Any saving from putting a timeswitch on the immersion heater?

tomstickland

I've got all Economy 7 heating. No gas or boiler, just an immersion heater. It has an Econ 7 element and a normal element.
It's on all of the time.

Thinking about it, I don't use any hot water in the morning (electric shower, clean teeth and go go go), it then sits unused all day and it's only used when do the washing up at night.

The tank will be slowly losing heat all day, so as it stands the system will be periodically heating all through the day and night. If I turn if off overnight and then back on the next evening then the water will be colder and it will take more to heat it up.

However, I've thought about this a bit. I believe that it will overall use more energy if it's kept topped up all day compared with just heating it when I need it.

I do wonder if I'd be better off boiling water when I need it. Bit of a faff, but surely cheaper.

Any idea on the cost of hot water in a tank?

mepone9

your economy 7 element is only on at night when your electricity is cheaper, it does get a boost during the day and this should keep your hot water tank hot. your normal element should only be used if your water is not hot enough and needs a boost outside these times. If you keep this switched on your thermostat will control the temperature of the water to whatever the thermostat is set at. So it will be on when the water has cooled below setting then off when above the setting. I don't know if this would be cheaper or more expensize than boiling a kettle.

Mr_Grumpy_7

You're right in thinking it is a waste in having a tank of hot water just sitting there waiting to be used. The hotter the hot water tank the hotter the airing cupboard, and that's wasted energy.

I'm not sure, but I suspect the economy 7 element is located in the bottom of the tank, worth checking. The normal element is fitted through a hole in the top of the tank, again worth checking. This being the case, the economy 7 element will heat far more water than the normal element, possibly enough to last the whole day. I would try turning the normal element off altogether and seeing how you go with regards to having enough hot water.

lovelldr

I've got an immersion heater in my house on economy 7. Don't know much about it, but I do know that I have timers on mine. The immersion has two sections, the top and full tank. I don't bother putting the full tank on to heat, and just heat the top part of it overnight between about 4 and 5 am. This then stays warm for the following day, and allows to do washing up the next night. Have electric shower, and dishwasher, so really don't use that much hot water. So this is ideal for me...

tomstickland

OK, thanks for the info.
The Econ 7 element is at the bottom of the tank.
The normal element is towards the top.
The water exits from about 2/3 of the way up the tank.

So I guess that the Econ7 is used for the main work and the normal element is a top-up/boost. I've turned it off. However, nothing currently stops the econ 7 element from heating the water during the day, so maybe I should fit a time switch inline with it so it can only work overnight.

I'm also considering putting loads more insultation (aka insulation) round the tank. It really is a massive tank and a bit of waste for a single person flat.

Mr_Grumpy_7

tomstickland wrote:

So I guess that the Econ7 is used for the main work and the normal element is a top-up/boost. I've turned it off. However, nothing currently stops the econ 7 element from heating the water during the day, so maybe I should fit a time switch inline with it so it can only work overnight.

Surely, being economy 7, it will only work at night and on the cheap rate.

tomstickland

Yes, you're right.

tomstickland

I just found this via Google http://www.wasteless.co.uk/html/lowcosttips.htm

5. If your home has a hot water cylinder with an immersion heater and circumstances arise which require its use, switch the immersion heater on half an hour before needed and switch it off after the task has been completed. NEVER leave an immersion heater on all day. If the domestic routine requiring its use is regularly repeated at similar times it can make economic sense to run the immersion heater via a timer if there is no cheaper and less polluting alternative fuel to electricity available to heat the water. Remember, no matter how well insulated your cylinder is, hot water will eventually cool down to room temperature so it makes sense to only heat up water just before using it, and only enough to match the heat demands of the task. For many households it makes economic and ecological sense to heat water only as, and in the amounts required using a ‘combi’ boiler (i.e. an instantaneous water heater) or even a jug kettle for jobs such as washing up. Hot water cylinders can more than double the energy use for hot water through standing losses from the cylinder and further standing losses in the pipes connecting it output points.

ollyshaw

Hi,

I have a similar question too. I have a boiler for my hot water. I flick it on and off when needed, its normally on for about 1hr 30 in the early evening. Would I save money by having a timer switch that turns it on at, say 5am for an hour (so I get my economy 7).

Also how much do you think it would cost for a sparky to do this for me?

Cheers,

Olly

RubyBish

tomstickland wrote:

However, nothing currently stops the econ 7 element from heating the water during the day, so maybe I should fit a time switch inline with it so it can only work overnight.

Our Economy 7 switches on and off via a radio signal.
So rather than have a mechanical timer and have to worry about daylight savings changes there is a signal sent across the radio airwaves that switches it on and off. When we first moved in this was broken as the light on the fuse box was on all day. An engineer from our energy supplier came round and changed the radio receiver on our meter.

We never need the normal element switched on. Even by late evening the water comes out >50 degress C.

tomstickland

Yes, the Econ 7 heater switches itself on during the Econ 7 hours.

I had an idea at work today....why not wire the Econ 7 to the upper heater?
Then the Econ 7 part will only heat the upper section of the tank, ideally saving a bit more?

I've been reading about the advantages of jacketing the tank too - costs around £12 for a water tank insulating jacker. Alternatively, I could pack the cupboard with insulating material.