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Andrew Smith
Andrew Smith, Plumber
Category: Plumbing
Satisfied Customers: 3629
Experience:  City and Guilds qualified plumber
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Glow worm 30SXi heat exchanger has been pressure cleaned running

Customer Question

Glow worm 30SXi heat exchanger has been pressure cleaned running free, pump, pcb board, interface board, 2 thermisters, 1 flowstat all replaced. Everything changed apart from fan and transformer. Voltage 36.9 volts across red and blue. Should it be 24 volts? When cold starts up perfect, when temperature for hot water reaches temperature switches off okay. When the external hot water storage tank requires heat stat comes on, water still hot in tank, boiler switches on modulates, fan comes on fires up, but keeps going on and off. Leave it to cool for 3-4 minutes, switch off, switch back on and works okay.
Can you help?
Submitted: 4 years ago.
Category: Plumbing
Expert:  Andrew Smith replied 4 years ago.
You have a cylinder?
Customer: replied 4 years ago.

Yes I have an indirect Tribune cylinder (sealed storage tank) for fully pumped system.

Expert:  Andrew Smith replied 4 years ago.
It sounds like you have a faulty cylinder stat?
It calls for heat but it does not need it as the boiler is up to temperature.
Do the boiler light every time but just run for a few seconds?
Customer: replied 4 years ago.

Yes the boiler lights every time and runs for a few seconds. Turn stat manually on higher boiler stops lit. Seems you are correct .

Expert:  Andrew Smith replied 4 years ago.
This can be caused by by 2 stats set about the same.
One way to solve this may be turn you boiler stat up higher to nearly maximum and let the system run itself.
You will have to be aware that the temperature of your rads will go up, but your house will heat up faster and then be turned off by your room stat - so you will use the same amount of gas, but you rads will be hotter to the touch.
Expert:  Andrew Smith replied 4 years ago.
Did you manage to resolve this?