Heating not coming on

[alison7148]

Hi - here's hoping someone has an idea what is going on with our heating. At the moment it won't turn on- we hear the thermostat click, but this does not trigger the heating to come on. If I manually move the switch on the mid-position valve it comes on, then turns off when the desired temperature is reached and does not come back on again. The plumber has checked the mid position valve (which was replaced around 3 years ago) and says it is working fine and that he thoughti t was most likely an electrical fault with the thermostat. Does that sound likely?
Added to that, tonight, only the upstairs radiators got hot, the downstairs ones remained cold.
Any thoughts before I call the plumber and/ or the electrician?
Many thanks
Ali xx

 

[seco services]

Sounds to me like the motors failed in the valve.

Give us some more info on the type of system valve etc.

 

[alison7148]

Valve is a ?Darfuss (sorry really hard to see the make as it is all in my daughter's bedroom in the airing cupboard....so I have been trying to creep around with a torch without waking her up!). Does that help? The hot water is coming on fine (although is super-hot)

 

[alison7148]

Oh and its a normal(old) Baxi boiler, not a combi or condensing one

 

[Hugh Jaleak]

A Danfoss valve. Sounds like valve is stuck, heating stat is calling for heat but the boiler is putting majority of the heated water into the HW cylinder.

If valve is stuck then cylinder stat setting wont make a difference either, hence super hot HW. The little flow getting through to the rads is staying upstairs as hot water is lighter than cold water and is obeying the laws of gravity.

 

[seco services]

Is it def a mid position valve you have ?

If so sounds like he's turned up the cylinder stat so it runs longer to give you heat to the heating if you open the valve manually then when hw satisfied it will close again till next time.

 

[mysteryman]

Please check that your pump is running.

 

[alison7148]

Sounds a silly question but how do I check that the pump is running? And I presume it is a mid-position valve as thats what we were told was being replaced 3 years ago....to be honest I have no idea! It used to make a noise when switching from heating to hot water and back again

 

[alison7148]

Is it really obvious?

 

[Hugh Jaleak]

Mid position valve will have 3 pipes attached, shaped in a 'T' with motor on the top, flow from boiler into base, the one side supplying HW cylinder, other to central heating.

Pump may make some noise when running, try moving the lever on the body of the valve, under the head. It should allow you to manually open the valve to both ports, allowing the flow from boiler to cylinder and central heating. If rads get hot then pump should be working.

 

[alison7148]

Yes then it is a mid position valve! If I move the manual lever across, then heating comes on (which is what we have had to do for the past couple of days) . It was just tonight that the downstairs radiators didn't heat up.

 

[alison7148]

I guess it makes sense that the valve is stuck........can it be fixed or will it need replacing? We live in a hard water area - could it be scaled up? And any ideas what we have no heat downstairs? It seems as though it probably isn't an electrical problem with the thermostat though, from all the replies on here?

 

[Hugh Jaleak]

On some valves the head can be replaced separately, this assumes the motor assembly is faulty and the actual valve itself is ok. If not or valve is goosed then the entire unit will need to be replaced.

Hard water wont make a difference, the heating system circulates the same water constantly, unless there's a major leak (noticeable!) then very little topping up is needed. It is however possible, there is oxide sludge in the system if little or no corrosion inhibitor is present in the water.

I'd get the valve problem fixed, then if downstairs rads still dont work, investigate further. Could be the valve is goosed, and what little flow is getting through to the heating circuit is staying in the upstairs rads.

 

[alison7148]

Thanks so much....will get on the phone to our plumber in the morning xx