Is this inline electric heater too many amps?

[Jeremy Harris]

10 minutes ago, Nickfromwales said:

A size 9 unit ( ~10.5kW actual ) lends itself to managing your DHW water use and deciding how / when you have to boost it with grid. 

My proposal to go to a size 12 unit ( ~14kWh actual ) will have much more space to store energy, allow for the drain from the HRC, and guarantee that you’ll be fine to charge once a day from low rate electricity ( allowing you to downscale the size of your intended PV array too ). At 5p/ unit with Octopus, plus the ( iirc ) 5.2p export tariff ( available now ) this would work out the best bang for your buck. 

 

PV won’t cut it all year round, but grid is constant ( at least as long as the supplier is in business ) but consumer deals for buying electric should get better with EVs becoming more popular ( or even mandatory ) and suppliers having to lend themselves to more sensible ( dare I say ‘consumer friendly’ tariffs. 

 

Having additional headroom in the capacity of the SA also means more energy can be harvested in times of plenty, for use when maybe the PV output the following day is poor. £300 well spent imho, as you’re paying for the smaller unit and installation anyway.

 

When given this option a lot of people are going for it. Cheaper than lithium storage and a much longer lifespan / near zero service & repair, so economics wise, for dumping excess PV or load-shifting,  a good option afaic. 

 

 

@Nickfromwales, this is a 60m² house, with the Sunamp just for DHW,  so I'm really struggling to see how it would need a 12 kWh Sunamp, TBH.  We use a LOT of hot water and just managed with a (regularly topped up) 4.5 kWh Sunamp, and now we have a 9 kW Sunamp we have more than enough hot water from a  single cheap rate charge (or solar charge).

 

What size UVC would you fit in a 60m² house?  I'd have thought a 200 litre one would have been more than enough, for years I lived in a two bedroom house with a 120 litre cylinder, heated by an immersion, and that was fine.

[Roz]

Thanks @JSHarris and @Nickfromwales ! To clarify, we dont have the intention to use PV for a long time, we cant afford it, but I like the idea that we could do it in the future. Not sure if that changes anything you have said. 

 

I think I am ending up on the same page in terms of burying a pipe so it's good to hear that advice. Originally when it was mentioned I didn't like the idea of taking up all our shed space with an UVC and running our hot water to the house from the shed, but not having a UVC, and running just the hot water underground TO the infrequently used shed seems much more reasonable.

 

Um, what is hot return circuit in? I understand the words but dont know what it does or is for.

[Roz]

Also @JSHarris and @Nickfromwales the installer recommended down here suggested a 6kw sunamp for the DHW for just the house. Just for interests sake I thought I would tell you that. So I had thought with this new plan of upgrading to 9 so it could cover the studio. 

 

If we got the 9 and used too much water, could it be charged up during the day if we were on octopus agile rate - as it has dips in cost during the day too

Edited August 1, 2019 by Roz

[Jeremy Harris]

5 minutes ago, Roz said:

Also @JSHarris and @Nickfromwales the installer recommended down here suggested a 6kw sunamp for the DHW for just the house. So I had thought with this new plan of upgrading to 9 so it could cover the studio. 

 

If we got the 9 and used too much water, could it be charged up during the day if we were on octopus agile rate - as it has dips in cost during the day too

 

The Sunamp can be topped up anytime, if needed.  It's easy to just connect to a standard immersion timer so that you can control it in pretty much the same way as a normal hot water cylinder.  In fact, our 9 kWh Sunamp is connected via a standard immersion timer, that is used to provide a boost top up on the E7 cheap rate if it hasn't charged up from PV during the day.

 

Much harder to do this with Agile, as it's a continuously variable tariff, so a timer doesn't know exactly when the next 30 minute rate slot has dropped to a low rate.  No reason why it couldn't work just fine with a normal off-peak cheap rate, or with one that has a fixed low rate tariff.

[Roz]

20 minutes ago, JSHarris said:

 

 

@Nickfromwales, this is a 60m² house, with the Sunamp just for DHW,  so I'm really struggling to see how it would need a 12 kWh Sunamp, TBH.  We use a LOT of hot water and just managed with a (regularly topped up) 4.5 kWh Sunamp, and now we have a 9 kW Sunamp we have more than enough hot water from a  single cheap rate charge (or solar charge).

 

What size UVC would you fit in a 60m² house?  I'd have thought a 200 litre one would have been more than enough, for years I lived in a two bedroom house with a 120 litre cylinder, heated by an immersion, and that was fine.

Yes so for additional context it is a small place and has one proper bathroom, then the shower room in the studio. But it's generally a home office.

 

At the moment there is just the two of us but we are youngish and might expand beyond that in the future. We also might not stay here forever so the sizing should be right for whoever might move in to a one double and one single bedroom house with one bathroom and a non residential studio.

[Ed Davies]

28 minutes ago, Roz said:

Um, what is hot return circuit in? I understand the words but dont know what it does or is for.

 

They're suggesting circulating hot water to/from the studio so that warm water is available quickly, not having to run off a lot of cold and wait for the hot to make its way through the pipe. Not all the time, just when the hot water is likely to be used there however that's timed.

[Roz]

25 minutes ago, Ed Davies said:

 

They're suggesting circulating hot water to/from the studio so that warm water is available quickly, not having to run off a lot of cold and wait for the hot to make its way through the pipe. Not all the time, just when the hot water is likely to be used there however that's timed.

So there's like a continual movement of hot water going to and back from the studio, then when someone wants to use it it's there?

[SteamyTea]

I have not read all this thread, and my suggestion is never popular with plumbers.

Have you looked into installing a small VENTED cylinder.  You may get away with having 2 kW element in it.  And you can do a lot of the work yourself.  And no certification on the water side.

I have a 200 lt E7 cylinder, way to big really.  Could get away with half the volume, even running it at 50°C.  Could get more storage if I ran it hotter (when guests come).

I have a pumped shower, flow rate is about 11 lt/min.  No one has ever complained and a few have commented how good it is.

[Ed Davies]

3 hours ago, Roz said:

So there's like a continual movement of hot water going to and back from the studio, then when someone wants to use it it's there?

 

Yep. Obviously some heat losses, less obvious how much particularly if you can keep the run time down to when hot water might realistically be wanted. Perhaps even have a press button to “precharge” the pipe.