Dodgy TRV's ?

[mindhawk]

Hi

I have had a new system put in and I am finding that the only way to keep the rads on (to even warm the room) is keep them all on at 5.
They are Bulldog TRVs. if i set them to 4 (range 23-25C), they all seem to go off far too early.. two upstairs still go off when they are set to 5 (range 27-29C).
One thing I've also noticed is that a rad in the living room (when set to 4) not only goes off, but the pipes to and from are not hot either. I would expect the pipe to the TRV to be hot and then the rad switch off via the TRV.
i've had a rad off for decorating and got all of the air out.
Its running a Worcester heat 29CDI and the rad setting is about 6 ish on the boiler.

 

[jtsplumbing]

Have you checked the room temperature with another thermometer ? are the radiators large enough for the rooms ? have you got a room thermostat fitted on the wall ?

 

[mindhawk]

Hi

I have the room stat downstairs in the hall, which shows 20-21 when i have heating on.
The BTU rating for the rads are about 500 more than the room's requirements.
I asked my neighbour and he put larger ones in to avoid decorating.. i was thinking of make the two bedrooms 600 x 1400 rads (as opposed to 600x 900, 600 x 1000 as they are now).
it may be a cold house.. rooms are 3x3x2 x and the smallest one is about 2.5x2.5x2m (got a 600x700) in there.

 

[Riley]

Is your room stat above a radiator?

 

[mindhawk]

the room stat is opposite the rad downstairs in the hall.
i dont see how this affects the rads going off when they are set on 5, as all other rads are set on 5 and its only these two that go off.
the hallway is the hottest area as it doesnt have a trv on the rad.

if i can only get these rads on if I remove the top of the trv then whats the point in a trv? I have knocked it several times and no difference.

is it worth swapping a trv from another rad ?

 

[Riley]

The thermostat should really be in the coldest part of the house as it is this that controls the boiler not the trvs

 

[doitmyself]

Remove all TRV heads
Set the room stat to a high temperature
Let all the rads heat up.

Feel the flow and return pipe at the boiler so you get an idea of the temperature difference.
Now check each rad.
The difference should, ideally, be the same as at the boiler.
If the differences vary a lot the system needs balancing.

The middle of each rad should also feel the same temperature.

 

[jtsplumbing]

Room stat in wrong place ! stat opposite convector radiator , air movement is satisfying stat, Get RF stat fitted if re-siteing one in hall is a problem, The room stat is the control point for the house, once up to temp will shut down boiler regardless of TRVs