Ditching gas, going electric immersion only, a wee project

Solarchaser

Yeah absolutely correct. 
The gas combi is in bits ready for the bin, the gas connection has been capped nearly 2 months ago, so it's gone. 
Combi was 15 years old and so I'm hoping the 75% is close, I'll either be right, or I'm paying more full peak electric right?
I mean worst case I go 4 hours instead of 3 and pay more for off peak, so 4 hours at 12kwh is 48kwh, that has got to be more than the 50kwh of gas, especially with gas prices keeping rising.

70sbudgie, yeah we have electric underfloor heating in the bathrooms and I really like it, and yes as you say, there are insulation matts to stop transferring through the floor, where in this case I'm relying on the heat transferring through the floor, with 200mm of insulation under the pipes to hopefully not lose too much to the atmosphere... its a suck it and see kinda deal I guess.

Solarchaser

michaels said:

Solarchaser said:

I specifically don't want to use the whole tank, there is a much larger chance of stagnant water, giving rise to bacteria growth, that's why I've went with coils, plus it should be the case that everything in the coil is too hot for any chance of legionella, and means the hot water should be just as potable as cold, if the kids want to use hot water doing their sensitive teeth etc.

It also reduces any contamination /corrosion coming into the tank as I can put inhibitors in the water and don't have any water coming in.

No cost involved now, they have been installed under the house giving hot water for over a month 🙂

Would potability be a concern if you used the tank for hot water and just a single coil for the central heating.  Or if you wanted the separation and ability to use inhibitor could you have put the tank direct into the heating loop (with a suitable blender valve) and used a single coil for the hot water - or as mentioned above a plate heat exchanger rather than a coil?

You have got me thinking about whether rather than just adding a hot water tank to support our whole daily usage we could add a tank in the garage to support the central heating too.

Starting to think about the 100A main fuse now though.  Potentially we will be charging the battery at 5kw and the car at 2.5kw.  Add on the existing hot water tank and possibly a second hot water tank and that is another 6kw.  Now add on 6 more kw to store central heating heat and we are up to 19.5kw or about 85A.  Then we of course plan to run the dishwasher and washing machine overnight (max 6kw if they are heating at the same time?) and we are at 110A!!

Also would we be able to store enough energy?  Our highest ever month of gas usage was 5,500 kwh = 183kwh per day, to pull all that in in 5 hours would be 36kw!!  So basically we would still need gas so couldn't also factor in the savings of going boiler and standing charge free.

Apologies, I read and responded to only half of this yesterday, was in the way out.

Could I have used one coil for hot water and used the full tank for central heating, yeah, and I did consider it for a while, there was a couple of things swayed me away from it.
Firstly when you drain your radiators, the amount of crud that comes out is pretty nasty, and it's mostly the inside of metal radiators that does it.
My tanks are stainless and so the only corrosion risk is one destrat metal pump, so I can have a pretty low mix of inhibitor,  if I plumb in the whole tank then I need to have a lot of inhibitor,  it also means the crud from the system will mostly sit at the very bottom of the tank, which will be pretty hard to flush out, and could in time kill the elements from what I've read.

There is also the amount of fluid in the radiator circuit.
If I drain the whole thing just now, it's around 100 liters, if I make the tanks part of the system, its almost 1000L.

And finally, separation of the systems.
If I have a problem with water I can just isolate the water, tanks can stay at 60c and no issues.
Same with central heating, as I'm going to have to drain the system to change pump position and add in loops and valves, I'll drain the radiator system, but the main tanks can stay at 60C, if they were all connected, id have to drain everything and cost myself say 50kwh to bring the water from 10C back up to 60C.

I'm not saying either of your propositions is wrong, not at all, this is just the way I decided to go, and what my logic was for doing it this way.

In terms of the 100A fuse, or 25Kw if you want to view it that way, I will have to balance demand... a bit.

My 20kwh of batteries charges from empty to full within the 3 hour period of go faster.
So around 7Kw

These 4 elements will charge at 12Kw

If I want to charge the car at 7Kw then I'm now over the 25Kw limit of the house.

And thats before considering background loads or washing machines etc.

Right now charging is still free in my part of Scotland,  but that won't last forever. 
Right now I have around 6kw "spare" for background and white goods.
I have no spare for the 10Kw showers, so they need to be gone and soon.

Part of the attraction of the myenergi system is that you can tell it your size of fuse and it will ramp down the power to either the immersion or the car depending on which you give priority too.

Again worst case scenario here is I move onto 4 hour Go instead of 3 hour go faster, the difference in cost is about 10%

In terms of wiring, the setup will be supplied with 10mmT&e and fitted with a 50a trip, this will come from removing one of the showers, which is currently on 10mmT&e and a 40a trip.
The incoming house main has a 125a cable which was fitted as part of my unlooping a few months ago in order for the zappi charger to be fitted.

As an aside of sorts, it may be worth checking the actual wattage of your white goods, we tend to class them all as 3kw, but its quite normal to find they are actually 2kw or thereabouts which reduces your worry.

gefnew

You could use double block and bleed system that can help with less draining.
How It Works: Double Block-and-Bleed and Double Isolation-and-Bleed | Schlumberger (slb.com)

Solarchaser

That's an interesting valve, I must admit, I've never seen that design before.

The way the system is, there are double valves on the pumps and double valves on the return magnetic filter,  so I probably don't need that now, but I think it would have been a good solution if I hadn't already done the valves 👍

Solarchaser

I took a wee pic of the central heating piping  before taking it apart, I thought it was interesting how well the one way valve does at holding back the heat 

And obviously you can see how hot the pump is and how hot the magnetic trap is on the other side.
Now to have one way valves at the entrance and exit so that the only times those oarts get hot is when the central heating is running

QrizB

Good stuff Solarchaser!

On a *much* smaller scale, I'm wondering if putting one of these in the kitchen and heating it with Go on a timeswitch will make sense this winter, both for the obvious reason and to provide some background heating since the kitchen is on the shady side of my house. It probably won't (it only stores 3kWh or so) but I like the idea

70sbudgie

Thank you @Solarchaser, this is very inspirational. 

I know it wasn't a very popular idea last time I raised it, but I am going to try out an FIR panel heater this winter. My experience so far is that it worked quite nicely as a spot heater, so I want to see how it does as low level intermittent heating in a room that is usually unoccupied or has a log burner for heat. At 700W, I figure the worst case is that it doesn't provide enough heat.

Reed_Richards

Solarchaser said:

I took a wee pic of the central heating piping  before taking it apart...

That's a very nice picture.  Can I ask what camera you used and how much did it cost?

silverwhistle

QrizB said:

Good stuff Solarchaser!

On a *much* smaller scale, I'm wondering if putting one of these in the kitchen and heating it with Go on a timeswitch will make sense this winter, both for the obvious reason and to provide some background heating

Why not use the oven if you have an electric one? It probably comes with its own timeswitch, although I've never used mine.

@70sbudgie, I used a hot air blower under my home desk last winter, normally using surplus solar, but spot heating is very effective in such circumstances.

Solarchaser

Reed_Richards said:

Solarchaser said:

I took a wee pic of the central heating piping  before taking it apart...

That's a very nice picture.  Can I ask what camera you used and how much did it cost?

It's a flir one, which is basically a small camera which attaches to your phone, its a clever wee idea.
They are normally £300 odds, and I was lucky that work gave me one.
There is one on ebay for £150 just now

https://www.ebay.co.uk/itm/115494241950?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=bXatEGCiQCW&sssrc=2349624&ssuid=DtbsXk1pRsq&var=&widget_ver=artemis&media=COPY

@70sbudgie my feeling is, if you think it will work, give it a go.
Sometimes "everyone " agrees something won't work until you try it and it does.
Everything is a theory until you prove or disprove it right??

I like the lateral thinking @QrizB clever solution to two issues imo 👍