Hot water is TOO hot...

[NeilT]

Hi, looking for some help...

Glowworm condenser boiler, and I have a hot water cylinder.

Cylinder stat set to ~60 but water is being heated to nearer ~80 (have tested the water with a thermometer running straight out of a kitchen tap).

Have changed the cylinder stat.

Motorised valve is now 5yrs old, but seems to be working ok i.e. valve opens according to whether the system is demanding CH, CH+HW or HW only.

Would appreciate any other ideas or thoughts.

Many thanks.

 

[aligorgon]

Does the cylinder stat have a good contact with the cylinder? Is it wired correctly?

 

[dave1]

Make sure the immersion isn't switched on

 

[heliotrope]

Check the motorized valve again.

I would be fairly certain that it's not closing properly and
is letting by.

Might be just the actuator playing up and needs replacing but
could be the valve itself knackered.

 

[NeilT]

Thanks for the replies:

- stat has good contact with tank
- immersion definitely not sw on
- stat wiring appears fine (have traced it back to the junction box and checked all of the terminals - the replacement of the wiring to the stat was performed at the stat end, not the terminal end)
- I was kinda suspecting the motorised valve might be sticking open but I wanted to see what other ideas people might have...

 

[StillLearnin]

Valve is most likely ..... easiest way to check is let the system go cold, then heating only on.... shouldn't get any heat going to cylinder, if you are then its the valve

 

[stevetheplumber]

just turn the stat down you can expect at least 10 degrees difference from top to bottom of a cylinder and stats are not that accurate i find the numbers are there as a guide

 

[NeilT]

thanks guys.

 

[AWheating]

i agree with steve, first thing to try is turn the stat down.

 

[NeilT]

Thanks, but I'm already registering a 20 degree variance between stat (which is set to 60) and actual water temp.

Think I'll try the suggestion from "StillLearnin"...

 

[bewsh]

I'd go with the zone valve being at fault. As previous comments, let the system go cold, put the heating on and see if the pipe to the cylinder gets hot. You'll get a little bit of heat straight after the valve from heat transfering through the valve, but thats about it. If it's red hot then valve is buggered!

 

[NeilT]

Started to investigate further...
Started by removing the actuator and trying to turn the valve manually (well, with grips)...it moves approx 1/8th of a turn. Even using some force the valve barely moves.
To my mind this suggests the actual valve is buggered...correct?

 

[Howsie]

What's the flow temp out of the boiler?

 

[NeilT]

Erm, sorry, don't know, and don't know how to check...

Does this affect the ability to turn the valve?

thanks.

 

[Howsie]

Try turning the boiler down a bit.

 

[NeilT]

Right, how does this affect the operation of the valve (sorry if I'm being Mr Thicky)?

 

[PlumbBobBob]

sounds like the valve is ok in itself, there shouldn't be very much movement on the spindle 1/8th is about right.

 

[Howsie]

Right, how does this affect the operation of the valve (sorry if I'm being Mr Thicky)?

It doesn't but will remove the immersion from the equation.

 

[stevetheplumber]

is this a wind up TURN THE CYLINDER STAT DOWN

 

[NeilT]

@Stevetheplumber - done that, it's now at <60, and it's a new stat (water reached nearly 80).
I've been given some advice previously, which appears to point to the motorised actuator.

 

[StillLearnin]

Have you let the system go cold and see if the heat is passing a closed valve yet?.... simple, quick, cheap ... and will point you towards the problem very quickly