Cost to have heating on per hour? 2 bedroom semi

Legacy_user

What would the cost be? 18 degrees required temp

Cardew

That is a 'how long is a piece of string' question!


Firstly Gas or Electric heating.


Assuming gas, how big is your boiler in kW.


What is the start temperature?


How cold outside?


What sort of insulation?


Assuming you are heating from a cold temperature, the boiler would run at full output. With gas at 3.5p a unit(kWh) a figure might be around 80p for the first hour.


When up to 18C a figure of 20p an hour to maintain that temperature would be a good guess.

HappyMJ

berbastrike wrote: »

What would the cost be? 18 degrees required temp

Cost to maintain 18 degrees in my property is under 6 pence per hour.

That figure assumes it is 12 degrees outside. If it's colder out the heat loss from the property is higher and therefore it costs more to maintain the heat. It's around 1 penny per hour per degree difference so if it's 18 outside it'll cost nothing to heat and if it is a freezing 0 degrees outside it'll cost about 18 pence per hour to maintain 18 degrees.

That figure also assumes a smallish property. Mine is 58 square metres. It's also very well insulated with full double glazing and cavity insulation. Floors and ceiling are also well insulated.

The figure also assumes heating is left on 24 hours a day 7 days a week.

You can get the average temperature of the last month from a local weather station then figure out what it cost to heat the property. You will need a summer bill to deduct normal usage for hot water and cooking so you get the additional cost of heating only.

I pay £45 for both gas and electricity per month on a dual fuel online managed fixed rate tariff with Scottish Power paid by direct debit.

MeterMan

Lets guess at your boiler being 28kw

And lets guess that you pay 4p pkwh

IF your boiler is running at full rate for 1 solid hour, it will use 28kw's of gas. If you times this by the 4pence you pay per kilowatt, we can roughly sumise that it shall cost you £1.12p per hour.

That being said, there are far to many variables.

Insulation, outside temperature, and not to mention that most boilers wont run at full rate, If it did, then the boiler is too small for the house.

System

Would a 28kw boiler not only use 28kw when it was set at the maximum temperate, for example 37 degrees or something?

matelodave

No a 28kw boiler will output 28kw when it's going flat out. It will do that until the either the room stat or boiler stat turns it off. Although as it's only about 90% efficient it will consume about 30-31kwh.

If the house is cold then the boiler will work hard to increase the house temperature to the thermostat setting, this could take several hours depending on how much it's got to raise the temperature by.

Once the place has reached the target temperature the thermostat will shut down the boiler and just fire it up when the temperature drops a degree or so to maintain the target temperature.

As said above if the outside temperature is 18 degrees then the boiler wont fire at all as the house should be at 18 degrees and wont lose any heat. Any less and the boiler will kick on and off to balance the heat loss once it's brought the house up to temperature.

HappyMJ

berbastrike wrote: »

Would a 28kw boiler not only use 28kw when it was set at the maximum temperate, for example 37 degrees or something?

It's very rare for a 28kW boiler to actually use the full 28kW in one hour. The temperature of the boiler has to be set at maximum. The thermostat has to be calling for heat. The return temperature of the water has to be low enough to require more heat to be added to the water. Most of the time the return temperature of the water is too high and the gas burner either shuts off or the burner flame is lowered so not as much is required. The pump still runs until the return water temperature is low enough and the boiler restarts the flame.

You would probably only ever see a 28kW boiler use the full 28kW when enough hot water is being drawn off for the full hour. That's also very unlikely unless you like having an hour long power shower.....but...you would be more worried about the cost of water than either the gas or electricity. My power shower uses at least 15 litres per minute which would be about 1,000 litres in one hour at a cost of £2.50 just for the water let alone the cost of gas and electricity used to heat and pump the water.

MeterMan

a boiler will use it full rate or there close, to get the internal boiler up to temperature, once its reached temperature the boiler will lower the rate at which it runs at.

You need to concentrate on the thermal efficiency of your radiators and house in order to limit the length of time the boiler is running for.

If your control device is set for one hours run time, the house might reach the thermostat temperature within half an hour, once achieved the boiler will turn off, but if within the rest of the hour the temperature around the thermostat drops then the boiler will fire up again.