Central Heating Help and information on all topics relating to your central heating, air conditioning and ventilation issues.

[JGJackson]

I've just noticed our central heating boiler fire up with both the CH and water set to be off on the timer. We've just had a Danfoss valve replaced in the airing cupboard after discovering a leak there through the white casing (actuator?) which wasn't replaced. The heating and water are working as expected i.e. timer switches both on as and when required and radiators get hot when CH on and water is hot when required.

Can anyone explain why the boiler is doing this, seemingly when it wants to and what is needed to fix it.

Thanks in advance.

Jim

PS
I'm not a plumber or CH engineer at all so please nothing too technical.

[plumbbob]

The most logical explanation is a frost stat has sensed low air temperature and over ridden the boiler controls to protect itself.

For older boilers a frost stat (which looks like a room stat) will be on the wall near the boiler. For modern boilers, it is normally integrated within the internal circuitry.

[JGJackson]

Thanks, Plumbbob,
The boiler is an Ideal Classic FF380 installed when the house was built in 2002. I've checked the boiler surroundings and can't see any type of thermostat at all around it. The only other thing on the wall where it is, is the programmer. As mentioned, the CH and water appear to be working as per the timings set.

Obviously, I can't work out exactly how often the boiler is kicking in outside of those timings but having recently been made redundant, I am more aware of costs these days so I would rather the boiler only fired up when it was supposed to. Is this problem going to be a costly one?

[plumbbob]

From what I can tell the FF380 does NOT have an internal frost stat so if one is installed it will be visible. The installer would have placed it wherever he thought the most likely threat of frost damage would occur. It's worth finding if you can because you need to check the trigger temperature as it may be possible to turn it down slightly.

I must admit it is unusual to have frost stats fitted in domestic properties unless the boiler is in an outhouse or garage which are unheated.

How much the cost is going to be is dependent on too many factors to be accurate, but unless we get continual severe frosts then I guess it will be minimal. Of course that has to be compared against the cost of damage and burst pipes if the system was allowed to freeze.