ACL Hot water/central heating system - question about pump All aspects of plumbing questions and answers, help, tips and information

[BS34]

I have an ACL Lifestyle TwinZone System with an LWC1 wiring box. I moved into this house earlier this year, and noticed that as long as the hot water is on at the programmer box, the pump is running whether the boiler is on or not. Thus if I have the hot water on for an hour, the pump runs continuously for an hour. This seems wrong to me - can anyone confirm whether this is the correct behaviour or not, and if not, what is likely to be wrong?

Cheers!

[htg engineer]

That's right, as the pump has to be running for the water to circulate and heat the tank/cylinder.


htg

[BS34]

OK, but I would assume that if the boiler wasn't going then the water in the tank/cylinder was at the correct temperature according to the tank/cylinder thermostat, and it certainly should be if it has been on for half an hour. Why does it need to continue running the pump in this case? Shouldn't it shut down until the thermostat detects that the temperature has dropped too far, in which case it starts up again and pumps the water to the boiler? Only the hot water going off at the timer seems to stop the pump.

[htg engineer]

It's probably the boiler stat that is cutting the boiler off, as the water in the boiler/flow and return will be hot, the water needs to continue circulating until the heat is transferred to the water in the cylinder.

Try turning the cylinder stat down, there'll more than likely be a pump over-run so it wont shut off immediately. Could be a faulty stat.


htg