Radiator thermostat query

psd99

psd99

psd99

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7 Sep 2008
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hey all,
I got quite a large radiator in my kitchen.

It's about 1400-1600mm I think from memory.
the problem is that the thermostat on the radiator is dodgy.

On level 1 the radiator doesn't even heat up, only on level 3 it will but it's just too powerful and makes the room too hot.

I just want it to be on very slightly like level 1 or 2, how can I fix this? will the valve need replacing?
 
It sounds more like the rad is too big, had the same in my office at work, very hard to control under these circumstances

Temp drops, hot water floods in, temp rises, water stops, problem is if you have too lareg a rad the temp goes up a lot
You can drop the rad water temp if its fine in the rest of house and see if this helps to stop overheating, but other rads may suffer.
Otherwise can reduce the valve at the other end of the rad to cut the flow back down, balancing the system

take a look at this
https://www.eua.org.uk/uploads/5AD7149297805.pdf
 
Ok thanks all

I got two radiators to fix actually

I think u are right about the big radiator its actually a monster at 1600mm

ok with respect to the pins
They moved down a little bit they felt a bit stiff but how much should they actually go down and up like?

I set my front room radiator to 2.5/3 (was 5 before and got too hot)

the big radiator in the dining room is set to 2.5 now but it felt very hot
Still testing but keyboard warrior has a good point

i will read that article thanks
 
Oh and to add

Do trv’s get impacted if something is in front of them?
Front room has a sofa in front of the radiator on level 2/3 still feels too hot
 
Just in case you're not aware, the TRV doesnt control the temp of the radiator.
On a properly balanced system the rad will get as hot as the setting on the boiler (give or take) and this can be up to 80C (ish)

A TRV has a capsule that expands and contracts with room temperature, shutting off the radiator or opening it up.
This action isnt instant, so depending what the thermostat is doing (expanding/contracting) you might find the rad heating up or cooling down by varying amounts. And a sticking pin can also affect the process. Pin movement is usually just a couple of mm.
Its also not very precise, but better than nothing. Valves are not all equal or accurate, hence the number scale and not a Temp (C) scale.

The location of the radiator and the area around a TRV (furniture/curtains etc) can also have an impact on their effectiveness.

All this doesnt take into account the heat output of the radiator and its suitability for the type of room.

Have fun ;)
 
Thanks

what is a sticking pin? The pins on the two radiators are very stiff
I read somewhere online that one could lubricate them with wd40 so they go up and down a bit
Is that a valid fix?
 
So looking online I also worked out that the change is not instant
I need to leave the changes I made for 12/24 hours to see if it makes a difference

I could also turn the heat output of the boiler down. Upstairs temps are perfect for now,
Dining room felt better this morning

but the front room is still very hot!
 
This is where Opentherm comes in, check if your boiler supports it, automatically changes the boiler temperature. Combined with a smart thermostat it would learn each room and not overshoot the temperature.
 
psd99 said:
Thanks

what is a sticking pin? The pins on the two radiators are very stiff
I read somewhere online that one could lubricate them with wd40 so they go up and down a bit
Is that a valid fix?
Click to expand...

The pins dont normally move that far, but you can try lubricating it a bit and moving it up and down with some grips. Normally if they continue to stick or not function properly the valve will need replacing.

robj20 said:
This is where Opentherm comes in, check if your boiler supports it, automatically changes the boiler temperature. Combined with a smart thermostat it would learn each room and not overshoot the temperature.
Click to expand...

Thats what balancing the system is for.
 
200sols said:
The pins dont normally move that far, but you can try lubricating it a bit and moving it up and down with some grips. Normally if they continue to stick or not function properly the valve will need replacing.



Thats what balancing the system is for.
Click to expand...
On an old fashioned system yes, on mine it tells you implicitly not to balance it. It does it itself. So lockshields stay fully open. Otherwise you can cause big issues.
 
robj20 said:
On an old fashioned system yes, on mine it tells you implicitly not to balance it. It does it itself. So lockshields stay fully open. Otherwise you can cause big issues.
Click to expand...

So the system balances itself using a smart valve I assume? Same result in the end.
 
200sols said:
So the system balances itself using a smart valve I assume? Same result in the end.
Click to expand...
Yes. Not the same result as the balcony changes constantly. If I've room is heating the balance is fully open, of two rooms it will close one room slightly and so on, also depends on what temp those rooms are asking for and the ambient temperature.

The first week of use it's rubbish every room overshoots and gets stupidly hot but it soon learns.
 
update - the sofa has been moved in the living room and is no longer in front of the radiator - we do this every 6 months for a change anyway. didn't realise how much day light this gives us back :)
the front room is much cooler now the trv is set to 2! (albeit I'm sitting here right now and thinking is it warm enough lol)

the dining room/kitchen is also better both trv's are set to 2 for the massive radiator and 3/3.5 for the smaller one. The bigger radiator is now just slightly on, the other one is perfect.

also I turned the temperature on the boiler down to around 66c which also I believe helped. That's a powerful boiler at 24KW and I'm feeling blessed to have it right now.

I will leave things like this for now, thanks all.

Does a TRV work as follows - Let's assume a TRV is set to 20C on setting number 3 - once the room is 20C the radiator turns off
but say the temperature drops to below 20C and the heating is still on, will that TRV let hot water through again to heat the room up?

p.s my only other main problem now is the hallway where the nest resides.seems to get a lot colder here than it did last year
so I am looking at further drought protection for the 30 year old front door (big replacement coming up next year inc porch hopefully money permitting) basically the temps drop there and the nest comes on more than usual but hopefully with the tinkering this weekend I won't need to keep feeling too hot in the living room or dining room
 
I had sticky pins.
I had to clean off years of muck that had stuck to them, then twist and fiddle with them to get them looser, used WD40 and eventually they worked - but only for one season then had to go through it all again.
I have found balancing radiators a time consuming business but I expect that the original poster needs to try this. For a start just feel the in and out pipes - the hot one should be much hotter than the out one.
 
notxn85 said:
I had sticky pins.
I had to clean off years of muck that had stuck to them, then twist and fiddle with them to get them looser, used WD40 and eventually they worked - but only for one season then had to go through it all again.
I have found balancing radiators a time consuming business but I expect that the original poster needs to try this. For a start just feel the in and out pipes - the hot one should be much hotter than the out one.
Click to expand...

it is much better now thanks

the heating system is only 2 years old all of my TRV's are this age too.
practically a brand now bosch boiler ftw :)
 
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