Radiator hot in the morning, cold in the evening

[RikkiHolland]

Hi

My radiator in my loft bedroom is hot in the morning but tepid in the evenings (some evenings it does work normally). I've tried balancing the system but to no avail.

Could there be other reasons? It seems to have no consistent time it doesn't work.

Thank you in advance.

 

[muggles]

Is the room warm?

 

[RikkiHolland]

Thanks for the reply. The heating system is on and running, other rooms and rads are hot but loft radiator is noticeably different.

 

[muggles]

You've not really answered my question...

 

[RikkiHolland]

I felt I had - the room is not hot.

 

[omega015]

Does the loft radiator get hot when the other radiators are all off? next time its tepid/cold, try switching other radiators off and see then if the loft one gets hotter. It could be balancing, it could be undersized boiler, or pump/valve issue etc... but switching off the other radiators and having the loft TRV open fully will help narrow it down a little and assuming the loft is cold enough and there is heat demand from the thermostat/controller.

 

[dilalio]

Is it hot at bottom not top?
Does it have a TRV that it fully open?
What temp does the room reach?

 

[RikkiHolland]

Is it hot at bottom not top?
Does it have a TRV that it fully open?
What temp does the room reach?

There is a difference between the top and bottom. The top doesn't get very hot however.
The TRV is fully open.
I haven't measured the room temp however it is noticeably different between the hall way/other rooms and the loft room.

As mentioned, since finding the problem, I have been around balancing the radiators but it is confusing why the rad/room can get scolding hot in the morning but not in the evening.

 

[omega015]

There is a difference between the top and bottom. The top doesn't get very hot however

That makes is sound like you have air in the radiator and it needs bleeding.

the rad/room can get scolding hot in the morning but not in the evening

That kinda contradicts the first quote.

 

[RikkiHolland]

That makes is sound like you have air in the radiator and it needs bleeding.


That kinda contradicts the first quote.

the radiator has been bled. In the morning, the radiator is very hot and there is minimal difference between the top and bottom. In the evening, I would describe it as the top is warm and the bottom is luke warm, edging on cold

 

[dilalio]

what system do you have installed?
Maybe in the evenings, your HW is on and the additional circuit added by way of the coil in a cylinder is taking flow away from the most distant rad on the circuit!
I would keep tweaking down the lockshield valves on the hottest rads and see if that pushes circulation to the loft rad.

 

[RikkiHolland]

Thanks, I will look at the hot water situation tonight.

 

[Davidl66]

It is to do with your controls
If you have a s plan. Or y plan system with a hot water cylinder in airing Cuboard. Dhw is first priority.
So it will heat the coil up first before going to rads. Depending on times you've set. I'd advise to turn Dhw demand off if you have it on in evenings and see if that makes any difference

 

[RikkiHolland]

It is to do with your controls
If you have a s plan. Or y plan system with a hot water cylinder in airing Cuboard. Dhw is first priority.
So it will heat the coil up first before going to rads. Depending on times you've set. I'd advise to turn Dhw demand off if you have it on in evenings and see if that makes any difference

Thanks - I have a combination boiler and no cylinder. I turned off the hot water last night but the radiator still struggled to get hot (and there as still a noticeable difference between the top and bottom of the rad). I turned on the hot water first thing this morning and again, the rad has got hot!

Very confusing!

 

[omega015]

Did you do what I suggested about turning off ALL the other radiators and seeing how hot throughout the day the problem radiator gets? Ensuring the TRV is fully open and the lockshield is open a good amount too?