Indirect vented cylinder - top immersion not working without gas supply All aspects of plumbing questions and answers, help, tips and information

[DeeRal]

Hello, I would be grateful for advice about why an immersion heating element at top of an indirect vented hot water cylinder is not working unless indirect system control panel is 'on'. I am puzzled about how it works/does not work.

I moved to a house with an indirect vented hot water cylinder which is connected to a boiler behind an old gas fire. However the gas for the house has been completely removed (i.e. no supply at all; pipes all capped off).

The hot water cylinder is in a cupboard upstairs. It has an immersion heater at the top which turns on with a fused electric switch. However the immersion heater at the top of the cylinder does not seem to work unless the thermostat/control panel downstairs that is linked to the old (not working) gas boiler is turned on. By this I mean the top of the hot water tank only gets warm if I turn on both the electric switch by the cylinder itself AND a switch downstairs that controls the indirect system (options for hot water/heating).

Electrician has checked and both the power supply to the tank and the immersion heater at top of the tank are working. But the top of the tank does not get warm unless the downstairs switch control panel is on.

My questions are: 1) is it correct that I must turn the downstairs control panel on even though there is no gas supply - and so no hot water to be fed through my tank (and thus no point having on). Is the downstairs switch needed because it is controlling a pump which is essential before the top immersion heater would kick in? I know it would only be pumping cold water through coil at bottom of tank so thought it should be able to stay off.

2) is there any danger or issue with trying to just use the immersion heating element at the top of the tank? This is not a long term solution, but I have an electric shower so only need a small amount of warm water for dishes etc.

3) is there any reason that the compression valve / pipes in the loft would be especially pressurised if just having the top immersion heater on (and the downstairs control panel on). Or anything else I need to worry about if using like this?

Thank you for your advice.

[stoneyboy]

Hi deeral,
If your electrician has confirmed that there is a main supply to the top immersion heater and this is controlled by a redundant controller I would suspect you have an economy 7 linked system.
You will have to get a heating/electrician to investigate.
Regards S

[DeeRal]

Thank you Stoneyboy - appreciate your feedback. Electrician visited and could find no issue with electrics. Immersion heater at top of cylinder goes on, warms a bit and then seems to go off. I mentioned Economy 8 following your helpful post but electrician said that didn't seem to be the issue. Really grateful that you took the time to assist.

[stoneyboy]

Hi deeral,
In that case the thermostat is either faulty or turned down in the immersion heater. Your electrician should have checked the operation of the thermostat.
Regards S

[DeeRal]

You are a star Stoneyboy - thank you. Very grateful for your time. Electrician checked the immersion heater and said there was electricity to it and all seemed to be working, but I will specifically ask him to check the thermostat and perhaps replace the heater as it is old. One query: there shouldn't be any reason why I need to turn the boiler on to have the immersion heater work should there? Could there be anything 'blocking' the heater from going on unless the boiler on/off switch is on? (e.g. does a pump need to be on or something?) Again, many thanks for taking the time to help me.

[stoneyboy]

Hi deeral,
Whether turning on the control panel somehow causes movement in the HWC and this lowers the temperature next to the IH stat, only fitting a new stat/immersion heater will tell.
Regards S

[DeeRal]

Thank you Stoneyboy. Appreciate your advice and the time you have taken to provide it.