Calculating Heating for one hour

cmbrookes

Can anyone tell me what I need to do to calculate how much it’s costing me to set my central heating to be on constantly for one hour. I’ve set it on the thermostat at a certain time to come on for one hour.

thanks

[Deleted User]

Read your meter before and after.

It's not a useful thing to know really though.

[Deleted User]

Get a smart meter and download the free App BRIGHT. If the supplier has sent the correct tariff to the meters, then the App will also show 30min; daily; weekly; monthly costs.



No two houses; boilers; boiler flow temperatures etc are the same. This is my 30 minute usage for today in kWh. I have a 24kW boiler.

Olly_J

cmbrookes said:

Can anyone tell me what I need to do to calculate how much it’s costing me to set my central heating to be on constantly for one hour. I’ve set it on the thermostat at a certain time to come on for one hour.

thanks

The first hour or two is always going to be the most costly, after which it will level off to equal the heat loss from the property, like below, so running it for a single hour is not an efficient way to run, as you are paying all the money, but for little benefit, whereas once heated up you can run for longer for a little more

cmbrookes

Olly_J said:

cmbrookes said:

Can anyone tell me what I need to do to calculate how much it’s costing me to set my central heating to be on constantly for one hour. I’ve set it on the thermostat at a certain time to come on for one hour.

thanks

The first hour or two is always going to be the most costly, after which it will level off to equal the heat loss from the property, like below, so running it for a single hour is not an efficient way to run, as you are paying all the money, but for little benefit, whereas once heated up you can run for longer for a little more

My boiler stays on but the thermostat knocks off when it reaches a certain temperature until the room temp drops below what I set it to heat to. 

victor2

cmbrookes said:

Can anyone tell me what I need to do to calculate how much it’s costing me to set my central heating to be on constantly for one hour. I’ve set it on the thermostat at a certain time to come on for one hour.

thanks

As you can see from the post by @[Deleted User] above, the energy used (and therefore the cost) varies tremendously for a one hour period.

If it's the first hour of heating up a cold house, it will be relatively high, where the next hour will be significantly lower.

Then there's the number of radiators, the individual controls they have, the rooms you are heating, the outside temperature etc. etc.

j.a.mcguire

Deleted_User said:

It's not a useful thing to know really though.

What makes you say that?

macman

j.a.mcguire said:

Deleted_User said:

It's not a useful thing to know really though.

What makes you say that?

For all the reasons quoted above. What you want is to know the average based on a week, a month, a winter...
In the first hour in a cold house, the boiler will run at a high output. As it gets nearer to the set temp, it will modulate back. So the first hour from start up will always be more expensive.
Would you measure your car's mpg based on how much it used in one hour? Or over the whole journey?

[Deleted User]

j.a.mcguire said:

Deleted_User said:

It's not a useful thing to know really though.

What makes you say that?

Exactly as macman, Dolor and victor2 say.

People ask the question "how much does my heating cost to run for an hour" when actually they mean "how much will it cost to keep my house at temperature X".  Measuring just the start-up cost in isolation isn't normally what they really want, and often gives a misleading impression that the heating is extremely expensive.

cmbrookes

So is it a good idea to set my the timer on my thermostat to say 0600 until 1200 to 22 degrees then when the room reaches 22 degrees the thermostat will turn off but the boiler will still be on? Wouldn’t this cost me a lot due to the boiler still working it’s magic even though the the thermostat would be off?

InvertedVee

cmbrookes said:

So is it a good idea to set my the timer on my thermostat to say 0600 until 1200 to 22 degrees then when the room reaches 22 degrees the thermostat will turn off but the boiler will still be on? Wouldn’t this cost me a lot due to the boiler still working it’s magic even though the the thermostat would be off?

It's not easy to say what's best. Your pattern of occupancy, standards of insulation, size and layout of house and the efficiencies and limitations of your heating system all affect things.

Many of us have found that running a condensing boiler for long periods at low demand is much better than allowing the house to go cold. It means a more gentle task for the boiler which can work at higher efficiency. For this you would need to choose

• a set temperature for most of the day (I aim for 19.5 between 0600 and 2300) and a setback for night-time which is not far below (I use 17.5), 
• a boiler flow temperature which is sufficient to maintain the required temperatures but no more. I find I can use 48C on my combi, even in this very cold weather. (You would need to set it at a higher temperature if you have a hot water cylinder because of the risk of Legionnaires' Disease.)
• Don't over-restrict your 'emitting surfaces'. Turning down radiator TRVs might look like a way to save money but this will limit the boiler's ability to give away its heat. It's like driving a car with the brakes on. You'll be forced to run a hotter, less efficient flow temperature. Also remember that radiators filled with sludge or air won't emit heat efficiently.

I can't promise that this will suit your home and lifestyle. Some people on this forum have preferred to run a much cooler home with occasional runs of the heating system at high output. I recommend running some tests and find out what works for you. But you'll need to be patient and monitor your gas use daily for at least 3 days. (There's a lot of lag in warming the fabric of a house). You might be surprised that it doesn't cost as much as you fear to keep your home warm and dry, which is healthy for you and for the building. At worst, you'll find that your home isn't economical for you, which might help inform decisions about investing in improvements or even relocating to something manageable.