A small example of worthwhile forward planning

[openspaceman]

The game as I am playing it now is towards gas off and disconnected.

I'm thinking of going the opposite way, electricity off to save £150 in standing charges and small gas chp to keep panels alive without grid excitation. Won't be for a while as I have to understand something about PV systems better.

[Joeboy]

The game as I am playing it now is towards gas off and disconnected.

I'm thinking of going the opposite way, electricity off to save £150 in standing charges and small gas chp to keep panels alive without grid excitation. Won't be for a while as I have to understand something about PV systems better.

That's excellent, looking forward to seeing how it plays out for you. The ideas that we manage to bounce off of each other are I think priceless. Is that a gas driven central heat pump (chp)?

[Stinsy]

Joe, you're right.

However I'd see it as a solar-diverter and cheap-rate thing. Resistive heating doesn't work in any other situation. A bigger tank would enable you to more effectively spread/shift the time you use the heat from the time you use it. You can use a willis heater (or two) if you want the simplest possible system.

[openspaceman]

The game as I am playing it now is towards gas off and disconnected.

Is that a gas driven central heat pump (chp)?

gas powered combined heat and power.

I would like to use a small Stirling engine but they are too expensive and touching on being vapourware rather than mainstream manufacturing. So I guess it will be a good old fashioned petrol engine converted.

If I can get my mind round the PV set up engine will only run in daylight hours to charge a battery which in turn will keep the solar PV producing electricity as per Nowty's islanded system. Then during the hours of darkness run off the battery.

I mostly heat by wood but depend on gas for DHW and very rarely CH in winter, which is really beginning of October to end of April here..

I would have to start with an air cooled genset as they are reliable and cheap enough to replace every couple of years but ultimately would need to go to liquid cooled to make use of the coolant and exhaust heat.

[sharpener]

Our hot water heat storage is provided via a bit of kit that exploits the big gain in stored energy that you can get from changing the phase of a material. It uses sodium acetate, the stuff used in hand warmers that are charged by putting them in boiling water and triggered to discharge and give out heat by a small "clicker" inside the gel capsule. There's some secret source in the box that enables nucleation to be triggered automagically and to stop automatically as well. The result is a box that's pretty small but which stores as much heat as a ~210 litre water tank.

Best bit about it is that the heat losses are tiny. We went away for a week, with the thing switched off (for safety), came back and found we still had a "tank" of hot water as the thing had just sat there with the sodium acetate in liquid form and was only triggered to start turning back into a solid when we ran off some hot water when we got home.

Would be very interested in what you are using, @Oldgreybeard, is it a Sunamp? They keep changing their product line-up, ATM they will not sell them as a thermal store for CH (though they have in the past and may again), only for DHW.

[Oldgreybeard]

Our hot water heat storage is provided via a bit of kit that exploits the big gain in stored energy that you can get from changing the phase of a material. It uses sodium acetate, the stuff used in hand warmers that are charged by putting them in boiling water and triggered to discharge and give out heat by a small "clicker" inside the gel capsule. There's some secret source in the box that enables nucleation to be triggered automagically and to stop automatically as well. The result is a box that's pretty small but which stores as much heat as a ~210 litre water tank.

Best bit about it is that the heat losses are tiny. We went away for a week, with the thing switched off (for safety), came back and found we still had a "tank" of hot water as the thing had just sat there with the sodium acetate in liquid form and was only triggered to start turning back into a solid when we ran off some hot water when we got home.

Would be very interested in what you are using, @Oldgreybeard, is it a Sunamp? They keep changing their product line-up, ATM they will not sell them as a thermal store for CH (though they have in the past and may again), only for DHW.

Yes, it's a Sunamp. Expensive bit of kit for what it is, but it was the only easy way that I could add hot water storage, as space for a cylinder was just a bit too tight (the original plan for the house was to use an LPG instant water boiler just for hot water). I opted for their 9kWh model, electrically heated. It has been working fine for several years now.

[sharpener]

I like the technology - but not the Sunamp pricing. I wanted to have a small ASHP running overnight on E7 and daytime on solar PV with storage to cover the rest. Sunamp looks good for this but their Rosie Reid told me recently they won't have a heat unit coming on the market until early 2023. But if I take the oil boiler out there will be space for 300 litres + of water tank as a big buffer on the ch circuit, however the phase change is much better as it delivers most of the stored energy at ~60C which is ideal for rads (mostly they are oversized already).

Starting from now I don't think the HP will be in by this winter anyway so that may be OK - finding an installer who can understand what I want to do has been a nightmare, as opposed to fitting the full MCS approved "keeping the entire house at 21C all day and all night" stuff which is all they will quote for.

[Joeboy]

A scheduled 3 hour power outage this afternoon, the apartment remains cool, as does the icebox. The fridge freezer has not kicked back in after power off for 3 hours, it just came back on. I think that's a good sign?

[Joeboy]

Another scheduled power outage for maintenance here in the village. 10am to 3pm. Have topped up the ice cube tray normal size) empty sockets to see if they will freeze over quickly just on the freezer big cubes in tupperware. Also spotted these rechargeable fans on amazon India. They would be great blowing across a big tupperware ice cube in a power cut.


https://www.amazon.in/Rico-Rechargeable ... B07NVLHCL9

Although it does say its a built in LA battery, not sure I want those fumes blown across the grandkids. Assuming a typo!

[Joeboy]

Damn, power outage ended after 3.5 hrs. Didn't get the full freeze of the wee cubes, yet it would have done going on progess to that point. Also found out that the freezer will go down to minus 24 on a manual over ride.

I may need to seek medical help on my cooling obsession.