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CS2242
Will try explain this problem best I can. I have a Ecocat thermal store (Chelmer heating) for central heating and DHW.
My understanding is the the cylinder has a hot water section at the top and a heat buffer below (for central / underfloor heating). The Chelmer diagrams show both of the tanks as seperated on diagrams, although housed in the same cylinder. From the diagrams no connection exists between the two tanks internally (apart from a common return from each tank to the heat pump). However I do seem to remember when I peaked inside before fitting it looked like a connection did exist between the two in form of a hole in the center of a plate between the two.
The problem:
Hot water stat on the upper cylinder calls for heat and the DHW tank heats to temperature. This works fine and as expected and holds temperature fine - until central heating kicks in.
Central heating demand kicks in and the heat buffer starts to call kicking in the heat pump and CH pump, radiators heat as expected.
Strange thing is that the hot water tank starts to loose heat as soon as the heating kicks in as if the central heating is drawing heat from the DHW tank as well as the buffer tank.
I don't quite see how this is happening as when the central heating demand is on water should only flow around the lower buffer tank. I've check all valve operation and this looks fine, hot water heating valve is only open when heating water and central heating valve only open when central heating is calling. It's a bit like the pump back to the heat pump is sucking water out of both top and bottom tank even though the valve is closed on the feed to the DHW tank.
How can the central heating be depleting the top hot water tank on central heating demand?
My understanding is the the cylinder has a hot water section at the top and a heat buffer below (for central / underfloor heating). The Chelmer diagrams show both of the tanks as seperated on diagrams, although housed in the same cylinder. From the diagrams no connection exists between the two tanks internally (apart from a common return from each tank to the heat pump). However I do seem to remember when I peaked inside before fitting it looked like a connection did exist between the two in form of a hole in the center of a plate between the two.
The problem:
Hot water stat on the upper cylinder calls for heat and the DHW tank heats to temperature. This works fine and as expected and holds temperature fine - until central heating kicks in.
Central heating demand kicks in and the heat buffer starts to call kicking in the heat pump and CH pump, radiators heat as expected.
Strange thing is that the hot water tank starts to loose heat as soon as the heating kicks in as if the central heating is drawing heat from the DHW tank as well as the buffer tank.
I don't quite see how this is happening as when the central heating demand is on water should only flow around the lower buffer tank. I've check all valve operation and this looks fine, hot water heating valve is only open when heating water and central heating valve only open when central heating is calling. It's a bit like the pump back to the heat pump is sucking water out of both top and bottom tank even though the valve is closed on the feed to the DHW tank.
How can the central heating be depleting the top hot water tank on central heating demand?
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