Unsure about kWh

JessandJon_3

Hi

I wonder if anyone could help.  I appreciate I may be embarrassing myself asking such an obvious question.

i am wanting to work out how much it costs to run my boiler/central heating  for an hour.  It’s a newish boiler A energy rated 

It’s a 26w boiler my new kWh cost will be 0.728 a kwh.  The way I’ve worked it out is that it’s essentially 26x0.728 an hour to run, which seems extortionate.  Is this the correct way to work it out and would it be that cost regardless of whether I run it at 16 or 18deg on room thermostat.

currently we’ve had no hearing at all for the past few days ( usually use a gas fire to
heat a single room, but this was condemned over the weekend) . I’m scared to put the heating on as cannot work out the cost.  The radiators are very old and the man from British Gas said they needed changing to double skinned ones, which unfortunately we cannot afford.  Since I need to save to replace the fire I wondered how much itll cost to run the heating a little as my daughters room was just 12deg this morning. 

sorry for the rambling 

Ultrasonic

Lower room temperature means the central heating boiler won't need to run for as long and so definitely saves money. It's best to just monitor total energy used per day rather than doing theoretical calculations for short time periods.

Phlik

The boiler will be 26kw max output and your units will be £0.0728 pence per kWh.

So for the boiler running at max output for an hour (which it won't unless you're filling a swimming pool) would be £1.89

It won't run at max output for an hour, think of it like an oven, once it reaches the set temperature it will click off and on to maintain it.

I think the max boiler rating is for hot water only, the rating for the central heating is lower, hopefully someone else can confirm our deny, me memory isn't what it once was

MWT

JessandJon_3 said:

It’s a 26w boiler my new kWh cost will be 0.728 a kwh. 

I think you have missed a zero in there, that should probably be £0.0728/kWh and that is most likely your price from April 1st, right now it should be cheaper.

Your boiler will not run at full power for the entire time either so it is going to cost you less than you think.

JessandJon_3

Thank you.  Guess I’m just so worried about the price increase ( as is everyone I know).  Scared to even put it on at the moment.  It was exceptionally cold last night the hallway 10 and lounge 11deg respectively so know I need to have some plan to heat. 

I’ve agreed to a smart meter to try see exactly how much it costs to run heating thermostat at max 16deg maybe an hour in morning and at night.


The engineer form British Gas said that my now condemned gas fire used 2-4kwh, but since my boiler was A rated and if I got new radiators would be cheaper to run the central
heating.  I really don’t understand how 26kwh costs less than 2-4.

Verdigris

You've missed a decimal point. 0.0728.

Remember your boiler won't be firing the whole time, so you'd need to observe it for an extended period to get an idea of how long it is firing for. Also, it will fire for longer in colder weather, of course. This will also be an ideal opportunity to check for short-cycling. If the boiler seems to fire up and down, frequently, for short periods, that is an indication that your return tempertures are too high. This reduces the efficiency of the boiler because it is not able to go into condensing mode, so you'll be throwing unnecessary heat out of the flue.

New, high output, radiators would help ensure return temperatures are lower, thus improving efficiency, but adjusting the the flows on the ones you've got could ensure you get better heat output and burnless gas.

Oh, and a final thought, a modern boiler will have a modulating burner, so it won't be running at 26kW the whole time it is burning, so you'll never get a totally accurate figure from timings. Probably better to take meter readings (some go to three decimal places), over a period, to work out what volume of gas is being consumed. The formulas for coverting volume (cubic metres or cubic feet) will be on your gas bills. If you have a smart meter, that may have a setting to read kWh directly.

Phlik

If your old boiler was too small for the number of radiators or size of house then it would have to work at maximum output for longer to reach the desired temperature.  Whereas a correctly sized setup or even slightly oversized may have the ability to use more they generally won't because they have suitable capacity to reach the desired temperature quickly and then use less maintaining the temperature.

[Deleted User]

Hi,

read gas meter, just put heating on for a normal day, read meter again next morning.

Deduct first reading from second reading = units used.

Now depending if metric meter, m3,

or imperial meter, cubic feet,

for a rough calculation, if metric multiply units used by 11.2 x price per unit

for imperial multiply units used by 32 x price per unit.

Gerry1

Much easier to think in terms of a kWh costing 7.28p from 1 April, less risk of getting it wrong by a factor of 10 or 100 !

Don't forget that the price per kWh shown on a bill will need to have 5% VAT added.

[Deleted User]

JessandJon_3 said:

Hi

I wonder if anyone could help.  I appreciate I may be embarrassing myself asking such an obvious question.

i am wanting to work out how much it costs to run my boiler/central heating  for an hour.  It’s a newish boiler A energy rated 

It’s a 26w boiler my new kWh cost will be 0.728 a kwh.  The way I’ve worked it out is that it’s essentially 26x0.728 an hour to run, which seems extortionate.  Is this the correct way to work it out and would it be that cost regardless of whether I run it at 16 or 18deg on room thermostat.

currently we’ve had no hearing at all for the past few days ( usually use a gas fire to
heat a single room, but this was condemned over the weekend) . I’m scared to put the heating on as cannot work out the cost.  The radiators are very old and the man from British Gas said they needed changing to double skinned ones, which unfortunately we cannot afford.  Since I need to save to replace the fire I wondered how much itll cost to run the heating a little as my daughters room was just 12deg this morning. 

sorry for the rambling 

I do have an IHD device, linked to both of my smart meters, which gives me additional information re how many kWh my utilities use.  So this morning the CH has been on for approximately 2 hours warming a cold house from 13C to 18C - it is now off with the thermostat left now at 17C.  The boiler flow rate for the rads has been reduced to 50C so the rads are not scaulding hot obviously.  Yes the heating takes longer to get to the set temperature but the combination boiler is is not working as hard as say a flow temperature of say 65-70C.  My boiler is rated at 32kW but as other posters have mentioned this is just the peak power rating so I would not expect it to run at this power for all the time it is firing up  So the kWh used for this 2 hour period today has only been approx 14.4kWh of Gas.  All bar 2 of my rads are set at max on the TRV's.  Paying my current gas rate of 3.75p/kWh this has cost approximately 54p.  Obviously if you paying gas at the present cap this usage would cost more like £1 for the same kWh.  Remember that the boiler will be working at its hardest whilst it is bringing the flow temperature up to whatever it is set at in the boiler controls i.e at the beginning.

If you don't have an IHD linked to your boiler just do an experiment where you fire up the boiler (to provide CH) from say 13C up to 18C (or whatever you feel comfortable with) and make a note of the start and ending gas meter reads (inc the decimals) and you can convert this fairly easily into kWh and thus give you an idea of the actual cost.  I'm sure posters will provide the calculation for your particular circumstances if you are unsure of how to do this.   

Gerry1

DerwentMailman said:

JessandJon_3 said:

Hi

I wonder if anyone could help.  I appreciate I may be embarrassing myself asking such an obvious question.

i am wanting to work out how much it costs to run my boiler/central heating  for an hour.  It’s a newish boiler A energy rated 

It’s a 26w boiler my new kWh cost will be 0.728 a kwh.  The way I’ve worked it out is that it’s essentially 26x0.728 an hour to run, which seems extortionate.  Is this the correct way to work it out and would it be that cost regardless of whether I run it at 16 or 18deg on room thermostat.

currently we’ve had no hearing at all for the past few days ( usually use a gas fire to
heat a single room, but this was condemned over the weekend) . I’m scared to put the heating on as cannot work out the cost.  The radiators are very old and the man from British Gas said they needed changing to double skinned ones, which unfortunately we cannot afford.  Since I need to save to replace the fire I wondered how much itll cost to run the heating a little as my daughters room was just 12deg this morning. 

sorry for the rambling 

If you don't have an IHD linked to your boiler just do an experiment where you fire up the boiler (to provide CH) from say 13C up to 18C (or whatever you feel comfortable with) and make a note of the start and ending gas meter reads (inc the decimals) and you can convert this fairly easily into kWh and thus give you an idea of the actual cost.  I'm sure posters will provide the calculation for your particular circumstances if you are unsure of how to do this.   

Gas kWh Conversion (Scroll down)