Storage Heaters

[Stinsy]

I considered these for making the cottage spine wall a big thermal mass.

The idea was to drill multiple holes in the solid stone wall that sits in the centre of the cottage, insert these into the holes with a grout to ensure thermal conductivity. Wire them up and put a false lift away plaster wall in front to cover the wires and I would have a sixty plus tonne thermal mass in the middle of the house.

Not sure how the mortar would accept the contraction and expansion over time though as the wall is 142 years old.

Moxi

I don’t think this would have worked. You’d need air channels to distribute the heat throughout the wall.

[Moxi]

ahh so these cartridge heaters wouldn't work to conduct to the surrounding stone then ? thanks for that - I'm glad I didn't go further than thinking about it !

Moxi

[AGT]

Was just thinking out loud, say them in a RS components flyer that was posted out.

Started to look at spaces in the house where a small heater could be squeezed in next to standard wet radiator in 1 area where it’s hidden by a radiator cover, at the back door

Might just go for a bog standard tubular heater and fit it vertically.

[Oldgreybeard]

ahh so these cartridge heaters wouldn't work to conduct to the surrounding stone then ? thanks for that - I'm glad I didn't go further than thinking about it !

Moxi

Depends on the ratio of thermal conductivities and how well you could grout them in. Here's a list of typical material thermal conductivities, chances are ceramic heaters use some form of porcelain insulator I expect:

Thermal conductivities.jpg (33.63 KiB) Viewed 3511 times

If the heater had a porcelain type outer casing, with a thermal conductivity of around 2.2 W/m.K, then it's not a bad match to limestone or granite, just needs a thermally conductive grout with a conductivity at least as good (ideally better) than the porcelain ceramic insulator.

Interesting thought experiment is to compare the wall thickness needed for a wall made entirely of some of the more practical building materials listed above (pretty impractical for some of them) to give a more graphic representation of performance. If you wanted a wall with a U value of, say, 0.15W/m².K (for reference the walls of our house have a U value of about 0.123W/m².K), then the thicknesses needed would be (bear in mind that this is just to highlight the differences between materials, just as a bit of fun):

Wall thicknesses.jpg (18.66 KiB) Viewed 3511 times

Makes you appreciate why thick-walled log cabins became popular in the colder parts of North America.

[AGT]

The link I posted the supplier had a thermal paste to help transfer.

For heating walls would it be better to hang UFH electric or wet on the wall? Hanging a picture becomes fun though!

[Joeboy]

There's a nice wee where to use them section on the link. Personally I'd bore the holes in a solid stone wall at an 1/8th" oversize, inspect for cavities in the bore wall, fit close tolerance stainless steel sleeves for easy change out of carts and then fit carts with thermal grease. Run it all year long on PV and see how it goes.

[AGT]

Delivered 10 days early, looking forward to playing with the energy monitoring aspect of the socket

[robl]

Are there any good standalone storage heater controllers out there? A friend of mine is considering ufh pipes in a new floor- it would be 200mm thick on 200mm insulation, with the intention of charging it up at night. It’s then a large installed storage heater. Are there controllers that understand Octopus Go, have a nice dial or similar temperature set point , maybe even lookup tomorrows weather ?

[ALAN/ALAN D]

When you say. “ considering ufh pipes in a new floor- it would be 200mm thick on 200mm insulation, with the intention of charging it up at night. It’s then a large installed storage heater. “

It will have 200 mm insulation underneath.
How much insulation will it have above it and all around the sides. ?

What is heating the concrete slab. Electric heaters in the slab. ?

Is the water then pumped through the heat store and then feeds radiators in the room. ?

[Oldgreybeard]

I think there are a few smart options that could do this, ranging from simple smart switches to something like Home Assistant with the suitable add-ons. I'm not sure there is anything off-the-shelf that will do this without some user input in terms of setting the thing up, though (or if there are then I've not heard of any).

I have a similar requirement to try and forecast what the weather is going to do and charge our UFH heated concrete floor slab up. At the moment I do it manually, by looking at the forecast and trying to guess, but frankly that gets it wrong at least half the time. The main problem is that pulling forecast data from the Met Office API is easy, but the Met Office very often gets the timing of weather events wrong by a few hours. It seems they are pretty good at forecasting what is likely to happen, not so good at forecasting when it's going to happen.

Timing is critical for a slow to respond system, I've found, and it's easy for us to end up with the house a bit too hot, or a bit too cool, if we get a period of weather where the temperature changes very rapidly (good example was the end of the cold spell recently).

Whilst, on balance, I think a long decrement delay house/heating system gives a slightly better level of comfort, there is no denying that the slow response time presents some challenges in deciding when to put heat into it when the weather is changing quickly.

I tried some home brew controls for a time, measuring the rate of change of outdoor temperature, forecast data pulled from the Met Office API and trying to predict how much heat energy to put into the floor slab. I failed miserably, and wasted a lot of time in trying to understand why I couldn't get it to work reliably before giving up and just using a time switch and thermostat, plus some manual intervention when I feel a degree of confidence in the weather forecast.

Sorry for not being able to give an easy answer, but I think you might be best starting with a simple timer that switches on and off at the cheap rate periods, then using manual controls for a while to get a feel for how it responds.