Cost of heating hot water from Central Heating v Electricity

Lex Luthor

Does anyone have an idea which is more cost effective to heat your hot water? Either using oil central heating or electricity on a timer?

I've been using my heating since time began to heat my hot water tank...typically my heating is on for 1hr in the morning, approx. 1hr 15 at 5pm and it might come back on for about 30min at half 9 at night if the temperature in the house has dropped and the stat on the wall kicks it on.

Always have a full tank of hot/scalding water

Last week someone told me that if I closed off the valve to my cylinder from the c/h, the house would heat up a lot faster as the cylinder is equivalent to about 30% of the whole houses heating requirements
Then they say to use my timer on my immersion to heat the water.

I've done this, so to get my hot water requirements I have to have the electricity timer on for about 45 min in the morning and same in evening. Need hot water as we dont have a dishwasher so plates/etc are washed in the sink. Having said that, this is just with the immersion switch set to SINK so if we needed more than a sink at any time we'd have to switch the immersion on for an extra 30min

It was becoming a bit of a nuisance so we went back to using the heating the last few days. What I did do though is close the valve on the cylinder a bit more as the water was piping hot coming out before...now its hot enough for our needs and doesnt burn your hand when it comes out of the taps but is still hot enough for dishes

I use the timer on the immersion for hot water in the summertime as normal when the heating is off

alexlyons

is there no thermostat for your hot water tank? set it to the right temp and you'll save a fair bit

heated

It's cheaper to heat water with your boiler than with electricity especially if you have modern heating controls, i.e. seperate zone for hot water cylinder controlled by cylinder stat. With this arrangement and a two channel programmer you will also be able to heat your water during summer months without heating the rest of the house.

air

Using the central heating is certainly cheaper.
I'm on gas myself, and gas is ±5c/kWh while electricity is ±16c/kWh so it's a no brainer really when you are running the heating anyway to heat your house.
I even use the central heating to do it in summer, I turn off the rads so that the heating is only going to the tank and I find it very economical.
The water in your hot tank shouldn't be getting "scalding" hot, you need to turn down your thermostat on the tank. This will help reduce your standing losses.

heinbloed

@ the OP:

What do you pay per used kWh thermal energy (DHW) generated with the two options?

Lex Luthor

alexlyons wrote: »

is there no thermostat for your hot water tank? set it to the right temp and you'll save a fair bit

Ya there is a stat for the immersion heater set to about 60 deg but I presume that is only for the immersion heater and has no effect on the temp of the water cylinder when the heating is used to heat the hot water

heated wrote: »

It's cheaper to heat water with your boiler than with electricity especially if you have modern heating controls, i.e. seperate zone for hot water cylinder controlled by cylinder stat. With this arrangement and a two channel programmer you will also be able to heat your water during summer months without heating the rest of the house.

So am I right in saying what you are suggesting is to have a stat on the cylinder to control the valve that is used for the hot water cylinder for the c/h? ie. If water in tank reaches pre set temp set by stat, then the valve on the outlet of the cylinder is closed thereby no more hot water goes through cylinder from c/h?

air wrote: »

Using the central heating is certainly cheaper.
I'm on gas myself, and gas is ±5c/kWh while electricity is ±16c/kWh so it's a no brainer really when you are running the heating anyway to heat your house.
I even use the central heating to do it in summer, I turn off the rads so that the heating is only going to the tank and I find it very economical.
The water in your hot tank shouldn't be getting "scalding" hot, you need to turn down your thermostat on the tank. This will help reduce your standing losses.

I have a manual 1/4 turn valve in my hot press that I could use to isolate my rads for summer time so c/heating just heats hot water in cylinder. Never used it like this before as I've always just used the electricty immersion heater on a timer for this....do you think it would be more cost effective to use my oil boiler in the summer to heat the hot water than electricty then?

heinbloed wrote: »

@ the OP:

What do you pay per used kWh thermal energy (DHW) generated with the two options?

Good question...havent a clue. How would I work that out?