Greenstar 28i - Heat setting advice

[gg]

Hi

I have a Bosch Greenstar 28i Condensing boiler and live in a large 3bed semi..

I have 9 rads all (but one) with TRV's. I also have a Bosch Wirless Room Thermostat DT20RF

We have large ceilings (its an old victorian house) and the house does take a while to heat up!. Can anyone advise what is the best method of heating? IE

Do I turn the boiler to full (I mean the MAX setting, as the dial has

1-6 then a MAX setting) and then set the Room thermostat to 21/22 ?? - and then leave all the RAD TRV's on the '4' setting (one of maximum) or all completely open - this will mean the RADS are nearly all constantly running (with exception maybe of kitchen etc)

Or is it best to control the heat from the room thermostat AND the TRV's....ie set rads to about number '3' which means they turn off at around 19'ish degrees...

At the moment I have the boiler set to '6' and the rads between 3-4 which is taking around 4 hours to go from a 'cold' 15-16 upto 21-22 when it fires up at 4:30pm....by around 8:30, the Room thermostat is turning the boiler off...

Is there a reason you wouldnt use the MAX setting on the CH on the Greenstar??

[Andy]

The room thermostat should be in a room where the radiator(s) have no TRV. That way you won't have the thermostat and the TRV in the same room trying to fight each other.

All other rooms have TRV's set to whatever temperature you want ( about II is what I set them to ).

As a refinement, make sure that the room in which you have the thermostat ( often the hallway, but can be the living room if there is no secondary heat source like a fire in the living room ) gets to temperature a little behind the other rooms, so the TRV's in all other rooms have achieved their intended room temperature and are regulating it before the thermostat turns the boiler off. This can be done by throttling the radiator in the room containing the thermostat, using its lock shield valve if necessary.

Andy.

[gg]

Thanks for that.

The thermostat is > >

[PM]

There's a recent thread called "TRV temp control or boiler temp control?" which might be helpful.

[Andy]

A fully open TRV is good in a thermostatted room. Whether it takes that room longest to heat up depends on how they've sized the radiators, but you sound as if you've got everything OK.

Opinions differ on CH temperature, it may depend a bit on whether you have a condenser or not*. Most people seem to think that hot is best, so that's no 6. I think that'll correspond to 82 to 89 C or thereabouts. I can't remember the reasoning: it may be something to do with the boiler being designed for operation at that temp, or the shorter boiler 'on' times ( and hence pump runs etc ) needed for hotter CH boiler setting.

You'll need to turn the temp up higher in cold weather anyway otherwise you won't get enough heat from your rads.

*There was a thread a week or two ago on this very subject. Google groups will have cached it even if its gone from your newsserver.

Andy.