Boilers without room stat

[steve1612]

Hi

Many of my customers have combi boilers without a controlling room thermostat. When the boiler is running from say 5pm until 10pm does the boiler burn gas continuously for the 5 hours or does it monitor the temp difference between flow and return and turn itself off if the temps are close?

Thanks
Steve

 

[Dan Robinson]

The boiler will cycle on and off based on its internal setpoint. Very wasteful.

 

[dcawkwell]

If the boiler can modulate down to match the heat dissipation
of the radiators. The boiler will run continuously getting the house hotter and hotter. Or until the heat loss of the house matches the incoming heat
using gas all the time.

If the radiators cannot dissipate the heat as fast as the boiler is producing it.
The boiler will then start cycling on and off.

Either way it is wasteful. I upgraded my radiator in our sitting room
and last night the temperature it started climbing up to 22 degrees , previously unheard of.
We don't have a wall thermostat as previous radiators were hopeless underpowered for the size of the rooms and heat loss.