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Discuss Understanding heating/water tank system in the Central Heating Forum area at

We moved into a new property yesterday and are a little baffled by the heating/water tank situation. The previous owners unhelpfully left any kind of instructions/manual and therefore trying to figure out ourselves.

We have what looks like a boiler/water tank system (coming from a standard combi-boiler this is all new to us) we are in a bungalow so all on the same ground level.

After testing the shower yesterday the pressure was really low, after looking in the boiler cupboard we have (image attach) what is seemingly is a pump?? Connected to the tank and the boiler? Some random wire/with plug coming from the tank that was unplugged and have no idea of its purpose.

The house has been unoccupied for a while and therefore when we moved in the heating was on but the hot water switched to off.

Now, when we used the shower again this morning something kicked in and the pressure increased and was very good.

My husband plugged the random plug in for all of 5 seconds and took out again before the shower so not entirely sure it was that? And not even sure where to start when it comes to googling.

Would be greatly appreciated if anyone can look at the images and help us understand the system we have and why maybe the pressure suddenly kicked in?

We did set the timer for the hot water to be on for an hour or so before we used it and as I said it hadn’t been on before - so not sure if this has helped??



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Basically, you have a boiler that can supply (primary) hot water to the CH (rads) or/and to the HW cylinder coil which heats the DHW (domestic hot water) or you can have both on together via that mid position valve in photo, programming the HW on for say a 1.5/2 hrs in the morning before the CH is required is a good idea as the cylinder thermostat will shut off the boiler anyway if its set to its normal 60C. the pump you plugged in for a few seconds is probably a booster pump to boost the hot&cold water but this should automatically start up only when there is a demand for hot & possibly cold water, you should see another pump somewhere, not that one shown in photo 4 which is for circulating the hot boiler water through the rads and the heating coil in the HW cylinder.
The hanging down wire is from a (Immersion) electrical heating element in the HW cylinder.

The cylinder stat (strapped onto the HW cylinder) is set to 50C, a bit on the low side, it should be set to 60C at least once/week, say for one morning heat up, for legionella protection.

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