@thisisnotaspoon

The problem is summed up in the title of the thread. Traditional UK mentality is that it is on or off. The progressive way is to move away from binary to controlling a system to extract maximum efficiency via modulating controls.

Every house has different characteristics, so replacing the heat loss will be different. This is why, you have to measure your use & try different settings.

A 70W electric banket obviously makes you feel a lot warmer than a 7kW boiler overnight, and uses 1% of the energy, even if it is 3x more per unit.

Doing kwh figures like this is a pointless excersise as neither the boiler or the blanket will be operating at 7kw or 70w per hour. What if the boiler was using the same as the blanket? I know where i’d rather live.

only heating a single room is definitely more efficient in terms of cost (if you can use trvs on gas) and energy usage.

heat loss is all about temperature differential. lets say (for a clean example) the external walls of a room allow 10% heat loss per hour (things are more complicated than this). if the room is 20c and outside is 0c, if the room is unheated, you’ll loose 2c the first hour, then 1.8c, then, untill the difference is so minimal as to effectively be nothing.

lets say you’re working from home, and heating the whole house. To heat that room (that you’re not using), you need to use enough energy to compensate for 2C the first hour, then 2C the second hour, and so on. A total for a 8 hour day of 16C “worth” of energy.

if you don’t heat the room, the loss after the first hour reduces. by hour 8 you’re losing less than 1C per hour. The total loss over 8 hours would be 11.4C (down to a temperature of 8.6C), which you then have to spend reheating the room, but that loss is about 28% less loss than the heated room.

There is some loss out of the room you are heating into the rest of the house, so the room you’re not using isn’t completely unheated, but the savings available are still considerable

Doing kwh figures like this is a pointless excersise as neither the boiler or the blanket will be operating at 7kw or 70w per hour. What if the boiler was using the same as the blanket? I know where i’d rather live.

No, it just demonstrates that it’s far more efficient to heat the thing you want to heat, rather than the whole house.

The better way to think about the whole system is by heat loss (which has to equal heat input – accumulation anyway).

It’s difficult to model (in your mind anyway) what’s going on with a 20kW boiler its duty cycle, what all the TRVs are doing etc.

Much easier to visualize that a wall with twice the differential temp to the outside loses twice as much energy, and therefore requires twice as much energy input also.

So if I only put the living room rad’s on, and heat that room to 20C (and say it’s 0 outside), even if those heaters are running flat out, and the rest of the house creeps upto 10, it’s still using only a little over half the energy as it would to heat the entire house. The better insulated the individual rooms are (i.e. how cold can you make everywhere that isn’t the living room) the better that gets. Take that to the extreme of turning the heating off and sitting in bed with an electric blanket whilst the rest of the house freezes is an extreme example, but would save 99%* in that case to demonstrate the point.

Lowering the temp of the circulating water lowers the entropy in the system which increases efficiency in other ways. But that’s tweaking the last 5% out of it rather than saving 30/50/70/90% just heating the rooms/people that need it.

*more or less depending on the duty cycles of the electric blanket and boiler.

hmmm, think our boiler is a bit beefier than that & it doesn’t have weather comp as far as I’m aware (it’s not mentioned in the manual anyway. It’s fairly old) That said, I do use our gas boiler for heating the house – the IR heater is for the shed (like I said 😂). I was just commenting that it’s probably not particularly terrible vs gas costs. 😃

Weather comp just turns the flow temp down. You can do that manually 👍

Smart TRVs don’t necessarily mean that you turn the room off it can (and generally is) just set lower. You can’t actually be suggesting that having the entire house at (say) 20° when you’re literally only using one room is somehow more energy efficient? 🤔

You made a point of them being ‘smart’ which means the only think they do differently to a normal TRV is be able to turn off via an app. 🤔

The problem is summed up in the title of the thread. Traditional UK mentality is that it is on or off. The progressive way is to move away from binary to controlling a system to extract maximum efficiency via modulating controls.

No idea what you mean. Most of us have thermostats and TRVs. Turning the heating ‘off’ just means forcing the system to not modulate upwards.

Or, run your 19kw boiler, which is modulated down to 7kw on weather comp for an hour. Of which it will only be firing for 30mins. (costs 10p/kw x 7kw = 70p/kwh = 35p/HR to heat the whole house).

Right but you don’t necessarily want the whole house heated all the time.

I see what you’re saying, that trying to heat a single room is like trying to heat an uninsulated house because the heat escaped relatively easily.

The heat escapes into the rest of the house, and quite slowly at that because the temperature differential is a lot smaller than that between outside, at least in our house. From experience, this 2kW eleectric heater only needs to be on for 10 mins to heat the room up very well, then it can be off for hours. I’m sure that’s cheaper than running a 9kW boiler for the same time.

And you often can’t heat a single room with a gas boiler depending on how your system is designed.

@thisisnotaspoon Your reply is getting crazy and is pointless.

My point is. Measure your useage and inform yourself of your actual useage.

It’s the only way you will know if its worth sitting in a freezing room with an electric blanket, or living in a comfortably temp house.

Ps – I’m not about to test the electric blanket theory 😅

You made a point of them being ‘smart’ which means the only think they do differently to a normal TRV is be able to turn off via an app.

yes and no. “smart” in current marketing parlance basically means “connected” so you are right in that sense. Although to me personally a device isn’t “smart” unless there’s some kind of AI behind it… and being connected is the first step towards that… lots of heating systems already will shut off if they detect open windows/doors/draughts etc for example, or if the heating is scheduled to be on but actually the room or property is unoccupied so can actually be turned down or off. So there’s hugely more to “smart” tech than just being controllable via your phone!!

does anyone know of any good guides/websites/app for calculating property heat loss?
I’m going back to basics, I need to target my efforts where they count, I know our house isnt very efficient but they numbers I’m seeing at taking the pish

@molgrips what I think buttonmoon is on about is systems that can auto change the temp of the water flowing thru your rads based on the weather, to make the boiler more efficient.
That assumes that your boiler and / or controller can do that, which I suspect most of the populations can’t.
My controller and boiler are opentherm compatible. It would have been an extra £80 for the opentherm box, I would have to be convinced on paper that its worth it to have a £80 box twiddle with your radiator water flow temps. I suspect it doesn’t make that much difference unless maybe you have a massive house, even then I’d have to be convinced.
It’s the same with tap water temp. My experience is that turning down my hot tap water flow temp didn’t make much difference to gas usage, it might if your having 12 baths a day.

I suspect it doesn’t make that much difference

Turning the flow down has made a big difference here. House is much more comfortable overall with slower flow and lower temps. However, it means that the hot water essentially doesn’t work at all because the circulating water is now cooler than the tank. So I’d love a programmable flow temperature.

Turning the flow down has made a big difference here.

I agree. But here is the problem for System boilers.

Again, a problem in the UK is the antiquated system design (S or Y plan) . You may be able to get around this problem with a cylinder relay box which would tell the boiler to heat the Hot Water to a higher temp than C/heating (W or X plan). I run this setup.

Heating hot water is relatively low energy, heating the house is where the bulk of the energy is needed, hence the need to control it properly and have a comfortable efficient house.

We are 30 years behind Europe 🙁

That makes sense. Thanks. Doesn’t help, but is interesting!

I’m thinking about creating an automated temperature control knob for my boiler, and setting the hot water on a different schedule. Maybe also automate the pump flow speed too.

I could build-in weather compensation at the same time.

You made a point of them being ‘smart’ which means the only think they do differently to a normal TRV is be able to turn off via an app.

the big power for us is the ability to schedule different temperatures in different rooms at different times of day. I work from home 4 days a week, my wife works part time, so on the days I wfh, the room I work on is warm, the bedrooms are cold. Downstairs is on lightly warm during the day when my wife is at home, and at the weekends, then the living room is toasty in the evenings. The bedrooms are warmest in the mornings and have a little heating in the evening as well. All of this will turn off if both my wife and I are out of the house. Whenever any room/zone is heated, there is heat called from the boiler, otherwise its dormant.

None of that is possible with “dumb” trvs, and significantly dropped our bills

None of that is possible with “dumb” trvs

I just walk up and down the stairs and adjust them as need be, not that we’re using any CH yet….

I just walk up and down the stairs and adjust them as need be

That’d be a right faff in our house.

I just walk up and down the stairs and adjust them as need be

how do you adjust a dumb TRV to make a room the exact temperature you want? Mine just had an arbitrary 1-5 scale on them I think 🤔

Same way you do it with a smart one. Play with the settings till the room is warmed to the temp you want.

how do you adjust a dumb TRV to make a room the exact temperature you want? Mine just had an arbitrary 1-5 scale on them I think

Define exact eg whereabouts – 10cm from the radiator or on the other side of the room?

Just because it has a degrees C scale on it doesn’t make it any more accurate than the dumb wax based ones….

does anyone know of any good guides/websites/app for calculating property heat loss?
I’m going back to basics, I need to target my efforts where they count, I know our house isnt very efficient but they numbers I’m seeing at taking the pish

Probably some forn of way of doing it but generally there’s so many variables it’s hard to ‘generalise’ heat loss. As mentioned above, it depends on a lot of factors, external and internal temperature difference being one – a more basic thermo calculation. For a house, you’d tend to look at insulation, surface area and how the wall is made up etc, but that may be looking in to it too much. I did my university project on this kind of thing.

That’d be a right faff in our house.

Generally I’m always looking for an excuse to get more steps in etc. My watch beeps at me every hour to say ‘get up and move’, so it’s not really a faff…

Turning the flow down has made a big difference here.

If you previously had your rads scalding hot, then yes you’ll notice a difference. I was talking in terms of already running rads at a sensible temp (45° in my case, maybe a touch higher in coldest weeks). I don’t feel there would be much to gain in my house from having an £80 opentherm box making micro adjustments, when I can do any odd tweaks if necessary by means of a big dial on the front of my boiler.

Heating’s on! I’ve lit the wood burner. It’s about 16°C in the afternoon and 6 in the morning which is a good few degrees higher than seasonal (unless this is the new normal). The house was down to 17.5 having left the doors open to air this afternoon. The thing stinks as it always does on the first burn of the year, something to do with the black finish Jotul use.

Still hanging in there, heating not on yet… But I’m getting close to caving in today I must admit!

I’m perfectly comfy at 17 degrees in shorts and a T shirt with bare feet, my wife likes it a couple of degrees hotter.

So we compromise at 19 degrees.

Still hanging in there, heating not on yet… But I’m getting close to caving in today I must admit!

+1

I should really put trousers on first though, still in shorts.

I agree. But here is the problem for System boilers.

It’s not specifically system boilers, its the old Y and S plan concepts.

I have a year old system boiler on hot water priority. It takes about 25 minutes to heat the well insulated water tank on full burn, then runs at whatever flow temp I specify, on a per degree basis. Currently 47°, but suspect I can go lower at this time of year

This Southern wuss has caved in but the musty smell is still lingering around the upstairs. Guess it’s a matter of time although not helped by a dead radiator in one bedroom.

This Southern wuss has caved in but the musty smell is still lingering around the upstairs. Guess it’s a matter of time although not helped by a dead radiator in one bedroom.

I put ours on for 2 days… dried out the house and it’s back off.

My wife caved last night (as we had people from social services doing a home visit and she didn’t want them thinking we live in a cold and damp house). Three hours later it was uncomfortably hot so it was switched back off and the windows opened LOL! 14deg outside at 7am in Harrogate this morning!

Heating is still off, turned the towel rail up a notch as the towels weren’t drying out. Like others I’m finding the musty/damp feeling more objectionable than the cold after the last few weeks of torrential rain. I guess we’re just used to the very dry centrally heated air feeling.

It was 16C according to the thermometer in the conservatory this morning. Which is just getting weird this time of year.

Just took a meter reading, about 43m3 of gas this month which corresponds to about a £60 ish bill I think. About twice as much as we used in the previous month and that’s with only about half the period using heating. That matches my rough estimate of heating using 3x as much as hot water and cooking combined.

Heating is still off, turned the towel rail up a notch as the towels weren’t drying out.

Electric or hybrid towel rails? I’m considering hybrid towel rails to help with drying stuff off during “summer” when the heating’s off.

thisisnotaspoon

Heating is still off, turned the towel rail up a notch as the towels weren’t drying out. Like others I’m finding the musty/damp feeling more objectionable than the cold after the last few weeks of torrential rain. I guess we’re just used to the very dry centrally heated air feeling.

The damp air takes more energy to heat and takes heat away from our body faster .. so it’s not entirely in your head.
The other thing is … if it were in your head does it matter?

I stuck the heating on for 2 days and doors/plaster etc dried out a lot… it’s off again now but FEELS much warmer.
It MIGHT actually be warmer, I didn’t really check.

I’m considering hybrid towel rails to help with drying stuff off during “summer” when the heating’s off.

Same here. Radiator in the bathroom is old and leaking, looking at a hybrid replacement to keep the damp at bay… and also as a back up source of heat if we ever have gas shortages or the boiler stops working.

Electric or hybrid towel rails? I’m considering hybrid towel rails to help with drying stuff off during “summer” when the heating’s off.

It’s plumbed into the hot water cylinder circuit, so it works all year round as long as people are in the house having baths/showers and the cylinder calls for hot water.
Unexpected benefits:
– The HW comes on an hour before the heating, so when I’m the 1st one up before the heating’s on in winter at least the bathroom is warm and the towels are toasty. Once I’m dry and dressed I’m not fussed how cold it is.
– Effectively modulates it’s own use, the more showers are had and towels used, the longer the HW is on to warm the cylinder again.
-The pipes run under the bathroom floor, so it’s cheap underfloor heating too! (see point 1).

It’s plumbed into the hot water cylinder circuit, so it works all year round as long as people are in the house having baths/showers and the cylinder calls for hot water.

Interesting, not heard of that.

Still holding out here, last year I’d have he the heating on by now but coping ok.

I live in a tower block that’s been clad so don’t get the sudden drops in temperature you get in traditional houses, or the dampness (even though it’s in Manchester!) The building generally holds on to residual heat until January, when the internal communal spaces and stairwells get cold, then the block becomes a bit of a fridge for the second part of winter.

It probably won’t be many days until I have to start using a little bit of heating in the evening. I should probably close my bedroom window.

I caved in the other night as the cold air started to trigger my asthma.

Temps have been near freezing outside here this week, and house temp has been dropping into single figures. Needless to say the heating has been on an hour or 2 each day. Brings it back up to 14-16 degrees, which feels absolutely tropical now. Living like a King.