One radiator not coming on.

[Trebor123]

Hello.....I am a newbie, be gentle !

Ok. Moved into the house in May and not needed heating so much...hot water no problem. Decided to make sure all ok before cold weather. Two rooms downstairs plus kitchen, loo and hall. Four bedrooms, one bathroom, one shower room, hall and landing. All rooms except the upstairs bathroom have rads, the shower room has a heated towel rail
Most of the rooms have Trv's. The downstairs hall and the bedroom that has a non working rad have thermostats on the wall. Every rad comes on and I control them using the trv. The one room that does not come on has a stat and I am not sure how this is relevant. It is a Danfoss TP5 and I have changed the batteries and set the clock. It has defaulted to the factory settings. I did some research and checked that the pin on the trv was not stuck.
Questions if I may. Which is the boss...the stat or the boiler when heat is needed ? Should the pipe feeding the rad be warm/hot where it comes out of the floor and goes into the trv.?
The boiler is a Vaillant Ecotec pro 24 and I control it using a Salut RT 500 RF which I am pretty sure I have mastered...at least everything comes on and goes off as per my settings, 7 days a week.

So...any help out there ? Sorry for the long post, I feel if you want help from someone you should give them as much info as possible.

Thanks in advance,
Trebor

 

[tincup]

Hi
Make sure
1 There's water in the radiator.
2 The lock shield valve is open.
3 Close a few TRVs noting what number they were set at to add more pump pressure to the non working one.

 

[Trebor123]

Hello and thanks.
I have to assume there is water in the rad as water came out when I bled it. I have done as you said and the system is about to kick in. I will get back here whatever happens.
Trebor

 

[Trebor123]

Sorry not got back before now.
Did as suggested but no difference.
??

 

[Murdochcat]

If said radiator has a trv then that could be stuck in the closed position. Remove the top part and see if you can push the bit you are left with down

 

[Trebor123]

Thanks. Done that at the beginning of this saga and when pressed down the pin returns. Should the pipe feeding the rad be warm because it is stone cold. All replies are much appreciated.
Trebor

 

[terryplumb]

Close every other rads TRV ,see if the cold rad now heats up and leave off the actuator head of the cold rad whilst doing so.
The pipes to cold rad won't get hot if there is no flow through the rad.

 

[Trebor123]

Thanks, most helpful. Will do as suggested tmrw morn and get back here.
Many thanks

 

[dilalio]

As @terryplumb and a couple of others.

Plus...

TRV pin on cold rad may still be stuck down... Tap it gently with hammer or something to make sure it travels full extent of its springed motion... I push them in and let them spring out a few times to make sure they are free.

Leave the TRV head off.
Fully open the lockshield.
Close all other rads - try to discern user control from balanced lockshield on those with 2 manual valves.
Running heating for a good hour.

It still no joy then it's either try some cleaner in and repeat the above OR rad off, flush it through and see if you can get flow into a bucket from both valves - make sure TRV doesn't let by while rad is off.