Bloomin Heating

[Julian Ashcroft]

With the warm weather with us at last, I decided to turn the central heating off, so I switched the Danfoss TP5 Digital Thermostat to Frost only. This didn't make any difference and the heating kept on coming on. Next I turned the Danfoss Central Heating / Hot Water Controller off, so it should have only provided hot water, still got hot radiators. Next I switched the Boiler to just hot water and no central heating, still got hot radiators.

The oil fired boiler (Worcester I think) was installed about 15 months ago to replace a gas system. I moved into the house about 4 months ago. There is now no hot water cylinder as the boiler is meant to provide hot water direct. It does this but will only fill a bath with hot water if the tap is running slowly.

Any ideas of what may be going on to allow the rads to keep getting hot, with everything switched off, would be gratefully received.

Julian Ashcroft Isle of Man

[Christian McArdle]

Dodgy zone valve?

Alternatively, and I don't know the design of the boiler in question, the radiator circuit may be pump controlled rather than valve controlled. If so, there might be some parasitic gravity circulation, although you would only expect the radiators to warm up when the hot water was actually being run then.

If the design is actually a small heat bank or similar, this may also gravity circulate and even cause boiler firing on its own accord.

It may be an idea to post the model of the boiler to determine how its control systems are likely to work.

Christian.

[John]

I'm guessing that you have a Heatslave Combi from what you have said so far. IIRC this has a diverter valve to switch the boiler output to radiators when required and the hot water demand is not overriding it. The hot water to the bath presumably starts off OK but runs out of steam before the bath is full? It is possible that the diverter on your boiler is a Danfoss with a white plastic motor head and if the motor had failed and someone put the manual lever across to give heat to the rads this will remain in the shared position until it is restored or the fault rectified. The symptoms will be as you describe i.e. heating on all the time the boiler is on heat or hot water duty and poor hot water performance. Its also possible to achieve the same symptoms with a stuck diverter or even "other causes" but try these first. If no good please come back for more

[Julian Ashcroft]

Thanks for that. Time to give the heating Engineers a call.

Julian Ashcroft