Gas fire v CH

oldskoo1

Would anyone be able to make an educated guess on the following.

I keep my CH on 24/7 on 16 - 18. We boost it to 18 in the evening purely for comfort and turn down to 16 for bed. Our boiler is about 14 years old so unlikely to be super efficient. Our 4 bed house is well insulated and our winter bills are normally very good.

We also have a 80% efficient gas stove. It uses 3 - 4kw of gas.

Would it be cheaper and use less gas to just use the gas fire for 30mins to an hour to get the comfort in the living room for the evening and leave the CH on 16c?


I know ideally to read the meter and test but the variables are so hard to control, like ambient temperature, and the fact that the CH uses the most gas as it starts.

Could anyone give a rough idea based on my situation.

Thanks

HappyMJ

16 °C is far too warm for sleeping in. Get a thicker duvet on all the beds. Get an electric blanket and turn the central heating off. Why are you heating the lounge at night when you are all sleeping in bed?

When you leave the house turn the central heating off. Pointless heating the house when no one is in.

When you say your bills are very good just how much are they?

MillicentBystander

Agreed. Unless there is a risk of a huge freeze, having the heating on in the house whilst you are in bed is crazy.

oldskoo1

We find 16c quite comfortable, even with our winter tog 13.5 duvets.

It's nice to have a warm environment 24/7. Our winter bill is usually around £220 which I think is v.good for the size Of the house. The usage isn't that much more compared to timed which is why we have it on 24/7. Like now for instance, it's 5c outside and the heating hasn't clicked on once. It's the added comfort for not that much more money.

However I wondered more about the gas fire.

twiz21

Could this thread be of any help?

https://forums.moneysavingexpert.com/discussion/3442913

rogerblack

As you say - the best way to do this is to test.
While the variables are hard to control, this can be done.
For the next 8 days.
On day 1,3,5,7 use the fire, on the other days use the CH.
Add up all of the differences in meter reads for the two sets.

This will let you compare reasonably fairly between the two methods, without the exact weather being so important.

HappyMJ

oldskoo1 wrote: »

We find 16c quite comfortable, even with our winter tog 13.5 duvets.

It's nice to have a warm environment 24/7. Our winter bill is usually around £220 which I think is v.good for the size Of the house. The usage isn't that much more compared to timed which is why we have it on 24/7. Like now for instance, it's 5c outside and the heating hasn't clicked on once. It's the added comfort for not that much more money.

However I wondered more about the gas fire.

That's amazing. The heating doesn't click on at all. Here in the midlands right now at 1.00AM it is 8.1 °C outside and the inside temperature without the heating on is 13.5 °C and I have a well insulated double glazed fairly new build semi detached house. The room that has the heating is reading 15.4 °C. It's an oil fillled radiator and it's clicked on and off a few times tonight. It's timed to turn off at 1AM and not come on again until 5AM.

You are enquiring about reducing costs so I am suggesting ways to reduce your bill. Gas central heating is cheaper than a gas fire in almost all cases. The gas fire works by taking the warm air from the room burning it and emitting a radiant heat and the exhaust gases go up the chimney or out the flue taking the warm air with it. The warm air is then replaced with cold air from outside through window or wall vents. A gas boiler takes cold air from outside burns it and heats water and the exhaust gas goes back outside again it doesn't use any of the air from the room.

For a comparison my annual bill is £360 and that's mostly for electric heating.

Ben84

HappyMJ wrote: »

That's amazing. The heating doesn't click on at all. Here in the midlands right now at 1.00AM it is 8.1 °C outside and the inside temperature without the heating on is 13.5 °C and I have a well insulated double glazed fairly new build semi detached house. The room that has the heating is reading 15.4 °C. It's an oil fillled radiator and it's clicked on and off a few times tonight. It's timed to turn off at 1AM and not come on again until 5AM.

You are enquiring about reducing costs so I am suggesting ways to reduce your bill. Gas central heating is cheaper than a gas fire in almost all cases. The gas fire works by taking the warm air from the room burning it and emitting a radiant heat and the exhaust gases go up the chimney or out the flue taking the warm air with it. The warm air is then replaced with cold air from outside through window or wall vents. A gas boiler takes cold air from outside burns it and heats water and the exhaust gas goes back outside again it doesn't use any of the air from the room.

For a comparison my annual bill is £360 and that's mostly for electric heating.

You are assuming everyone has a modern boiler and an old (or far worse a decorative) gas fire. Many older boilers do burn air from the house and some newer gas fires now have external air intakes. An old back boiler might be 60-70% efficient and a new direct vent gas fire well over 80% efficient.

All this aside though, turning on the central heating, even if we assume its efficiency rating is better than the gas fire, usually means heating a much greater area. I would expect that in most cases the large reduction in space being heated more than compensates for some additional energy losses when using a fire. So, gas central heating may be cheaper per unit of energy delivered to the house than some gas fires, but it's not a definitive rule. Also, in almost all cases central heating is going to burn more gas as it's heating more space. There's no way that turning on every radiator in the average three bedroom semi when everyone is spending the evening in the living room is going to be a cost effective option. You really have to decide if you want to heat the whole house or just a room to tell if this is good value or not.

HappyMJ

Ben84 wrote: »

You are assuming everyone has a modern boiler and an old (or far worse a decorative) gas fire. Many older boilers do burn air from the house and some newer gas fires now have external air intakes. An old back boiler might be 60-70% efficient and a new direct vent gas fire well over 80% efficient.

All this aside though, turning on the central heating, even if we assume its efficiency rating is better than the gas fire, usually means heating a much greater area. I would expect that in most cases the large reduction in space being heated more than compensates for some additional energy losses when using a fire. So, gas central heating may be cheaper per unit of energy delivered to the house than some gas fires, but it's not a definitive rule. Also, in almost all cases central heating is going to burn more gas as it's heating more space. There's no way that turning on every radiator in the average three bedroom semi when everyone is spending the evening in the living room is going to be a cost effective option. You really have to decide if you want to heat the whole house or just a room to tell if this is good value or not.

Sorry I was taking the pee a bit. The OP claims the central heating boiler does not come on yet keeps the temperature at 16 somehow which I find impossible. If it doesn't come on then of course it's cheaper to use the gas central heating. It's free. A gas fire is not thermostatically controlled. It's either on or off so therefore usually more expensive.....and I did say also in almost all cases. The OP and everyone else needs to compare the actual costs. The thread referred to earlier by twiz61 is against a 90% efficient gas fire with a 65% efficient gas boiler so in that case the gas fire is cheaper.

oldskoo1

Ok tests are in

Property is a 4 bed detached, UPVC DG, Composite doors, good amount of loft insulation, balanced rads, 14 year old boiler, 78% efficient gas stove.

Scenario 1
Test from 6pm to 10:30pm
CH on 16C all day
Water heated from 6:00pm - 6:30pm (previously heated at 6am - 6:15am)
Gas Fire on high for 30mins - 1hour, then on low for the rest of the evening.

Units used 0.853
KWh used 9.57
Cost 38p


Scenario 2
Test from 6pm to 10:30pm
CH 16C on all day
Apart from boost to 18C between 6pm and 10:30pm
Water heated from 6:00pm - 6:30pm (previously heated at 6am - 6:15am)

Units used 1.096
KWh used 12.30
Cost 49p


Thats around a 30% saving using the fire to heat the living room during the evening instead of boosting the CH. To us it makes sense because we only really use the living room and then it gets turned down to 16 when we go to bed.


Over 24 hours, we are currently consuming £1.37 worth of gas.

Or in 21 days since out last meter submission, 4 people have consumed : £26.04 of gas (typical, 16C 24/7 apart from variable timed boost to 18C in evening) and £19.28 or electricity.

So far so good.


Anyone else thinking of using your fire as an alternative to CH, don't rely on this result; do your own tests because my fire if one of the more efficient types + my house is pretty well insulated and draft proofed. My bills are typically low for the size, hence why we run the ch 24/7.