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Priority fed hot water/heating system

Postby stuartcarr » Wed Jul 14, 2010 9:21 pm

I have a heating system where due to the presence of a priority valve, I have to run off hot water from a tap for a few minutes, in order to get the central heating to come on. Is this correct or has my system been plumbed incorrectly? If I chose to replace my boiler for a standard open vented system boiler, will I have to have the priority valve removed to allow me to use the system in a more efficient manner? I currently have an old Corvec 45 BF.
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Postby htg engineer » Thu Jul 15, 2010 8:34 pm

It's obviously wrong - and a waste of hot water.

Not familiar with the boiler, does it have a water store on the boiler ? or just a tank/cylinder.

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Postby stuartcarr » Fri Jul 16, 2010 8:50 am

It was a Corvec 45BF with no onboard water storage. Water was sent to a hot water cylinder. I say was, because BGas condemned the boiler and I am now without heating whilst I source quotes. Hence my question about the priority fed water. Of the 3 quotes so far, only one has stated catagorically that I must remove the priority valve because if I don't I will still have to run off hot water to bring on the heating, irrespective of which new boiler I chose. The other two have stated that with a new boiler I will be able to have heating on demand, without running off hot tap water, with the old priority valve. Who is telling the truth?
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Postby eggers » Fri Jul 23, 2010 5:02 pm

That is one oldddd system! the priority hot water valve will have to be updated because of energy efficiency regulations! They do look extremely similar to newer 3-port valves and only really distinguishable because the priority valves has 3 wires instead of 3-port valve's 5 wires. So when the people you had round to give a quote, probably saw it and not really understood what they were looking at.
They work like a combi diverter valve where the hot water must be heated and reach temp first before the heating will activate, which means having the hot water on all the time.
I suspect it is faulty to begin with if you need to run the hot water off first, because it's not bringing boiler on for heating... but i'm not entirely sure as i have never ever seen one outside a training bay!
htg eng, the Corvec is an old Chaffoteaux boiler, looks like one of their instanteous water heater units. They stopped making it in 1984 so not many left, watch out for asbestos risks
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