Immerser Controls? Ask questions and find answers to many subjects relating to electrics and electrical work

[Quartermass]

I'm buying a flat which uses an immersion heater to heat the water.

The wall control panel for it is quite old and it's mechanical, and I don't think I'm able to set it to do things the way I want.

Essentially I want it to be on in the mornings and evenings mon-wed, different times on a thurs/friday and again different times on a sat/sun. If that's too much for me to expect to be able to do, then just setting it to turn on at 6am and back off again at 8am and then on again at 8pm and off at 11pm would do the job, as long as there was also a time limited override where I could force it to go on for an hour or so.

Am I right in thinking it's basically the same principle as a light switch, and any wiring I'll have to do should be pretty simple... or is it a complex thing to change over. Finally would someone recommend a switch to me? I'm thinking that within reason the more control I have then the more money I'll save over time, so an expensive switch will pay for itself.

[stoneyboy]

Quartermass,
Google "economy 7 immersion heater timers" and buy one which suits your needs.
end

[ericmark]

Much depends on lagging. With a modern tank there is no real need to allow it to cool down as the tanks are very well insulated.

The whole idea of timing is mainly to take advantage of off peak tariffs and unless you have varying charges then switching off the system is not going to make much difference.

The way the tank is heated is important too. Willis system has the immersion fitted in a sub tank and heats the water from the top of the tank down. With this system using tank thermostats at different heights can reduce heat loss without having a time where no hot water is available.

The idea of timed heating comes from the old tanks with little lagging, and off peak charges, plus with boilers using thermo-syphon reducing loss of heat from the pipes by reducing cycling times.

So first question is why do you want a timer? Are you using off peak? If not will better insulation save more money than a timer?

[Quartermass]

The lagging does need replaced, it's a little bit loose, and it makes sense to me to put the best insulation on it that I can get. Should I just grab it from B+Q or Wickes etc or can I get better lagging through a plumbers merchant etc?

I'm not yet sure what the electricity charges will be. I'll find out reasonably soon though. I have just done some searching and I'm not sure.. but I think it seems that you either have an Economy 7 tariff where off peak units are cheaper or you don't. And if I don't then there's no advantage to heating up the water over night so it's ready for the morning? My research into prices etc leads me to think the go fix 5 one from nPower is the cheapest for me, and I don't think it has a peak/off-peak difference... I think that means timing the immerser isn't that important?

The reason for the wall timer was simply to make sure that I wasn't heating water when I didn't need it.

It's certainly not a modern tank. I would guess it's not been replaced since 1964 as it appears to be the same (with the same lagging) as the tank in the flat directly below. I've no idea how good or bad the tank is - I'm assuming it'll be worse than what's available now. I also don't know how much it would cost to get it replaced with a modern one.

[ericmark]

I would not bother with a timer switch. The lagging is a balance between drying cloths (Assuming in an airing cupboard) and saving energy. The more cloths you pack around the tank the less energy escapes anyway so if used to air cloths adding more insulation may mean your cloths are not aired as well.

Because a tank with approx 40 gallons will not cool down between the timer going off and back on again switching it off for less than 24 hours is pointless. Switch it off when going on holiday but not while living in the flat.

Lagging is the way forward.