HeatSlave 20/25 - Operation of Diverter Valve

11 Apr 2007
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United Kingdom

With reference to a recent post I think that I have a problem with the Diverter Valve in our HeatSlave 20/25 oil fired boiler.

Recently we found that we need to have the CH on in order to get HW at a sustained decent temperature which suggests that the diverter valve is jammed partly open.

When the CH comes on there is a clicking noise as the valve moves over. When it does the boiler fires which suggests that it makes it to the point where the microswitch is made.

When the HW comes on there is a loud sustained whine as the valve moves back to the default ( no power applied ) position. Again the boiler fires.

When looking at the Diverter the lever on the side of the valve never moves.

Q1. Is this lever supposed to move at the valve diverts ?

Needing the CH on to get HW suggests that the actual valve is stuck

Q2. Can it be serviced ? I see that there are replacement parts available for it ?

Q3. I take it that valve is a V4073 mid position valve and not a V4044 3 port valve.

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The replacement valves for the heat slaves come with a terminal block attatched to connect to the pcb,should take bout an hour to drain boiler and replace whole valve.You may not see the lever move but in dhw mode the lever will move with some resistance,in ch mode the lever will move freely.
Q1, Lever doesn't normally move.

Q2+. You probably just need to replace the synchron motor. This is the c licking bit. The valve itself can often be fixed by wiggling the spindle with grips/spanner.

Thanks for your replies.

If the valve is stuck partially open and the syncron motor has failed I am confused as to how the microswitch is still activating ?

Any suggestions ?
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Regrettably, I'm not clairvoyant at the moment as my crystal ball has gone in for servicing. Hope to have it back next year. Anyone with a combi has a problem waiting to get out, if anyone has a Worcester combi, they are usually bigger and more spectacular. (and expensive)

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