SunAmp : Snog, Marry, Avoid?

[scottishjohn]

the "bean counters " have always been the problem --not the idea of the unit

[readiescards]

Just to say about from a relay issue, the two Sunamps in our holiday cottage (with UFH & Triple Glazing) have worked fine and no complaints of a lack of hot water (from up to 6 guests). so still 'marry'

[ToughButterCup]

And a quick note to say that my SunAmp starts to recharge (from 'Up To Temperature ' notification on the Diverter) as soon as hot water is run . In this case after a hot  shower (say 3kWh demand)

 

[Dan G]

Hello!

This thread is linked from at least one prominent place, and after reading it (twice! Once over a few days, once again quickly) I feel it needs a proper conclusion.

 

The main issue was that ~2018 vintage electrically-heated Sunamps would only begin charging once about 50% depleted, which led to two problems:

 

• With charging provided by a single 3ish kW element, "charging" a unit back to full could take several hours, and if a unit was at say 51% at the start of a day,  the rest of the charge could be used up leaving no hot water for some time

 

• Charging units using diverted PV was difficult as the units wouldn't accept charge unless significantly depleted.

 

However this issue was fixed in 2019 with new firmware in the controller, as explained in this post:

 

On 06/06/2019 at 20:43, willbish said:

Has been very quiet on the Sunamp front for a while. I take that as a good sign

 

I've finally received a response back from Sunamp, which Ive pasted below. I asked them would any mechanical or software changes be made to my Sunamp units, which are currently sat in Sunamp HQ, before being delivered

 

@JSHarris Did you receive a new controller? How is it performing?

 

 

I do apologise for the delay however I managed to track down our Technical Director who has responded as follows:

 

My comments:

 

As part continuous process of product improvement, we have improved the heat transfer rate between the heating element and the heat battery heat store. The power input is managed by the controller by cycling the heater on and off during the charging phase. With the above improvement, the cycling of the heater is now rarely required and therefore this has allowed us to increase the power input during heating from cold phase of charging the battery.

 

In addition to the above,

1. charging control algorithms have been refined and the charging is now re-enabled as soon as a small quantity of water has been run off, OR when the heat battery has lost some heat through standing losses after several hours.
2. ther compatibility problems with some makes of diversion controllers have been resolved.

 

Your unit will have an updated controller.

 

 

Kind regards

 

 

 

 

This meant that electrically-heated Sunamps would begin to accept charge after only a small amount of discharge from full, meaning they play much more nicely with PV divert.

 

(There's still a bit of an issue with night charging on cheap-rate electricity: balancing the risk off running out of hot water against leaving sufficient room for PV divert energy. I think @DamonHD and others are looking at that.)

 

My personal opinion of Sunamps is that they are space-efficient and vastly simpler than fitting an unvented cylinder system when replacing a combi boiler, although using grid electricity to charge is much less energy-efficient than a heat pump charging a UVC: heat pumps invariably achieve a CoP of at least 2 when heating domestic hot water. The lower rate of heat loss from a Sunamp than from a UVC only partially offsets that difference.

 

But a primary reason this thread was started to discuss has been addressed.

 

[joth]

38 minutes ago, Dan G said:

(There's still a bit of an issue with night charging on cheap-rate electricity: balancing the risk off running out of hot water against leaving sufficient room for PV divert energy. I think @DamonHD and others are looking at that.)

 

I wouldn't hold this against SunAmp: a standard UVC hot water cylinder and even an electrical house battery require the same compromise/ trade off to charging strategy

 

38 minutes ago, Dan G said:

But a primary reason this thread was started to discuss has been addressed.

 

 

The other key issue discussed at length (but only indirectly mentioned in the OP) is heating from an indirect heat source, esp ASHP with the lower output temperatures, has some technical challenges.

This has been partly solved by them introducing various new PCM types, but last I looked into it a much larger issue was SunAmp had to individually test & qualify each and every ASHP controller to ensure compatibility, and in many cases they needed to physically ship out a different SunAmp controller board depending what ASHP you wanted to hook it up to. Has this situation changed at all? It seems a crazy and unsustainable business practice.

Obviously not an issue for anyone keeping with direct electrical Sunamp charging only.

 

 

Edited February 2, 2022 by joth

[Russdl]

If there is no sun our Sunamp charges overnight on the Octopus ‘Go’ tariff which is 5p/kW. We do not have an ASHP or boiler, just the Sunamp. 
 

The Sunamp provides DHW (not heating) for a household of 4 taking 4-6 showers a day, the bath is rarely used. 
 

It has always charged up in the 4hr cheap tariff window, normally taking around 3hrs. It’ll charge from PV if the sun is out and it will start charging after minimal discharge. We have never run out of hot water. 
 

It cost us £1500 and despite our one little hiccough with it I think it’s an absolute bargain and brilliant. 

[DamonHD]

FWIW my installation is finally back on track and I've written about half the control system, see the status page here:

 

https://www.earth.org.uk/_heat-battery-target.html

 

(I may have chosen the wrong place to split the control problem, in which case a re-think and re-write will be on the cards!)

 

Rgds

 

Damon

[Nick Laslett]

On 02/02/2022 at 10:46, Dan G said:

Hello!

This thread is linked from at least one prominent place, and after reading it (twice! Once over a few days, once again quickly) I feel it needs a proper conclusion.

…EDIT…

This meant that electrically-heated Sunamps would begin to accept charge after only a small amount of discharge from full, meaning they play much more nicely with PV divert.

 

But a primary reason this thread was started to discuss has been addressed.

 

Hello Dan,

 

Thank you for the update and clarifications. The PV divert was my main concern. The other re-heating issue seems to be improved too. I’m very close to having to commit to my DHW solution, the Sunamp needs some serious thought as from previous discussions I had discounted it. 

[Onoff]

On 02/02/2022 at 11:22, Russdl said:

It cost us £1500 and despite our one little hiccough with it I think it’s an absolute bargain and brilliant. 

 

What swung you to go for the Sunamp ?

 

From the best thing since sliced bread they seemed to turn into a bit of a Marmite solution from comments I've seen on here. Old ones maybe being "better" than new. I remember @Jeremy Harris was well into it and giving Sunamp lots of feedback. 

 

I think a lot is down to the installer knowing the quirks and how to get the best out of it.

 

Good to hear it's working for you.

[Russdl]

36 minutes ago, Onoff said:

What swung you to go for the Sunamp ?

 

As soon as I read about them on @Jeremy Harris's blog I was sold on the idea and, even though there have been plenty of negative comments on here, it seemed that Sunamp were listening and trying to adapt. From my perspective, that is what they did. 

 

I believe the old ones were considered better purely because they took a charge after the slightest of discharges, the next generation didn't and as there was no indication of the charge state that caused consternation for some.

When we got ours I thought the charging issue would still be there, but I'd missed the fact that there had been an update and, as I said, it recharges after the slightest of discharges (if I allow it).

 

42 minutes ago, Onoff said:

I think a lot is down to the installer knowing the quirks and how to get the best out of it.

 

I would say that plays absolutely no part in it.

 

Attach incoming cold feed and outgoing hot feed (with a couple of small expansion vessels). Connect the mains, turn it on. The end. There are no pumps or any other moving parts, there's nothing to 'tweak'

 

We've got about 11 months left on our Octopus 'Go' tariff, so whilst that 5p/kW window is open for 4 hours in the morning, we're sitting pretty. (with the soon to hit price rises that'll mean we'll be heating our DHW cheaper than if we were using gas and 5p/kW would be the equivalent of a COP of 4 or 5 to 1!

 

I'll enjoy it while it lasts but I don't expect to be getting a 5p rate this time next year so we'll have to see what's available. ? 

 

[joth]

12 hours ago, Russdl said:

 

13 hours ago, Onoff said:

I think a lot is down to the installer knowing the quirks and how to get the best out of it.

 

I would say that plays absolutely no part in it.

 

 

Again, to clarify: this is likely true when using direct electrical heating (immersion heater) only

 

Anyone attempting to charge it from an ASHP would do well to have an installer that understands how to get the two to work together.

 

[Russdl]

2 minutes ago, joth said:

 

Again, to clarify: this is likely true when using direct electrical heating (immersion heater) only

 

Anyone attempting to charge it from an ASHP would do well to have an installer that understands how to get the two to work together.

 

Yep. Very good point. Ours of course is the direct electrical and it is as simple as a simple thing. 

[ToughButterCup]

On 02/02/2022 at 10:46, Dan G said:

Hello!

This thread is linked from at least one prominent place, and after reading it (twice! Once over a few days, once again quickly) I feel it needs a proper conclusion.

...

 

Thank you @Dan G very much indeed for your summary. 

So many threads need someone to make the effort to summarise (in this case 24) the arguments presented over many pages. It takes a lot of mental effort and time.  

[DamonHD]

I have plonked down some (electronic) cash and have ordered a Thermino 150 today:

 

https://www.earth.org.uk/note-on-solar-DHW-for-16WW-UniQ-and-PV-diversion.html#2022-02-04

 

Rgds

 

Damon

[lakelandfolk]

 We have Solar panels with retrofitted 12.6kwh batteries and Solax AC TO DC inverter. Where would a Sunamp electric supply be connected for one with electric heaters only or one with electric heaters + solar? We would hope to use off peak and surplus Solar when available.

[DamonHD]

The Sunamp's own control supply must be permanently wired.

 

The Sunamp's heater supply should be via something like a myenergi eddi for diversion.  I will also be using the eddi under software control to top-up 'off-peak' in winter mainly.  See my lengthy page above.

 

You will need different a Sunamp model if you want to provide a second (non-electric) heat source to it.

 

Rgds

 

Damon

[martinwinlow]

On 18/07/2019 at 10:35, Ed Davies said:

 

6 kWh input

 

Sorry, pedantic I know, but it's no wonder so many are confused on this subject when even the professionals who know better are sloppy about it.

It's not in the least pedantic, it's just *correct*!

[joth]

On 26/06/2020 at 18:47, ProDave said:

If you are going to take this any further, then clarify just where the thermostat for that high power heater goes.

 

I seemed to have been a wally. I ended up forgetting this thread, buying the upgrade anyway 6 months later, sitting on it for 12 months, and now struggle to install it as it has no thermostat pocket, exactly as you predicted.

Emailed oso to try and get some clarification 😬

 

[Cooeyswell]

My experience with Sunamp can be found here