spread-tee wrote: ↑Wed Dec 07, 2022 9:07 pm
There's something wrong here, I think, If your boiler is modulating down to 6kW or so that consumption figure would imply the burner is firing for more than ten hours a day!! Does that seem likely to you? Have you checked the gas rate while it is firing?? that could be revealing.
Desp
Not yet but I can.
I can audibly tell when its in low-rate mode - but what seems to be happening is that on a call it ramps up to say 60%, then overshoots desired temp, then just vents via flue. Rinse and repeat. It never really settles into the lowest modulation mode, apart from that section of continuous burn in the morning.
Charging the hot water tank is about 10kwh a day. (I charge it with gas since it's cheaper than electric export).
I was surprised to see our ancient potterton suprima 50 was using as much of this to heat our 100 litre DHW tank , it is short cycling because it only has the DHW coil as a load, I tend to only fire it up for an hour every other day unless I am working, we boil kettles for everything else.
Morso S11
FIT
16 Sharp PV panels facing WSW 4kW
Solarmax 4200S inverter
Non FIT
3 Canadian solar DC coupled 1.75kW facing SSE
Storage
Growatt SPA3000TL BL inverter ac coupled
Growatt GBLI6532 6.5kWh lithium phosphate battery
Charging the hot water tank is about 10kwh a day. (I charge it with gas since it's cheaper than electric export).
I was surprised to see our ancient potterton suprima 50 was using as much of this to heat our 100 litre DHW tank , it is short cycling because it only has the DHW coil as a load, I tend to only fire it up for an hour every other day unless I am working, we boil kettles for everything else.
Boiler works nicely when it gets 80C call to charge the 250L tank. Runs for about 30mins to get it to 50C. Keeps heat for next session. Ironically coil is well sized, no restrictor though and no way to change 80C hot water call temp with the logic boiler.
Ok well I rigged up an opentherm gateway with home assistant to have query into this boiler.
What a pile of poo!
It seems that logics weather comp introduces some not documented behaviour when it's set to lower parts of the curve. Setting the exact same target flow temps via opentherm allow the boiler to set and run a minimum modulation nicely.