Green Building Forum - Electric hot water boilers Tue, 19 Dec 2023 06:25:49 +0000 http://www.greenbuildingforum.co.uk/newforum/ Lussumo Vanilla 1.0.3 Electric hot water boilers http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17619&Focus=298389#Comment_298389 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17619&Focus=298389#Comment_298389 Mon, 24 Oct 2022 12:57:40 +0100 owlman If possible, I realise I would need a three-phase supply in order to get a boiler with sufficient output to feed a 2000l buffer tank. The beauty of the idea would be that everything else stays the same with only the heat source changing.
I wondered if anyone had attempted this?]]> Electric hot water boilers http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17619&Focus=298391#Comment_298391 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17619&Focus=298391#Comment_298391 Mon, 24 Oct 2022 13:29:08 +0100 Doubting_Thomas Electric hot water boilers http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17619&Focus=298399#Comment_298399 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17619&Focus=298399#Comment_298399 Mon, 24 Oct 2022 14:32:15 +0100 Gareth J Electric hot water boilers http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17619&Focus=298400#Comment_298400 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17619&Focus=298400#Comment_298400 Mon, 24 Oct 2022 16:21:17 +0100 Peter_in_Hungary What is the heat load / day needed ?
Is a heat pump out of the question ? (cost or other)

Rather than buy a electric hot water boiler could you get the TS modified by welding in a few bosses as required. I have a screw in immersion heater on my DHW tank for summer use and it is 3kW and plugs into a wall socket. It is self contained in that it has its own thermostat up to 60 deg. but I suspect you could get ones with a higher temp if needed. It screws into a 1 1/2 bsp thread with a sealing washer at the end]]> Electric hot water boilers http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17619&Focus=298405#Comment_298405 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17619&Focus=298405#Comment_298405 Mon, 24 Oct 2022 18:19:58 +0100 WillInAberdeen
If you want to store off-peak electric heat to heat the house, then add up how many kWh of heat you need on a cold day. Divide that by the duration in hours of your tariff's off-peak period, to give the kW power rating of the heater. Then, you need about 100l of thermal store for each 3-4kWh you need to store.

Eg if you only need 2.5kW to heat the house, so 60kWh of heat each day, and run on E7 with 7 hours of off-peak, then you need 60/7= 9kW heater and you need 60/3 *100 = your 2000l storage. You might be able to run your 9kW heater on 2-phase, or use 3x 3kW immersions.

But if you need more than 2.5kW to heat the house, then you can make the heater bigger than 9kW, so it heats the house and the store simultaneously off-peak. Or run the 9kW heater during peak time as well as off peak, at greater cost.

Alternatively, if you only want to store up DHW, a 3kW heater in that store will be plenty big enough.

Different tariffs have different off-peak hours, eg some EV tariffs have 2 supercheap hours, whereas Octopus Agile had about 15-20 somewhat cheaper hours (if it's still available).

In the long run, a heatpump might work out cheaper?]]> Electric hot water boilers http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17619&Focus=298407#Comment_298407 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17619&Focus=298407#Comment_298407 Mon, 24 Oct 2022 19:27:23 +0100 djh
But to help we'd need more information about what your plans are and what the heat requirement is (numerically).]]> Electric hot water boilers http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17619&Focus=298408#Comment_298408 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17619&Focus=298408#Comment_298408 Mon, 24 Oct 2022 20:38:59 +0100 owlman I was musing over the idea of replacing one batch burn device, the 10-year-old log gas boiler, with another, possibly a small commercial, electric water heater. The current wood boiler is 42kW and replacing with a like for like three phase electric equivalent at about £1500-£2000.
An uneducated guess could mean install and wiring changes possibly add another £3-4000, possibly more.
The real fly in the ointment is therefore going to be three phase supply. The cable run is short as there is a three-phase supply on the post opposite my house, so under a rural village road and about 15metres to the current fuse box. The existing supply is, I'm guessing in ducting, but can't be certain. I've been advised it could be well in excess of £10,000 which would make the exercise a non-starter and another air-to-air split heat pump the better option.

Incidentally, I don't generally buy the existing wood as most of it is my own supply, but age is creeping up and processing logwood is a young man's game.
As I mentioned above, I just wondered if there was an easy replacement fix, as the existing hydronic system works fine.]]> Electric hot water boilers http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17619&Focus=298409#Comment_298409 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17619&Focus=298409#Comment_298409 Mon, 24 Oct 2022 20:52:41 +0100 WillInAberdeen Posted By: djhnot sure what 2-phase is? sorry, my typo.

Edit: 42kW would reheat the 2000l store in a couple of hours, but you likely don't need that much power to reheat it that fast? How about pricing the biggest electric boiler that your present supply can support, then compare that to the house's heat load?

Cheaper running cost for the a-a heatpump option, or an a-w ashp heating the store on overnight rate, you might get a grant for it?]]> Electric hot water boilers http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17619&Focus=298411#Comment_298411 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17619&Focus=298411#Comment_298411 Tue, 25 Oct 2022 08:48:19 +0100 revor Posted By: djhI'm not sure what 2-phase is?

2 phase is 380 V and will be taken by tapping into 2 phases of a 3 phase supply. It is used in specialist applications. I only learnt about it a few years ago when I was looking at purchasing a 2nd hand disc sander for my workshop and noticed the label. Then more recently I discovered my roller shutter door to my agri shed is powered by a 2 phase motor when my neighbour took out a phase. Seemingly they are also used in hoist application such as lifts but do not know how widespread they are. Also used in certain electric welding equipment.]]> Electric hot water boilers http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17619&Focus=298414#Comment_298414 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17619&Focus=298414#Comment_298414 Tue, 25 Oct 2022 12:58:01 +0100 djh Posted By: revor
Posted By: djhI'm not sure what 2-phase is?


2 phase is 380 V and will be taken by tapping into 2 phases of a 3 phase supply. It is used in specialist applications. I only learnt about it a few years ago when I was looking at purchasing a 2nd hand disc sander for my workshop and noticed the label. Then more recently I discovered my roller shutter door to my agri shed is powered by a 2 phase motor when my neighbour took out a phase. Seemingly they are also used in hoist application such as lifts but do not know how widespread they are. Also used in certain electric welding equipment.I know what two-phase means in the USA, where it is available (meaning 2 phases 180° apart), but I just looked up two-phase power and discovered it is "Two-phase electrical power was an early 20th-century polyphase alternating current electric power distribution system. Two circuits were used, with voltage phases differing by one-quarter of a cycle, 90°." And apparently it is also used to describe some devices powered by a supply taken between two phases of a three-phase system, as you describe. I can't see why anybody with a three phase supply would want to use a two-phase motor for anything; it seems bizarre. Three phase is just so natural. I can just about conceive of something like a welder using it instead of deriving the voltage with some extra components to save cost.

But it seems the whole thing was just a typo, so :bigsmile:]]> Electric hot water boilers http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17619&Focus=298415#Comment_298415 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17619&Focus=298415#Comment_298415 Tue, 25 Oct 2022 13:02:30 +0100 djh Posted By: owlmanI was musing over the idea of replacing one batch burn device, the 10-year-old log gas boiler, with anotherBut you have a large buffer tank, the purpose of which is presumably exactly to allow the use of a batch burn device like your log burner to be used for a more continuous load. So why replace it like for like? Why not consider the end use of the heat and the requirements of the load and view the buffer as an extra resource that can be used if desirable, but definitely doe NOT need to be heated in the same way.]]> Electric hot water boilers http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17619&Focus=298416#Comment_298416 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17619&Focus=298416#Comment_298416 Tue, 25 Oct 2022 13:50:27 +0100 owlman I agree that utilising some other heat source is possible and, in many respects, cost wise preferable.
I had considered an A-W heat pump but discounted it because of site constraints, lengthy pipe runs, etc in respect of a monobloc device.
I know I could consider a split A_W with the heat exchanger next to the store, incidentally IMO, superior to monobloc. However, it would still need microbore refrigerant lines to the heat exchanger, although much easier than the large water pipes of a monobloc.
PiH's idea of welding a new threaded boss on the side of the tank to introduce e.g., a 6kW immersion to supplement the existing 6kW immersion, is the cheapest option, I think. 12kW may? give sufficient input to satisfy water temp needs and just needs another slot or two on the CU.
I'd simply have to decide on the best, most efficient location, up the side of the tank. I think heating the whole 2000l would be wasteful, the cooler temperature returns stratify the water anyway.]]> Electric hot water boilers http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17619&Focus=298417#Comment_298417 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17619&Focus=298417#Comment_298417 Tue, 25 Oct 2022 14:16:55 +0100 Gareth J
It's a pain really as 3phase is so much better set up for running big kit while split phase is relatively obscure. And you're supposed to make an attempt to balance the phases somewhat. Does give a bigger supply than standard single phase though and is generally seen on remote places. Must be cheaper than running proper 3phase to places.]]> Electric hot water boilers http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17619&Focus=298418#Comment_298418 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17619&Focus=298418#Comment_298418 Tue, 25 Oct 2022 14:57:45 +0100 djh Posted By: owlman12kW may?Well 12 kW is 48 A or so, so I could happily pull that from my normal single phase supply. But a 12 kW continuous load is 105,120 kWh, which is rather more electricity than I would want to pay the bill for! So I'd be looking for another plan.

And if you're planning to use it as a 'batch burner' only running some of the time, then my point was that you should at least look at the alternatives including a continuous heating system at some lower power level. You really haven't told us very much at all in order to make any sensible suggestions.]]> Electric hot water boilers http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17619&Focus=298419#Comment_298419 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17619&Focus=298419#Comment_298419 Tue, 25 Oct 2022 15:39:30 +0100 owlman Electric hot water boilers http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17619&Focus=298424#Comment_298424 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17619&Focus=298424#Comment_298424 Tue, 25 Oct 2022 21:15:43 +0100 djh Posted By: owlmanWho said anything about running at 12kW continuously, simply there as a backupIf you actually gave us a straightforward statement of what the requirements are, then we wouldn't have any confusion :devil:

You haven't said anything about the system being a backup either. My point still applies. :bigsmile:]]> Electric hot water boilers http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17619&Focus=299357#Comment_299357 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17619&Focus=299357#Comment_299357 Fri, 23 Dec 2022 09:20:42 +0000 ianh100
I only have a single phase 100amp supply and have added EV charging which has to be limited to 16amps at the moment due to risk of taking out the main fuse. I am waiting for a load balancer for that.

If you are going to go electric I think you really need to look at something that can use lower cost energy overnight, I am looking at TEPEO as an option for my place. I think this is about £6k but could mean most of my electricity use is at the lower night rate so could pay for itself in just a few years. There are a number of smart hot water tank solutions that can store heat or just heat what you need.

It sounds like you have a larger property, you can runs several of these boilers in parallel but that would need your expensive 3 phase supply.

I have to say if you main reason to change is the work of preparing wood to burn its going to be way cheaper to pay someone to do that for you but better for the planet to stop burning stuff if you can.]]>