CH flow temp's

[Gasguru]

Many heating systems have no room/cylinder stats or TRV's despite part L and adjusting the heating flow temperature provides an easy way to control temperatures rather than adjusting the radiator valves.

Many underfloor heating systems work at around 50 centigrade and use an injection valve coupled with a TMV head to allow them to work with a boiler flow temp up to 82 centigrade ie they can be integrated with a radiator system.

 

[pannierstan]

Thanks Guru. Make sure you wind your neck back in on the way to bed

 

[Gasguru]

Neck turns 360° - it needs to - repairing boilers in some of the places you find them.

 

[ChrisR]

If you don't turn a boiler stat down a bit in spring and autumn, you're likely to have temperature overshoots. Especially with poorly controlled 24kW combis in small flats. Boiler comes on, and the rads are at 82 in a few minutes. Crude thermostat might be just about to switch the boiler off, but the rads are still piping hot. Stat turns off (they're a bit slow anyway, on the whole, to avoid draughts making them switch rapidly), and the rooms overheat.
If it takes a bit longer for the rooms to get up to temp, they don't overshoot so much.
Also, old boilers are much more likely to kettle when wound up.


I think the Delta T 50 you mean is the one applied to radiators - the difference between the average radiator temperature, which would have been say 75 on a conventional system (80 flow, 70 return), and the air around it. Condenser systems would perhaps be better designed with the rads' delta T40 figures - I expect there's standard advice somewhere!