Not putting the heating on – how’s it going…?

Anyone estimated what they are likely to save on energy use yet?  I’ve got a back of the envelope calculation running which seems to suggest that dropping from 19 to 16 degrees is going to save me 30% over the year.  This sort of matches what I see on the web which suggests 7-10% per degree but given the sorts of monitoring people seem to be doing here I’m sure others have estimates running as well so I’m interested to see what you think

Ours is already at 16°C and as I keep telling my wife, IT ISN’T CALIBRATED so probably doesn’t click on at a real 16. And being in the hall, is probably in the coolest place in the house which means it probly stays on longer than if it was somewhere else.

If I reduced it further, it might never come on… 🤔

As long as I use less than last year and reduce our usage I am happy enough. With the recent cold spell I am not so sure but we will see, our heating is off from May/June to partway through November anyway as the temperature is stable throughout that time.
I keep forgetting to take daily gas readings to check up on our usage, I only have the Nest daily usage figures which got up to 3 hours a day on the most coldest days. I’ve also now reduced the flow temp to 60c ish. I’ll reduce that further on the warmer winter days to see how it goes.

This guy says you shouldn’t lag your indoor pipes as can reduce boiler efficiency. Any thoughts?

Your rooms don’t all have the same heating requirements. Our kitchen and hallway are cool due to the doors, floor and the fact it’s on the ground floor; but the living room above them is fine. Unlagged pipes in the ceiling void put heat into the living room where it’s not needed instead of the kitchen where it is.

As for boiler efficiency – you do need to be able to dump enough heat to have a low return temp. But unlagged pipes are the same effect as slightly larger radiators, except you can’t control where the heat goes.

As always – it depends.

Just received Decembers bill, £800 for the month. Wife thinks that’s not too bad. What planet is she on? That’s more than my annual bill used to be.

Just received Decembers bill, £800

As of midnight yesterday, we’d used £186.59 in total for Dec. I’m crying as I type this as we’ve still 6 days of usage to go.

800 quid. Does your wife like to wander round in her smalls? Or is your house very poorly insulated (like my new crappy installed but very expensive windows so I expect a similar bill but not generating underpant friendly conditions)

If it’s anything like.my in-laws….

They turned the heating off at 10pm last night – it was about 1 billion degrees . – they don’t have a thermostat.

It was -1 outside.

We all woke up cold this morning.

I suspect they have the sum of **** all in the way of insulation anywhere……

their heating bill will be similar I’m sure…

Just received Decembers bill, £800 for the month. Wife thinks that’s not too bad. What planet is she on? That’s more than my annual bill used to be.

Does she have a job?

Sister in law is a stay at home mum and spends money like water, she has absolutely no concept of money / value / worth and pisses her other half’s salary up the wall playing keeping up with the other stay at home mums in her social group. Both kids are at private schools and not actually at home…

Mine has come to 320 split almost 50:50 gas and electric. Considering they were demanding 450 in DD payments before I cancelled it, I’m pleased its not as high as I feared, but unhappy that its as high as that.

I’ve not had an opportunity to compare kWH consumption with last year though.

Actions this year so far are dropping ambient temp from 20° to 18° on the stat, wearing jumpers, and reducing flow temperature of our boiler from 60° to 47°.

We also turned off a few more standby gizmos and changed how we dry our clothes from forced electric heating to standing next to the living room rad where there is heat anyway.

Ours is sitting at £320 for the month today

For anyone with a smart meter wanting a decent running comparison I find the U Switch app really good.

Much better than the BG one (I’m with them for both gas/elec) weirdly its almost like BG want to keep up by having an app but don’t actually want you to have any idea of how your consumptions compares by day/week/month/year

Do we need some perspective… If you’re in 300sq ft detached in Scotland you’ll be spending more than a 100sqft terrace in London (probably)

I’ve no idea what mine is. They Only do bills every 6 months and I’m not on a smart meter. Apparently you can’t have smart u16’s.

reducing flow temperature of our boiler from 60° to 47°.

That’s pretty low. Do you not get short cycling?

Re our £800 bill, we’re in a 1930s 4 bed detached with poor insulation, 1 year olds twins and obviously it was pretty cold recently. I WFH but I’m happy to wear extra layers. She won’t let the thermostat go below 16.5 overnight because of the children. She also sees the heating as a first resort, whereas I’d only put it on if I were desperate. I stil can’t believe she thinks it’s a reasonable figure, but I won’t raise it with her, it’s not worth the argument.

Went to friend’s house for Xmas dinner, I thought it was summer by comparison to my flat. LOL!
The temperature never went below 17c and was 21c to 23c (think he set it to min 17c and max 23c) during the evening; and I was actually sweating. LOL! Told me his gas bill was around £250 per month excluding electricity but told me electricity was about 1/3 of that. 3 beds old house, used to have the toilet outside, with minimum insulation. I guess the heating bill must be the norm for old houses?

That’s pretty low. Do you not get short cycling?

No, I switched the boiler a year ago to one that will modulate down to 1.5kw. I alao have quite large radiators.

I get lovely base line heat and almost absent steam from the flue.

My bill is for 121m2 1980, 3 bed detached.

C250 here for whole dec in a detached bungalow min 14 deg max 18. Elec 50gbp gas 200gbp.

Combi on 24 7 I turn it down to c12 at night on 18 all day. Effectively just topping up lost heat during day.

New roof and breathable membrane last year so no drafts up there.

Pretty pleased tbh as it was -10 mid Dec.

It’s on and off when I want it to be; thermostat is programmable but I use manual over-ride.
Fully acknowledge that I’m very fortunate in being able to absorb the extortionate energy prices when so many others cannot.

Heating still off. I have a log burner on the go most of the time and a pretty consistent 17 degrees through the day. I cut and sort all of my own wood, but as we are an end terrace 1900 build I reckon we are as low as you can go. The gas is sitting at about £80 pm so not doing too badly.

Ummm.

You know a log burner is heating right?

Which is less bad from efficiency perspective- low temp and cycle more or high temp and cycle less?

Pretty similar to you Edward- I keep the kids bedroom warm in the night in the vein hope it helps them sleep better!

Not sure I follow the connection between short-cycling and lower temperatures; surely short-cycling is a function of thermostat offset, rather than temperature?

I’m not sure either ..but if the temperatures are lower then the boiler takes less time to reach the flow temp and so then switches off, but if the room isn’t up to temp it then comes on again after not long and repeat. Whereas higher flow temp the boiler runs full tilt and room heats up quicker so maybe less cycling?

This guy says you shouldn’t lag your indoor pipes as can reduce boiler efficiency. Any thoughts?

Your rooms don’t all have the same heating requirements. Our kitchen and hallway are cool due to the doors, floor and the fact it’s on the ground floor; but the living room above them is fine. Unlagged pipes in the ceiling void put heat into the living room where it’s not needed instead of the kitchen where it is.

As for boiler efficiency – you do need to be able to dump enough heat to have a low return temp. But unlagged pipes are the same effect as slightly larger radiators, except you can’t control where the heat goes.

As always – it depends.

In short, boiler efficiency is sort of irrelevant compared to total heating system efficiency. Useful output is hard to calculate though since as above it’s the heat transferred to the rooms you need heating

Not sure I follow the connection between short-cycling and lower temperatures; surely short-cycling is a function of thermostat offset, rather than temperature?

When a boiler is oversized for the heat that is required, or can’t reduce its output adequately, the temperature of the returning central heating water is so hot that the boiler thinks it’s done it’s job and it turns off the burner.

This means the boiler can’t get anywhere near its dew point for recovering latent heat, and maximising its efficiencies, and it will need to fire up again fairly shortly because insufficient heat it lost from the rads into the room due to the short burn time – you get repeating firing events which adds wear and tear into the boiler.

No, I switched the boiler a year ago to one that will modulate down to 1.5kw. I alao have quite large radiators.

Nice. I can’t splash for a new boiler currently but bigger rads might be on the cards in some rooms. I figured that the efficiency gains from a colder return temp would not pay for a new boiler very quickly.

Not sure I follow the connection between short-cycling and lower temperatures; surely short-cycling is a function of thermostat offset, rather than temperature?

Muddyjames has it right. There are two reasons for short cycling. One of them is as you say – if the on and off temp of the thermostat is too close then it will be short cycling.

However in the other case, if I set my flow temp to 50 then the rads are at 48 or so. The heat output of the radiator is therefore lower so it takes longer for the room to hear up and the stat to switch off. Ideally, the boiler would heat up the circulating water to 50C and then turn itself down so that it stays at 50 and the return temp at say 30. But for that to happen the heat input of the boiler has to equal the heat lost by the radiators. When they are at 47C the heat lost is lower so the boiler has to turn it’s flame down to match that. But many boilers can only go so low. Mine has a minimum of 9kW so 9nce that 50C is reached it has no choice but to switch off. The flow temps then drop towards to the return temps. But because my boiler is shit, it sees the temps drop and goes “oh, better start up again” within a minute or two.

The only way to stop this is to increase the flow temp so that the rads can dump 9kW of heat, or fit bigger rads so they can dump 9kW at the lower temps. I can increase the flow through the rads to make them hotter, but whilst they emit more heat, more heat is going into them to begin with, so the return temps are higher. The boiler is simply adding to the return temps, so it reaches its target temp more quickly! And then the return temp is higher so it condenses less well.

When it was cold, the rooms would not heat up fast enough so I had to set the flow temp to 60C. The cold weather didn’t mean my radiators were dumping more heat since although it was -4C outside it was still 16C inside just as it is when it’s 10C outside. It did mean that they needed to run for longer though, and more frequently.

Now that it is warmer, I could turn the flow temp down, but that makes it take longer to warm the room. I have to position the thermostat so that it will warm up and switch off before the flow temp exceeds the set value and it short cycles. But if it shuts off too soon in the hallway the other rooms have not got up to temp!

So I have to adjust the flow temp, flow through the hallway rad and the distance from that rad to the stat to keep the return temps as low as I can whilst avoiding short cycling and giving the other rooms time to warm up!

When a boiler is oversized for the heat that is required, or can’t reduce its output adequately, the temperature of the returning central heating water is so hot that the boiler thinks it’s done it’s job and it turns off the burner.

Mine shuts off based on the flow temp not the return. Mine is still condensing, with the return temps slowly climbing to 42C or so because the flow tops out at 65C. If I increase the flow temps then the room heats faster so no short cycling, but the return temps are 50C or 55C. So it’s a toss up which is less efficient – short burn times or higher return temps.

It also matters what temp the stat is set to Vs the TRVs in the rooms. If they shut off, then the system can dump far less heat so short cycling is more likely. But the rate of heat loss is different for different rooms, but the heat input from our activity is the same, so when it’s colder I theoretically need different parameters to when it’s mild. And when it’s cold and the air has been heated more the relative humidity is lower in the house, so I need lower temps to feel comfortable and perversely higher temps in the house when it’s mild.

Argh!

So many people buggering about with boilers and CH but none claim to be heating engineers.
Call me old-fashioned but I would stick with people who do this stuff for a living – aka ‘experts’.

£390 for the month so far. £1700 for the year but it would appear most of that is the past few months.

‘’So many people buggering about with boilers and CH but none claim to be heating engineers.
Call me old-fashioned but I would stick with people who do this stuff for a living – aka ‘experts’.’’

With all due respect I really don’t like attitudes like this. And it’s common in many formats. People are just trying to help themselves a bit and share new found knowledge. You don’t have to be a mechanic to diagnose a flat tyre.

I reckon we’ll be on ~£220 for December including wood. 3 bed, mid terrace, solid wall 1880’s build. Thermostat at 18 daytime and 14 nighttime.

I used to think it was pretty inefficient but this thread has changed my mind dramatically. Even in the really cold snap with -5 overnight we were only loosing ~3 degrees overnight, on normal nights it’s more like 1.5 degrees.

Call me old-fashioned but I would stick with people who do this stuff for a living – aka ‘experts’.

You are old fashioned.  A lot of ‘heating engineers’ are people who were just fine with boilers when they were just an on/off thermostat and that was it but they struggle with modern heating systems where you have to estimate the thermal mass of your house in order for the control system to work.  On a similar theme I just had a quote for solar panels but the ‘expert’ completely missed the fact that our house requires a three phase inverter rather than single.  The person who proposed our underfloor heating didn’t want to insulate over the concrete beams because ‘heat goes up you know’.  It never hurts to do a bit of research yourself.  I would love to believe that everyone in a profession is an expert but it really isn’t true.

but the ‘expert’ completely missed the fact that our house requires a three phase inverter rather than single

What makes it require a three phase inverter ? Are you hooked up to all three phases in your house. That would be very unusual.

What makes it require a three phase inverter ? Are you hooked up to all three phases in your house. That would be very unusual.

It is unusual but i am.  The oven is on all 3, various other parts on the house are on different phases. I have to add though that i am in Brussels and we are a bit unusual in that not only is it 3 phase it is 3 phase delta.

With all due respect I really don’t like attitudes like this. And it’s common in many formats. People are just trying to help themselves a bit and share new found knowledge. You don’t have to be a mechanic to diagnose a flat tyre.

Yeah, My friend was complaining about heating prices, I tried explaining a bit about flow temp, told him about the heat geek YT channels (hes an avid YT watcher)..and he’s like, my boiler only has one dial, not seperate ones for water and CH… I was like really? you sure.. he went to look… “oh yeah, there’s 2 dials”.

I said turn your hot water down to 40c (combi/condenser boiler), there’s no point having scalding hot water comming out of the shower head only to have to mix back down with cold.

The response? “nah, I can’t be bothered messing about with it”

He literally has no idea how to use his boiler and doesn’t seem to care, but does care about his high bills ¯\_(ツ)_/¯

Equally, wallking around my neighbourhood the other day having a nose at peoples flues – the number of houses with huge plumes of steam errupting from them was staggering.

That flow temp pointer above is one of the most useful things I’ve ever read on here!

I never though about it before but I always mix down the shower with cold, just checked, the hots set to a scalding 60c, I’ve just wanged it down to 45c and I’ll go from there

Thanks!

^ that’s OK if you have hot water on demand but ours comes from a cylinder, and with daughter and wife in particular taking long hairwashing showers they can deplete the cylinder sufficiently that by the time son and then me get showers they’re lukewarm or even cold

By having the water hot, they use less / cut it with more cold that is unrestricted supply and I’ve at least then got a fighting chance.

I might look at adjusting when she goes back to Uni and then adjust again when back, it would be interesting to see if it has any impact on bill / usability.

 I’ve just wanged it down to 45c and I’ll go from there

You might want to put it a bit higher.  I know that my boiler has a feature where if the water tank temp is as low as that for a few days then it will crank it up over 60 once to prevent legionella

Managing legionella in hot and cold water systems (hse.gov.uk)

I don’t know how much of a real issue this is.  I just know that my boiler has a feature to avoid this and also the link above.  I also did some measurements over a few weeks with the temp set at 58 and also down at 45 and didn’t find that I saved a detectable amount of gas.  My tank is well insulated so it takes a couple of days to cool down on it’s own so that may help.