Cheapest way to use gas central heating

oldskoo1

As mentioned the cheapest is off but everyone needs a comfortable house

I personally dont like the skin check method. Our skin is essentially a super thermostat as we can detect minute changes in air temperature but we are always too quick to whack up the heating.

I think some others here have hashed out the best way to configure everything.

Essentially, make sure you have the TRV set to max on the hall radiator. Most TRV's follow similar temperature ranges so... 2 - 2.5 for bedrooms, 3 for living spaces and back down to 2 for small rooms or rooms used infrequently. 2 - 2.5 is around 18c - 20c (comfortable sleeping temp). 3 is around 20-23c comfortable living temp.

This ensures that once the radiators have reached temperature they should off and direct hot water elsewhere. Ideally this should be matched with well balanced radiators. As you have just had a system refit hopefully they will be well balanced already.

As for the timings, the hall is usually quite drafty so try to ensure you have fitted draft excluders, keyhole covers, closed windows etc but dont close window vents, keep air flow moving where intended. Normally 18c is a pretty good starting temp in the hall. Providing you have the correct sized radiators your living rooms should have no issue hitting their desired temperature.

I ran many experiments over the last 3 years and keep a log of meter readings as i have to using co-op. The lower the temp the better but not at the expense of health obviously. Turning if off overnight saved around 12%-15% in costs. But if you ran it 21c timed and switched to 18c 24/7 you would see a negligible difference in cost.

But switching from 18c 24/7 to 18c timed saved you that further 12% - 15%. Proving you do a decent job of setting up the system and it is running efficiently only having the heating on when you need it at a realistic temperature like 18c is the cheaper it will ever be.

We have people home all day so our heating comes on just before 6am and goes off at 11pm. The biggest factor in all of this is of course the outside temperature.

thor

oldskoo1 wrote: »

Turning if off overnight saved around 12%-15% in costs.

What was the previous more costly configuration? Were all the TRVs on the radiators turned off when the thermostat was turned up?
Essentially I am asking were the savings made even though the radiators were not providing any heat before or after the thermostat was turned off?

macman

thor wrote: »

What was the previous more costly configuration? Were all the TRVs on the radiators turned off when the thermostat was turned up?
Essentially I am asking were the savings made even though the radiators were not providing any heat before or after the thermostat was turned off?

Such an 'apparent' saving is impossible to verify, as it would depend on the ambient temps being exactly the same every night over the two periods being compared. It would also depend on all the 'non-heating' gas consumption also being exactly the same. So it's an approximation at best.

Likestowrite

oldskoo1 wrote: »

As mentioned the cheapest is off but everyone needs a comfortable house

I personally dont like the skin check method. Our skin is essentially a super thermostat as we can detect minute changes in air temperature but we are always too quick to whack up the heating.

I think some others here have hashed out the best way to configure everything.

Essentially, make sure you have the TRV set to max on the hall radiator. Most TRV's follow similar temperature ranges so... 2 - 2.5 for bedrooms, 3 for living spaces and back down to 2 for small rooms or rooms used infrequently. 2 - 2.5 is around 18c - 20c (comfortable sleeping temp). 3 is around 20-23c comfortable living temp.

This ensures that once the radiators have reached temperature they should off and direct hot water elsewhere. Ideally this should be matched with well balanced radiators. As you have just had a system refit hopefully they will be well balanced already.

As for the timings, the hall is usually quite drafty so try to ensure you have fitted draft excluders, keyhole covers, closed windows etc but dont close window vents, keep air flow moving where intended. Normally 18c is a pretty good starting temp in the hall. Providing you have the correct sized radiators your living rooms should have no issue hitting their desired temperature.

I ran many experiments over the last 3 years and keep a log of meter readings as i have to using co-op. The lower the temp the better but not at the expense of health obviously. Turning if off overnight saved around 12%-15% in costs. But if you ran it 21c timed and switched to 18c 24/7 you would see a negligible difference in cost.

But switching from 18c 24/7 to 18c timed saved you that further 12% - 15%. Proving you do a decent job of setting up the system and it is running efficiently only having the heating on when you need it at a realistic temperature like 18c is the cheaper it will ever be.

We have people home all day so our heating comes on just before 6am and goes off at 11pm. The biggest factor in all of this is of course the outside temperature.

Thank you. Very helpful.

malc_b

Basic physics says that the lower the difference to the outside temperature the less the heat you lose so the less energy you need to put in. However, real world has a few gotchas.

You don't want rooms to be damp as redecorating will cost more that the fuel saved as well as being a pain. So you should aim to keep unused rooms warm enough to stop damp. There is also a suggestion that cold rooms will leak heat faster due to damp in the walls lowering their insulation.

If you have a condensing boiler then these work more efficiently at lower temperature so running the (gas and modulating) boiler set as low as possible will give savings. But the lower the boiler temperature the longer it will take to heat the house so you'll have to run for longer. This should still give a saving as the difference between say 16/24 and 24/24 is not that much. But the figures are close and the better insulated your house the more likely you'll see saving running longer but condensing as opposed to shorter and non condensing.

oldskoo1

thor wrote: »

What was the previous more costly configuration? Were all the TRVs on the radiators turned off when the thermostat was turned up?
Essentially I am asking were the savings made even though the radiators were not providing any heat before or after the thermostat was turned off?

The previous more costly configuration was the same TRV settings, just simply keeping the heating on overnight.

I made a concerted effort to test my consumption several times all within a 2 or 3 week period when the outside temperature and weather was as similar as weather can be.

Therefore, as the outside temp could vary by a few degrees and wind and drafts vary, its still an approximation.

I remember the test being around early November, the outside temp was around 8-10c.

If you tested mid january when it was consistently -5c overnight you may just find this gap widens by turning off overnight.

As pointed out, the colder the outside temperature the higher the rate of heat loss and when temperature drop at sun down the heat loss rate increases requiring more energy needed to pump back into the house to keep it maintained.

I even tested during -5c by lowering the overnight temp to 16c on the stat and back up to 18c in the morning. Turning it off and letting it drop to -13c / -14c by 6am and back up to 18c was still cheaper, but i wasnt really surprised.

I think i worked out my boiler costs about 80p per hour, on a cold winters day that equated to roughly £5.60 per day. On a -5c day the boiler would come on for roughly 1 hour at a time with my explained configuration. Boiler on for 30 mins when it was warmer.

Dropping the temp lower overnight would still see the boiler fire around 3x - about £1.80. Where as accounting for a slightly longer heat from a lower temp, heating from 13c might only cost about £1.60 max! That's 12% less but... it never really took 2 hours in reality so the saving was probably higher.

Either way in my situation, my usage, my boiler and circumstances it was cheaper to just switch it off overnight. Which as pointed out with a basic physics lesson is unsurprising. Dropping the temperature but keeping on overnight was also more costly, even when compared to having to heat from a lower starting temperature.

As we are on cost savings, i didnt really notice any significant different in cost by adjusting the boiler max temperature. I just left it on max, it heats up much quicker. TRV balancing didnt make much difference either as the radiator next to the stat always had good flow... balancing them did however greatly improve the heat across the house, some rooms were quite bad (cool rads).

rattler1111

HappyMJ wrote: »

Yes you need to keep the radiator closest to the room stat on full (the radiator supposed to be in the hall too not in another room...around the corner without doors in the way should be ok) so that when all the other radiators have shut off then the heat being generated by the boiler is being output by this one radiator and eventually the hall will get to 18 degrees and shut off the boiler.

It's also the quickest room to lose heat due to the front door so it should come on before the other rooms have cooled down too much.

If going on holiday should thermostat be turned off completely or left at about 10degrees

Biggles

rattler1111 wrote: »

If going on holiday should thermostat be turned off completely or left at about 10degrees

The latter. If it's turned off completely, you could come back to burst pipes.