I have a conventional 'wet' central heating system with radiators in each
room fed from a wall mounted boiler in the garage. The boiler also heats the
water via an indirect cylinder. There is a thermostat on the hot water tank
which controls a motorised valve thus shutting off the supply to the tank
when set temp is reached. There is a room thermostat in the hall that
controls (I believe) the pump located near to the boiler. The room
thermostat has a terrible lag on it and room temperature tends to get too
hot and then too cold waiting for the stat to switch. I have put TRV's on
the radiators in my lounge/dining room which have improved things somewhat -
but in order to keep a hot supply feeding to these radiators I have to keep
the room stat high which then overheats the rest of the house! I am now
considering putting TRV's on all radiators apart from the bathroom (to allow
for at least one 'by-pass'). One question: If after carrying out this work I
then leave the room thermostat set high, will this result in the pump
running virtually permanently, and if so is this likely to cause any
problems?

Kev

One question: If after carrying out this work I then leave the room
thermostat set high, will this result in the pump running virtually
permanently, and if so is this likely to cause any problems?

Yes it will cause problems and you will technically break the building
regulations for energy effiency. It isn't the pump running that is the
problem. It is the boiler running continuously, short cycling trying to keep
the central heating water hot when no radiators are on.

The correct solution is to replace the room thermostat with a modern
electronic, preferably programable type. If the poor performance is because
it has been placed in an unheated space, then move it. Although many people
favour the hallway, I prefer to place the thermostat in the most occupied
room. The room with the thermostat should have lockshield valves both ends
of any radiators to prevent users turning them off.

An alternative solution is to install a flow switch, which can turn the
boiler off when the flow through the radiators falls below a certain amount.
This will also comply with regulations. If you do so, it is best to replace
the pump with something like a Grundfos Alpha, which won't mind operating in
these conditions.

Christian.

Christian McArdle wrote:
One question: If after carrying out this work I then leave the room
thermostat set high, will this result in the pump running virtually
permanently, and if so is this likely to cause any problems?

The correct solution is to replace the room thermostat with a modern
electronic, preferably programable type. If the poor performance is because
it has been placed in an unheated space, then move it. Although many people
favour the hallway, I prefer to place the thermostat in the most occupied
room.

But don't do that if you use a gas fire or have open fires etc in that
room, as the effect of the extra fire will be to turn down the CH and
make the rest of the house colder!

"John Stumbles" wrote in message
...
Christian McArdle wrote:
One question: If after carrying out this work I then leave the room
thermostat set high, will this result in the pump running virtually
permanently, and if so is this likely to cause any problems?

The correct solution is to replace the room thermostat with a modern
electronic, preferably programable type. If the poor performance is
because
it has been placed in an unheated space, then move it. Although many
people
favour the hallway, I prefer to place the thermostat in the most occupied
room.

But don't do that if you use a gas fire or have open fires etc in that
room, as the effect of the extra fire will be to turn down the CH and make
the rest of the house colder!

Thanks both for that!

Kev

Clearly, renew your roomstat, and get your trv's barr the one where the rstat is.