Hot water Cylinder Stat

[iceman2010]

have noticed for a while now that the hot water cylinder stat might not be working correctly. Hot water is timed for morning and evening only however as it only comes on for a few hours i just put it down to it not heating up fully, stat is on 55c.

Now this morning, i switched on the immersion heater which heated the water, all this while the boiler was still heating the HW. After all baths were done with, the immersion gets switched off at 7 as we have an economy 7 meter, the boiler was still going, central heating was not calling for heat. I started hearing tapping and bizzare sounds in the hw cylinder after an hour or so. The pipeline coming out the top was very hot. I turned down the hw stat and it didnt click off until it got to 40c. I left it off for a few minutes until boiler and pump were off, so this all works. Then turned the stat back up and it immediately clicked at 40c and pump started running. the water in the tank is def above 40c though not sure how i can check for sure.

So does this mean that the stat is faulty?

 

[ImpededLoop]

Where about on the cylinder is the stat? The top of the cylinder will be hotter than the bottom. The stat is normally about 1/4 up from the bottom of the cylinder.

Also it could be that the stat is not making good enough contact with the cylinder, so it's not responding to the actual cylinder temperature.

 

[iceman2010]

it is at the bottom of the cylinder. It looks like its pushed all the way, how do i know if its making enough contact?

 

[ImpededLoop]

Measure how far into the insulation it's sitting. You can also buy heat paste which helps heat conduction from the cylinder to the stat.

 

[ImpededLoop]

it is at the bottom of the cylinder.

The bottom of the cylinder (100mm or so) could be full of limescale. The stat needs to be raised up if it's that low.

 

[iceman2010]

Measure how far into the insulation it's sitting. You can also buy heat paste which helps heat conduction from the cylinder to the stat.

will measure when i get home tonight

 

[davesparks]

Cylinder stats should be 1/3 the height of the cylinder. Which would be roughly the top of the heating coil inside it.

 

[Octopus]

Its a bit ironic that "iceman" has cold water!

 

[iceman2010]

Measure how far into the insulation it's sitting. You can also buy heat paste which helps heat conduction from the cylinder to the stat.

goes all the way to the copper tank.

 

[Leesparkykent]

Sounds like you are having lots of issues with your heating system from this thread and the other other thread about your thermostat. You can get a whole Drayton lifestyle y-plan pack for about £80, maybe worth considering and getting a sparky to re terminate the wiring centre and change the controls over at the same time.