I have a potterton promax boiler in and s configuration with 2 - Zone valves. One for the Central Heating (ch) and one for the Hot Water (hw). When I switch the hot water on, the boiler does not start. The boiler Diagnostics identifies that the Flow Switch is not operating. If I switch on the Central heating, then both work OK. I have tested the HW Zone valve and it is definitely turning ON. I have even manually operated it, without sucess. However, when the CH is ON the discharge pipes of the CH and the HW both get hot simultaneously. So some water is flowing through the HW valve. I have taken it apart and cannot I/D any problem. Is there any data on the flow rate of these valves and the the Flow switch requirement? I have tried the Grundfos Pump in positions 1, 2 and 3, again with no success. Everything else is operational. I am at my wits end.
Hot Water only works when CH is on
- Thread starter M6
- Start date
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Sealed or open vented? If open where is the feed pipe joining the system?
I'm a bit confused here 
your hw zone valve may be appearing to open/close but the micro switch in it is probably knackered therefore not telling the boiler to come on. Don't know why the boiler would give a fault code though as this is external to it. But then it is a Potterton
your hw zone valve may be appearing to open/close but the micro switch in it is probably knackered therefore not telling the boiler to come on. Don't know why the boiler would give a fault code though as this is external to it. But then it is a Potterton Thanks for your prompt responses.
Dan, It is definitely open vented, but I am not certain where the feed pipe joins the system. Unfortunately all the pipes are enclosed in a boxed up conduit, so it will not be easy to locate.
Dave, I have taken the motor apart and checked the switch - they are both opeational. And there is definitely power to the boiler when the timer is asked to switch on the hot water.
What next?
John
Dan, It is definitely open vented, but I am not certain where the feed pipe joins the system. Unfortunately all the pipes are enclosed in a boxed up conduit, so it will not be easy to locate.
Dave, I have taken the motor apart and checked the switch - they are both opeational. And there is definitely power to the boiler when the timer is asked to switch on the hot water.
What next?
John
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I say this because there could be a blockage where the feed inters the system - probably by the cylinder somewhere.
Also the boiler gives a fault code because it is failling to light up when there is a demand. This is a new condensing boiler and two green LED's flash after about 3 minutes. the manual says this is a dry fire failure and asks to check the flow meter. Potterton engineer has checked the flowmeter and it's OK. It must be OK as the system fires when the CH is on.
John
John
See my last post.
Thanks a bundle Dan. I'll have a look tomorrow as I am busy most of the day.
You guys are helping a lot and it is great to get some outside expert and experienced advice.
If you think of anything else that I should have a look into, please let me know.
Thanks and best regards,
John Michigan
You guys are helping a lot and it is great to get some outside expert and experienced advice.
If you think of anything else that I should have a look into, please let me know.
Thanks and best regards,
John Michigan
How did you get on? I hope my little challenge didn't put you off too much .
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