Radiators not heating up

[Wisconsonian]

If the pump is quiet, then it shouldn't have air and should produce it's full pressure, which should be enough to move a little air through the system to the bleeders. The pump should hum or whirr when running and continue to make noise for second after it's shut off if it's turning, or you can tell by the system if it's circulating to radiators far away horizontally and not just ones higher vertically.

As long as there's a pressure relief valve, and you don't defeat it, it should be safe to add pressure. The pressure makes the bubbles smaller, and reduces cavitation in the pump, it doesn't add to the pump circulating pressure, so if the pump is air free already, it's less needed to increase the pressure.

Those are general ideas to deal with air, which is overwhelmingly the problem in cases like this. There's no way for anybody not there to know if a pipe or valve is blocked, that would be unusual if the system is closed and has not had water added consistently.

 

[Jsmith2211]

If the pump is quiet, then it shouldn't have air and should produce it's full pressure, which should be enough to move a little air through the system to the bleeders. The pump should hum or whirr when running and continue to make noise for second after it's shut off if it's turning, or you can tell by the system if it's circulating to radiators far away horizontally and not just ones higher vertically.

As long as there's a pressure relief valve, and you don't defeat it, it should be safe to add pressure. The pressure makes the bubbles smaller, and reduces cavitation in the pump, it doesn't add to the pump circulating pressure, so if the pump is air free already, it's less needed to increase the pressure.

Those are general ideas to deal with air, which is overwhelmingly the problem in cases like this. There's no way for anybody not there to know if a pipe or valve is blocked, that would be unusual if the system is closed and has not had water added consistently.

I believe it is air. One more radiator has started to work but there are still several not working. I’ll turn the pressure up a bit further tomorrow and see if that helps, it’s on 2 bar at the moment

 

[Adeptandy]

I believe it is air. One more radiator has started to work but there are still several not working. I’ll turn the pressure up a bit further tomorrow and see if that helps, it’s on 2 bar at the moment

That should be high enough tbh

 

[Still Farming]

I believe it is air. One more radiator has started to work but there are still several not working. I’ll turn the pressure up a bit further tomorrow and see if that helps, it’s on 2 bar at the moment

Watch things don't start leaking also?

 

[Bury the Trash]

yeah or go boooom

 

[Paddington]

Same problem as OP here, one radiator not getting warm at all. Turned all the others off and after an hour the feed pipe is just warm, boiler pressure 3bar. We also have a constant drip of hot water out of the boiler overflow pipe, don't know if these are 2 different problems ?

 

[Jsmith2211]

Well we are back to how it used to be at least... all of them hot except for 4. 3 of these i'm not overly worried about, but one of them is a right pain as its in the coldest room of the house. All 4 are stone cold, no air in them or anything like that, but they seem to have preassure (which increased when i turned it up by the boiler) at the bleed valve. So I assume it must be an airlock rather than a blocked pipe, just seems odd that it has preassure but still does not flow! Mind you, I dont remember any of these 4 working in the 5 or 6 years we have lived here - doesnt mean it hasnt been annoying me for all of those years. And yes I've tried switching them all off bar one of the cold ones, did nothing except make the house colder...

Watch things don't start leaking also?

it leaks anyway, have to top it up every few days. No idea where it is leaking from though. no obvious wet spots

 

[Netherfield]

Work of the devil is central heating, we've two radiators the never hardly worked, blamed on the fact these two are fed by 10mm pipes was opposed to the rest in 15mm.

New boiler and pumps 18 months ago, these two radiators started working well, now got a pump for upstairs one downstairs and one for the hot water. Last month said two stopped altogether, I went and switched all other rads off, these two came back warm and have worked ever since.

Three times in the 18 month period the pressure drops to zero suddenly, open the loop fill it to 2 bar and all's well until it does it again, it's not like it goes down slowly just goes all at once.

 

[Still Farming]

Well we are back to how it used to be at least... all of them hot except for 4. 3 of these i'm not overly worried about, but one of them is a right pain as its in the coldest room of the house. All 4 are stone cold, no air in them or anything like that, but they seem to have preassure (which increased when i turned it up by the boiler) at the bleed valve. So I assume it must be an airlock rather than a blocked pipe, just seems odd that it has preassure but still does not flow! Mind you, I dont remember any of these 4 working in the 5 or 6 years we have lived here - doesnt mean it hasnt been annoying me for all of those years. And yes I've tried switching them all off bar one of the cold ones, did nothing except make the house colder...

it leaks anyway, have to top it up every few days. No idea where it is leaking from though. no obvious wet spots

If leaking somewhere also sucking air possibly too?

 

[Adeptandy]

Same problem as OP here, one radiator not getting warm at all. Turned all the others off and after an hour the feed pipe is just warm, boiler pressure 3bar. We also have a constant drip of hot water out of the boiler overflow pipe, don't know if these are 2 different problems ?

Drip will be because your right on the limit of the Pressure Relief Valve.

 

[Adeptandy]

If leaking somewhere also sucking air possibly too?

Presurrised systems will only leak outwards and not draw air in.

 

[Adeptandy]

Work of the devil is central heating, we've two radiators the never hardly worked, blamed on the fact these two are fed by 10mm pipes was opposed to the rest in 15mm.

New boiler and pumps 18 months ago, these two radiators started working well, now got a pump for upstairs one downstairs and one for the hot water. Last month said two stopped altogether, I went and switched all other rads off, these two came back warm and have worked ever since.

Three times in the 18 month period the pressure drops to zero suddenly, open the loop fill it to 2 bar and all's well until it does it again, it's not like it goes down slowly just goes all at once.

Good chance the Pressure Vessel is knackered ( test by dropping the system pressure to 0 then put a pressure gauge on the expansion vessel, should be 0.8 bar, if water come out of the schraeder valve, its shot, if not, pump back up to 0.8 bar ) if so, then system water is most probably going out of the pipe to outside from the pressure relief valve, put a balloon on the pipe to prove this is the way it's disappearing.

 

[Bury the Trash]

Well we are back to how it used to be at least... all of them hot except for 4. 3 of these i'm not overly worried about, but one of them is a right pain as its in the coldest room of the house. All 4 are stone cold, no air in them or anything like that, but they seem to have preassure (which increased when i turned it up by the boiler) at the bleed valve. So I assume it must be an airlock rather than a blocked pipe, just seems odd that it has preassure but still does not flow! Mind you, I dont remember any of these 4 working in the 5 or 6 years we have lived here - doesnt mean it hasnt been annoying me for all of those years. And yes I've tried switching them all off bar one of the cold ones, did nothing except make the house colder...

it leaks anyway, have to top it up every few days. No idea where it is leaking from though. no obvious wet spots

leaks can let air in as well as water if its only little ones you can get an affective additive. tochuck in ,wull mix ok with normal corrosian additive and does work ime. but then again thats on an unoressurised system

if someoines akready saud that sorry but i cant read ,lost my specs

 

[Paddington]

Any updates @Jsmith2211 ?

 

[Macsky]

Well we are back to how it used to be at least... all of them hot except for 4. 3 of these i'm not overly worried about, but one of them is a right pain as its in the coldest room of the house. All 4 are stone cold, no air in them or anything like that, but they seem to have preassure (which increased when i turned it up by the boiler) at the bleed valve. So I assume it must be an airlock rather than a blocked pipe, just seems odd that it has preassure but still does not flow! Mind you, I dont remember any of these 4 working in the 5 or 6 years we have lived here - doesnt mean it hasnt been annoying me for all of those years. And yes I've tried switching them all off bar one of the cold ones, did nothing except make the house colder...

it leaks anyway, have to top it up every few days. No idea where it is leaking from though. no obvious wet spots

If it is a sealed system with air in it somewhere, maybe as the system heats up the trapped air expands increasing the pressure in the pipe worm to the point where some water is released by an integrated pressure relief valve out a spout through the wall or something? So you may well be losing water, but have no obvious leaks.

 

[ladycrofter]

Doesn't sound like it's your problem but possibly cavitation in the pump. We had an older pump and the blades were so worn that the cavitation introduced air in the line, a constant problem.

In another old house had two systems joined together and there were two PITA bleed points in the loft. Ended up putting a second pump on the system as the contortions in the pipework hindered flow. If I were you I would ask around and get an engineer out who has really sharp at this. Good luck, been there!

 

[serf]

But have you tried turning them all off….and turning just one on at once?

(as others have suggested above)

Tried this couple days ago after seeing idea on here , fek knows why I dint think of it

Unbelievable difference

Over 14 radiators from pallet wood stove the DHW feels nearly half as hot again so it must have done something to that system too and the main four / five rads in most used rooms are well hot again !

 

[Lincsman]

If one rad is stubborn take it off and go outside and flush it, they can get totally full of sludge, sometimes only hot at TOP.

Also the pressure vessel has to be big enough for the system the air bag part of it has to compress with heating up expansion so it does not expel water out the relief valve, if its always needing more water adding to start from cold, its faulty or not big enough.

 

[Jsmith2211]

Nope. Those 4 radiators still dont work even after continued bleeding.. My only thought is it could maybe be a blockage in a pipe, perhaps the return as the radiators seem to have preassure at the bleeds. Curious problem.

 

[BrianV]

Nope. Those 4 radiators still dont work even after continued bleeding.. My only thought is it could maybe be a blockage in a pipe, perhaps the return as the radiators seem to have preassure at the bleeds. Curious problem.

If the radiators each have their own thermostat it is possible the valve is stuck down, you can remove the thermostat cover by either unscrewing or by undoing the Allen key & make sure the needle has come up to let the water through.