Immersion Heater Spur and Switch Replace With Timer Ask questions and find answers to many subjects relating to electrics and electrical work

[Billjg]

Hi,

I have an immersion heater upstairs which is hard wired into a fused spur which is in turn wired to an 'on switch' downstairs.

Is there anyway I could replace either the fused spur or switch with a timer?

Thanks,
B

[ericmark]

I am sure there is. However with modern water tanks there is really no need. In fact even old tanks can be lagged and if you don't use the water the power to maintain the heat is quite low and in real terms after 24 hours when the water is not used the temperature will still be rather high.

The timers are used for off peak, and alternative heating like with solar, central heating, or solid fuel and the why it is required will alter the options used.

A unit like the Horstmann - Electrisaver E30 will give a set time to heat water where the Horstmann BX2000 will heat during off peak times. The Horstmann - Electrisaver E30 is really for when there are other ways to heat the water. So if the central heating or solid fuel fire has not been used you push the button to get 2 hours of heating to keep you going until the next time you have the other heating running.

However there is also the use of lower temperature settings on the thermostat. By setting the thermostat low one hopes that the solar panel, central heating or other means to heat will always keep the tank above the electric heaters setting so it will never turn on.

But yes any 3kW timer can be fitted but the question has to be why.

[Billjg]

Thanks, this would just be a temporary measure for a month or two.

So are you basically saying just leave the immersion on all the time? We basically run out of hot water on an evening after bathing kids, washing up etc but would obviously need hot water for showers in the morning. My thinking re the timer would be to switch the immersion on in the early hours of the morning to provide hot water throughout the day, we are on Economy 10.

[ericmark]

[quote]we are on Economy 10[/quote]
That makes a big difference. I would have expected you already have a timer some where. There are many ways to ensure you mainly use the off peak power.

Economy 10 is a tariff not a system and there are a number of ways to control the system to make use of the tariff. In some cases you have a completely separate supply to the items using the off peak supply with for example duel immersion heaters.

The Irish are very clever and many years ago they worked out a system to heat the water in the cistern from the top down rather than from the bottom up the Willis system has now expanded to use with Solasyphon try to google Willis Renewables you should find it.

Since this is all in a tube at the side of the cistern rather than in the cistern its self it can easy be added to an existing system.

The English and Welsh system was no where near as clever we used two immersion heaters some times both in the same unit but there were placed a different heights and the lower one is used with the off peak and the higher one uses a timer so if you run out you press a button and warm just a little water at the top of the tank. In some cases it just relies on the two thermostats also being at different levels and temperatures automatically keeping the top hot but heating whole lot during off peak times.

The other system does not have a separate supply for off peak but your timers have to line up with the suppliers timers and all items plug into same supply and the user has timers on tumble drier, washing machine, immersion heater, dish washer and of course the storage heaters to switch them on during off peak times but also allows an over ride during peak times.

Before you can select a timer you need to know what system you have.

To be frank in my area most people use gas or solid fuel for heating and there are not many using off peak electric power and as a result I have not worked on that many. I know they exist but to remember exactly how they are used is hard for me. I hope some one who lives an an area where they are used more will pop up and help.

Although this forum will take pictures now it's a real pain with very limited formats and can't link to existing pictures on the web. There are other forums who do allow links and you may find them better, however the control is not as good and you do get some very rude replies. Posting pictures of your consumer unit and meter may help those in the know to identify the system in use which will in turn help finding the best way to use your immersion heater.

[Billjg]

At the moment I just need to fit a timer to a basic immersion tank which is wired to a fused spur which in turn is wired to an on/off switch, I just need to know if I can replace the switch with a hard wired timer.

We are installing an unvented cylinder for our hot water in the next couple of months so the timer will only be temporary.

[ericmark]

Yes you can big question is if you have neutral at the switch. Most will have neutral but some will not and if no neutral then you need timer with a battery.