PigletJohn can I ask you a heating question please?

[HauntedNoddyCar]

Getting to grips with the quirks of our house after moving and we have realised with the warmer weather that the central heating is misbehaving.

Radiators upstairs come on whenever the heating is on even if the thermostat hasn't triggered. Means we have the upstairs heating wildly even on hot days. DH figures it is probably the three way valve and we know where that is but can't explain why it would only be the upstairs rads coming on. Downstairs rads seem to be behaving themselves.

Could you explain why? Or suggest any other causes?

Thank you in advance!

This happened to us too and only some radiators were affected (all upstairs). I think someone mentioned a valve but were getting s new boiler anyway, which thankfully has fixed the problem.

Thanks Marmite. I don't think the boiler needs replacing. At least I hope not!

it probably is the 3-port valve. Hot water is rising to the upstairs radiators by convection.

Turn off the radiators with their knobs. To reduce heat wastage, set the HW timer on the boiler to about an hour in the morning and evening.

A typical hot water cylinder holds about 100 litres, and (if modern) heats up in 20-30 minutes, so if the boiler heats up before and during your morning ablutions, it will stay hot all day for washing up, and you can top it up in time for evening showers. A well-insulated cylinder loses very little heat, and is more economical in summer than a combi because the boiler does not keep turning on and off every time you use a tap.

Thank you. HW only on briefly as we have solar tubes for sunny days and rads turned off now.

Right we'll get that fixed.

I'm getting that too. When the hot water has been running for while on our combi boiler the radiators warm up upstairs.

combi boiler, so yours is the diverter valve. It's inside the boiler.

the 3-port valve is for people with cylinders. Not inside the boiler so often cheaper/easier to change.