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Immersion heater

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Eels | 16:46 Sat 12th Nov 2005 | Home & Garden
14 Answers

What's cheaper - leaving the heater on permanently so that the water never cools, or switching it on and off as it is needed? It's a very very old heater (think '71!) and there don't appear to be any timer switches on it.


We've always just had a bath, but now we have a new electric shower, we only need an immersion for the washing up!

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To heat the water for your washing up, the heater only needs to be on for about 30 minutes. If you leave it switched on all day, even though the thermostat will cut in and out periodicaly, it's likely that the aggregate time that it's actually consuming power will be much longer than this.

Fitting a timer switch to an immersion heater circuit is a fairly easy job. (From the electrical viewpoint it couldn't be simpler. The only difficulties you might experience are with fitting the switch to the wall or bending the cables to get them to fit into the switch).

If you really want to save money, switch off the immersion heater for good. Head to Tesco to buy a cheap kettle for a fiver. Then just boil up a couple of kettles of water when you want to do the washing up. (If you use the immersion heater, you're paying to heat a bath full of water when you only need to fill a sink).

Chris
Your best bet Eels would be to get a water heater like a Mains Seven or a Chafoteaux Britony instant water heater, that way the only hot water you pay for is what you actually use.

There may be smaller cheaper versions but it would pay for itself in the long run.

If your current hot water cylinder is the standard (about) 30 gallon capacity you are heating all that to fill a sink full of water which is only one or two gallons.
Question Author

Gad, I'm such a GIRL!


My 'leccy bill is around �40-50 a month (we have oil central heating, it's a 3 bedroom bungalow) - is that too much?

If you only want it for washing up you could knock that down to �20 or less.
If you only need hot water for the dishes then just use the kettle.
Sorry, Buenchico's last paragraph said that and I missed it.
Question Author

Wow, that's �200 a year!


The Immersion will be going into retirement as of now - apart from the odd deep bath of course!

Eels:
I can't work out exactly how much electricity you're using because tariffs vary but �40 to �50 per month equates to about �135 per quarter.

On the Eastern Gas direct debit tariff, for my part of the country (East Anglia) this equates to using about 14 kilowatt hours per day. That's a lot.

Your fridge and/or freezer probably use about 2 kWh each day.

Your lighting requirements probably don't use more than 1 kWh per day.

If you leave your TV in standby mode, rather than turning it off, it's probably costing you at least �30 per year but it's total power consumption (even if you watch lots of TV) is probably still no more than 2kWh per day.

Your laundry requirements (washing & drying) probably average out at around 2kWh per day.

You can probably throw in a maximum of 2 kWh more to cover average use of your computer, scanner, printer, DVD player, radios, hi-fi, etc.

So we've got a grand total of 9kWh hours per day. But you're paying for 14kWh per day. So where's the rest come from?

Well, if your immersion heater is actually running for just 1 hour 40 minutes per day, it will use, surprise, surprise, 5kW hours per day. (i.e. over a third of your total electricity usage)

Now are you going to turn it off?

Chris
Question Author

OMG Chris, that's scary! I mean, the money is one thing but I generally try to be a bit green where possible and I'm wasting an awful lot of energy!


It's off - and staying off!

If it's really 1971 and still working, I suspect the Science museum might be interested in it. Also the condition of the wiring and insulation are highly suspect after that many years.
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Everything in this house is original - it's never been properly inhabited really, as it was built to provide tied accomodation for staff who didn't use it. You really don't wanna see the flooring that's being replaced tomorrow - original vinyl in a gorgeous shade of sick-yellow. As the house doesn't belong to me there's going to be a limit on the improvements I can reasonably ask for at a time - new kitchen and bathroom are a good start but perhaps the hot water and heating systems should be next on the list.

I think you can reasonably ask for a safety check by an electrician.


If it's as you describe it there's likely to be a lot of stuff that's potentially dangerous.


For example is there a just an onl fashoned fuse box or is there a RCD (that's a trip switch that'll cut out if you have a problem) ?


You should only need to put your immersion heater on to have a bath. Washing up in cold water won't do much harm. Use kitchen towel to clean excess grease. This way it will help reduce your electric bill.
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In response to jake-the-peg, when the kitchen and bathroom were done, a shower was fitted, and the kitchen wiring was all redone and a new fuse box fitted at the same time. It's quite scary to think of all these things! My sister's boyfriend is a sparky so maybe I'll give him a ring and see what he thinks ...

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