One radiator cold - how do I tell if pipes are frozen or problem is something else

[glenfargon]

1 radiator did not heat up when timer kicked in. Input/output for all other rads feed up from under the floor, but this rad is in a converted garage which has no floor space. As such, a portion of its pipes run 'inside' an external wall. I have checked these pipes (at least the part that can be reached underfloor) and input/output are both cold. Could this be a danfoss problem (hopefully) or would you feel heat in pipe below danfoss in this case. My worry is that the pipe(s) are frozen as we have hit -10 degrees here during last few nights. If it is frozen, how can I thaw it safely, bearing in mind that 2-3 metres of pipe is hidden in wall (can't bear to contemplate a burst in there!!)? Have tried bleeding the rad and get cold water, but no air. Any advice greatly appreciated.

 

[Blake]

Re: One radiator cold - how do I tell if pipes are frozen or problem is something els

Have you tried to bleed the radiator and if so did you get any water out?

 

[djboyd]

Re: One radiator cold - how do I tell if pipes are frozen or problem is something els

Hi

What do you mean - Danfoss problem? If you mean the TRV, then wind it fully open to reduce the possibility of a stuck TRV. If there was a blockage here, then unlikely to be any flow at all, which means pipe would stay cold, because as you describe it is some way from nearest warm pipe run - no heat transfer up pipe. IF the room is very cold, or the pipe run is outside the thermal insulation, then it may well be frozen. It is not so likely that the pipes burst - hopefully (as I do) whoever laid the pipes did so without compression joints and the minimum of other joints behind the wall. Best bet is to allow the pipes to thaw out by using another heat source for that room. It may be an idea if you have a vented system with a feed and expansion tank to turn off the supply or tie up the ballcock so that only the minimum amount of water would escape, if the worst happens.

 

[glenfargon]

Re: One radiator cold - how do I tell if pipes are frozen or problem is something els

Yeah - tried bleeding radiator - just got cold water. Also tried tapping the thermostat on radiator as I occasionally get probs with them jamming (although this one has not stuck before)

 

[Billy Bob Bob]

Re: One radiator cold - how do I tell if pipes are frozen or problem is something els

its highly unlikely they are frozen if the rest of the systems working they would quickly de frost with boiling water hitting them,you either have a stuck trv or air lock as a quick test turn every other rad in the house off with the heating on full see if this helps

 

[glenfargon]

Re: One radiator cold - how do I tell if pipes are frozen or problem is something els

Thanks djboyd - yeah I meant the TRV. I have tried opening it fully, closing, tapping etc. This one hasn't caused me any issues in past. About 2-3 metres of the pipes to this rad are unaccessible as this room (former garage) juts out from rest of house. The room itself is not freezing, but the radiator is against the part of the room which is an outside wall and its absolutely brassers out there just now..!! I did try a fan heater and hairdryer pointed at that wall, but it didn't help so may try it in the floor void, blowing on the parts of the pipes I can access before they disappear into the wall space. Is it worth bleeding some of the water out of radiator to make way for any expansion in pipes (leaving TVR in open position of course) or could this just create more issues with air in pipes - ie if indeed the input or output pipe is frozen? It is a combi boiler, so no header tank.

 

[Blackcatgas]

Re: One radiator cold - how do I tell if pipes are frozen or problem is something els

turn off the left hand side valve, then bleed if water comes out then that side isnt blocked, then turn off the right hand side and bleed if water comes out then that pipe isnt frozen, iff all ok take off the trv head and try the pin by gently pushing on it, dont get some pliers anf try and pull it up as it could end in tears.

 

[glenfargon]

Re: One radiator cold - how do I tell if pipes are frozen or problem is something els

Hi Gas Man, tried turning off other rads (except heat leak rad in hall) and turned boiler up, but rad stayed cold. I can see where the pipes from cold rad meet larger, main pipes under floor. Main pipes are hot, but only first few inches of the cold rad's pipes are warm. It is about 6-7 metres from main pipes to this rad and I can't access the last 2-3 metres. The main reason I am concerned about frozen pipes is that I (stupidly) left heating on timer, so it was off overnight when temp had dropped to about -10 degrees.

 

[dontknowitall]

Re: One radiator cold - how do I tell if pipes are frozen or problem is something els

I'd try Blackcatgas's method and if it doesn't work then put some electric heating in there.

 

[Billy Bob Bob]

Re: One radiator cold - how do I tell if pipes are frozen or problem is something els

Bcg methods a good suggestion

 

[glenfargon]

Re: One radiator cold - how do I tell if pipes are frozen or problem is something els

Thanks Blackcatgas - I'll give that a go tomorrow - don't fancy any mishaps at this time of night... If I can eliminate the possibility of frozen pipes I'll be happy. I can cope with a cold room until I fix TVR, but burst pipes, ruined laminate floor etc etc is not my idea of a good Xmas!! Cheers