Trianco Eurostar Combi 70 - 3 Port Pump Confusion???

9 Jan 2011
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United Kingdom
Hello Folks

Finally have my old Eurostar Combi 70 running (oil pressure gauge helped!) but have now discovered that the DHW is not hot when the CH in running. Turn off CH and plenty of hot water.

Checking the the electrical connections to the 3 port pump I found that there was 230v on the wire for the pump to deliver hot water with no CH on but 230v to BOTH the DHW and CH wires when CH on. How can this be? The pump is supposed to change direction - one way for CH and the other direction for DHW! it cant go both directions at once, so how do I now get hot water when CH is on. Seems like CH over rules DHW. Hmmm?

All help greatly appreciated as my wife won't let us move in the house until it's sorted (living with Mother-in Law at the moment and desperate to escape!).

Thanks in advance
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Problem looks to be with thermostat in DHW store. Follow the schematic in conjunction with the fault finding chart.
Thanks Oilhead - will do.

I still don't understand how the DHW can work if the CH has the flow through the pump. Can anyone enliughten me?


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