Sunamp PV - Heating Element

[Cooeyswell]

12 hours ago, TerryE said:

TBH, if my current PVs failed or became End-of-Life unrepairable then I would still have SunAmp at the top-of-list as a replacement supplier. 

I'm the exact opposite. I am very close to binning my Sunamp PVs, the replacement will be a well insulated UVC (OSO or similar). I am spending far too much time without hot water to justify continuing with them.

 

You may detect a hint of exasperation in this post. The crud filled Y-Strainer was a red-herring, the Sunamp-PV is still tripping out every half hour or so. I'll see if technical support have any ideas.

[TerryE]

Sorry to hear that.  Maybe ask them to scan this post.  🤣

[Cooeyswell]

Just to follow up on my recent posts regarding my Sunamp PV.

 

A few weeks ago it started thermal tripping each night (it is charged on E7 electricity). It was storing sufficient energy for two/three quick showers, nothing more. I had to open the unit and reset it every morning.

 

I called Sunamp and asked for technical support - I was told they would call back, they didn't.

I assumed they were busy and waited a week, still no response.

I called again got though to the support person I worked with two years ago.

 

Great support (Thanks Ivan), worked through the issue and agreed that the trip was occurring due to a mismatch between the flow measured and the temperature of the flow, The culprits being either the pump, the flow sensor or the temperature sensor. Unfortunately the lack of any debug interface/information on this version of the Sunamp PV means that there is no telling which is at fault. To make things more complex this was my support persons last day, but I was promised a call back from his colleague to pursue a solution.

 

I waited - no contact from Sunamp.

The Sunamp-PV stopped charging completely. The pump still appears to be working but the immersion is never energised.

The Sunamp is now in the garage, replaced by an OSO direct cylinder very swiftly delivered by Wolseley.

 

So with the benefit of 20/20 hindsight my Sunamp journey is something I should never have embarked upon.

- Purchase 2016 for £2K (including expansion unit)

- Breakdown in 2021 (Circuit board and thermal trip replaced)

- Breakdown in March 2023, (immersion and sensor replaced)

- Breakdown December 2023 (Unit is replaced and heads to landfill)

 

To clarify some points. I am extremely techy - this is probably the reason I was drawn to this system in the first place - and was happy to work through the initial breakdowns. However I have my 91 year old mother living with me and lack of hot water is just not acceptable, neither is the lack of reliable technical support on a £2k product less than 10 years old.

 

 

 

 

 

 

Edited December 9, 2023 by Cooeyswell

[MikeSharp01]

When it was working did it do what it says on the tin? If it did then you wonder why, in the forth manufacturing age, it cannot be built to last. We are still on track to get one but the more I read the less I like the idea. 

[Cooeyswell]

It worked very well for 5/6 years with no problem. Then it started to get issues.

My guess is that Sunamp realised that the Sunamp PV was overly complex relying as it does on multiple sensors, a modulated water pump and a control board with relays etc. Such a system may have been viable if sufficient debug information had been made available but it wasn't - at least not to the end user.

 

My understanding is that the current systems have been simplified but that an immersion failure requires a return to base. So the question is what do you do for hot water while your Sunamp is on a trip to Edinburgh.

 

There may well be a place for a Sunamp in size constrained locations. But if you are just looking for a low thermal leakage solution then a hot water cylinder such as the OSO unit I have just installed may be a better long term solution. It uses vacuum panel insulation just like the Sunamp (so low loss) but has built in redundancy (two immersions) and very low complexity so can be fixed by your local plumber - A feature I feel will be important as I continue to age

 

[TerryE]

That SunAmp PV of mine has failed again,  so I am down to 1 × SunAmp PV again.  It looks like the safety thermostatic cut-out has tripped again.  No good reason.  I had a DS18B20 on the heater wall and it never got near a cut-out temp threshold.   I like the unit but the control electrics board is crap.  I am seriously considering replacing it by an off-the-shelf ESP32-based control board, and reimplementing to control myself.  

[SteamyTea]

10 hours ago, Cooeyswell said:

There may well be a place for a Sunamp in size constrained locations.

My house has a total floor area of 48m² over two floors, so stairs and landing take up 10m² of that.

I have a 200 lt water cylinder, had to change it a few years back.  The previous one lasted 33 years I think.

As much as I like the idea of phase change materials and vacuum panel insulation, for DHW it is just technical overkill.

Edited December 10, 2023 by SteamyTea

[MikeSharp01]

I notice that they are offering a 10year Warranty on the heating element in their latest marketing material.

 

11 hours ago, Cooeyswell said:

There may well be a place for a Sunamp in size constrained locations. But if you are just looking for a low thermal leakage solution then a hot water cylinder such as the OSO unit I have just installed may be a better long term solution.

Looks like the OSO is about half as good as the Sunamp in heat loss terms ( OSO (150 Litre): 1.2 kWh/24hr (source) and Sunamp 150 0.67 kWh/24hr (source) so if you charge it each day on night rates @ 20p/kWhr the OSO cost you 24p / day (£87.60 PA) while Sunamp costs you 13.5p / day (£48.91 PA) and in a passive house you get less unwanted warming and no plumber calling every year to check your system over and re-certify.  

 

10 hours ago, TerryE said:

 I like the unit but the control electrics board is crap.  I am seriously considering replacing it by an off-the-shelf ESP32-based control board, and reimplementing to control myself.  

Sounds like a good plan. Looks like element failure, even with 10 year warranty, is still a return to base, no heating (although you have two units so not so much a problem for you), challenge though - which sounds like poor design at the very least - why can it / they not be pocketed one wonders?

 

 

[TerryE]

  

1 hour ago, SteamyTea said:

for DHW it is just technical overkill.

 

In our case, all of our services are in a small cupboard off the utility room toilet.  We would have difficulty fitting in a cylinder and the hot losses would turn the toilet into a sauna. 

 

And @MikeSharp01, I will talk to SunAmp first. 

Edited December 10, 2023 by TerryE

[SteamyTea]

1 hour ago, TerryE said:

hot losses would turn the toilet into a sauna. 

With a modern cylinder you just don't get that many losses these days.

[JohnMo]

Mine is cold to touch and its only a C rating, piping losses will exceed any cylinder losses.

[Cooeyswell]

3 hours ago, MikeSharp01 said:

ILooks like the OSO is about half as good as the Sunamp in heat loss terms ( OSO (150 Litre): 1.2 kWh/24hr (source) and Sunamp 150 0.67 kWh/24hr (source) so if you charge it each day on night rates @ 20p/kWhr the OSO cost you 24p / day (£87.60 PA) while Sunamp costs you 13.5p / day (£48.91 PA) and in a passive house you get less unwanted warming and no plumber calling every year to check your system over and re-certify. 

 

Exactly the argument I used when I originally bought the Sunamp PV. However your calculation of cost doesn't factor in the additional cost of purchase (£2K Sunamp Vs £1k OSO) or the replacement cost when the element fails just after the 10 year warranty period expires - the OSO has a 25 year tank warranty with easily replaceable immersions. The unwanted has warming is largely irrelevant in our large-ish passive house given its exposed, northerly location. Given that the OSO is cool to the touch when fully heated I don't see it being an issue for me.

Edited December 10, 2023 by Cooeyswell

[Nick Laslett]

What does the AEC (annual electricity consumption) comparison actually mean?

 

The OSO SUPER XPRESS VIP 300L has an AEC of 4490kW/year

 

The Sunamp 300 ePV has an AEC of 2701kW/year. 
 

Is this just because the Sunamp uses 50° temp for its AEC measurement and the OSO uses 70°? Or is this a standardised measurement for all devices? BRE talks about 55°. 
 

Does the Sunamp need less electricity because the volume being heated is smaller and the material is easier to heat? That was my original assumption, but my physics knowledge is very poor. Or is it just the heat loss calculation difference annualised?

Edited December 10, 2023 by Nick Laslett

[Cooeyswell]

1 hour ago, Nick Laslett said:

What does the AEC (annual electricity consumption) comparison actually mean?

 

The full horror is exposed in

https://eur-lex.europa.eu/legal-content/EN/TXT/HTML/?uri=CELEX:32013R0812#d1e32-123-1

 

In particular Annex VIII - Section 4.

It is calculated from a load profile given in Annex VI and may have no relationship whatsoever to your usage.

 

 

[TerryE]

@SteamyTea, I just checked the  SX 210 - VIP model which has a 193L water capacity.  The heat loss is 1⅓ kWh / day which is about 30-40% higher than 2× SunAmp PV, but I could live with that.  The killer (for me) is it's dimensions (1.3m high × 0.58m).  I can't put it on the deck because of the other stuff in the services cupboard that I can't move (the UFH pipework, manifolds, rising main, etc. so it would have to go on a shelf -- pretty much in the same place as the SunAmp.  I have 600mm depth to work with so it would be very tight, and I'd have to move my Control Panel.   And then the OSO is a UVC so all plumbing would need to be done and signed off by a certified plumber, so he or she would need to sign off the installation.    So this isn't an easy refit for me. ☹️

 

 

[MikeSharp01]

The sunamp system has to be a winning idea, it's just it seems not to be implemented that well as it stands give this and other threads but still not fully put off.

[TerryE]

We have a democracy in our house.  It's just that Jan has 1.1 votes. 😉  What she hates about the SunAmps is their unreliability (due to control board failures):  we are both in our 70s now, so reliability is becoming more important than ever. TBH, if we were in the situation of @Cooeyswell and only had one unit then we would have given up on the SAs long ago.  We have been looking at our utility room and we can fit an OSO tank opposite the toilet; a job for next summer, maybe.  This needs more mulling time to refine options.

 

@MikeSharp01, I really like the idea of the SunAmps and the physics behind them, but they seem to be really let down by the engineering implementation. 😪

[SteamyTea]

1 hour ago, TerryE said:

The heat loss is 1⅓ kWh / day which is about 30-40% higher than 2× SunAmp PV

I seem to remember that there is a strange methodology for testing hot water storage systems. Our old mate @Jeremy Harris highlighted it as the Sunamp did not score highly on the energy rating (at the time).

 

As with all energy analysis, how you use it makes the biggest difference.

[Cooeyswell]

5 hours ago, TerryE said:

We have a democracy in our house.  It's just that Jan has 1.1 votes. 😉  What she hates about the SunAmps is their unreliability (due to control board failures):  we are both in our 70s now, so reliability is becoming more important than ever. TBH, if we were in the situation of @Cooeyswell and only had one unit then we would have given up on the SAs long ago. 

 

 

I have exactly the same democratic discussions and house voting system. After 40 years my better half is used to my tech inspired diversions but is equally well versed in analysing  them.

So after two periods of extended cold showers this year I got the following questions :-

- Are you happy to be having cold showers ?

- Do you think I'm happy with cold showers ?

- Do you think your 91 year old mother was expecting to have cold showers when she moved in with us ?

- If we don't replace it now then when ? ( Please show your working with a detailed schedule)

- Who the **** is going to fix this **** after your demise ? (that was after day 3 of cold showers, the "imminent" was implied)

- If you die "unexpectedly" due to a freak cold shower incident, who do I call ? (Number for plumber not undertaker required).

 

I took the hint.

 

 

 

 

 

[Susie]

Have you looked at open vented thermal stores no annual tests required and with 2 electric immersion elements.  Provides main’s pressure water and heating.

https://www.gledhill.net/products/alternative-energy/torrent-stainless-ov/

[Cooeyswell]

That's an interesting option - I don't think I have come across one of these before

[JohnMo]

On 10/12/2023 at 21:48, Susie said:

Have you looked at open vented thermal stores no annual tests required and with 2 electric immersion elements.  Provides main’s pressure water and heating.

https://www.gledhill.net/products/alternative-energy/torrent-stainless-ov/

Have had a thermal store and now have UVC, UVC wins hands down, way more usable hot water for the quality of water heated. 

[Susie]

13 hours ago, JohnMo said:

Have had a thermal store and now have UVC, UVC wins hands down, way more usable hot water for the quality of water heated. 

What in your opinion @JohnMo makes the UVC better, why more usable water?

my thoughts are that UVC need safety checking annually and could invalidate home insurance if not done and the insurance companies could play difficult in the event of a claim. We could self install the thermal store.  

Was your thermal store and UVC on a similar set up or in different houses.

I am hoping to have lots of solar, 11kW or better 30 panels fit, with spare for our business. 
I am hoping the thermal store will provide hot water and some UFH if needed. I’m hoping the 350l model will be large enough for the two of us, and we are going to be very good insulation pre built SAP 96A.  
wood burner in lounge and electric heated towel rail in bathroom might be all we need making the UFH a back up. 
Start foundations next year so could still have a UVC if it would be better. 

[JohnMo]

52 minutes ago, Susie said:

What in your opinion @JohnMo makes the UVC better, why more usable water?

So thermal store or UVC we will assume heating by immersion. So the same as far as heat input.

 

Thermal store contains a heating medium, the UVC is wholesome water.

 

Thermal store, hot water is produced via a heat exchanger. Heat exchangers require a dT between hot and cold side to function and are sized for a given dT. Once the dT lowers the heat transfer falls off rapidly. So if you require 45 deg water, your cylinder could be at 70 deg, and once it has been depleted to 50 the heat transfer has diminished enough so you no longer get 45 deg water.

 

An UVC contains water only heated to 45, nearly the full cylinder contents can be used as hot water as a thermocline is formed, cold below and hot above, warm at the thermocline.

 

So UVC, can be heated less, has less standing losses, can utilise more of the hot water heated.

 

52 minutes ago, Susie said:

my thoughts are that UVC need safety checking annually and could invalidate home insurance if not done and the insurance companies could play difficult in the event of a claim. We could self install the thermal store.  

If you have the skills to install a thermal store do the UVC course, cert is valid for 10 years and training is one day at your local college. That's what I did. So self install and self service.

 

Thermal store are not a future proof install and they are not that good with a heat pump, although some do use.

 

There are two of us and we are using a 210 heat pump cylinder heated to 49 degs. Takes 45 mins from the heat pump.

 

I would also consider a heat pump, simple single zone, 3 way valve and heat pump cylinder, just do a self install. Bargain come up the time on eBay etc.

Edited December 17, 2023 by JohnMo

[ProDave]

22 minutes ago, JohnMo said:

So UVC, can be heated less, has less standing losses, can utilise more of the hot water heated.

And there is a more fundamental issue.  If you are heating with an ASHP (rather than direct electricity) an ASHP will never get a thermal store hot enough in the first place.  So a thermal store is a complete non starter if a heat pump is in your plan.