Rads not heating unless TRVs on high level

[Jameswren]

My radiators heat very little (almost stone cold) unless I turn the TRVs past setting 4.

Any ideas why this would be?

The TRVs are Drayton, it's a pressurised system in a town house with the same issue on all radiators.

 

[seco services]

Whats the pressure reading on the sealed system gauge ?

 

[Jameswren]

About 1.3

If you're suggesting it's pressure related, I have had dropping pressure but thought I found the leak so hadn't considered this the problem now.

 

[seco services]

Did you bleed every rad etc after finding leak and refilling ?

 

[JohnD]

what is the temperature in the rooms?

 

[Jameswren]

I haven't been particularly systematic about bleeding the rads but they have all been bled a few times (we're refurbing so have taken rads off walls when plastering etc). They were all bled a couple of weeks ago and the problem is still there but if that's a likely issue I'll give it a go again in case I wasn't thorough enough.

Regarding temperature, I have absolutely no idea. To get any response from any rad I need to have it at least 3.5/4 on the TRV, then the room gets pretty hot.

From responses it sounds like it's pressure related but I'm curious why it needs to be 3.5/4 before there's any heat generated.

 

[1983]

As johnd says if the room temperature is above set point on thermostat the rad won't heat or will be Luke warm. If you turn it to 5 and rad gets nice and hot circulation is ok.

 

[Jameswren]

It may be they're getting to temperature then shutting off but my uneducated feeling was they're just not switching on - I'll give that a shot after bleeding the system fully again.

Do I start with any particular rad when bleeding? ie ground floor or top floor first?

 

[JohnD]

time for you to save up and buy a thermometer.