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Rick Ridley
Rick Ridley, UK Heating Engineer
Category: UK Plumbing
Satisfied Customers: 1561
Experience:  30 Years on the tools, now retired, Ex CORGI
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Betacom 24C combi. DHW does not rise above 40C and it keeps

Customer Question

Hi Dan
Betacom 24C combi. DHW does not rise above 40C and it keeps on cycling on/off even with a steady flow of water from tap, DHW thermister recently replaced. HW demand is acknowledged by 24C so assuming the flow switch is ok. Why the temp does not go above 40 and that too briefly (from LED status indicators). Is there any limit settings preset on the pcb which will stop temp rising above 40, other than the Hi temp limit switch?
Please advise.
Thank you
Submitted: 10 months ago.
Category: UK Plumbing
Expert:  Andrew Smith replied 10 months ago.

Do you think the plate heat exchanger is scaled up and cannot transfer enough heat into the water?

Customer: replied 10 months ago.
Did not check the heat exchanger for scale build up. The central heating works fine. The DHW sensor is located on the pipe after the diverter valve, an inch above the HW isolation valve. why does the boiler cycle on (get good hot water around 40 degrees for around 30-45 secs) and off? Is it the control electronics or heat exchanger?
Customer: replied 10 months ago.
Customer: replied 10 months ago.
Thank you
Expert:  Andrew Smith replied 10 months ago.

The main stat is on the main heat exchanger.

If the boiler cannot transfer the heat into the water then the main thermostat will shut the boiler down until it cools down again