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SunAmp : Snog, Marry, Avoid?

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16 minutes ago, PeterW said:


As per previous, the Sunamp will only recharge if it’s reached its 50/90% discharge level. Unlike a hot water tank that will call for heat when the programmer goes to hot water mode, a Sunamp could potentially be 52% full, which is still over its recharge point and won’t trigger the boiler. 
 

Next time you want 2 showers in quick succession, the Sunamp will empty rapidly. You can’t always guarantee to have a full Sunamp and there is no way to force it to regenerate when it is 75% full for example. 


In reality it’s much worse than that. You may receive a unit that is more like 40 or it could be 60. The technology for measuring the discharge is beyond basic (a length of wire with temp sensors hand soldered on and poked down a copper tube). The wire is not fixed in place and can be pulled or pushed moving the measurement points.
 

But more importantly you do not have ANY control. Unless they’ve changed something in the most recent controllers there is absolutely no way to override this. Although I believe some have fixed this by power cycling the controller which frankly is a bodge.  

Edited by Barney12
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27 minutes ago, Marco Van Bowden said:


Because specification is absolutely key and Sunamp have made it very clear they are a “manufacturer” not a “specifier”.

 

I note you have included the warranty document. Once you’ve had the pleasure ?😳? of moving a 12kw unit you may start to understand why a return to base warranty provides some unique challenges. 
 

My advise is to fit them near an outside door ideally with an electric winch and head rail system. Something like this should do it:

 

image.jpeg.8280bf6551f3ae2ab35c44d3eb636af6.jpeg

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It’s all the above points that make me feel glad I did not have a sunamp but a proven if basic DHW tank, as an aside I had two thermostatic pockets fitted to my tank, half way and bottom so I could choose to heat half of the tank (just us two at home) or whole tank (family and visitors ). I also have two immersions for the same reason as a backup if the ASHP Fails/needs a service. Belt and braces but it works (and I understand it!). In two years we have never run out of hot water. (Even when I forgot to switch to lower stat when having visitors!).

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29 minutes ago, Barney12 said:

...

My advise is to fit them near an outside door ideally...

 

Exactly correct.

Our was fitted upstairs by a reliable installer. We have two suicide doors in upper bedrooms (soon to be Juliette balconies) Ours popped straight through one. Two blokes, bit of sweat, tea, medals. 

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58 minutes ago, Barney12 said:


In reality it’s much worse than that. You may receive a unit that is more like 40 or it could be 60. The technology for measuring the discharge is beyond basic (a length of wire with temp sensors hand soldered on and poked down a copper tube). The wire is not fixed in place and can be pulled or pushed moving the measurement points.
 

But more importantly you do not have ANY control. Unless they’ve changed something in the most recent controllers there is absolutely no way to override this. Although I believe some have fixed this by power cycling the controller which frankly is a bodge.  

Do you have issues with running out of hot water then?

 

42 minutes ago, Barney12 said:


Because specification is absolutely key and Sunamp have made it very clear they are a “manufacturer” not a “specifier”.

What aspect of the setup is a 'specifier' required for? Surely calculating your DHW requirements can be done yourself and then its a case of sizing the SunAmps to how much you require?

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1 minute ago, LA3222 said:

Surely calculating your DHW requirements can be done yourself and then its a case of sizing the SunAmps to how much you require?


I think the issue here is that DHW sizing is traditionally done on full size tanks of capacity. 

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Just now, PeterW said:


I think the issue here is that DHW sizing is traditionally done on full size tanks of capacity. 

So if I understand where you are coming from - say you need 500l of hot water a day, you buy a tank that holds 500l. With a SunAmp you buy a size equivalent to 500l but due to ambiguities with the charge state you never know if you have 500l or 50l?

 

(Crude numbers just to clarify if that's what you mean?)

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13 minutes ago, LA3222 said:

So if I understand where you are coming from - say you need 500l of hot water a day, you buy a tank that holds 500l. With a SunAmp you buy a size equivalent to 500l but due to ambiguities with the charge state you never know if you have 500l or 50l?

 

(Crude numbers just to clarify if that's what you mean?)


Correct.
 

Equally the ability to “hit the override button” on a standard DHW tank is (in my view) a feature that is as old as the product itself. Sunamp provides NO such functionality. 

 

But then there is another problem which is key if you’re wanting to maximise solar. Because there is no ability to charge them “on demand” you have absolutely no way of maximising your solar generation.

 

All of this may have been fixed in newer controller versions but I’ve read nothing that suggests that’s the case. 
 

Again all of this points make specification absolutely key. Sunamps capacity is NOT comparable to a cylinder. 

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29 minutes ago, LA3222 said:

Do you have issues with running out of hot water then?


Yes, but my system was specified to provide heating and DHW. 
Also one of my units still doesn’t work properly.

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1 hour ago, joe90 said:

It’s all the above points that make me feel glad I did not have a sunamp but a proven if basic DHW tank, as an aside I had two thermostatic pockets fitted to my tank, half way and bottom so I could choose to heat half of the tank (just us two at home) or whole tank (family and visitors ). I also have two immersions for the same reason as a backup if the ASHP Fails/needs a service. Belt and braces but it works (and I understand it!). In two years we have never run out of hot water. (Even when I forgot to switch to lower stat when having visitors!).

 

I'm with you Joe. We have a 300L DHW tank which can be heated by the ASHP, directly by PV (via diverter) or via the immersion. Belt, brace and a safety pin 😊

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I ruled out the SunAmp very early on because you simply cannot charge it from an ASHP so in winter when there is not much PV you would be heating most of your hot water with resistance heating rather than taking advantage of the COP of the heat pump.

 

The early ones did appear to have a simpler control system that made it easier to charge with variable solar PV, but the later ones have a more complex control system that causes issues with that.

 

It's a shame because I like the concept, particularly the vacuum panel insulation system for low standing heat loss, which would be probably my only reason for wanting one.

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If you have a heat pump, or use resistance heating, it is easy to divert the power to a normal cylinder.

If that electricity comes from your PV, and goes via a heat pump, there will be times when for every kWh of PV generated, you get 3 or 4 kWh of thermal energy.

Edited by SteamyTea

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3 hours ago, PeterW said:


As per previous, the Sunamp will only recharge if it’s reached its 50/90% discharge level. Unlike a hot water tank that will call for heat when the programmer goes to hot water mode, a Sunamp could potentially be 52% full, which is still over its recharge point and won’t trigger the boiler. 
 

Next time you want 2 showers in quick succession, the Sunamp will empty rapidly. You can’t always guarantee to have a full Sunamp and there is no way to force it to regenerate when it is 75% full for example. 

Same for an UVC though isn’t it? That uses a cylinder stat at the 1/4 - 1/3 height, so if that hadn’t seen depletion occur to the point that it changes state, that also will not call for heat ;)  Not as problematic as with a SA for sure, but still a consideration. Good thing with an UVC is you can easily boost via immersion if the primary heat source is a boiler, whereas it’s a pita to do with a SA.as it’s a single call for heat for both boiler and immersion ( so you can’t force feed it like you can a cylinder / UVC ). 

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47 minutes ago, SteamyTea said:

If you have a heat pump, or use resistance heating, it is easy to divert the power to a normal cylinder.

If that electricity comes from your PV, and goes via a heat pump, there will be times when for every kWh of PV generated, you get 3 or 4 kWh of thermal energy.

But a traditional cylinder will waste upwards of 3kWh / 24hrs of heat energy vs 800-900W with a SA. So, at least 2 kWh of PV will go each day to offset losses from the previous day.
If you’ve not used much / any DHW, a cylinder will still go cool very quickly, whereas a SA will retain heat ( useful heat ) for much, much longer, eg extending times between full recharges.

Horses for courses though, and all have pros and cons. Ball ache with an UVC will always be G3 and D2 discharge, ball ache with SA will always be cost / weight / lack of control feedback ( unless you remortgage and buy a massively inflated Uniq9 via Fisher ) as SA prioritised giving those ‘customer friendly’ internal controls and LED indicators so Fisher could market them more easily. The 12’s got neglected ( don’t know if they still aren’t going out with this upgrade? Anybody? ) as Fisher were primarily fitting 9’s and that’s where the volume sales / money was........

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42 minutes ago, Nickfromwales said:

But a traditional cylinder will waste upwards of 3kWh / 24hrs


I know that @Jeremy Harris had heat loss problems with his DHW tank which led him to replace with a Sunamp but in all honesty our airing cupboard is very nearly the same temp as the house. (Well insulated as bought with more insulation added) I know we are in a heatwave at the mo but most of the year the house needs a Little heat so I don’t consider the “waste” heat much of a problem.

Edited by joe90
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43 minutes ago, Nickfromwales said:

But a traditional cylinder will waste upwards of 3kWh / 24hrs of heat energy vs 800-900W with a SA. 

 

Really? Heat loss on our 300L Panasonic Aquarea is quoted at 85W (so circa 2kWh per day) which at a COP of close to 4 is 0.5kWh to replace via ASHP and free if the sun is shining anyway.

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36 minutes ago, NSS said:

Really? Heat loss on our 300L Panasonic Aquarea is quoted at 85W (so circa 2kWh per day) which at a COP of close to 4 is 0.5kWh to replace via ASHP and free if the sun is shining anyway.

Exactly.

They may not be perfect, but still pretty good, and one can always add more insulation inside the airing cupboard, worked a treat for me.

39 minutes ago, joe90 said:

I know that @Jeremy Harris had heat loss problems with his DHW tank which led him to replace with a Sunamp

He had one of those horrible cylinders where the feed and header tank was combined.  And then it was more a problem where it was situated as the power loss was heating up the bedroom.

 

I like the technology of the SA, but they are too expensive and have control limitations.

 

 

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1 hour ago, NSS said:

 

Really? Heat loss on our 300L Panasonic Aquarea is quoted at 85W (so circa 2kWh per day) which at a COP of close to 4 is 0.5kWh to replace via ASHP and free if the sun is shining anyway.

Yes, but not a cheap cylinder compared to other generic offerings. Still 2kW is not insignificant. You get what you pay for etc, so get better offerings from bigger name manufacturers. It’s a lot to do with all the additional connective pipe work in the worst cases. 
Can you recall the price of the cylinder at all? Or was it a package offering with the ASHP?

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The 17 pages here with no clear answer provided the  clear "no" answer for me, as after the thrill of researching and installing the system, I honestly never want to have to think hard about it again, and the risk of unscheduled maintenance seems  too high. Likewise I eliminated the Mixergy tank for over-complexity. Getting a reliable knowledgable ASHP installer in our area is damn hard,  without making an extra stick for my back.

 

Instead, for better or worse, I've settled on an OSO geocoil:

https://www.osohotwater.com/en/domestic/delta-geocoil

 

300L with claimed 49W heat loss is just over 1.1kWh per day, so not entirely out of the SA domain. But with massive benefit that every single heating engineer in the country will know how to hook it up or work on it, and even if OSO go bust I've got a very good chance of long term maintenance on it, as there's virtually no active components in it. (Much less any cloud dependency, no thank you Mixergy).

It's also actually cheaper than the Ecodan matched UVC my installer originally quoted for, so if all goes well it's exceptionally good VFM.

 

Biggest downsides vs any other UVC are it's only available with one immersion heater slot (so I am reliant on ASHP for reliable reheat times, unless I can retrofit a 6kW+ element?), and there's always a risk about longevity and unrepairable nature of VIPs (OSO say it's no more likely to fail that the tank itself leak, and they have 25yr warranty).

 

Edited by joth
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16 minutes ago, joth said:

unless I can retrofit a 6kW+ element?

That is an option, but check that won't stuff your warranty up first ;)

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On 12/06/2020 at 19:26, Nickfromwales said:

£2995 ?

 

Is the £2995 a price for you to supply and install a SunAmp?

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10 minutes ago, Adrian Walker said:

 

Is the £2995 a price for you to supply and install a SunAmp?

I can't answer that as it may constitute commercial content, which we never discuss on public forum.

 

There. ;) 

Edited by Nickfromwales
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Depends on how its read I suppose. Was only said in jest.

I'll edit it to save the feint-hearted. 

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