Hot water problem

[metalsteve]

Probably the control PCB, my Baxi Solo developed a similar proplem last week but mine will come on once for about 10 mins then not come on again despite recieving a demand for heat.

[metalsteve]

Good point.

That might then suggest that its your motorised valve thats at fault. Does it work ok with both CH and HW on? Could also be tank stat

Edited by metalsteve on Wednesday 26th October 12:35

[Deva Link]

giw12 said:

However, over a 30 minute period, it fires up, runs for 2-3 minutes then goes off for 4-5 minutes before repeating the cycle. I try the water after each on-off cycle and it's getting hotter but nowhere near the 60 degrees setting on the thermostat.

That's short-cycling - common on older systems which rely on gravity where the circulation wasn't very good.

However you mention a thermostat so that implies your system has pumped hot water.

You also say it's a commercial boiler - the issue could well be that it's just too powerful and the system can't get rid of the heat into the tank fast enough. The boiler's control system may prevent it restarting until a few mins have elapsed - a function which is itself intended to limit short-cycling.

[Arthur Jackson]

Poor circulation through the cylinder coil and associated pipework?? Airlocking? Sludge?