Heating on low all day- experiment

[User129867588]

Not sure anyone will find this useful as I know we all have different houses and boilers etc, but I trialled having my heating on all day yesterday, reduced my thermostat to 18 degrees and I spent the same on gas as previous day when the heating was on 18.5 but only on for just over an hour in morning and then for 3 hours in evening! Both days the temp on my thermostat after boiler being off all night was 14.5 degrees 🥶

House is a 2 bed semi, mid 1980’s build. Double glazing that’s over 10 years old and some getting replaced soon. House had insulation added but again that was about 15 years ago.

As seen on pictures the main expense on the gas was when heating first came on and then around tea time. I cooked on my gas hob and then all 3 of us had showers and we use a mixer shower connected to boiler for hot water. I’m with EDF on the variable rate.

I’m doing it again today and if it stays around the same I don’t see any reason for me to work in a cold house in the daytime when it costs the same (or just a tiny bit more) to heat most of the day! I can manage with 18 degrees too and still wear a jumper and extra thermals. Last years 20 degree heat is but a distant memory…….

I've been experimenting over the last few days. 1920s stone built semi, large rooms; fairly new boiler. Outside temp not really got above freezing in this time.

Thurs - flow rate 70. Night thermo setting 15. Heating came on 1/2 hour before getting up, thermostat set at 17. Down to 16 for a couple of hours in the morning, then 17 for the rest of the day except for 2 hours at 18.5 before bed (toasty bliss!). Total gas spend about £11.50.

Friday - same pattern but flow rate 60. Total spend about £10.50 BUT it took a lot longer for the house to reach target temperature.

Sat - Flow rate turned to 64. Went away at 11am so thermo on at 17 until then, then down to 10. Spend about £5.30.

Today (Sun) -- monitored internal house temp from away and it dropped to 10.5. Heating on for 5+1/2 hours before getting home, the house temp is still only 15 (and my bedroom, where the radiator was off, was only 8.5c!) . Spend to get it up to that temp £5.25. I've turned the gas fire on in the lounge now as well to try to boost the temperature as I'm not sure it's going to reach target before bedtime at this rate!

It seems that in the current low external temp, the flow rate here needs to be up even though it costs more.

It also doesn't seem worth it, to me, to allow the house to get too cold - I'll spend as much today trying to get the temp back up, as if I'd simply left it on about 16 all day.

Food for thought there. Stay warm, y'all.

That's a very interesting observation.

If you're spending £10 per day, that equates to roughly 110 kWh of gas. Which suggests your house is losing 4.6 kWh of heat each hour.

That's probably fairly easy to replace if you run your heating at x°C 24x7, but any attempt to raise the temperature requires additional heat (more than 4.6kW).

It looks like your radiators aren't capable of delivering enough kW at the lower flow temperature, but they might be capable of maintaining the temperature.

If it saves you money running at the lower flow temperature, perhaps you could try temporarily turning up the flow temp to get up to your target temperature and then reducing it again to maintain your target 24x7?

That might be cheaper than always running a higher flow temperature so that you can bring the temperature back up each day.

If it saves you money running at the lower flow temperature, perhaps you could try temporarily turning up the flow temp to get up to your target temperature and then reducing it again to maintain your target 24x7?

I'd like to be able to do that, but sadly the boiler in is in the cellar, which is accessed via the garden down some stone steps, so it's not easy to get to especially in the dark! Otherwise I'd definitely give that a go.

I don't know of any other tricks to retain heat in my house. I think the fact that I've got uninsulated cavity walls carries a lot of blame, but I was told (after having been offered a grant to get them insulated) that stone houses can get major condensation issues with CWI.

The other issue, I think, is that my house sits on a hill facing southwest so in sunny weather, it's lovely and bright and warm, but it also catches the prevailing winds! I can see the weather coming 1/2 hour before it hits!

Oh, and I checked again before I went to bed and I was right -- total gas spend yesterday £11.50 and it never reached target temp.

So the next time I'm away overnight, I'm going to leave the thermo on at about 15 and avoid the massive drop. It's different if you're away for a few days when I'd be happy for the house to get as cold as it wants!

I’m currently running this experiment it’s been -6/7 many nights the last week and sometimes not getting above 0. I have a nest thermostat that clicks off when we leave and on when we come in. Heat set to 17.5 in the morning and usually gets to there by the time we leave and gradually drops to 13 over the course of the morning. Then when I come in at 2 it’s on again and take about 1 and 1/2 hours to get back up to 17.

over the weekend I trialled leaving it set at 16.5 after the initial heat up in the morning of 17 as it’s fairly comfortable ay 16.5 and the heating was only on for 5 and 3/4 hours compared to 7 and 3/4 hours on Thursday and Friday.

today I let it do the usual when out at work it dropped to 13 and clicked back on once up to 17 I’ve clicked it down to 16.5. Will see the comparison tomorrow

i have found that leaving it on over the weekend meant it only worked hard first thing and then just came on for 20 min bursts to maintain the heat the rest of the day over the weekend.

unfortunately I’m not sure there’ll be much in it, over this last week with it being so cold it’s costing me over £8 per day for gas 😭 I am on prepay meters that were here when we moved in and I do prefer them but still it’s awful how expensive it is just to be warm and often wonder if it can be right

Sat and Sunday compared to Thursday and Friday

So this week (similar temperatures on each day) I found out that having my heating on 24/7 at 18 overnight and 21 in the day uses about 84kwh.

Heating on for part of the day (off for 8 hours overnight when the boiler lost pressure and switched itself off, and again for an hour and a half when i went out) used...

84kwh

Yes I have just discovered that keeping a nighttime temp of 17deg instead of basically off means it heats up quicker in the morning so overall was on for the same amount of time, but more comfortable with the faster morning heat up

Yes I have just discovered that keeping a nighttime temp of 17deg instead of basically off means it heats up quicker in the morning so overall was on for the same amount of time, but more comfortable with the faster morning heat up
same but I do 14 or 15 overnight.

Wow, that’s so interesting. Thanks for sharing. I wish I could try and keep mine on during the night but I’m such a light sleeper and it would wake me. The worst of the creaky pipes noise is in my bedroom! I have continued with my heating on all day at 17/17.5 and going to continue with it. From tomorrow it’s going to be milder too so my bill can recover slightly from the last two weeks !! 😱

I have always kept my heat on all day on a low setting, unless it's especially cold when I put it up a notch. That way the house is always warm but the radiators and water aren't boiling hot and a burn risk for the dc. I have no idea what it costs but turning it on and off and having the house freezing in between just never seemed like a good idea to me.

This is exactly what I found. No change in used units but house more pleasant.
I've been recording gas and electric units since 3rd Dec, every day, so I also know exactly whether I need to top up my energy DD a bit, but so far, looks like I'm going to break even for December. (I pay £200/month DD and then repay the £66 government refund, so £266/month).