The minimum boiler output is 9.3kw so the dT at 2.5LPM is 53.3C, my mains cold water temp is 18.3C just now so would expect a DHW temp of 71.6C which may trip the burner since the DHW setpoint range is 35C to 65C, so if the DHW control is set to mid scale, 50C, then you might expect the burner to trip (at 55C) once the flowrate is reduced below 3.6LPM.
Baxi Combi 80e...is this normal operation?
- Thread starter daKlone
- Start date
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OK, so the minimum flow rate I measured at 2.57 l/m, so I would say that the manual is correct.
What happens with the burner and DHW temperature (at minimum flow) is this:
Burner starts, water increases from cold (~18C) to 48C.
Burner stops, water increases to 53C.
Burner starts, water drops to 48C.
Burner stops, water increases to 53C.
And cycles...
With a moderate flow, the burner stays on and the temperature is pretty stable at around 49C.
At full flow, the burner stays on and the temperature is stable at around 47C.
I would guess that the reason the burner activity/temperature seems inverted is because the boiler recognises the change in temperature internally before the tap (or rather my thermometer) can?
What happens with the burner and DHW temperature (at minimum flow) is this:
Burner starts, water increases from cold (~18C) to 48C.
Burner stops, water increases to 53C.
Burner starts, water drops to 48C.
Burner stops, water increases to 53C.
And cycles...
With a moderate flow, the burner stays on and the temperature is pretty stable at around 49C.
At full flow, the burner stays on and the temperature is stable at around 47C.
I would guess that the reason the burner activity/temperature seems inverted is because the boiler recognises the change in temperature internally before the tap (or rather my thermometer) can?
Get a heating engineer to look at the boiler, one that knows how that boiler works.
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Why? If the minimum output of the boiler is 9.3kw and the DHW demand only requires 6.28kw at a flowrate of 2.67LPM at a mid scale SP of 50C then the boiler has to cycle and IMO is doing quite well to maintain only a
3C to 5C deviation.
3C to 5C deviation.
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