Boiler frost setting

samcrawford

Hello,

I have a Biasi M90E.24S boiler in my recently purchased flat. I've left it on the frost setting, as I don't feel the cold very much. As I understand it, the frost setting is supposed to light the boiler when the temperature sensor hits 4C.

However, I've noticed two things:

1) The boiler is switching on roughly every 5 minutes for approx 1-2 minutes in this configuration, even when the temperature is above 4C. I assume this constant on/off can't be good for the boiler?

2) The frost setting also seems to heat the radiators (which are also set to the frost setting). Is this expected?

Pardon the naivety, in previous homes I've mostly just left it on Auto and it's been fine!

Thanks,

Sam

Yorkie1

Re. 1, I expect that is unrelated to the frost setting. It's the boiler's way of keeping hot water in the system so when you run a tap, the water doesn't take ages to heat up.

Mankysteve

Is it the pump turning on or the whole boiler firing up?

Most boiler will periodically switch on to stop the pump from seizing.
Another option could be that its switching on to move water around the system so that no rads in other rooms from that houses the thermostat get cold enough to freeze.

macman

The frost 'stat usually measures the temp on the CH flow side, so you'd expect it to briefly warm the CH circuit and so heat the rads.
Is the boiler in a garage or loft-if not what is the ambient temp getting down to where it is situated?

samcrawford

Sorry for the extremely slow reply!

Mankysteve wrote: »

Is it the pump turning on or the whole boiler firing up?

The whole boiler is firing up.

macman wrote:

The frost 'stat usually measures the temp on the CH flow side, so you'd expect it to briefly warm the CH circuit and so heat the rads.
Is the boiler in a garage or loft-if not what is the ambient temp getting down to where it is situated?

The radiators stay permanently warm whilst on the frost setting (certainly not hot, but warm). The boiler is in the kitchen, near a window. The boiler manual says the frost setting kicks in at 4C, but the ambient temperature should be nowhere near that low (I'd guess about 18C)

At the moment (whilst it's cold) I don't really mind the behaviour, but I'm concerned the constant on/off might harm the boiler.

Any suggestions?

Thanks,

Sam

gas4you

Could be a faulty ntc