Energy myth-busting: Is it cheaper to have heating on all day?

Heinzbean

That was just created from the information from previous gas bills.......ft3 readings .So completley GAS usage.

I need to find some way of including the temps...but would have to have recorded them. So any ideas ??

Swipe

Heinzbean said:

That was just created from the information from previous gas bills.......ft3 readings .So completley GAS usage.

I need to find some way of including the temps...but would have to have recorded them. So any ideas ??

Historical temps will be available from this website

https://www.timeanddate.com/weather/uk/

Spies

I record my own outdoor temperatures so I should be able to compare apples with apples. 

Still waiting for data which doesn't include extra gas usage in the form of hob and shower. 

tux900

Heinzbean said:

That was just created from the information from previous gas bills.......ft3 readings .So completley GAS usage.

I need to find some way of including the temps...but would have to have recorded them. So any ideas ??

'Degree days' are what you're interested in here, and the aptly named Degree Days website will provide you them for any given date range for a monitoring station near you. 

Heinzbean

i previously posted on this thread that my boiler would cost  24kWh x 4.01p = 96p an hour.to run..Someone pointed out that my calculation was incorrect and you cannot work out the boiler running costs this way. They are probably right.

So i run my boiler for 20 minutes (timed accurately) monitored the gas meter it showed 1418 7/10 before and 1418  9/10 after wards. So 2/10  = 1/5 of a ft 3 (old meter).  1 ft3 = 31Kw of gas so 0.2 x 31=  6.2 Kw of gas (20 min) 6.2 x3 = 18.6 kw (for the hour). so my boiler uses 18.6 kw x 4.01p =  74.5p per hour to run........

I have found a couple of sites that were calculating the gas usage probably the wrong way.................

QrizB

Thanks for the info!

My GCH has an 18kW boiler.

• During October, my GCH was running for 1hr 50mins each day for DHW only. Over 31 days (~57 hrs running) it used 347kWh, an average of 6kW.
• I switched the heating on on the 2nd of November, for 6 hours a day. The hours for heating and DHW overlap. Over 12 days (72 hrs running) it has used 358kWh, an average of 5kW.

I guess all this really proves is that my thermostats work

milgo

Albeit you switch your heating on for 6 hours, surely it's not running for the full 6 hours unless your thermostat is set to 30 c

QrizB

milgo said:

Albeit you switch your heating on for 6 hours, surely it's not running for the full 6 hours unless your thermostat is set to 30 c

Agreed, and the same for the hot water; once the tank is hot the boiler turns off.

Heinzbean

Heinzbean said:

i previously posted on this thread that my boiler would cost  24kWh x 4.01p = 96p an hour.to run..Someone pointed out that my calculation was incorrect and you cannot work out the boiler running costs this way. They are probably right.

So i run my boiler for 20 minutes (timed accurately) monitored the gas meter it showed 1418 7/10 before and 1418  9/10 after wards. So 2/10  = 1/5 of a ft 3 (old meter).  1 ft3 = 31Kw of gas so 0.2 x 31=  6.2 Kw of gas (20 min) 6.2 x3 = 18.6 kw (for the hour). so my boiler uses 18.6 kw x 4.01p =  74.5p per hour to run........

I have found a couple of sites that were calculating the gas usage probably the wrong way.................

But having a cup of tea and thinking about it some more.if my 10ths  wheel was 1/2 around (on the way to 3/10). this would change the whole calc.
2.5/10 = 1/4 of 1ft 3= 31kw gas 0.25 x31 =7.75kw (20 mins)  7.75kw x 3 = 23.25 kw (1 hour) 23.25 x4.01 = £0.93p per hour.like my original workings out. Dam the old fashioned meter ...I think i need modern smart metering where i can monitor it online.

Petriix

Heinzbean said:

Heinzbean said:

i previously posted on this thread that my boiler would cost  24kWh x 4.01p = 96p an hour.to run..Someone pointed out that my calculation was incorrect and you cannot work out the boiler running costs this way. They are probably right.

So i run my boiler for 20 minutes (timed accurately) monitored the gas meter it showed 1418 7/10 before and 1418  9/10 after wards. So 2/10  = 1/5 of a ft 3 (old meter).  1 ft3 = 31Kw of gas so 0.2 x 31=  6.2 Kw of gas (20 min) 6.2 x3 = 18.6 kw (for the hour). so my boiler uses 18.6 kw x 4.01p =  74.5p per hour to run........

I have found a couple of sites that were calculating the gas usage probably the wrong way.................

But having a cup of tea and thinking about it some more.if my 10ths  wheel was 1/2 around (on the way to 3/10). this would change the whole calc.
2.5/10 = 1/4 of 1ft 3= 31kw gas 0.25 x31 =7.75kw (20 mins)  7.75kw x 3 = 23.25 kw (1 hour) 23.25 x4.01 = £0.93p per hour.like my original workings out. Dam the old fashioned meter ...I think i need modern smart metering where i can monitor it online.

The first 20 minutes of running the boiler are obviously going to use more energy than any subsequent period. Once the system is up to temperature, the boiler will modulate the power rather than running at full whack. Then, once the air is up to temperature, the thermostat will stop demanding heat from the boiler and it will use even less power.

My smart thermostat records the length of time that heat is demanded from the boiler. I can roughly estimate the amount of gas used for cooking and hot water and extrapolate how much gas is required (on average) per hour of demand for heat.

In the last 12 months my heating has been 'on' (thermostat asking for heat from the boiler) for just under 400h, using around 5,000kWh of gas (with about 3,000kWh for cooking and hot water out of the ~8,000kWh total). So, my 28kW boiler averages about 12.5kW while it's 'on'.