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Heating, Hot water, ASHP, and Sunamp Design Needed


Triassic

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11 minutes ago, joe90 said:

Ah didn’t spot that (despite looking!).

In some ways, it may be better having 2 heat pumps, one to do the house heating, the other just for DHW.

A non inverter type for DHW would be a good option.

Trouble is, we all want one device to do everything i.e I want my car to have the acceleration of a Tesla S, the economy of a Nissan Leaf, the handling and road holding of a 911, but the comfort of the original DS5. And the ability to do 1000 miles between fuel stops.

It must also get me home when I am drunk (though I found the forging handing and 70 profile tyres on my old 309 helped here), and it must not cost any more than a Dacia base model.

Needs to tow 2 tonnes as well, and be convertible into a camper, with bog and shower.

 

Can't see even the best gas boiler doing all that.

Edited by SteamyTea
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18 minutes ago, joe90 said:

Why, mine does both and others here have the same set up?

You can tune a system to be very efficient when you have a regular outcome i.e known volume and temperature of water to heat.

Somewhere, along the line, a regular setup will only hit that point I frequently.

The problem is, for most people, the higher capital costs.

But worth thinking about and costing out if your DHW usage is high i.e lots of baths in a day.

Worth remembering that a modulating gas boiler is sized, generally, for the DHW load and not the space heating load.

And my E7 setup is sized and controlled on a room by room basis. I can totally, and easily, disconnect the space heating and still have DHW, or the other way around.

Space heating and DHW do different things, at different times and at different temperatures.

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7 hours ago, Russdl said:


Have you tried approaching Sunamp directly? I believe you were screwed around a bit last year...

 

They may be sympathetic. 

I did, they sympathised and suggested contacting one of the Distributors. I’m loosing faith in Sunamp.

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27 minutes ago, Triassic said:

I did, they sympathised and suggested contacting one of the Distributors. I’m loosing faith in Sunamp


That's a shame. They were very helpful when I had problems with my supplier/installer and sold to me direct.
 

I can’t comment on the product itself as many months down the line it’s still not been commissioned by said (non)supplier/installer and partly because of that we have had to go our separate ways. 

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On 12/02/2021 at 07:02, Triassic said:

You are right about the price, but you don’t mention the price of the unit to heat the UVC. When you add that into the mix you must be at the same price or greater? Mind you, Sunamp prices do appear to be on the up and the number of stockist on the way down! I contacted three fir prices and only one came back with a price, £3,300, a £600 increase over a quote I got a year ago.


Yes you are right, I should have been clearer. I was trying to make a comparison between electric +PV Sunamp vs Eco7 all electric UVC. My original interest in Sunamp was the idea that I could heat tomorrow’s DHW with today’s PV and have it store the heat for the following morning. It seems like a real pain to get the Sunamp to work this way as you can’t force it to take a charge. The other suggestion was to power it overnight. This seems a bit pointless as you can get a UVC with A rated heat loss for a lot less money and still easily use the PV divert. The VIP insulated UVC have nearly the same heat loss as the Sunamp, they both have 3kw heating elements, my simplistic understanding is that they use the same amount of electricity to heat to the same capacity (maybe I am mistaken here), the Sunamp is just more compact, which could be a deal breaker for some installations. 
 

I don’t know how the ASHP heated Sunamp compares to the equivalent UVC setup. My naive goal was to get my DHW heated by PV when it was feasible. Solar pipe heating is probably a much simpler answer, but that is a definitive no from SWMBO. 

Edited by Nick Laslett
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The problem about using multiple inputs to any heating system is the both the inputs and outputs vary.

Inputs very in time and temperature, as do the outputs.

If we knew in advance the load we wanted from a system  then the problem would be greatly simplified.

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4 hours ago, Nick Laslett said:

I don’t know how the ASHP heated Sunamp compares to the equivalent UVC setup. My naive goal was to get my DHW heated by PV when it was feasible. Solar pipe heating is probably a much simpler answer, but that is a definitive no from SWMBO. 

Sunamp is really awkward for heating hot water with an ASHP - the PCM58 they use in most of their units needs water at ~65°C to recharge, and the PCM34 is really too cold for DHW use.

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My hunch was that losses from a cylinder are largely related to the amount of plumbing connections.

 

Hence I decided on a plain direct UVC  cylinder heated by an immersion. From my reading about sunamps the electrically heated models had issues. I don't know if this is still the case. 

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I had a look on Facebook market place last night, there are quite a few new or nearly new ASHP on there,  some of the new ones are years old and I do wonder if they are too much of a risk, particularly when you can’t send them back.

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28 minutes ago, LA3222 said:

A new ASHP isn't a lot of money when considered against total build budget. An ASHP is around the same price as a Uniq 12.

So around £3300 then. I know a few on here have found second hand bargains on line and I must admit I do like to save money where I can. If anyone has spotted any special offers on a new ASHP, then please let me know.

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38 minutes ago, Triassic said:

So around £3300 then. I know a few on here have found second hand bargains on line and I must admit I do like to save money where I can. If anyone has spotted any special offers on a new ASHP, then please let me know.

I agree, I got mine for £250 new on the pallet... took a punt and I am happy with it... although it’s only 5kw and I probably need about 8kw.  Not sure I would ever pay thousands for one though. They are not responsive enough for ‘normal’ family life, and you need to plan ahead with your heating DHW demand. 

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12 minutes ago, Triassic said:

I:looking at between 7 to 9 kw.

 

I will look at my calculations again today


Hitachi RASM4 is 11kW and change of £3k ex vat inc all the bits. Nice units too

 

You may struggle with stock levels between now and June due to the Green Home crap as suppliers are trying to get ASHPs into houses to get the £10k grant for installing a £3k heat pump ... 

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