Calculating the cost of running a boiler

pgw71

Hi

I need to calculate how much it costs to heat a Hall that's used for community groups - so that hire charges can match the costs of heating.

The boiler is a 70KW gas model, and the current energy tariff is 3.044p per kWh, and standing charge of 195.530p per day.

I'm thinking that its a case of multiplying 3.044 x 70 and adding in 1/24th of 195.530. That equates to £2.21 per hour.

Can it be that simple? Or am I just doing it all wrong?

HappyMJ

The standing charge you should add to the hall hire costs. If the hall is hired on average once a week then you would add a weeks worth of standing charges to the cost of hiring the hall dividing that by the average number of times the hall is hired. The heating you could read the meter at the beginning of the hall hire period and at the end of the period and charge for the exact amount used. It's rare that a boiler will use the full 70kW every hour over a period of 6 hours or so.

Wywth

pgw71 wrote: »

Hi

I need to calculate how much it costs to heat a Hall that's used for community groups - so that hire charges can match the costs of heating.

The boiler is a 70KW gas model, and the current energy tariff is 3.044p per kWh, and standing charge of 195.530p per day.

I'm thinking that its a case of multiplying 3.044 x 70 and adding in 1/24th of 195.530. That equates to £2.21 per hour.

Can it be that simple? Or am I just doing it all wrong?

Take the annual heating costs and divide them pro-rata across the days you let the hall out.

Otherwise you will need to explain to Mr Jones why he is paying a different price for hiring the hall for his AGM in May to that of Mrs Smith who hires it for the same duration in December.

And what if it was hired at the beginning of this month when the average temperature was above normal compared with recent days when the average temperature is below average? Would that result in different costs? How would you be able to quote in advance?

And unless you follow my advice, how would you fund periods the hall was not let?

I would urge you to get an accountant.

pgw71

Perhaps I should clarify

We're well aware that hire charges reflect a range of costs - gas, electric, insurance, maintenance, 'wear and tear' etc - so I'm not suggesting a straight line between the boiler cost and hire charges. And, yes, obviously, it varies seasonly...

But, putting that to one side, we still do need to be able to calculate the cost of running the gas boiler. It's also partly because we have a thought that we might replace it with something more economical when funds permit

So, back to the opening post, can someone tell me whether my calculation is valid?

rogerblack

pgw71 wrote: »

P
So, back to the opening post, can someone tell me whether my calculation is valid?

No.
That is the maximum.
It will vary with outside conditions, the internal temperature, and to some degree usage.

Approximations.
To heat the building from cold will need the boiler on full for a period roughly proportional to the difference between the temperature inside and out.
To maintain the building at a constant temperature will need an amount of gas per hour again dependant on temperature difference.

Then there is the complication that a hall with 70 people in may need less heating due to their heat output.

The boiler will (hopefully) be sized so that it can warm the hall promptly even in cold weather.
But it will take some time - if you want it warm for an hours meeting it will have to be turned on some time beforehand.

Unfortunately, you need to actually measure it.
Measure temperature outside, and then read the meter.
Turn it on, wait for it to get to temperature, wait an hour, and then read the energy use so far.
Wait, and read the second hours.


The first gives you a figure representing the amount of gas needed to warm it up and keep it warm for an hour - the second is how much is needed to keep it warm only.

If the difference between inside and outside temps was 15C (5C out, 20C in), then divide this by 15, to get the amount the heating will cost per degree of difference.