Mid position valve or pump ?

[Kevski67]

Hi

I have no heating or hot water , when I turn on the heating or hot water the boiler fires up but nothing happens . Have a Honeywell V4073A mid position valve on my 3 port which seems to opening fine (pipes are hot) but how do I know if its the valve not telling the pump to start or the pump itself is broken ? What is the easiest way to find out ?

 

[D_Hailsham]

It all depends on where the pump is connected. If it's directly to the boiler the problem will be either the pump or the boiler. If the pump is connected, directly or via a link, to the same terminal as the valve orange wire, then the pump will be the problem.

Which make/model boiler do you have?

You can hear the pump running if you use a screwdriver as a stethoscope.

 

[Kevski67]

Its a Pottterton performa I think am at work so not sure .The pump definitely connects to the valve via the orange wire . Thinking about it the pump did seem to be getting louder recently would this be a sign that it was on its way out ?

 

[simond]

If the boiler starts.... then stops (you haven't mentioned this bit) you have no flow.

The three port valve is always open one way or another so change the pump.

 

[D_Hailsham]

Its a Potterton performa I think am at work so not sure .The pump definitely connects to the valve via the orange wire.

Are you sure?

The Performa System and Combi boilers have built in pumps. Only the SL versions have external pumps, and they have to be wired directly to the boiler!

The problem could then be in the PCB which controls the pump.

 

[Kevski67]

Sorry it is a Suprima HE. When I turn the heating or hot water on the boiler fires up but nothing happens . The pump does get hot but that's all it does . Is there something inside the valve that tells the pump to come on or is the fact that the boiler is firing up confirmation that the valve is ok and it is definitely the pump thy ha gone ?

 

[D_Hailsham]

Sorry it is a Suprima HE.

The pump is controlled from the boiler and should be connected directly to it (probably via the junction box).

The pump does get hot but that's all it does.

Pump sticking or knackered

Turn system off

Remove large silver screw on front of pump (Only a little water will come out so put rag etc underneath to catch it.

Try and turn the shaft with a screwdriver. That will tell you if it's sticking (hard to turn) or knackered (easy to turn but not doing anything).