# Cost per hour of gas heating



## Delboy (22 Jan 2018)

Been doing a bit of detective work on my gas heating following a near €300 bill arriving in for November/December 17 which weren't exactly the coldest months on record.
There is someone in the house during the day so I'd expect high heating costs but €300 totally caught me by surprise.

We don't have the heat on constantly - the only time its set for is 6.00-7.00am to heat the house up before everyone is awake. We usually hit the boost button for 1 to 2 hour slots whenever we feel it needs it (some occupants feel the need to do that more than others!).
So the house is rarely every really warm. It's just grand most of the time.

Over the weekend I worked out that 1 hour of heating only is using 1.6m3 or 17.6kWh (12 rads in total).
Surprisingly having the heat and water running together didn't increase the unit usage by much at all (about 10%).
Using the gas hob wasn't heavy on usage either.

17.6kWh works out at €0.84c incl VAT with the plan I'm on. So if the heating is on for say 5 hours a day (which it easily is I'd guess), that's over €4. Add in water and hob use and it quickly gets to that €300 over 2 months.

I'm only a couple of years in this house and was previously oil before that which wasn't costing much at all (much smaller house however). So the gas bills/cost per hour has proven to be a bit of a shock.

Anyone else work out the gas heating cost per hour and coming up with similar figures of nearly €1?


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## Leo (22 Jan 2018)

You don't say what size the house is, or indicate how well insulated it is. Those will play a very significant role here.

Did you get a BER at the time of buying the current house? That should have given some rough guidance on expected heating costs. You can see some example estimates here for various building types and efficiency ratings here. Note those estimates are based on 'typical occupancy', they don't state what that is anywhere, but I'm guessing that doesn't assume constant occupancy which will result in higher heating & lighting costs.

If you don't have a BER for your property, but your house is typical of an area, look up similar houses that have been on sale of the last while. The online ads should include the BER ratings.


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## jim (22 Jan 2018)

Leo said:


> You don't say what size the house is, or indicate how well insulated it is. Those will play a very significant role here.
> 
> Did you get a BER at the time of buying the current house? That should have given some rough guidance on expected heating costs. You can see some example estimates here for various building types and efficiency ratings here. Note those estimates are based on 'typical occupancy', they don't state what that is anywhere, but I'm guessing that doesn't assume constant occupancy which will result in higher heating & lighting costs.
> 
> If you don't have a BER for your property, but your house is typical of an area, look up similar houses that have been on sale of the last while. The online ads should include the BER ratings.



Im not sure how relevant it is regarding size of house ber rating etc. the question is how much is heating costinng per hour of use. This is going to be the same regradless of how insulated the house is or how many windows are open. Of course those factors would certainly determine the amount of hours you might need your heating on but they arent relevant to cost of usage per unit of time.


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## shweeney (22 Jan 2018)

4-bed semi, built in the 70s so no insulation worth speaking of (except in the attic).
We average about 26000kWh per annum, obviously most of this is October-April, but I have it setup on a level-pay plan to spread it out over the year.  But yeah €300 for 2 months over the winter is not huge in that context.


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## vandriver (22 Jan 2018)

Your bill sounds on par with mine.
I call the constantly jabbing the one hour button boostitis.


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## Delboy (22 Jan 2018)

The BER was C3. All walls have internal insulation except the wall with the stairs.
We had an extension built to the kitchen last year and that room alone would surely be A rated.
House is around 1,800 sq ft now.
Upstairs gets very warm when the rads are on even for a short time. There is no zonal heating.

But as Jim says, not sure how relevant that info is. I'm purely trying to work out if €0.84c is the rough cost of heating per hour and that translates to €5 or so per day for heating during the winter which seems expensive to me.


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## Leo (22 Jan 2018)

The size of the house will have a direct bearing on the boiler model. If you only want to work out an hourly rate, just look at the rating of your boiler. That'll tell you the maximum energy consumption, then just calculate with whatever rate you pay for gas. Typical boilers would be in the 18-35kWh range.

But that alone won't give you the full picture, as factors such as the starting temperature and how thermally efficient the building is will have an impact on the boilers cycle time. When the water returning to the boiler hits a certain tem (how much of the time the burner is running while the heating is on). 

A middle of the road 25kWh boiler could cost around €1.30 to run for a hour assuming it burns for the full hour and you're on a discounted rate of 5.2c/kWh. 

The extension is unlikely to be A-rated. To build to that level without addressing the rest of the house would have little overall effect on energy efficiency as a whole while costing a lot more to build.


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## jim (22 Jan 2018)

Leo said:


> The size of the house will have a direct bearing on the boiler model. If you only want to work out an hourly rate, just look at the rating of your boiler. That'll tell you the maximum energy consumption, then just calculate with whatever rate you pay for gas. Typical boilers would be in the 18-35kWh range.
> 
> But that alone won't give you the full picture, as factors such as the starting temperature and how thermally efficient the building is will have an impact on the boilers cycle time. When the water returning to the boiler hits a certain tem (how much of the time the burner is running while the heating is on).
> 
> ...




Whilst these are of course relevant factors, in terms of the cost associated with heating a house, I think it is over complicating what is a very simple question by the OP. How much do people pay for gas per hour (total bill for the period divided by hours of use in the period).


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## huskerdu (22 Jan 2018)

jim said:


> Im not sure how relevant it is regarding size of house ber rating etc. the question is how much is heating costinng per hour of use. This is going to be the same regradless of how insulated the house is or how many windows are open. Of course those factors would certainly determine the amount of hours you might need your heating on but they arent relevant to cost of usage per unit of time.




Its very relevant. 
If you put the boiler on for an hour and the temp is set at to 70C, the boiler doesnt stay on for an hour, it switches on until the system is at 70c and then switches off and then goes back on when the temp drops to approx 68C and switches on and off enough to keep the system at approx 70C. 

If the house is badly insulated or the doors are open, the rads will cool down quicker and the boiler will have to do more work and use more energy to keep the system at 70C. 

I would consider €300 for two months in winter for a house of that size which is occupied during the day to be fairly normal. 

The best way to lower this is to only heat the rads that are required during the day and turn on the rest of the rads when required ( Dont baulk  at the 3/4 minutes this takes each day, this is the sort of manual zoning my mother did every day of the winter for decades).


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## jim (22 Jan 2018)

huskerdu said:


> Its very relevant.
> If you put the boiler on for an hour and the temp is set at to 70C, the boiler doesnt stay on for an hour, it switches on until the system is at 70c and then switches off and then goes back on when the temp drops to approx 68C and switches on and off enough to keep the system at approx 70C.
> 
> If the house is badly insulated or the doors are open, the rads will cool down quicker and the boiler will have to do more work and use more energy to keep the system at 70C.
> ...



Yes its relevant if your heating is such that it can be set to a temperature. Then its 100% relevant for obvious reasons...if windows are left open heating will stay on longer to reach desird temperature etc.

I was referring to a heating system that you just switch on for a set period as opposed to for a set temperature.


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## huskerdu (22 Jan 2018)

jim said:


> Yes its relevant if your heating is such that it can be set to a temperature. Then its 100% relevant for obvious reasons...if windows are left open heating will stay on longer to reach desird temperature etc.
> 
> I was referring to a heating system that you just switch on for a set period as opposed to for a set temperature.



Same principle applies. The boiler has a temperature that is it aiming heat the system to. 

If you leave the heating on all day, it does not actually run all day, it runs for as long is it needs to, to keep the system at the required temperature.


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## Delboy (22 Jan 2018)

When I switch on the boiler for an hour, it seems to run for the full period. No shut-downs that I can hear.

Anyways, maybe €300 for 2 months in winter is normal. It surprised me and perhaps now explains why OAP's get a winter fuel allowance as it's bloody expensive to heat a house in winter. Much more so than I had expected.


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## Leo (23 Jan 2018)

jim said:


> Yes its relevant if your heating is such that it can be set to a temperature.



The 70C refers to the return temperature, that temp is set at the boiler.


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## Leo (23 Jan 2018)

Delboy said:


> When I switch on the boiler for an hour, it seems to run for the full period. No shut-downs that I can hear.



The circulation pump will run for the whole time the system is switched on, but unless it's a large house or is starting from a low ambient temperature, it's likely the burner cuts in and out.


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## RETIRED2017 (27 Jan 2018)

What make /modelof boiler is it    how old is it  baffles  may need replacing ,


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## Delboy (28 Jan 2018)

Boiler is a Baxi combi make. It's about 10 years old but I had it serviced a few months ago and the lad who worked on it said it could go another 10 years as was in very good nick and was well over 90% efficient when he monitored it.


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