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Best practice for heating the house (in current climate)?
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zeesaffaFree Member
Hi all,
So, just got our monthly utility bill and it’s insane… we must be doing something wrong!! £290 (just for gas).
3/4 bedroom detached. 1930s but part of the house has been extended so 80% cavity walls. Recently fully double glazed. Loft insulated to regs.
Standard gas central heating with underfloor heating in kitchen and utility room.
Over the last couple of months we’ve been running the underfloor heating for 2 hours max per day.
The zone for the rest of the house (bedrooms, living room etc) is set to be very cold during the day (14/15 degrees) and then we increase it for a couple of hours in the evening to about 18 degrees for the kids bedrooms and living room. The thing is… the temperature drops in the house during the day to around 14 degrees (or lower) temperatures and the boiler kicks in frequently anyway to keep it above 14 degrees.
The kids are complaining, sleeping with several layers etc. I don’t want to drop it any lower, ideally.
However, I read something once that said that setting the thermostat to a low temp is a false economy because the internal walls get too cold and actually makes it harder to reach the comfortable temperatures in the evening – and then the walls just chill the rooms very quickly again.
Is tis correct? What should we be doing?
FunkyDuncFree MemberOver the last couple of months we’ve been running the underfloor heating for 2 hours max per day.
Is that gas or electric? Underfloor heating really needs to be left on to be effective.
This question of what to do with heating has been asked many times and I dont think a real answer has ever been found.
I think your assumption is correct the if the house is cold its going to take a lot of energy to raise the temp a little. When it was -10 we started leaving the heating on all the time and we are sure it used similar amounts of energy, prob not less, but at least we were warm.
Unfortunately at the minute there is no ‘cheap’ solution.
zeesaffaFree MemberThanks FD. The underfloor heating is a wet (gas) system. To be fair, it is set to only come on for 2 hours and it manages to hit a comfortable temperature in that time which lasts all day (we work from home in the kitchen / diner now).
Fresh Goods Friday 696: The Middling Edition
Latest Singletrack VideosFresh Goods Friday 696: The Middlin...fossyFull MemberIt’s a tricky one. We’ve been running the heating most of January during the day but not at night as someone has been in. we have to knock it off early evening or the house is too warm to sleep. Our bill was about £150 for gas, and £180 for electric (WFH 2 days – conservatory to heat and 2 gaming PC’s on many hours).
Ours is a 3 med modern semi, so is really efficient on gas. Electric is insane, but that’s due to gadgets. Conservatory costs about £2-3 a day to heat, so £24 for the month). The issue is the price of gas, it’s 3x more than it was this time last year, so we’re all noticing it more.
You’ll struggle with a 1930’s house. Our heating is around 17c (not smart). If we are out the heating will run a couple of hours in the morning, 5:30am to 7:30am, then in the evening for about 4-5 hours, going off around 8pm
If someone is in, like most of December and Jan (daughter not out at Uni) then the gas is on during the day. Only stays on overnight if it’s really cold, and we’ll drop it manually to say 15/16.
Dual bill Sept £180, Oct £200, Nov £300, Dec £400, Jan £350
DickyboyFull MemberHowever, I read something once that said that setting the thermostat to a low temp is a false economy because the internal walls get too cold and actually makes it harder to reach the comfortable temperatures in the evening – and then the walls just chill the rooms very quickly again.
If you are heating all day then yes it will be easier to reach the temperature you are already at rather than getting it from 14 to 18C but it will cost you £££ to maintain it at 18C all day. If it’s zero outside your deltaT will be 18 instead of 14, so quite a jump up. However if the walls are getting at all damp it may be false economy as they will take more energy to heat than dry walls, so try it one day / one week when outside temps are consistent & see what the relative energy use is 🤔
aberdeenluneFree MemberIt’s a tricky one. Put a thermometer upstairs and downstairs and see how quickly the temperature drops when the heating is not running. I have a modern house and I observe a 1 degree drop overnight sometimes 0.5 if it’s mild. If the temperature drops a lot then you know you are spending lots heating the atmosphere.
Ive had my heating on constant since October at 18 degrees. I drop it to 16.5 when I go to bed it normally falls to 17 overnight then I set it to 18 again.
The theory is the heating just runs every now and again to top up. If you switch it off and the temperature drops a lot the heating will run for hours to get up to the thermostat setting again. Then if you switch it off you are back to square one again.
in a poorly insulated house you are on to a loser so it’s well worth spending money and effort making the house less leaky.
ScienceofficerFree MemberHave you had the cavity walls insulated or is the cavity too small to be viable? What type of floor do you have? Do you know your indoor humidity levels? What its the ventilation like? Any fireplaces? How wet are the solid sections of wall?
What type of boiler do you have? Do you know its flow temperature? Are you underfloor heating throughout? Is it zoned? If you have radiators are they big or small? Do you know how insulated the floor is?
Only thing I’m certain of at the moment is that double glazing wasn’t going to do much for the spend and;
the day to around 14 degrees (or lower) temperatures and the boiler kicks in frequently
Sounds like the boiler could be short cycling.
IHNFull Membervery cold during the day (14/15 degrees)
14/15 is not very cold, it’s just chilly. Under 10 is very cold. Anyway, is anyone in during the day and, if not, why have he heating on at all when no-one;s in?
dbFull MemberDon’t think you are doing anything wrong.
Last bill for us for period 20/09 – 9/12 is £588 electric and £375 gas +vat! Same bill last year was £303 electric and £158 gas. So electric up c100% and gas up c140%. We are a 1990s 4 bed detached house, 2 adults working from home all week.
(These are all before any government ‘help’ or feed in tariff for our solar)
joeyrFree MemberA couple of things that have helped us:
1. If you haven’t, get a smart meter or get your existing meter tested if you think it might be excessive. Our old meter was over charging us, we’ve just got around £800 back from British Gas after our consumption dropped to 1/5th of previous consumption upon receiving the new installation.
2. Get electric blankets etc and heat the human rather than the room. Costs us around 1p per hour compared to £1 an hour for our heating on.
MarkyG82Full MemberIf you keep the underfloor on for longer and get a good amount of energy into the slab that will help the rest of the house. For the days you are home keep it on at 18 (or whatever you need) all day. If it genuinely needs only that 2hr block then you won’t be spending more.
As mentioned, you need to keep the leakage down. That’s both air and heat. Cold bridging is a big problem. Do an interweb search and see what you can do. Curtains help too. Currently sat in the living room with them shut at one end. Can feel the cold from the open curtains the other end.
MarkyG82Full Member2. Get electric blankets etc and heat the human rather than the room. Costs us around 1p per hour compared to £1 an hour for our heating on.
Problem with this is not heating the fabric of the house can cause damage with damp etc.
solamandaFree MemberI’m not sure having the heating really low actually keeps the bills down as much as you think. Our bills for the last couple months have been around £420 total (Electric £190, Gas £230), we have a 70’s 4 bed detached with cavity insulation and fully smart heating control (Tado) and a recently replaced boiler (3yrs old). I have the rooms set to 17 – 20, (children’s rooms 19 all night). The major change we’ve made is going from using a tumble dryer daily to only a few times a month, we have a large dehumidifier running all the time and we’re being mindful with cooking energy, (lots of use of an air fryer, using a combi mircowave/oven or cooking two things at the same time).
joeyrFree MemberProblem with this is not heating the fabric of the house can cause damage with damp etc.
I agree – we did get a Drimaster fitted a few years back – https://www.nuaire.co.uk/product-list-page/drimaster-eco-range – which helps eliminate damp (a few hundred £ up front but not much in the way of running costs) and we only dry washing outdoors to cut down on the moisture in the air.
MarkyG82Full MemberOh another thing about oven heating. Try putting food in at the same time as turning on. Makes a surprisingly small difference in cooking performance and uses loads less leccy (assuming electric oven). Same for boiling in a pan. Put the veg in cold water instead of bringing to a boil first.
mickyfinnFree MemberProblem with this is not heating the fabric of the house can cause damage with damp etc.
Surely that depends on the house? Modern house yes but older house were designed to breath and not be centrally heated?
didnthurtFull MemberSet the heating to 18 degrees (or less if you bear it) but don’t turn it off, then concentrate on either heating yourselves or just the room you use.
Turn your boiler down as well as your hot water temperature.
One other place to insulate is under your ground floor if you have a timber raised floor.
You can hire thermal imaging cameras which would show where the heat is escaping to. Around window frames is often not insulated.
MarkyG82Full Memberolder house were designed to breath and not be centrally heated?
But older houses tend to be built with solid materials that take a lot more energy to get up to temperature. A modern house will respond to heat better due to the improved insulation and cold bridging.
simon_gFull MemberSimilar house but semi and no UFH – sorting out the cold suspended floor is on the list for this year. We’re running at about £300pm on gas before the rebate.
Previous owners zoned the heating, and I now control with an evohome. So middle floor (bedrooms) gets a quick blast in the morning and evening, converted attic where wife and I WFH mostly stays warm from lower floors and a bit of sun but will get a bit of heat if it’s been cold overnight and the downstairs we warm a bit in the morning then in the late afternoon but mostly leave colder during the week. Front room is carpeted and gets the afternoon sun so tends to be warmer for the evening without needing extra heat. When it’s below freezing though I find we need to raise the ground floor daytime temp otherwise it can fall right off and there’s not enough radiator to bring it back up in a sensible time.
I set 16 for overnight/daytime and 19 for heat.
TallpaulFull Member80’s 4 bed detached house, gas central heating, cavity walls, double glazed (all recently adjusted to ensure good draught seals on openings!) and loads of loft insulation.
Thermostat set to 16°C at lowest and 20°C for 2 hours in the morning and 4-5 hours from when the family get home in weekdays; Constant 20°C all day at weekends.
2,177kWh of gas used in January (£233). House very very rarely drops below 16°C, even when we were hitting -10°C here at night in December.
I think a constant 18°C might actually be cheaper but my family wouldn’t tolerate that!
pictonroadFull MemberSimilar house to us, similar bills. I don’t think you’re doing anything ‘wrong’, this is just how much it costs now.
Biggest differential seems to be where you live, South Coast resident here, I think we get off lightly.
JonEdwardsFree MemberWe both work from home – heating is never on during the day – I think its on for an hour in the morning and 2 hrs in the evening. (economy/background heating is at 8°C, comfort at 17°C)
House is a 1920s semi. Uninsulateable cavity wall, but double glazed throughout and otherwise as well insulated as we can.
Thermometer in my office is saying 14°C at the moment, and that’s absolutely fine for me.
During the proper cold snaps it gets a bit chilly, but just wear more/move more. We’ll stick the log burner* on (yes, boo-hiss, sinners, etc) on for a couple of hours in the evening to get 1 room properly warm and let that permeate through the house.
On a sunny day, her office and the lounge get a lot of solar gain (good in winter, not so much in summer), so I quite often have lunch in the lounge for a bit of free warmth.
Sleeping wise – thick duvet and we have a pair of those microwavable wheat heat-packs which get zapped for 3 minutes each and prewarm the bed nicely at a fraction of the electricity consumption of boiling a full kettle for a hot water bottle. Most of the year we need a window open to be able to sleep comfortably
The thing I notice makes the biggest difference for me is physical activity. A 10 minute brisk walk, or better yet a bike ride gets my internal boiler working nicely and with appropriate clothing afterwards keeps me warm for a good few hours.
*I can get free wood and it literally grows on trees, so is reasonably sustainable compared to burning more fossil fuels, albeit more polluting if done badly and bugger using electricity for heat at current prices!
chiefgrooveguruFull Member“So, just got our monthly utility bill and it’s insane… we must be doing something wrong!! £290 (just for gas).”
Bear in mind that this will vary a lot depending on where in the country you are. If you’re up in the north and on a windy hill it’ll cost a lot more to heat your house than if you’re on the south west coast and sheltered from northerly and easterly winds.
I’ve done quite a lot to cut the heating bills of our extended and loft-converted originally 3 bed semi (heat exchange ventilator, cavity wall insulation, modern windows and doors, boiler and radiators all adjusted as well as possible, Hive thermostat and valves) and we’re in Brighton and it’s still about £6 a day in gas in the winter (there’s often someone at home, would be cheaper if we all left the house during the working day).
thisisnotaspoonFree MemberHowever, I read something once that said that setting the thermostat to a low temp is a false economy because the internal walls get too cold and actually makes it harder to reach the comfortable temperatures in the evening – and then the walls just chill the rooms very quickly again.
<span style=”font-size: 0.8rem;”>Is tis correct? What should we be doing?</span>
No it’s bollocks.
Ignore the heat input side of the the energy balance for a minute. Heat output from the house (Q) is
k= thermal conductivity of the wall
Ti = internal wall surface temp
Te = external wall surface temp
Q = k(Ti-Te)
So any time spent with a low internal temp is also lowering the dT, which lowers heat lost.
So yes it costs twice as much to heat form 10 to 20C than 15 to 20C in the short term (1 hour or so). It costs you twice as much to maintain a temp of 20C Vs 15C if the external temp is 10C over the medium term (12h).
FunkyDuncFree MemberInteresting comment above about heat loss.
Our 15 yr old house can go from 20 deg to 11 deg in the space of about 4hrs ! Some rooms that we dont heat but that are directly next to ones that we do drop to 5 !
thisisnotaspoonFree MemberPut the other way around, overall 5 hours at 20C costs twice as much as
1/2 hour art 20
1hour at 19
1hour at 18
1hour at 17
1hour at 16
1/2 hour at 15.
(simplified but you get the idea, in reality assuming the outside is 10C, that last hour takes twice a long to cool 1deg at 15 than it does to cool 1deg at 20C).
The transient effect of having to heat up a greater mass of bricks in an old house is of no overall effect, that same mass is retaining heat that takes longer to cool later. If you drew the house as a thermodynamic heat engine you only have energy in (gas, electric, solar gain) and energy out (boiler efficiency and lost as heat).
birkyFree MemberSmall, 70s, 2 bed semi-detached bungalow using a Nest thermostat set to 16c overnight and 18-20c during the day/evening. All rads fully on.
WFH 5 days a week.
Last monthly gas bill was £80, last monthly elec bill was £23
House doesn’t hold heat well and could do with better loft insulation.
MarkyG82Full MemberTINAS is right even though it contradicts my previous statements. As with a lot of these things it depends how you use the space. If you use the whole house and you WFH then it’s worth having it at a steady state with a couple of blasts. If you leave the house for a 9-5 then heat it when you need it.
<span style=”font-size: 0.8rem;”>We’ve never heated our at night apart from in the recent cold snaps. And that was only to keep it dropping below 16. Left it the first night and no2’s bedroom (west facing) got to 11 before we got up. Not doing that to our 2 year old thanks.</span>
flickerFree MemberInteresting comment above about heat loss.
Our 15 yr old house can go from 20 deg to 11 deg in the space of about 4hrs ! Some rooms that we dont heat but that are directly next to ones that we do drop to 5<span style=”font-size: 0.8rem;”>!</span>
Unless I’ve misread your post that’s a huge heat loss in a very short space of time, there’s something wrong there.
For perspective ours is a three bed 1960 bungalow, cavity wall, 300mm insulation in the loft and 100mm under the suspended floors and we were seeing a drop of around 1.5-2 °C over 8 hours when external temps were hitting -9 °C
molgripsFree MemberIt depends on how your heating is set up and how well insulated the house is. Generally the better your insulation the better off you are keeping it warm all day, I think.
Also, £290 isn’t insane these days. Some people on the other heating thread are spending £700.
Our 15 yr old house can go from 20 deg to 11 deg in the space of about 4hrs
something wrong there. Our house is 15 years old and during the day with heating off and typical winter temps and not sunny weather would only loose a couple of degrees all day.
paladinFull Member1900’s 4 bed semi, we’ve got Tado trv’s fitted and heat the rooms as they’re being used. Heating off all night and when rooms unoccupied, although I’ve set the minimum setback temp to 12 now. Weekdays Living room and kitchen/diner heat to 17 in the morning then off til late afternoon when they come on at 17. Living room up to 18 in evening. Teenagers bedroom is at 17 in the evening. Bedrooms have a quick blast in the morning.
all rooms are On more during the weekend and school holidays
Boiler is set at 50 degrees.
2154kWh in december, 2069 in January.
bensalesFree MemberWith the greatest respect, I’d ignore anyone above proffering advice based on houses more modern than the 1930s. I’m sure it’s well intentioned, but 20s and 30s houses do behave in quite different ways to more modern houses due to their construction, namely often the presence of fireplaces in all rooms with corresponding ventilation, solid brick walls, and suspended ground floors. They lose heat quick.
Here’s what’s worked for me in a 1928 built 3 bedroom, with solid walls for 90% of the house, 300mm loft insulation, 20 year old double glazing. I work from home, but everyone else is out during the day, apart from the cats.
Last winter I set a pattern of
06:30-08:00 – 20c
08:00-15:00 – off (I used a small electric heater in my office room)
15:00-20:00 – 20c
20:00-06:30 – off
For the most part this was comfortable, although we did get some mould issues, and we averaged about 100kWh of gas per day in Jan and Feb, peaking at about 140kWh on really cold days. I did find the house tended to overshoot the set temperature quite often and then drastically drop, basically bouncing up and down rather than being steady. I think because the house loses heat so quickly, it was causing the system to overreact to get back to temp.
After a fair bit of reading, this year I made the following changes…
– range rated the boiler after doing heat loss calculations on the whole house. Our heat loss is around 16kW, so I limited the 30kW boiler to 20kW. This should prevent it going excessively high and help mitigate the overshooting of set temperature.
– used the controller setting to change to a slower heat up, again this mitigated the overshooting and lead to a more steady temperature.
– properly balanced the radiators, after reducing the flow temperature at the boiler to 55c from its previous 70c. Now the boiler condenses properly.
– replaced a couple of Type 11 radiators with Type 22 to better support the lower flow temperatures
– changed the heating programme to06:30-15:00 – 18.5c
15:00-17:00 – 20c
17:00-20:00 – 18.5c
20:00-06:30 – off
Net result has been about a 25% reduction in gas use over 2022 compared to 2021 (average in Dec/Jan was about 80kWh per day, peaking at 120kWh in the real cold snap), no mould issues, and a much steadier consistently comfortable temperature in the house. You need a jumper, but it never actually feels cold. Obviously the bill is substantially higher than it was in 2021 but far from as high as it would have been if I’d left the system as it was. As an aside, I did experiment with the same heating programme as 2021 with it off during the day but found it didn’t save much gas at all, and the mould and damp issues resumed. So I’d prefer to have it on “low, slow, and long”. January bill was about £220 after government kickback. Without the changes it would have been £370 ish. January 2021 was £119 🙁
molgripsFree MemberYeah you do need to know how your house and your boiler behave. Our boiler’s minimum output is 9kW. Our radiators are undersized, they can’t dump that much heat, so the flow just keeps warming up until it reaches the set flow temp then it short cycles which is both inefficient and bad for it. The amount of heat the radiators can produce is between the building heat loss and the boiler’s minimum output. So it’s a case of balancing the time taken for the boiler to hit its flow temp ceiling with the time taken for the hallway to warm up, and trying to set it up so the rooms warm up before the hallway does.
This situation is not covered by heatgeek…
tenacious_dougFree MemberModern house yes but older house were designed to breath and not be centrally heated?
They were not designed to be centrally heated, but still designed to be heated. The nature of the materials means they can breathe but also absorb moisture, under normal circumstances the moisture from the exterior is evaporated by the heat of the interior, so if interior heat is not sufficient then the moisture remains in the walls. This is one of the reasons why impairing breathability is problematic as not enough heat goes into the fabric of the building to evaporate moisture.
*Not an expert, just based on what I have picked up from experts like Peter Ward (The warm dry house) and various period property forums and groups.
FunkyDuncFree MemberUnless I’ve misread your post that’s a huge heat loss in a very short space of time, there’s something wrong there.
I am not sure how warm it is outside today, but it is currently sunny and no wind, probably about 5 deg
The kitchen was heated to 19 deg this morning at 8am it switched off. Currently the temp is 13deg, when its been proper cold and windy that drops off much quicker. No draughts coming through as I stopped them. There is a loft void above it with insulation.
Our house was built by a builder. There is no loft space in most of the house, and I dont think he insulated the roof. Not sure if there is anything in the walls, i wouldnt know how to check !?
poolmanFree MemberI leave gas heating on 24 7 at 15 deg, big bungalow but south facing and lots of glass. Costs 5 GBP per day, so 150 pcm plus standing charges.
Top advice on here, used to turn heating on and off. It’s proved cheaper to leave on at lower temp.
Electric blankets but rarely used, living flame fire in lounge if really cold but rarely used. Also set trv s to concentrate heat in living areas.
Been to a few houses heated to 23, they feel like a sauna to me.
simondbarnesFull Member14/15 is not very cold, it’s just chilly
Indeed. My house hasn’t been that warm at any stage since October.
I’m not sure having the heating really low actually keeps the bills down as much as you think
Really? My gas bill for the last quarter (Oct/Nov/Dec) was £45.
Energy is expensive. The only realistic way of cutting bills is to live in a colder environment and wear more clothes which is what I’ve chosen to do (not just this year, I’ve done it for the last 20 years)
TallpaulFull MemberThe kitchen was heated to 19 deg this morning at 8am it switched off. Currently the temp is 13deg, when its been proper cold and windy that drops off much quicker. No draughts coming through as I stopped them. There is a loft void above it with insulation.
Bloody hell! I don’t think our conservatory loses heat that fast!
Quick check of various thermometers around the house suggest biggest temp drop is 3°C since heating went off at 08:00 (~6 hours ago). Coincidentally this is the kitchen but I’m not suprised it’s cooled fastest as it’s on the NW corner of the house. Rooms with the sun on all morning have only lost 1°C.
ScienceofficerFree MemberMolgrips – have you seen the radiator fans designed to increase heat from a rad? Might be a way to dump more heat from your rads. Dont know how effective they are though.
bensalesFree MemberMy gas bill for the last quarter (Oct/Nov/Dec) was £45.
After the government energy discount though, I assume?
Assuming 10p per kWh that’s about 27kWh per day. Impressively low. Less than a third of what my house requires.
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