without taking up carpets + floorboards + which I'm trying to avoid.
c) a lack of circulation caused by a + b

Now my plan is to drain the system and fit an automatic air vent in the horizontal pipework, hopefully solving the problem of air in the pipe.
At the same time, I was going to fit 2 full-bore iso valves in the vertical section of both flow + return pipes so I can later fit a towel rad with a heating element in, without having to drain the whole system and losing all the inhibitor.
I also thought it might be a cheap alternative to fit 2 tees in the vertical return pipe, connect a drill-driven pump between them and use it every 2/3 days to assist the circulation in the system.
I know that seems extreme but it might be enough to get us thru winter and the rad may work more continuously when the weather turns cold and we have the heating on longer.

Thanks again everyone and the more I discuss this, the more common this fault seems to be. It's nice to know we're not alone!
 
is there a rad on the other side of the wall you could tee into doing away with the up and over pipe
 
im confused by what you mean 'return pipe'. i thought you said you dragged water through the flow pipe, which is it?

if its an air lock you need to drag water through the flow and then the return, they are both seperate pipes. this is how you get rid of an air lock, no need to auto air vent mate

it is either an air lock - if so fix as i advise
pump underpower - new pump
bi passing - new tee as i suggest or re pipe closer boiler for reverse return to 'even' pressures
 
fuzzy said:
im confused by what you mean 'return pipe'. i thought you said you dragged water through the flow pipe, which is it?

if its an air lock you need to drag water through the flow and then the return, they are both seperate pipes. this is how you get rid of an air lock, no need to auto air vent mate

it is either an air lock - if so fix as i advise
pump underpower - new pump
bi passing - new tee as i suggest or re pipe closer boiler for reverse return to 'even' pressures
Click to expand...

ok rad has 2 pipes - 1 bringing hot water, other returning water to boiler. I think of them as the flow and return pipes.
There is a drain valve on the return pipe which I can use to drain about 2/3 pints.
This is replaced by hot water thru the flow pipe and, once I have some circulation, the rad will work for 2/3 days, until the water in the system cools. Then I have to drain again. ( obviously I can't keep draining so I'm looking into why the rad works for 2/3 days then stops )
I think you're right about the hot water by-passing the flow pipe but I can't get at the joint to put in a swept tee.
Not the pump - it's new + working fine.
Thanks
 
reduce the flow toradiator which comes off the tee to allow flow through this rad
 
YOU NEED TO GET A PLUMBER/HEATING ENGINEER OUT NOW AS THIS IS WORTHLESS.
Its down to something you have done whether you believe that or not. This cannot just happen for nothing, Fitting air vent wont do nothing, fitting tees and a drill pump is pointless.
It needs draining, putting drain off on this problem rad pipework, fit higher powered pump, fill back up, then turn every other rad off completely, if no heat still leave running and start draining from rad with hose, this will draw water around.
 
I'm beginning to wonder if the flow and return to/from the radiator have both been plumbed into the flow (or return) on the heating circuit.
 
Plus this tee wont do anything, if no water will get round with others all off it aint gonna do anything.
If it all worked OK before then the system needs getting back to how it was.
You do not know if pump is working OK, just because its new means nowt.
Get a more powerfull pump. If you cannot draw heat to this rad with others off its circulation problem, be that air (no), This tee you have been told (no as it was fine before), Maybe faulty rad or pump causing obstruction of flow or not enough power to feed rad.
 
When you have eventually been getting heat from this rad after removing and putting a link between, have you then gone to all other rads and just opened them up??
As I feel it is pump and when you open them back up again it is just easier for the water to flow around these other rads that are piped closer. balance the system correctly after getting heat to it.
 
PaulRB said:
ok rad has 2 pipes - 1 bringing hot water, other returning water to boiler. I think of them as the flow and return pipes.
There is a drain valve on the return pipe which I can use to drain about 2/3 pints.
This is replaced by hot water thru the flow pipe and, once I have some circulation, the rad will work for 2/3 days, until the water in the system cools. Then I have to drain again. ( obviously I can't keep draining so I'm looking into why the rad works for 2/3 days then stops )
I think you're right about the hot water by-passing the flow pipe but I can't get at the joint to put in a swept tee.
Not the pump - it's new + working fine.
Thanks
Click to expand...

you could be drawing air from the flow yes, and this may heat up the rad yes, but if theres an aitr lock on the return it wont work or will partially work. shut the flow valve and draw the water through, that will drag water from the return pipe

is the pump the same size and power? what setting is it on?
 
Reply to Halesowen 1

Ok Ok I hear you!
Trouble is, I phoned around to get a plumber in.
Regular guy said he was just too busy, 3 others didn't even get back to me.
I've spoken to about a dozen plumbers down at the local plumbers merchants and they've all said the same thing ie; air lock, sludge, long pipe run, by-passing tee etc.
When I tell them what I've done they all scratch their heads and say they would've done the same.
If I could find 1 plumber who said " I know what that is. I've come across it before. Do this." I'd jump at it.
The only thing I want to avoid is taking up the carpet/floorboards in the other room to access the pipe joint.
However, that may be the only way.

Can you tell me why I can get hot water into the rad AND it will carry on working fine for 2/3 days before stopping.
If the new pump can circulate the water ok for 2/3 days why do you think its the pump?
Appreciate your help, thanks.
 
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well its certainly something causing it, im still not convinced you have all the air out of it, until you isolate the return and draw it from the flow pipe then do the same with the flow you will never be sure all the air is out

air can be trapped at the top of pipes but not the full bore, therefore restricting flow but not stopping it. if thi sis a long run when it fires from cold it may bi pass. you have to keep trying these things or you may never find out

once you have eliminated this check the pump power, the speed you have it on.

then if all this is fine and you say valves are fine and pipework fine you only have option of putting swept tee in and/or re pipe if you want a proper solution
 
Thanks.
When I drain down the system to fit an air vent and iso valves I suppose I could also fit a drain valve in the flow pipe and try shutting off the return valve + drawing water thru the flow pipe.
I've tried running the pump on all 3 settings but no joy.
I really think it needs a swept tee but I didn't want the hassle of gaining access.
Might have to swallow it and take up the carpet.

Thanks again
 
Why are you fitting iso valves and air vent??
All the system worked fine before with nonw of this. This will not solve your problem.
Have you balanced the system correctly once you have had heat to the rad??
Did you buy the identical pump??
Why would it need a swept tee?? it has never had one before.
Think logically, none of these things on system when it was working fine so why would you put one in now??
Where abouts are you?
 
are the pipes level, bit of a long shot but if they have air in a bit of pipe which isnt straight, the air will stay there, with using for a few days steam (or something similar as wont be steam as has to be 100 degrees to get steam) could buid up and cause it to completely block, when draining slightly it is removing a little bit of air and then building up over a few days?

told you it was a long shot, but to find out if this is even remotely possible, check the pipes in loft to see if they are level. if not, try to lower them.
 
Last edited by a moderator:
have you altered the height of the peipes when you swapped the rad? that may have put a air lock situation in the pipes?

dont worry about aav's just draw the water from each pipe seperately, that will clear the air if there is any

if its dragging air in it will be poor vent inlet position or a leak on the negative side of the system
 
Ok.
Fitting air vent in pipe in case it is an air lock.
To do this, I will have to drain the system so I might as well fit iso valves in 2 pipes feeding the rad so that, at a later date, if I can't solve the problem, I can fit a towel rad with heating element without having to drain the whole system.

Yes I bought the identical pump.
I'm in Dorset and around here plumbers are like gold-dust. It does P me off though, when they don't even return a call.
Haven't altered height of pipes. Already thought of that and I took up floorboard in wardrobe to access pipework in the hope that I could lower the pipework and reduce chance of air lock.
Not possible because pipes travel over 2 walls.
I will try dragging hot water into rad with all others turned off and leave the system like that for 3/4 days to seee if rad continues to work.
If it does, that would point to balancing of system.
If it stops working after 3/4 days I don't know what could be the cause.
I suppose I find it so frustrating because it does work properly for those 2/3 days.
Thanks
 
If all else fails pressurise it, with a Expansion vessel , filling loop and Prv valve you can buy them as a kit. Not too expensive that would be my next move,bit of a strange one, .Good to hear all the idea's though.
 
PaulRB said:
Ok.
Fitting air vent in pipe in case it is an air lock.
To do this, I will have to drain the system so I might as well fit iso valves in 2 pipes feeding the rad so that, at a later date, if I can't solve the problem, I can fit a towel rad with heating element without having to drain the whole system.

Yes I bought the identical pump.
I'm in Dorset and around here plumbers are like gold-dust. It does P me off though, when they don't even return a call.
Haven't altered height of pipes. Already thought of that and I took up floorboard in wardrobe to access pipework in the hope that I could lower the pipework and reduce chance of air lock.
Not possible because pipes travel over 2 walls.
I will try dragging hot water into rad with all others turned off and leave the system like that for 3/4 days to seee if rad continues to work.
If it does, that would point to balancing of system.
If it stops working after 3/4 days I don't know what could be the cause.
I suppose I find it so frustrating because it does work properly for those 2/3 days.
Thanks
Click to expand...

may work for 3/4 days if a partial air lock, thats why i asked if the pipes had moved, ive had it before, long shot i know but we are running out of options. dont put aav iin, its a waste of time, drawing water out of each pipe will solve air problem if it is. shut of both valevs and take off rad, connect hose to each outlet and drag through
 
Thanks Fuzzy.
Haven't moved any pipes.
I'll have to fit a drain valve on the flow pipe in order to drag water thru.
Already have one on the return pipe.
Are you saying that, once I draw water thru both pipes, any air should be gone and the system should work as normal?
What worries me is that after working for 3/4 days air may be getting back into the system, or do you think I'm not actually purging the system of air and its the same air gradually returning to the pipe, causing a blockage?
Wouldn't an air vent cover that possibility?
When you talk about a poor vent inlet position, do you mean the pipe that hooks over the expansion tank in the roof?
If so, couldn't I extend that pipe to end underwater, so it couldn't suck in any air?
Thanks
 
i cannot ensure you that it will fix the problem but it will eliminate the problem being air.

fitting a aav could cause issues, if air is entering the system theres a problem, if you try to fix this by aav you will keep bringing in fresh water which is untreated and has fresh oxygen, therefore it will cause corrosion, not a good idea. aavs are only there to help initial filling

dont extend the pipe, it shouldnt suck in air, were is the vent (hooked pipe) inlet, cold feed to sysem and pump in conjunction with each other?
 
There is a vent pipe hooked over the expansion tank in the attic.
Directly below the expansion tank is the airing cupboard with a copper hot water tank, pump and 3-way valve.
The boiler is in the garage.
I think I need to shut the wheelhead valve on the flow side and then drain some water from the system, clearing it of air in the return pipe.
Then shut the lockshield valve on the return side and drain some water from the system, clearing it of air in the flow pipe.
Then I shouldn't have any air in those pipes.
You may be right that air is trapped in the return pipe which is stopping the circulation, and I thought it was in the flow pipe.
Thanks.
 
Hey PaulRB....let me know how it goes. I am trailing you trying to work this out.
I eventually got my rad to warm up by turning all other rads off but it took a loonnnngggg time and it didnt even get hot....just warm to the touch!!
Put the rads back on and kitchen rad still does not work.
 
whats the output of the new rad compared to the old rad?

im guessing that restriction in a towel rad is greater than normal rad which may restrict flow more than previous and contribute to it not/struggling to circulate
 
Thing is, I've shut off all the other rads and I've shut off just the towel rad and it still hasn't helped.
The new rad is a direct replacement for the old one.
I know from talking to people that this is a very common problem. A rad stops working for no apparent reason, usually when you switch on the heating for the first tine after summer.
Thanks
 
Can't really suggest anything that hasn't already been said other than fitting auto air vent is a bad idea. Yes if it is air it will work but when you move house it will be still there under the floor unseen and may cause a plumber agro!

Like the diy'er who tiled his bathroom floor over his c/h pump and a year later it needed replacing.

Nothing worse than working on a system thats been 'messed with'.

Get those carpets up Paul!
 
Sorry, haven't had time yet. Still gotta work!
I hope to have a go on Thursday.
Realise I don't need to put a draincock on the flow pipe, I'll just turn off the valve at the rad. That way I know when I drain some water from the return pipe it must be replaced with water from the return pipe, and hopefully will flush out any air in the pipe.
I'll let you know how I get on.
Thanks
 
some drain off valve combinations require the return valve to be open, it may be difficult for you to ensure flow from the flow pipe if this were to be the case
 
Ok, but I plan to shut off the flow valve while I drain water from the system.
With that valve closed I know the water coming out must be from the return pipe ( can't come from the rad because there will be nothing to take its place ).
I hope that will force any air out of the return pipe ahead of the water.
If it works I will then re-open the flow valve knowing there must be no air in the pipes.
Then I'll see if the circulation returns to the rad.
I'm really hoping that, when I open the draincock, I will hear spluttering and know air is coming out!!
If I can clear all air out of these 2 pipes there should be no reason for the water not to circulate.
If it still doesn't work at least I know it can't be an air lock.
Gonna try this tomorrow.
Thanks again.
 
PaulRB said:
Ok, but I plan to shut off the flow valve while I drain water from the system.
With that valve closed I know the water coming out must be from the return pipe ( can't come from the rad because there will be nothing to take its place ).
I hope that will force any air out of the return pipe ahead of the water.
If it works I will then re-open the flow valve knowing there must be no air in the pipes.
Then I'll see if the circulation returns to the rad.
I'm really hoping that, when I open the draincock, I will hear spluttering and know air is coming out!!
If I can clear all air out of these 2 pipes there should be no reason for the water not to circulate.
If it still doesn't work at least I know it can't be an air lock.
Gonna try this tomorrow.
Thanks again.
Click to expand...

mmmm, id be more confident if you did the same with the flow, your only pulling water from return, you really should do the same with the flow to ensure 100% you have no air
 
let us know how it goes

remember you must do the same with both pipes to ensure there is no air in them. doing it with one valeve closed only ensure that pipe has not air in it

if you only do it with the return as you suggest it only ensure the air is out of that one, doesnt prove anything with the flow

after tyhis it may not be air but at least you can eliminate it once and for all
 
Ok Guys, ( especially Fuzzy ), this is what I've done today, Saturday.
Tied up the ball-cock in the expansion tank so it doesn't fill with new untreated water.
Turned off both valves on problem rad. So any water I drain must come from return(-) pipe and not from rad or flow(+) pipe.
Opened draincock and drew off 1/2 bucket of water. Plenty of spluttering and flow stopped for 1/4 to 1/2 a second before continuing, so obviously a lot of air in return(-) pipe.Took bucket up into attic and refilled expansion tank.( level had not dropped below outlet pipe so no air being drawn into system )
Repeated process and this time water flowed as normal.( refilled expansion tank )
Opened both rad valves and drew off another 1/2 bucket in case there was air in the flow (+) pipe but water flowed nicely. ( refilled expansion tank )
Went round and turned off all other rads and put heating on.
5 mins later we had hot water coming thru pipes and rad got very hot. Turned all other rads back on and ran system for 1 hour. Everything ok.
However, I've had the rad working before so I won't know if this has solved the problem yet. I've turned the heating off and I'm gonna let it cool right down for 24 hours and then fire it up again.
Fingers crossed!!
At least I know there was air in the pipework, now I have to wait and see whether air is getting into the system, which is a different problem. I hope the air was trapped in the pipe when I refilled after replacing the pump and, now I've purged the system, it works as normal.
I'll let you know tomorrow.
Thanks guys.
 
Ok.
So far so good.
Put the heating on this pm and hot water came thru straight away.
Still not 100% sure the problems solved. It'll take a few days of working before I can relax and put it out of my mind.
I still have to balance the system
Meanwhile I will keep you all posted as the week goes on.
If air isn't getting into the system I should be alright.
I know a lot of people have this problem and are following the thread so I think I should point out some of the main points because different systems and installations would require different solutions.
However, with all the help on hand here, I'm sure most problems can be solved.
I have a gravity fed, 2 pipe system with an expansion tank in the attic.
There is a cylinder in the airing cupboard together with a 3-port valve and pump.
The boiler is in the garage.
Downstairs our floors are concrete so all the downstairs rads are fed from above in a "loop" system.
All downstairs rads have draincocks on their pipework so that when you drain the system, you have to go round each rad and drain them individually if you want to completely drain the system.
I understand that the "loop" system is susceptible to air locks when filling up the system and that appears to be whats happened to me.
I've been lucky because I have draincocks on every rad but other people may not so the things I've tried may not work for everyone.
However, the amount of help and support provided by the guys on this forum should enable everybody to solve their problem.
I thank you all for taking the time and trouble to help out and sticking with it when nothing seemed to be working.
My wife thanks you all too!!!
Hopefully I will report that all is working fine in a weeks time.
Cheers
 
What you have is a regular pumped Y plan system, these are very common. Your problem is not so common though, every system is full of air when it gets filled but 9/10 are vented easily. So lets hope for your sake it is not drawing in air or air catching somewhere.
 
Ok Guys,
I have done exactly as described by Paul and still something not quite right.
My kitchen rad has a lockshield with bleed valve on return and wheel type on flow. I have shut off both valves, put bucket under bleed valve opened bleed and no water has come out!! but if i open the flow valve water starts flowing out lovely and the hot water starts coming thru the flow pipe....rad then starts warming up. Filled about half a bucket shut off flow valve and refilled the F+E tank. There were small small splutters of air so did the same thing 2-3 times more by opening the flow valve again.
Now with the flow valve off i open the lockshield fully and open the bleed valve............a trickle of water coming out!!!!
BLOCKAGE?????? As i am writing this the bleed valve is open fully and the water is still trickling out.
 
1 more thing.
Thought i would try the rad with the heating on again.
Shut all other rads off at there lockshields, turned on the heating, boiler fired and lasted for about 60 seconds then went off. Boiler fired again a further 2-3 times then eventually cut out on the boiler overheat thermostat. Could this be due to the blockage there is a build up of heat at the blockage and circulation is affected????
 
067256 said:
Ok Guys,
I have done exactly as described by Paul and still something not quite right.
My kitchen rad has a lockshield with bleed valve on return and wheel type on flow. I have shut off both valves, put bucket under bleed valve opened bleed and no water has come out!! but if i open the flow valve water starts flowing out lovely and the hot water starts coming thru the flow pipe....rad then starts warming up. Filled about half a bucket shut off flow valve and refilled the F+E tank. There were small small splutters of air so did the same thing 2-3 times more by opening the flow valve again.
Now with the flow valve off i open the lockshield fully and open the bleed valve............a trickle of water coming out!!!!
BLOCKAGE?????? As i am writing this the bleed valve is open fully and the water is still trickling out.
Click to expand...

is the pump on?
 
067256 said:
1 more thing.
Thought i would try the rad with the heating on again.
Shut all other rads off at there lockshields, turned on the heating, boiler fired and lasted for about 60 seconds then went off. Boiler fired again a further 2-3 times then eventually cut out on the boiler overheat thermostat. Could this be due to the blockage there is a build up of heat at the blockage and circulation is affected????
Click to expand...

heat not getting round, is pump working? rad vales open? valves on pump open? history of sludge?
 
pump is working,
rad valves open,
no history of sludge as far as i am aware, only been in the house 18 months.
heating on, pump running, open bleed valve on return...just a trickle of water coming out. Rad has a new valve aswell.
 
dont vent when pump is on, make sure its off or could actually suck air in

make sure vales is open, sometimes if new and dpendant on type the washer can be stuck on seating, leaves valves shut, take off rad and slowly open valves to check
 
Do you have microbore pipe anywhere? 10mm or less.(Sorry, but I couldnt be bothered reading 10 pages!)
 
Pump switched off.
Closed both valves on rad and removed the rad in question. Opened flow valve and get a good flow of water.
Open lockshield valve and only a trickle, there is nothing wrong with the valve as i have actually tried it on another rad when i fitted a TRV.
I'm just convinced now that it is a blockage.
 
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