2 port valve failure

manocheese · Dec 2, 2014

I have an S Plan heating system at home with upstairs and downstairs split as 2 zones. The downstairs heating stopped working recently, but all was still ok with the hot water and the upstairs heating. It appears that the 2 port valve on the downstairs zone has failed, as when the system calls for heat in that zone, the boiler is not firing up.

When I switch the valve to manual, the heating works.

Questions:

1. The valve is installed in the roof space under the loft insulation - is this advisable - can this cause the electrics to overheat or are they designed for this?

2. With the downstairs zone valve on manual, the heating downstairs only comes on when the upstairs zone is on - is that what would be expected of a failed valve ie there is only hot water circulating when another zone is calling for it? Or does it suggest another fault somewhere.

Thanks...

townfanjon · Dec 2, 2014

1 - defiantly NOT under insulation.
2 - when you go to the manual setting, you are only opening the valve, if the auxiliary switch is gone it wont fire the boiler.

What type of valve is it ?

AWheating · Dec 2, 2014

it may not be the valve but its the most likley fault, get a competent person in to test the controls before any changing of the valve is undertaken.

manocheese · Dec 3, 2014

Thanks for the replies. Will move the insulation. The valve is a Danfoss HPA2.

When the fault occurred a plumber identified the valve was the problem, although he didn't seem to look at or test the controls. Should I expect that all that is needed is for the actuator to be replaced, as the manual operation of the actual valve is ok? Is a DIY job advisable here?

townfanjon · Dec 3, 2014

IMO the danfoss 2 ports are ok, yes you can just change the actuator, obviously electricity is involved and if you have a go yourself please take care, but a sparky should not charge much for changing one (LOL)
The only thing you get told not to do on here is gas.