Heat in the home

Use this board for general non-cycling-related chat, or to introduce yourself to the forum.

My central heating is set for what range?

I don't have central heating
8
13%
below 18
22
36%
18-20
24
39%
21-22
2
3%
23-25
2
3%
25-plus
3
5%
 
Total votes: 61

Biospace
Posts: 2008
Joined: 24 Jun 2019, 12:23pm

Re: Heat in the home

Post by Biospace »

853 wrote: 29 Sep 2022, 5:28pm I tried a first experiment yesterday, when it was nice and sunny here. The 'cold-frame' was a quick lash together of a transparent acrylic sheet resting on bricks, so drafty, uninsulated and without any reflectors. Heated the one brick I put inside slightly, but not significantly. Looking like the marginal end of 'marginal gains'
Draughty and uninsulated, mmm. Even the heaviest bricks painted mattest black, nestled in cotton wool, with hot sun pouring through triple glazing on to them will not warm so much if there's a draught.

You'd be better off like this chap with a small candle under a flower pot :wink:

candle heat.jpeg
candle heat.jpeg (31.34 KiB) Viewed 675 times

On the other hand, a ~ 20'x4' wall built with some heavy older bricks painted black, facing south and in a properly insulated box will warm a room very comfortably, as described up-thread. A double row with a small air gap between even better. Eliminating draughts at the very minimum is essential, otherwise the heat gained will be lost through convection pretty effectively, especially if outside.

Think about how warm the interior of a car grows on a sunny day in October or March/April. Open the windows a little and it soon cools.
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853
Posts: 261
Joined: 23 Sep 2022, 6:01pm

Re: Heat in the home

Post by 853 »

Biospace wrote: 29 Sep 2022, 5:37pm
853 wrote: 29 Sep 2022, 5:28pm I tried a first experiment yesterday, when it was nice and sunny here. The 'cold-frame' was a quick lash together of a transparent acrylic sheet resting on bricks, so drafty, uninsulated and without any reflectors. Heated the one brick I put inside slightly, but not significantly. Looking like the marginal end of 'marginal gains'
Draughty and uninsulated, mmm. Even the heaviest bricks painted mattest black, nestled in cotton wool, with hot sun pouring through triple glazing on to them will not warm so much if there's a draught.

On the other hand, a ~ 20'x4' wall built with some heavy older bricks painted black, facing south and in a properly insulated box will warm a room very comfortably, as described up-thread. A double row with a small air gap between even better. Eliminating draughts at the very minimum is essential, otherwise the heat gained will be lost through convection pretty effectively, especially if outside.

Think about how warm the interior of a car grows on a sunny day in October or March/April. Open the windows a little and it soon cools.
You are, of course, correct. I did say it was a first experiment and "a quick lash together".

I have discovered, from experience, that when you try something completely new your first attempt is something of a failure. Except it's not a failure, because if you analyse it properly you can see were it went wrong and get a better appreciation of the whole project and learn from it. I expect my second experiment to be better.

I believe that a large, properly built (I know who to ask now!), cold-frame could possibly heat enough bricks to a hot enough temperature to be viable. I am a bit reluctant to spend, what could turn out to be over £100, until I've proven to myself I will get some benefit back.

The forecast is for sun here tomorrow, so I will try the same arrangement as experiment 1 but try and stop the drafts. I'll let you know how I get on, as it will be a change from reading Woodburners Weekly :)
Jdsk
Posts: 24636
Joined: 5 Mar 2019, 5:42pm

Re: Heat in the home

Post by Jdsk »

Today's agreement by the Member States of the EU: demand reduction, windfall tax on fossil fuel providers, and price capping on some other providers:
https://www.consilium.europa.eu/en/pres ... gy-prices/

Guardian commentary:
https://www.theguardian.com/world/2022/ ... ergy-firms

Jonathan
jois
Posts: 334
Joined: 22 Sep 2022, 12:29pm

Re: Heat in the home

Post by jois »

Biospace wrote: 29 Sep 2022, 5:37pm
853 wrote: 29 Sep 2022, 5:28pm I tried a first experiment yesterday, when it was nice and sunny here. The 'cold-frame' was a quick lash together of a transparent acrylic sheet resting on bricks, so drafty, uninsulated and without any reflectors. Heated the one brick I put inside slightly, but not significantly. Looking like the marginal end of 'marginal gains'
Draughty and uninsulated, mmm. Even the heaviest bricks painted mattest black, nestled in cotton wool, with hot sun pouring through triple glazing on to them will not warm so much if there's a draught.

You'd be better off like this chap with a small candle under a flower pot :wink:


candle heat.jpeg


On the other hand, a ~ 20'x4' wall built with some heavy older bricks painted black, facing south and in a properly insulated box will warm a room very comfortably, as described up-thread. A double row with a small air gap between even better. Eliminating draughts at the very minimum is essential, otherwise the heat gained will be lost through convection pretty effectively, especially if outside.

Think about how warm the interior of a car grows on a sunny day in October or March/April. Open the windows a little and it soon cools.
Tried that not impressed, my first big candle of the winter stood in a pot the right way up, then have a fan to create air flow to mix the heat back up from the top.

It will take two days and my whole flat will be toasty, it's not bad now,

Candle costs a fiver and lasts a week, just don't let it cool down
axel_knutt
Posts: 2880
Joined: 11 Jan 2007, 12:20pm

Re: Heat in the home

Post by axel_knutt »

853 wrote: 26 Sep 2022, 6:30pmI am considering an insulated, south-facing, cold-frame to heat up bricks which could then be brought inside to dissipate their heat.
The specific heat of brick is ~800J/kg/K, so if you assume you can get a temperature of 40C (~20C above room temp), then to collect 5kWh of heat (not much more than a quids worth), you'll need over a ton of bricks. If you're willing to cart a ton of bricks in and out of the house for a quid you don't value your time very highly. Water has five times the specific heat of brick, which is why it's used for heating & cooling, and you can move it with a pipe instead of a wheelbarrow. You can also make simple DIY solar panels from central heating radiators sprayed matte black.

I fancied making a DIY solar system about 30 years ago, I've still got a booklet from the CAT somewhere, but I never did because of various practicalities like finding somewehere accessible to put the panels. The most efficient way to utilise the heat is for preheating the hot water supply rather than space heating, because you don't need such a large temperature rise, but as I don't have tanked hot water, that's another reason why I didn't consider it practical.
“I'm not upset that you lied to me, I'm upset that from now on I can't believe you.”
― Friedrich Nietzsche
Biospace
Posts: 2008
Joined: 24 Jun 2019, 12:23pm

Re: Heat in the home

Post by Biospace »

axel_knutt wrote: 1 Oct 2022, 1:27am
853 wrote: 26 Sep 2022, 6:30pmI am considering an insulated, south-facing, cold-frame to heat up bricks which could then be brought inside to dissipate their heat.
The specific heat of brick is ~800J/kg/K, so if you assume you can get a temperature of 40C (~20C above room temp), then to collect 5kWh of heat (not much more than a quids worth), you'll need over a ton of bricks. If you're willing to cart a ton of bricks in and out of the house for a quid you don't value your time very highly. Water has five times the specific heat of brick, which is why it's used for heating & cooling, and you can move it with a pipe instead of a wheelbarrow. You can also make simple DIY solar panels from central heating radiators sprayed matte black.

I fancied making a DIY solar system about 30 years ago, I've still got a booklet from the CAT somewhere, but I never did because of various practicalities like finding somewehere accessible to put the panels. The most efficient way to utilise the heat is for preheating the hot water supply rather than space heating, because you don't need such a large temperature rise, but as I don't have tanked hot water, that's another reason why I didn't consider it practical.

I agree, water is a great way of moving heat from one place to another and it's how I did it years ago with an M67 ex-army heater as the 'boiler', viewtopic.php?p=1713599&hilit=m67#p1713599

However, if you've space, passive solar heating can work well and it's simple. Other than a fan to shift air, there are no moving parts and nothing to leak, freeze or corrode.

My friends who have successfully used a solar wall are about to try out solar heating with water. They have a very well insulated place and are happy with 16C-17C ambient until the wood stove is lit - the solar element as much as anything saves wood (and so work). From memory, they've measured brick temperatures of 50C+ in Autumn and Spring sunshine.
Biospace
Posts: 2008
Joined: 24 Jun 2019, 12:23pm

Re: Heat in the home

Post by Biospace »

853 wrote: 30 Sep 2022, 6:23pm
You are, of course, correct. I did say it was a first experiment and "a quick lash together".

I have discovered, from experience, that when you try something completely new your first attempt is something of a failure. Except it's not a failure, because if you analyse it properly you can see were it went wrong and get a better appreciation of the whole project and learn from it. I expect my second experiment to be better.

I believe that a large, properly built (I know who to ask now!), cold-frame could possibly heat enough bricks to a hot enough temperature to be viable. I am a bit reluctant to spend, what could turn out to be over £100, until I've proven to myself I will get some benefit back.

The forecast is for sun here tomorrow, so I will try the same arrangement as experiment 1 but try and stop the drafts. I'll let you know how I get on, as it will be a change from reading Woodburners Weekly :)

Experimentation is my way with most things too, as you say, everything is better understood and the rate of learning is high. It's great to be able to browse the Internet and look at other approaches, depending on space, country and cost. As axel_knutt says above, a lot of mass is needed for a modest amount of heat, it's never going to be hotter than what liquid or solid fuels can provide unless it's enormous in relation to the space heated, although the solar wall inside an insulated box which is itself within a glasshouse does work well in the case I described.

They sourced the bricks for the cost of collecting them, I think the same for the other materials apart from the black paint and fan. I did some rudimentary sums but there are some really quite complex calculations needed to give even a vaguely definitive answer, so I suggested a single thickness wall 18' x 4' might well not be sufficient to raise one roughly 15'x18'x8' room's temperature to comfortable. There was the likelihood of building another behind the first, he was even considering mirrors to reflect the sun onto the rear wall. :shock:

As it turned out, the heat is modest but makes enough difference to be worthwhile for a well-insulated room when the air is cool and sun is warm. It was decided a second wall behind the first may improve output by a half or more, but not worth the effort. If a room to be warmed is draughty or poorly insulated, then the modest heat from such a setup is unlikely to be effective.
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853
Posts: 261
Joined: 23 Sep 2022, 6:01pm

Re: Heat in the home

Post by 853 »

axel_knutt wrote: 1 Oct 2022, 1:27am
853 wrote: 26 Sep 2022, 6:30pmI am considering an insulated, south-facing, cold-frame to heat up bricks which could then be brought inside to dissipate their heat.
The specific heat of brick is ~800J/kg/K, so if you assume you can get a temperature of 40C (~20C above room temp), then to collect 5kWh of heat (not much more than a quids worth), you'll need over a ton of bricks. If you're willing to cart a ton of bricks in and out of the house for a quid you don't value your time very highly. Water has five times the specific heat of brick, which is why it's used for heating & cooling, and you can move it with a pipe instead of a wheelbarrow. You can also make simple DIY solar panels from central heating radiators sprayed matte black.
My current heating is by two electric storage heaters, one large and the other small, located in the lounge. I haven't switched either on yet, but normally in early November I switch the large one on and only use the smaller one as well when it is very, very cold. As I'm sure you know, the storage part of the heaters is actually glorified bricks (they claim they are special high-density bricks). I did help the installer fit them, and I did handle the bricks. I estimate the weight of the bricks in the large one to be around 50kg in total.

Water does have a very high specific heat capacity, but there is no water in a storage heater so the manufacturers clearly believe that the specific heat capacity of high density bricks is sufficient. I'm open to experimentation, so I might try a full, black-painted radiator in a cold-frame arrangement. First of all I'm just experimenting to see if it is worth putting some time and money into the idea.
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853
Posts: 261
Joined: 23 Sep 2022, 6:01pm

Re: Heat in the home

Post by 853 »

853 wrote: 30 Sep 2022, 6:23pm The forecast is for sun here tomorrow, so I will try the same arrangement as experiment 1 but try and stop the drafts. I'll let you know how I get on, as it will be a change from reading Woodburners Weekly :)
Following advice from my consultant ( :) ), I am very happy to report success in experiment 2

I managed to find an old plastic cool-box, from about 30 years ago, so I used this with the acrylic sheet on top. Although it has been sunny here in the North Midlands, it has also been very windy with gusts of 30mph. I couldn't angle the cool box to the sun because of the wind, and I had to use two bricks on top of the acrylic sheet to keep it down. My thinking was that only the top brick would get any real heat, and this would only be if it was raised within the box. To my surprise, when I came back about 6 hours later I had four hot bricks which I carried inside the house within the cool box. I don't have measuring equipment to find out how hot they were, but they were definitely hot to touch and probably around 50 degrees C.
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853
Posts: 261
Joined: 23 Sep 2022, 6:01pm

Re: Heat in the home

Post by 853 »

A while back, someone mentioned about an energy tariff without a standing charge. Whilst looking for my historic energy prices, I came across this bill. The tariff was called Ebico Zero, as it had no standing charge. As a low user this worked well for me; the unit prices were higher than other suppliers, but with low usage the lack of standing charge more than made up for this.

After a couple of happy years they sent me a letter, (around 2019 I think), saying that the tariff was being terminated, as the regulator had decreed that a standing charge had to be charged.
Attachments
No standing charge.jpg
Biospace
Posts: 2008
Joined: 24 Jun 2019, 12:23pm

Re: Heat in the home

Post by Biospace »

853 wrote: 1 Oct 2022, 6:31pm
853 wrote: 30 Sep 2022, 6:23pm The forecast is for sun here tomorrow, so I will try the same arrangement as experiment 1 but try and stop the drafts. I'll let you know how I get on, as it will be a change from reading Woodburners Weekly :)
Following advice from my consultant ( :) ), I am very happy to report success in experiment 2

I managed to find an old plastic cool-box, from about 30 years ago, so I used this with the acrylic sheet on top. Although it has been sunny here in the North Midlands, it has also been very windy with gusts of 30mph. I couldn't angle the cool box to the sun because of the wind, and I had to use two bricks on top of the acrylic sheet to keep it down. My thinking was that only the top brick would get any real heat, and this would only be if it was raised within the box. To my surprise, when I came back about 6 hours later I had four hot bricks which I carried inside the house within the cool box. I don't have measuring equipment to find out how hot they were, but they were definitely hot to touch and probably around 50 degrees C.
A good result. Time to work quickly if you want any free heat this year, there are only a few weeks left where the sun will significantly warm things up!
pwa
Posts: 17366
Joined: 2 Oct 2011, 8:55pm

Re: Heat in the home

Post by pwa »

If you have a cold day and have heated bricks outside your home that you want to bring inside to warm your home overnight, you will be opening and closing the door repeatedly, losing heat as you do that.

We have large south facing windows that result in warming of the south facing rooms on cold but sunny days. We keep the curtains wide open on those days and it makes a big difference. On hot summer days we keep the same curtains drawn to keep sunlight out. The curtains are also thick, making them insualtors too. Curtain management is a significant part of our temperature control regime.
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Cugel
Posts: 5430
Joined: 13 Nov 2017, 11:14am

Re: Heat in the home

Post by Cugel »

pwa wrote: 3 Oct 2022, 5:36am If you have a cold day and have heated bricks outside your home that you want to bring inside to warm your home overnight, you will be opening and closing the door repeatedly, losing heat as you do that.

We have large south facing windows that result in warming of the south facing rooms on cold but sunny days. We keep the curtains wide open on those days and it makes a big difference. On hot summer days we keep the same curtains drawn to keep sunlight out. The curtains are also thick, making them insualtors too. Curtain management is a significant part of our temperature control regime.
Do those techniques really work? I've never been able to picture (using my 6th form physics of 55 years ago) how closing the curtains can make any difference to heat loss or gain in a house from radiant heat (the sunshine) coming through the window glass. Once the radiant heat is caught in the house (by the furnishing, walls, etc. or just the closed curtains) it'll heat whatever it shines on to excite their molecules so they produce heat that'll get convected, won't it? The house air is heated by the warmer furnishing (including curtains) and the house warms up. Perhaps the curtains are made of reflective foil, though? Or perhaps the curtains store a great deal of the heat, only warming the air a wee bit compared to what the sunlit sofa would?

To prevent inner house heat gain from sunshine on the windows, you'd have to have the curtains (or shutters) outside the window, wouldn't you?

But I await a better education of the physicals, should someone (we might guess who :-) ) like to provide it.

Cugel
“Practical men who believe themselves to be quite exempt from any intellectual influence are usually the slaves of some defunct economist”.
John Maynard Keynes
Jdsk
Posts: 24636
Joined: 5 Mar 2019, 5:42pm

Re: Heat in the home

Post by Jdsk »

Yes, they work.

The two sources that I found most useful when we renovated our house were:

"Ecohouse 2: A Design Guide"
Roaf
https://www.amazon.co.uk/ECOHOUSE-desig ... B005CI2LO8

and

"Natural Home Heating"
Pahl
https://www.amazon.co.uk/Natural-Home-H ... 1931498229

There's an introduction to the subject in:
"Passive solar building design"
https://en.wikipedia.org/wiki/Passive_s ... ing_design

Jonathan
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al_yrpal
Posts: 11537
Joined: 25 Jul 2007, 9:47pm
Location: Think Cheddar and Cider
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Re: Heat in the home

Post by al_yrpal »

We have huge Georgian sliding sashes in all 4 main rooms. When the sun shines on them these rooms heat up rather in the way a greenhouse does. We also inherited insulating blinds which trap air in concertina like horizontal pockets. In the winter we drop these blinds at nightfall to conserve heat. We also have thick curtains. Blinds and curtains trap insulating air pockets.

It aint rocket science!

Because the house is listed we arent allowed double glazing, but, on one window we have secondary glazing which is rather ugly. We love our house and wouldnt want ugly secondary glazing everywhere. With its 11 foot ceilings and sliding sashes its easy to control interior temperatures in summer.
We know some folk who have constructed a highly insulated eco house in the Georgian style. It looks wonderful but in high summer its hell because it it slowly heats up and wont cool down making the bedrooms unbearable. They are going to have to install air conditioning.

Those Georgians knew a thing or two...

Al
Reuse, recycle, thus do your bit to save the planet.... Get stuff at auctions, Dump, Charity Shops, Facebook Marketplace, Ebay, Car Boots. Choose an Old House, and a Banger ..... And cycle as often as you can......
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