Worcester Boiler and room thermostat

[James Palmer]

Hi,
I have a worcester oil boiler (danesmoor utility), it is run by a drayton lp522 timer and I have a room thermostat.
The internal thermostat is set to the 3 (there are 5 positions).

My question is; The boiler is firing and the radiators are getting pretty hot, but I have noticed on the thermostat that the room temperature is say 18deg, I set the "CH on" temp to be 19 deg, but after a while the boiler stops firing even though the room temperature hasn't reached my set temp of 19 deg.
Is this likely to be because the internal boiler thermostat has reached its desired temperature and switched off?
So, should I set the internal thermostat to the next position (4), so it is presumably a higher set limit, so is likely to go higher than 19 deg and is then controllable by the room thermostat?

Any thoughts on this would be really helpful?
Thanks
James

 

[Leesparkykent]

Where abouts is your room thermostat? Is there a rad in the same room?

 

[James Palmer]

The room stat is in the hall and there is a radiator there.

 

[Leesparkykent]

No TRV on the rad?

 

[James Palmer]

There is no TRV on that RAD?

 

[davesparks]

Does the boiler stop firing completely or does it come back on after a while?

 

[James Palmer]

Yes the boiler does fire up later on ....

 

[telectrix]

i'd say that the room stat is not accurate to 1 degree. try it at , say 22.

 

[James Palmer]

Ok ill set it higher tonight, and see whether the room temp can come close to the set temp ....

 

[sean_ork]

Is this likely to be because the internal boiler thermostat has reached its desired temperature and switched off?
So, should I set the internal thermostat to the next position (4), so it is presumably a higher set limit, so is likely to go higher than 19 deg and is then controllable by the room thermostat?


Thanks
James

A few degrees of inaccuracy between stats is to be expected - also, whilst your boiler may have stopped firing (which may be due to its limit stat) the circulation pump may well still be running, so the heated water will still be being pumped through your rads. The boiler limit stat may well cause the boiler to fire again if the circulated water temp has dropped before the room stat is satisfied.

How long are you allowing the temperature to get to the room stat set point ?

 

[davesparks]

Yes the boiler does fire up later on ....

Then it's likely the boiler stat is operating before the rooms are up to temperature.
If it never reaches the temp set on the roomstat then you should turn the boiler stat up a bit.

 

[James Palmer]

An our or more

A few degrees of inaccuracy between stats is to be expected - also, whilst your boiler may have stopped firing (which may be due to its limit stat) the circulation pump may well still be running, so the heated water will still be being pumped through your rads. The boiler limit stat may well cause the boiler to fire again if the circulated water temp has dropped before the room stat is satisfied.

How long are you allowing the temperature to get to the room stat set point ?

 

[James Palmer]

Yes that's what I thought but wouldn't the high limit stat cut in?
QUOTE=davesparks;1151485]Then it's likely the boiler stat is operating before the rooms are up to temperature.
If it never reaches the temp set on the roomstat then you should turn the boiler stat up a bit.[/QUOTE]

 

[sean_ork]

What's the insulation like in the house, when it's up to temperature does it get cold quickly after the boiler really is fully off ?

If you've got a draughty leaky house and an undersized or marginal boiler you'll always struggle to get it up to temperature, especially now when it's finally a bit nippy outside.

 

[sean_ork]

Yes that's what I thought but wouldn't the high limit stat cut in?
QUOTE=davesparks;1151485]Then it's likely the boiler stat is operating before the rooms are up to temperature.
If it never reaches the temp set on the roomstat then you should turn the boiler stat up a bit.

[/QUOTE]

The boiler limit stat will stop it firing, but your circulation pump will still run (putting heated water through the rads) until the room stat is satisfied, which should then turn the pump off as well.

 

[davesparks]

Yes that's what I thought but wouldn't the high limit stat cut in?
QUOTE=davesparks;1151485]Then it's likely the boiler stat is operating before the rooms are up to temperature.
If it never reaches the temp set on the roomstat then you should turn the boiler stat up a bit.

[/QUOTE]

If the boiler hits it's high limit stat then you've got a problem. The high limit stat should only operate if the boiler heats past the upper limit of the boiler stat