cold rad

[PaulRB]

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

 

[fuzzy]

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?

 

[PaulRB]

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.

 

[067256]

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.

 

[fuzzy]

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

 

[PaulRB]

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

 

[Phil]

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!

 

[fuzzy]

have you drawn the water through each pipe yet?

 

[PaulRB]

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

 

[fuzzy]

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

 

[PaulRB]

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.

 

[fuzzy]

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.

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

 

[PaulRB]

Yeah, I will.
Thanks

 

[fuzzy]

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

 

[PaulRB]

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.

 

[fuzzy]

fingers crossed, keep us posted

 

[Halesowen1]

Balance the system.

 

[PaulRB]

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

 

[PlumbBobBob]

fingers crossed all goes well

 

[PaulRB]

I'm crossing everything mate!!!

 

[Halesowen1]

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.

 

[067256]

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.

 

[067256]

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????

 

[fuzzy]

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.

is the pump on?

 

[fuzzy]

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????

heat not getting round, is pump working? rad vales open? valves on pump open? history of sludge?

 

[067256]

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.

 

[fuzzy]

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

 

[PlumbingBud]

Do you have microbore pipe anywhere? 10mm or less.(Sorry, but I couldnt be bothered reading 10 pages!)

 

[067256]

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.

 

[PaulRB]

Rad still working!!
Fingers still crossed!!
Back again tomorrow.

 

[067256]

10mm microbore drops down to the rad in question. Microbore behind 'dot and dab' plasterboard.
Could i force mains water up the return pipe via the bleed valve and 'hope' the blockage shifts?

 

[PaulRB]

067256
At the start of my troubles I took off the rad and attached a hose to the flow valve, connected to the outside tap ( but any mains tap will do ). Then I opened the valve and opened the outside tap. The mains pressure should force water into the pipework and hopefully shift the blockage.
I then repeated the process for the return valve.
BUT only run the mains for 5-10 seconds or it will back-fill the F + E tank ( you will know this because water will start coming out of the overflow!!! )
Also, it can be fiddly trying to attach a hose to the valves but worth persevering.
It might clear the blockage.
Good luck.

 

[fuzzy]

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.

sounds like it mate, maybe force mains pressure back up

 

[PlumbingBud]

Microbore is well known for being soft and getting squashed easily. It is also prone to blockage being of narrow bore.
I wonder if there is a squashed bit behind the dot and dab?

Its like a garden hose being kinked. Water may well flow through, but will be unable to reach top flow rate.

 

[fuzzy]

if its worked before and no works been done its unliekly to have become kinked