Has anyone gone back to using a timer on the electric immersion heater for cheaper hot water rather

Gobsh

Has anyone gone back to using a timer on the electric immersion heater for cheaper hot water rather than using a gas boiler?

At the moment we're heating the water with gas twice a day for an hour for baths and showers, and I was wondering about whether to install a timer on the immersion heater to heat it by electricity which will be cheaper than the gas I guess

QrizB

Gobsh said:

At the moment we're heating the water with gas twice a day for an hour for baths and showers, and I was wondering about whether to install a timer on the immersion heater to heat it by electricity which will be cheaper than the gas I guess

Even on the October cap, electricity is more than 3x the price of gas.

pochase

The only scenario where that would be the case if you have an old inefficient boiler with a pilot light.

The pilot light might use so much energy that it the price advantage of gas gets lost. 

For a boiler installed this millennium gas will be cheaper.

JohnPo

Gobsh said:

Has anyone gone back to using a timer on the electric immersion heater for cheaper hot water rather than using a gas boiler?

At the moment we're heating the water with gas twice a day for an hour for baths and showers, and I was wondering about whether to install a timer on the immersion heater to heat it by electricity which will be cheaper than the gas I guess

Yes - I currently do that but ONLY because of the cheap night rate with my EV tariff (I use a optimum Wifi immersion heater timer).  As other's have said at normal rates, gas will definitely be cheaper even accounting for losses in the boiler itself and pipework for the usage you describe.

Tarmacexpert1962

Typical Immersion runs at 3 Kwh so about £1.56 per hour, on new Oct prices, my boiler uses about 7 kw when running for one hour so about  £1.05 per hour on Oct Prices when purely heating the Hot Water Cylinder  (New 32KW Worcester Bosch Boiler). Just a guide as so many variables but I do have a timed immersion, for me at the moment seems gas is still the cheaper option by about one Third. I have found that just reducing the timer to one hour a day is sufficient and boost it if needed. One tip is lag your Hot Water Cylinder more even if its foam dipped, my cylinder was foam dipped but I added a Screwfix Padded Insulation Jacket  + Foam pipe insulation for just £12 and its made a huge difference in the water staying hot all day and even longer. I have been amazed at the difference in heat retention. 

[Deleted User]

It is not a simple gas price versus electricity price equation. I use solar diversion for HW heating from March through until October, and gas over the Winter Period. 

Gas heating is in a single 3 hour window and electricity heating is when the sun shines.

My average gas consumption is about 7kWh/day. Yesterday, reheating the cylinder with electricity used 3.9kWh.

Every home will be different, but the key factors are:

1. When a gas boiler is heating water it runs at a flow temperature of TMaxSet; ie, there is no condensing. This is to give faster re-heating times.

2. The boiler flow also has to heat up the water in the pipes. Unless these are lagged, they act as mini radiators so heat is lost/radiated to the surroundings.

3. Whilst the water temperature in the cylinder circuit is heating, then the temperature of the water in the cylinder will fall as heat is removed via the coil.

4. All gas boilers are less efficient than an immersion heater.

Slinky

Gobsh said:

Has anyone gone back to using a timer on the electric immersion heater for cheaper hot water rather than using a gas boiler?

At the moment we're heating the water with gas twice a day for an hour for baths and showers, and I was wondering about whether to install a timer on the immersion heater to heat it by electricity which will be cheaper than the gas I guess

How many in your household? Twice a day for an hour each time? Or twice a day for an hour total?

We're currently having to use the immersion because we're having a new boiler installed and the old one has been switched off. We use ours for 40 minutes daily on E7 and that's enough for 2 showers and some dishwashing.

spongeh

pochase said:

The only scenario where that would be the case if you have an old inefficient boiler with a pilot light.

The pilot light might use so much energy that it the price advantage of gas gets lost. 

For a boiler installed this millennium gas will be cheaper.

We had our 1980s boiler replaced a couple of months ago with the latest Worchester Bosch and once I'd done the calculations I was amazed at how much the pilot light used, we're now heating our water tank twice a day for a 1/3 of the cost of just the pilot light.

[Deleted User]

spongeh said:

pochase said:

The only scenario where that would be the case if you have an old inefficient boiler with a pilot light.

The pilot light might use so much energy that it the price advantage of gas gets lost. 

For a boiler installed this millennium gas will be cheaper.

We had our 1980s boiler replaced a couple of months ago with the latest Worchester Bosch and once I'd done the calculations I was amazed at how much the pilot light used, we're now heating our water tank twice a day for a 1/3 of the cost of just the pilot light.

I will bet my pension that your new boiler will not last 30 years. Old boilers with cast iron heat exchangers were built like tanks. My 4 year old WB has already had a new fan; heat exchanger and syphon.

A word to the wise. It is worth paying for a Worcester Bosch engineer to carry out your first boiler service. They have a PC which contains the build/set up parameters for your boiler. This information is not available to a GSE. The engineer also had all the replacement parts on his van.

Scrounger

pochase said:

The only scenario where that would be the case if you have an old inefficient boiler with a pilot light.

The pilot light might use so much energy that it the price advantage of gas gets lost. 

For a boiler installed this millennium gas will be cheaper.

This is my situation exactly: 50,000BTU Potterton Kingfisher II boiler (bought s/h for £50 out of the paper) installed mid-1990's, gravity hot water, single pipe c/h.

Even though my gas is cheap at only 3.64p/kWh, I've found it's cheaper for me to use my last hour of E7 electric (@ 10.40p/kWh off-peak) on a timer to heat my water  The gas boiler is currently shut down.
(These unit prices include vat and my energy plan is fixed until March 24)

My E7 electric usage is currently 40% so well worth having.

EDF recently suggested reducing my DD from £125/month to £79/month but I told them to keep it at £125 - as I don't want to be cold this winter!

I've looked at upgrading the boiler but that would cost ££, be more unreliable and there's nowhere to run a condensate pipe.


Scrounger

Section62

[Deleted User] said:

Every home will be different, but the key factors are:

1. When a gas boiler is heating water it runs at a flow temperature of TMaxSet; ie, there is no condensing. This is to give faster re-heating times.

2. The boiler flow also has to heat up the water in the pipes. Unless these are lagged, they act as mini radiators so heat is lost/radiated to the surroundings.

3. Whilst the water temperature in the cylinder circuit is heating, then the temperature of the water in the cylinder will fall as heat is removed via the coil.

4. All gas boilers are less efficient than an immersion heater.

6. In most cases the physical position of the cylinder stat for the gas system will be different to the (effective) position of the immersion heater stat, meaning different volumes of water are heated to the set temperature.