What's the actual cost of having the heating on? 16 October 2022 at 5:56PM in Energy 30 replies 2.1K views

Naomim

MrM has been to his parents today. His mum had the heating on for two hours this afternoon and an hour this morning. MrM senior is fuming about the cost. He's asked me to work it out but I don't have the brain power.  I just need to give an estimate.

They are with Octopus Energy and gas is 10.34p per kwh. Estimated annual bill is £5k!  I have spoken to them about this but they are set in their ways. MrM senior has been turning off the water tank heating.

Background on house and bills. 1930's house with double glazing. Boiler is 25+ years old and  heats a water tank too. I'm not sure of the wattage of the boiler but it's a big old beast. Central heating is old so it's either on or off. There is one of the old fashioned dials in the hallway.  Radiators can't be turned down or off in rooms not in use so three rooms rarely used are heated. Back room where they sit downstairs has two huge radiators so the room gets very hot and she uses them to dry her washing. 

Hoping someone can help give me an estimate. 

Thanks.

Emmia

I think you'll need meter readings e.g. one at 9am on one day, and 9am the following day to try and estimate the cost.

It's possible a newer, more efficient boiler might save them more money than it costs them to buy / install.

Naomim

I've tried convincing them a new boiler will help and be far more energy efficient. 

I'll see if I can get a couple of sets of readings from them.

Spoonie_Turtle

TRVs on the radiators would hugely help for the rooms that don't need to be heated.

What temperature is the heating set to?

You say they're stuck in their ways, which unfortunately is a common complaint for adult children up and down the country.  The question is, which is more painful: changing, suffering unnecessarily, or a massive bill?  (The answer to that of course will be different for different people/families.)

MattMattMattUK

Naomim said:

I've tried convincing them a new boiler will help and be far more energy efficient. 

I'll see if I can get a couple of sets of readings from them.

A really old boiler might be 75% efficient, a modern condensing boiler can be in the 90-98% range. You need to work out how long it might take to recover the £3-5k cost of the new boiler and installation, the return period would be between 100k and 250k kWh, which is 10-25 years of usage for the average household.

QrizB

Naomim said:

MrM has been to his parents today. His mum had the heating on for two hours this afternoon and an hour this morning. MrM senior is fuming about the cost. He's asked me to work it out but I don't have the brain power.  I just need to give an estimate.

At this time of year it's unlikely to cost a huge amount, since it's still relatively warm outside. A higher-end guess (aand it is only a guess) would be 10kWh for the first hour (to warm the house and system up) and 5kWh for each hour therafter.

So that would be 25kWh for the day, about £2.60-worth.

If it was colder outside, it would cost more.

FreeBear

QrizB said:

Naomim said:

MrM has been to his parents today. His mum had the heating on for two hours this afternoon and an hour this morning. MrM senior is fuming about the cost. He's asked me to work it out but I don't have the brain power.  I just need to give an estimate.

At this time of year it's unlikely to cost a huge amount, since it's still relatively warm outside. A higher-end guess (aand it is only a guess) would be 10kWh for the first hour (to warm the house and system up) and 5kWh for each hour therafter.

So that would be 25kWh for the day, about £2.60-worth.

If it was colder outside, it would cost more.

I'd go 13-16KWh for the first hour and maybe another 10-12KWh for the afternoon burn depending on what the thermostat was set to.

If they have a smart meter, it would be pretty easy to work it out.. And with a 25+ year old boiler, it probably has a pilot light burning through 4.2-6KWh each day.

Fitting a new boiler will trigger a need to fit TRVs and a modern heating control. It would also be worthwhile fitting more modern radiators sized to run at a lower water temperature. If they are getting through £5K of gas per year, a new heating system could cut that in half.

Chrysalis

Yep I have the 24/7 pilot light problem.  That combined with gas SC means most of my gas bill is not for actual usage.  I am sure I am not the only one in this boat.

Mine is about 0.014 m3 per hour, so about 3-4 KwH a day if my maths is right for pilot light.

Not sure why Octopus dont just put KwH usage on the usage dash for gas it be easier.

Miser1964

Such an antique system should give quick payback for basic improvements such as TRV valves and moving from a basic hall thermostat to a roomstat.

Also a dehumidifier may be needed if washing is draped over rads. A damp house always feels colder.

>MrM senior is fuming about the cost<

Yep. Elderly people can get paranoid about heating costs thanks to the media scares,  despite them likely receiving cold weather payments and other benefits. 

An early indication that discussions about financial affairs lasting power of attorney need to be considered by adult children.

BUFF

MattMattMattUK said:

Naomim said:

I've tried convincing them a new boiler will help and be far more energy efficient. 

I'll see if I can get a couple of sets of readings from them.

A really old boiler might be 75% efficient, a modern condensing boiler can be in the 90-98% range. You need to work out how long it might take to recover the £3-5k cost of the new boiler and installation, the return period would be between 100k and 250k kWh, which is 10-25 years of usage for the average household.

It could easily be under 60% efficient (e.g. balanced flue rather than fanned). It wouldn't be unusual for a modern boiler with modern controls (incl. TRVs) to save 30% or more when going from such an old system.

At current prices that could mean a ROI of as low as 3 years.
More info would be useful though.

FreeBear

Chrysalis said:

Yep I have the 24/7 pilot light problem.  That combined with gas SC means most of my gas bill is not for actual usage.  I am sure I am not the only one in this boat.

Same boat here. Now turn the gas off at the meter during the summer months and have my projected consumption down to 4500KWh for the year (vintage Baxi Bermuda back boiler, late 1920s semi).