Electric hot water All aspects of plumbing questions and answers, help, tips and information

[Annie50]

Please could someone advise me on our water heating.

We currently have an immersion water heater but it only comes on with the timer once a day and its not really enough hot water for us. ( We have underfloor electric heating) We can overide it by turning the clock round - but only if we know all the hot water is used - which we dont always know until it runs cold!! Is there an immersion timer/programmer available that switches itself on when the temperature of the water drops? I would be really grateful if someone could give me some advice.

[plumbbob]

An immersion element contains a central probe type thermostat that usually can be manually set to the desired water temperature. The probe is used to prevent the water temperature exceeding the 60 degrees maximum limit.

This means that the element can be safely left on 24/7 but for the sake of energy efficiency, is normally only heated during the night on the low rate tariff, and perhaps with a boost in the afternoon to ensure sufficient water for the evening.

Why do you think the hot water must all be used up before the immersion can be turned on again?

[nitro23456]

Your immersion should have a thermostat on it that turns the immersion off when it reaches temp. These are normally set at 60 celcius. You could set this to a higher temp or leave you immersion on for longer.

If all the water in the tank is hot, then it is hot I'm afraid and that is the limit of your capacity.

I would imagine that your timer is for economy 7 rates. If your not bothered and want to experiment you could keep the immersion on for a longer period say from 5am to midday so that you all have renewed hot water for a shower each and the washing up. The immersion thermostat should switch itself off when it gets to temperature and thus reheat the tank as hot water is used, whilst also preventing the water from boiling over.

You will need to check this though as boiling immersion tanks are dangerous!!

Another thing to bare in mind is your electricity bill!!

[Annie50]

Many thanks for your answers. It is much appreciated.

Ive worked out that my immersion cannot be working properly then - according to your replies.

It gets nice and hot when it has been on - thats no problem. Its just that it only comes on once a day with the timer. Other times it never comes on during the day when the temperature of the water goes right down. At the end of the day there is no hot water at all - till during the night its heated again. The mornings are fine - its lovely and hot. Where would the thermostat be controlled by ? The box with the timer on or the immersion itself ? or would we need to get both replaced?


Plumbob - I didnt mean that the immersion can only be turned on when the hot water goes cold - its just that that is when I want to turn it on - so I can use some for a bath etc.

[nitro23456]

Then it doesnt sound like its faulty. You just have it on the timer so it can only turn on at night with the economy 7 cheap rate electircity.

Just change the times on the timer to suit.

[Annie50]

Thanks for your reply but the timer hasnt got anything changeable on it - only "off" or "timer" when switched to timer it comes on automatically for 1 hour a day - I cant change it to come on twice a day or anything. I can swizzle the clock round to make out its later than it is - so the immersion switches on but then the clocks all out of sinc for the following day. Nightmare!

Please can someone tell me - when the water on an immersion heated tank goes cold - should the immersion switch itself on?