Freezing 3yr old son's bedroom HELP!

[SimonG]

Valves red hot. Radiators cool. Trv stuck. Hit it harder. You will see immediate result, unless not hitting it hard enough. Hit it harder.

 

[smglasgow]

Never worked in my view. Home purchased after previous owner renovated from 2 bed to 4 bed bungalo (extended in every direction you can think of). So dont know if all rads were added to the system when the boiler was installed (2010) according to home report or after final building works complete in 2012. I suspect rads were added, but upstairs they all have teh same PVC pipework (15mm diameter) and are identical rads, so might all have been done at the same time. Just dont know.

35kw vokera compact he Comi boiler, so no cylinder.........(sorry not really sure what you are asking)

not looked at performance when hot water demand is ON, as every test I perform I make sure no one turns on the hot water or goes for bath/shower to max heat into t he rads

No zone valves in the system and certain the HIVE system is calling for heat as thermostat set well above room temps in my tests (as I type I wonder if the boiler is reaching the set water temp (70 odd degrees) and cutting out - but again, doesnt explain why his brothers radiator 8ft away in another bedroom shoots up to 65 degrees in no time yet problem rad is still 50 degrees after a couple of hours normally - so I do think the system is calling for heat constantly

 

[Best]

Valves red hot. Radiators cool. Trv stuck. Hit it harder. You will see immediate result, unless not hitting it hard enough. Hit it harder.

Exactly! Nearly always that's all it is. I have to whack them TRV pins hard sometimes.
And it can be inside the body of the TRV and the only way to fix it properly is replace the TRV.
I know it can also be the internal 'pin' seized, which ain't fixable.
Balancing is possible to be the main issue if problem ALWAYS was there, but not otherwise.

 

[SimonG]

Yep. Beat the snot out of it till it works as a makeshift. Dump pressure snatch two new trv's and jobs sorted. 5 pages later.

 

[Leo21]

If it's a combi, the pump should be on 3. Replace the trv,s and go from there.

 

[smglasgow]

p.s only addressing this now as always thought the insulation in the boys room was the issue and so improved that first, which I did last summer and before having a IR thermometer. Brothers room is toasty warm now, but 3yr olds is freezing in morning. Homed in on rad issue afetr buying an IR thermometer to directly compare two rads, and was shocked at how much difference between the two with 8ft separation (10+ degrees typically)

 

[Best]

No zone valves in the system and certain the HIVE system is calling for heat as thermostat set well above room temps in my tests (as I type I wonder if the boiler is reaching the set water temp (70 odd degrees) and cutting out - but again, doesnt explain why his brothers radiator 8ft away in another bedroom shoots up to 65 degrees in no time yet problem rad is still 50 degrees after a couple of hours normally - so I do think the system is calling for heat constantly

Either get the TRV pin thumped with a hammer or whole valve replaced.
By all means fire ahead with a basic balancing of system, - try turning the lockshield valves nearly off on nearby rads that are heating very fast.
Ignore all the technical talk. You are trying to get a radiator improved that has never worked fully. That should have been narrowed down to what is likely wrong, or fixed - a couple of days ago.

 

[smglasgow]

Can I just ask one more favour - Im seeing 1.25 bar pressure rise from cold to hot and have a cold pressure of 1bar, hot goes just over 2bar after 3 1/2 hours tonight. Does this indicate I should check/re-pressurise the expansion vessel or is +1bar from heating acceptable? The vokera 35h EV should be at 1bar.

If I test the EV, I understand the system should be drained of water (so diaphragm has air on both sides) is this correct?

Just trying to get as many jobs done at one time if the system does need draining of all water (not sure if it does for these two jobs -TRV replacement and EV checking).

 

[Best]

You are supposed to get the expansion vessel air charge checked minimum once a year when boiler is serviced.
Remember you can't open the gas boiler or work on it unless you are gas qualified.
Separate expansion vessel is a different story.

 

[Leo21]

Can I just ask one more favour - Im seeing 1.25 bar pressure rise from cold to hot and have a cold pressure of 1bar, hot goes just over 2bar after 3 1/2 hours tonight. Does this indicate I should check/re-pressurise the expansion vessel or is +1bar from heating acceptable? The vokera 35h EV should be at 1bar.

If I test the EV, I understand the system should be drained of water (so diaphragm has air on both sides) is this correct?

Just trying to get as many jobs done at one time if the system does need draining of all water (not sure if it does for these two jobs -TRV replacement and EV checking).

If the case has to come off you can't do that without being gsr.