Glowworm Combi central heating zone problem

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alfier
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Glowworm Combi central heating zone problem

Post by alfier » Tue Jan 29, 2019 4:12 pm

My daughter has the above in a new Charles church house. The lower zone works fine but the upper zone doesn't work (never has). If you turn the thermostat all the way down the boiler goes off but if you turn it up anywhere the boiler never stops even when the room temperature greatly exceeds that set.

Any ideas please?

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aeromech3
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Re: Glowworm Combi central heating zone problem

Post by aeromech3 » Wed Jan 30, 2019 5:03 pm

Experts need to know what system she has, are there 2 zone valves and 2 thermostats, have the rads got e.trv's and has she checked with neighbours if there C.C house system works as it should but it does sound like a wiring problem?
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Re: Glowworm Combi central heating zone problem

Post by alfier » Wed Jan 30, 2019 5:20 pm

Thank you.
Yes 2 zone valves and 2 thermostats, all the rads have got e.trv's
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ericmark
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Re: Glowworm Combi central heating zone problem

Post by ericmark » Wed Jan 30, 2019 5:44 pm

Since the TRV should control the temperature of each room, and the programmer selects between living area and sleeping area, the thermostat is there to stop the boiler cycling as summer approaches, it is not designed to control room temperature.

With oil central heating it is a different story, they are seldom modulating and even if they are, oil modulating is 15 - 20 kW where with gas it's 6 - 28 kW so a whole different story.

The problem is some times people take short cuts, they don't design a system for the house and fuel supply, but they select a pre-designed system, and to be frank that may be better, as if following a Y, W, C or S plan then easy enough for some one to in the future work out what you have. And with a modern boiler zone valves may not be appropriate but if the government says you must split into zones then no real option.

With an oil fired boiler having the programmer select the thermostat and the thermostat control the zone valve and the zone valve work the boiler makes sense, but not with a modulating boiler, so as said you need to find out how it has been wired.

OK just seen answer before finished so two thermostats does look as if old S plan where programmer feeds thermostat, then thermostat feeds motorised valve, which in turn turns on the boiler. So when set to run if you move thermostat up and down can you hear the motorised valve working?

Is so then a micro switch inside motorised valve most likely, and swapping heads could prove it.
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