FredBristol

ASHP, Solar PV & SunAmp (Storage) Control Problems?

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Hello

Having read quite extensively on the use of an ASHP for heating, a SunAmp unit for hot water and a solar PV diversion, I'm wondering whether its the equipment or the control system that's the problem. I appreciate that, if you buy, for example, a SunAmp heat store and they also supply a controller, then, if it doesn't work it is the whole thing that is identified as unreliable. (Similarly for the ASHP and PV Diverter)

 

What I'm hoping for is a better understanding of where the problems lie. I've used a German made boiler controller which has never given a problem, but setting it up was a nightmare. It was too easy to set it up wrongly.

 

What is the experience with the control systems? Which ones work most reliably?

 

 

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I discounted a Sun Amp as our hot water source as you cannot heat them via the ASHP, it is just direct electricity or diverted solar PV.

 

There were issues around some versions of the Sun Amp controller where they could not accept any more charge until they had been more than 50% depleted of heat which some found meant their surplus solar PV was going to waste.  I believe most of those issues have been resolved.

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51 minutes ago, FredBristol said:

What I'm hoping for is a better understanding of where the problems lie.

Maybe you can clarify which problem you are asking about? There's been several, from reliability of parts to compatibility with certain ASHPs to the need for high temperature heat pump (depending what pcm is used) to errors in system design to certain controllers not allowing recharge from solar until it's basically depleted to ... probably several other problems I've forgotten 🤣

After a shed load of research I went for a r good low temp ashp and really well insulated UVC and my life is much happier (largely as I can find local trades to install and maintain these much easier)

 

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6 hours ago, FredBristol said:

SunAmp heat store and they also supply a controller,

I believe the controller now comes built into the main SA unit. Not sure if that's a good thing or not.

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1 hour ago, oranjeboom said:

I believe the controller now comes built into the main SA unit. Not sure if that's a good thing or not.

It’s subsequently garnished with 4 ( iirc ) status led’s, so, depending on the accuracy of what they depict, one can assume it’s definitely a good thing. Better than the original offering of grey-box-sat-on-wall-fingers-crossed-it’s-doing-something.........

It still cannot live up to its claimed reputation for absorbing any and all  ‘potentially otherwise lost’ / excess PV input etc due to the fact that it cannot absorb ANYTHING until it’s crudely scaled controller decides that it is wiling to allow it to do so. As proven here, and seems apparent in the new installation / user literature, it will always have a potentially huge empty void which cannot be filled when there is space to do so. 
I can’t help thinking that there is a better way for SA to ascertain a level / state of charge, but maybe the commercial incentive isn’t there yet to provoke further investment in this pursuit. 
Just my opinion, and can be taken with a pinch of salty yogurt. 

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1 hour ago, oranjeboom said:

I believe the controller now comes built into the main SA unit. Not sure if that's a good thing or not.


Keeping electrikery bits with the warm wet bits does seem a bit of a strange idea given their history with bowing and bending panels etc. 
 

A smaller control panel would be more in keeping and easy to do - but that’s not their usual RTM so why would they ..??

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47 minutes ago, Nickfromwales said:

It still cannot live up to its claimed reputation for absorbing any and all  ‘potentially otherwise lost’ / excess PV input etc due to the fact that it cannot absorb ANYTHING until it’s crudely scaled controller decides that it is wiling to allow it to do so

I think this may be more to do with the nature of phase change materials.

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8 hours ago, SteamyTea said:

I think this may be more to do with the nature of phase change materials.

Years or R&D identifies that type of  issue and then you design that out with strategic mitigation. 

Edited by Nickfromwales

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The only appeal of SunAmp is its compactness because of the very limited space we have that cannot accommodate a full size tank, or something like a Mixergy (which reminds me of a 1960's Sadia water heater). I guess if SunAmp don't have a way of knowing how much of their phase change material is in its energy storing state then that's a problem I'm not going to be able to solve.

Anybody do high density water? 🙂

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3 minutes ago, FredBristol said:

The only appeal of SunAmp is its compactness because of the very limited space we have that cannot accommodate a full size tank, or something like a Mixergy (which reminds me of a 1960's Sadia water heater). I guess if SunAmp don't have a way of knowing how much of their phase change material is in its energy storing state then that's a problem I'm not going to be able to solve.

Anybody do high density water? 🙂

Exactly what space do you have, and what exactly do you need to achieve in terms of water delivery and how you will heat it? Electricity only?

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29 minutes ago, FredBristol said:

Anybody do high density water?

Just cool it to 4°C

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28 minutes ago, FredBristol said:

The only appeal of SunAmp is its compactness

 

… plus the lower standing heat losses for a passive house.

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Plus no G3 or annual service / inspection nonsense that you have with a cylinder. 
Of course, everyone “forgets” to spend £100 a year on somebody to stand for 15mins stroking their chin and constantly remarking “nice job, that.....”. 
Good luck when you go to claim on your warranty, and even better luck when something pops at full mains potential and floods your nice new house because there’s no expansion pre-charge left in the expansion vessel 👊👎

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Can I PM members? If so, how?

I'd like opinions of members regarding possible installers within a practical range of north Bristol, think M4/M5 junction, and that may transgress the forum T&Cs if I did it on here. 

 

(I'm asking for opinions because it has become apparent that you can be listed as an installer without having ever installed the equipment.)

Fred

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Click on the name ( eg. @joe90) Then on their  page there is a “message” tag, allows you to private message them. On the subject of recommendations I don’t think it’s against T@C,s and I think it’s a good idea to recommend people that have a proven track record (admin will correct that if wrong) I have recommended our builder down here in Devon as he was brilliant.

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On 12/10/2020 at 22:01, Nickfromwales said:

It still cannot live up to its claimed reputation for absorbing any and all  ‘potentially otherwise lost’ / excess PV input etc due to the fact that it cannot absorb ANYTHING until it’s crudely scaled controller decides that it is wiling to allow it to do so.

 

So the only workaround is still for a CTRL-ALT-DEL each day on the Qontroller either manually or via a timer as per  @Jeremy Harris (https://forum.buildhub.org.uk/topic/7743-sunamp-container-bulging/?do=findComment&comment=136938) ? Not ideal, but an easy fix still for someone still contemplating going down the Sunamp route.

 

 

 

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2 hours ago, oranjeboom said:

 

So the only workaround is still for a CTRL-ALT-DEL each day on the Qontroller either manually or via a timer as per  @Jeremy Harris (https://forum.buildhub.org.uk/topic/7743-sunamp-container-bulging/?do=findComment&comment=136938) ? Not ideal, but an easy fix still for someone still contemplating going down the Sunamp route.

 

Pretty much. TBH SA should have strategically hemmed that in as a work around to get these things stuffed to the gunnels. It's an expensive box to have laying around semi-utilised. My workaround is to size above the known requirement, which has not hit a problem on any of my installs to date, and the only issues I've had have been with 'Friday units' not working from day 1. The real bodge solution would be a 6-event / 24hr timeclock ( interrupter ) which bumps the SA every other hour through the daytime. ( IF only feeding via excess PV ). If no diversion, then a dual event timeclock bump at midday, in unison with a strategic timed event for midday top-up boost, followed by a full recharge overnight on cheap rate tariff such as Octopus @ 5p/kWh. Use those as a benchmark and elongate the top-up as required in line with however much more DHW you need to get you through an evenings cleansing of ones "back, sack 'n' crack" :) 

 

 

Disclaimer. Please omit "sack" as applicable ;) 

Edited by Nickfromwales

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While power cycling is an "easy" fix, it makes me nauseous to think of designing a new installation to depend on it.  What if SA change the controller (again) betweeen system spec and delivery? What if the controller fails and the replacement unit works in some other way? What if it turns out that this hack causes the life expectancy to be halved? etc.

With a barge pole I would not touch it.

 

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