Water not getting warm, heating fine.

[industryspark]

Hi guys, just after some pointers as to where might be a good place to start with a certain fault on a central heating system.

The system i believe is what you call a Y-plan type. It consists of boiler, room stat, 3 port valve, timer and cylinder stat. There is also a water tank in the loft.

I haven't had time to look at this yet in much detail but will be having a better look tomorrow. The basic description is that the hot water doesn't get hot. Heating is fine.

This problem has existed across a few different tenants hence the half stories I've had fed to me. A plumber replaced the 3 port valve motor last year but maybe not the mechanical valve body(not sure on that).....as it happens i don't think this really cured anything. Old tenant said that water did eventually warm up to hot but that it took 12 hours so they just left it 'ON' on the controller which had it working.

Things i know from a brief look is the pipe to the top of the cylinder from the 3 port valve never gets hot, just warm (convected heat?).........bottom pipe out of cylinder is clock cold.

Cylinder was replaced due to it leaking 2 years ago...don't think its really worked right since that point.

Only other thing i noticed is the dial on the cylinder stat feels a bit loose and broken, i.e keeps turning and doesn't stop at either end.

Initial thoughts might be faulty stat or maybe the mechanical valve underneath the motor? Thoughts?

Heading up there tomorrow for a better look but maybe someone with good knowledge of heating systems might point me at a good place to start.

Thanks for reading.

I-spark

 

[terryplumb]

Cylinder thermostat to check first. followed by the three port and the wiring centre.

 

[Hugh Jaleak]

Might be worth just wedging the 3 way valve open on the manual control, then firing the boiler to ascertain hot water will flow through the cylinder coil, assuming this checks out ok, then as above, check the electrical side to see if all is operating as it should be. If the cylinder stat is goosed it may not be giving the valve the call for heat, so it wont open to HW.

 

[industryspark]

Thanks for the reply guys. Turned out to be the 3 port valve had been wired incorrectly by the guy who replaced it last time. Hope the thread may help others in the future!