Central Heating Temp.

[kenny1234]

When a desired boiler temperature has been set (say 20.0c)---I assume the boiler will cut out when this is reached. How long before it drops to 19.9c and the boiler restarts? Am I right in thinking that we are talking about every 2 or 3 minutes it will keep going off and on?

[bhg481]

There are three thermostats in a central heating system. One controls the temperature of the water in the boiler and will be around 70 deg C. A second controls the temperature of water required at the taps and will be set to around 60 deg C. The third is the temperature of the room containing the room thermostat which will be set at around 20 deg C. The speed at which the water temperature in the boiler cools down, so needs reheating, depends on both hot water usage at the taps and the outside air temperature cooling the rooms.

[davebro]

Depends on the sensitivity of the thermostat. I wouldn't have thought that quickly - may 15 - 20 mins?

[The Builder]

I doubt if the boiler will restart at 19.9 Kenny.
There is a certain amount of "common sense" built into the logic circuitry in the boiler.

There's no set time for a restart. There are so many parameters.
All I can say is that even though the roomstat may be "calling", internal sensors in the boiler would override it if they detect that there is still a high temperature in the boiler.

[kenny1234]

Many thanks to the three of you.