disappointed of lincolnshire Sunamp - new label showing only C rated energy efficiency

[paulmb]

Ah, @JSHarris, I'd mistakenly assumed you were using one of the PV specific configurations ePV or dPV 

Quote

dPV: Heat battery designed for utilising on-site solar energy by buffering heat for DHW heating and/or space heating and which is fitted with DC electric heaters and is heated directly by solar PV system.

ePV: Heat battery designed for utilising excess on-site behind-the-meter solar PV electricity (above what is consumed by on-site AC electricity loads) and which is fitted with AC electric heaters and is heated by means of AC electricity diverted by a power diverter controller. The stored heat can be used for DHW heating and/or space heating.

 

The terminology is quite confusing, but I'm starting to get the hang of it I think.  Any SA with the term 'Dual' in it refers to providing 'dual' space of hot water heating right?  And as there are only 2 water circuits (high and low power), then all 'Dual' SA's are powered by electricity, which either comes from a PV specific supply (from which it will accept charge at any time), or from the 'grid' (i.e. local home power circuit which may or may not be being supplemented from PV).  That being the case, (notwithstanding the fact that @JSHarris has apparently a controller with a PV suffix which is still confusing me), the 50/90% threshold is a little more understandable, as I assume the intention is to drain the charge down and re-charge it overnight from E7 power, though clearly that's problematic if you've got a system capacity that doesn't use > 50% during a day...?  Does the control unit of the 'e' systems have the option of when to charge, or is it all charge-threshold based?

 

For my potential use-case, I was hoping that an eDual system would be able to supply space-heating via UFH, on the low-power circuit and DHW on the high power circuit, enough for 2 adult occupants of modest 1BR  well insulated holiday unit which has low space heating requirements.  However if it does seem problematic if guests showered in the morning, but it failed to use enough DHW to trigger a charge, and return in the evening and want to 2 further hot showers but run out of hot water...  That can't be right - I mean how are these units intended to be used, regardless of maximising their PV usage...?

[Jeremy Harris]

Both the ePV and dPV seem to be new designations that weren't around when I replaced our Sunamp PV towards the end of last year, and until now I'd never heard of these versions - maybe someone at Sunamp is sorting this mess out at last (be nice if they communicated this a bit better, though).  The options available when I bought our Sunamp UniQ eHW were:

 

Sunamp UniQ eHW

 

Sunamp UniQ eHeat

 

Sunamp UniQ eDual

 

Sunamp UniQ HW+i

 

Sunamp UniQ HW+iPV

 

Sunamp UniQ Heat

 

Sunamp UniQ Dual

 

Sunamp UniQ +LTHP

 

The Sunamp UniQ 9 eHW I have is supposedly optimised for PV and was the only unit available that could charge at 2.8 kW from either the grid or diverted PV, at DHW temperature (58°C).  The controller I have is the PV specific version, the UniQ_SBC_01_PV.  I've got a lot of experience of dealing with Sunamp, as I was one of the very first to take the plunge and install a Sunamp PV, back in 2015.  There were no Sunamp installers at that time, so I spent a long time exchanging emails and on the 'phone with them getting up to speed on all the installation and technical details, such that Sunamp agreed that I was competent to install and commission the unit.

 

 

[Barney12]

Sorry to be grumpy and to the point but;

 

All of this conversation about model types (which frankly is as clear as mud!) is secondary to the core issue. Surely Sunamp just simply need to change the software configuration so that the units will accept charge once the temp sensors have detected any level of depletion. The temp sensors clearly know when the units are full so it can switch off the heating elements thus the reverse must be equally capable? This would allow optimisation of PV in the same way as the old units.

 

I remain of the view that there is something they are not telling us. Does the above have some form of detrimental effect on the phase change material hence their decision to impose the 50% level?

 

[Barney12]

31 minutes ago, paulmb said:

That can't be right - I mean how are these units intended to be used, regardless of maximising their PV usage...?

 

According to the literature the units are a "direct replacement" for a vented or unvented hot water cylinder or thermal store (depending on the model variant). But as has been pointed out; they are not because you have insufficient control of the ability to re-heat/charge regardless of whether your using grid electric or diverted PV.

 

And low and behold we're back to the same question again; Surely Sunamp just simply need to change the software configuration so that the units will accept charge once the temp sensors have detected any level of depletion?

[oranjeboom]

+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

Could the admin teams @Admin perhaps cut and paste the last few pages on these Sunamp issues and create a new thread as it's clearly not about efficiency labels any longer. "Sunamp charging issue not addressed. Buyer beware!" may be more of an apt thread title and may actually get the attention of Sunamp themselves. Although I am sure people have given them the very precise link as well no doubt.

+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

 

 

[Jeremy Harris]

19 minutes ago, Barney12 said:

Sorry to be grumpy and to the point but;

 

All of this conversation about model types (which frankly is as clear as mud!) is secondary to the core issue. Surely Sunamp just simply need to change the software configuration so that the units will accept charge once the temp sensors have detected any level of depletion. The temp sensors clearly know when the units are full so it can switch off the heating elements thus the reverse must be equally capable? This would allow optimisation of PV in the same way as the old units.

 

I remain of the view that there is something they are not telling us. Does the above have some form of detrimental effect on the phase change material hence their decision to impose the 50% level?

 

 

 

You're probably less grumpy than me about this; I'm getting sick and tired of having to reset the bloody controller every day, just to be sure we can have hot water for showers the next morning.  It's a wholly unacceptable state of affairs, IMHO.

 

Sunamp aren't saying, but I think I can guess pretty much what the problem is.  I've read up a fair bit on managing phase change material heat storage and one of the biggest challenges is finding a way to evenly heat the PCM, such that all of it can be changed from solid to liquid.  As it melts, the PCM tends to get a bit clumpy, with lumps of solid mixed in with the liquid.  Much like ice melting in water, the relatively poor thermal conductivity of the solid makes it hard to determine accurately when all the solid has melted.  This problem is worse in the reverse direction, when lumps of solid PCM are floating around in liquid, as there's no way to be sure if any particular temperature sensor is surrounded by liquid or solid at any time.

 

With a direct electric heating element, there is the added risk that the heating element could locally overheat the PCM - it will be permanently damaged if heated above about 120°C.  In the Sunamp PV this problem was solved very elegantly, by using a hot water charging circuit.  This charging circuit couldn't get much above 100°C even under the worst fault condition, and it was relatively easy to just control the temperature in the charge circuit such that it stayed at around 65°C.  It didn't matter if all the PCM was in liquid form; heating it to around 65°C was always safe, so the charge control system didn't need to do anything more that work like a hot water tank thermostat.  If the charge loop was below, say, 60°C (not sure what the cut-in temperature was, could have been as low as 55°C) then the unit would accept charge, if it was at 65°C the unit would stop accepting charge.  Nice and simple and it ensured that the unit would always make the best use of any excess PV generation, just like a hot water tank.

 

The UniQ eHW has been "value engineered" and the hot water charging circuit has been removed.  In addition, a poorly designed control unit has been implemented, that can only very crudely sense the temperature in the heat cell.  Because this temperature is a pretty poor indicator of state of charge (due, I strongly suspect, to the "clumpiness" problem) then the controller isn't able to detect when discharge starts, and so makes a massive error and holds off charge until the cell is around 50% discharged (this is, apparently, a variable threshold, according to Sunamp - suggests they don't know whether it's 50%, 40% or 60% to me).

 

The daft thing is that the unit has, I presume, been engineered to safely work after a power cut, which has the effect of resetting the controller.  I'm simulating a power cut every morning, as I accidentally discovered that the power-off reset got the unit to accept charge.  I'm assuming this is safe, because of the above guess about it being engineered to cope with power cuts OK, but have no confirmation of this.  When I've tried to get clarification from Sunamp I've just been given the party line about the 50% threshold maximising PV charge, which it quite obviously doesn't at all, all it does it allow the hot water to run out.

 

 

[oranjeboom]

16 minutes ago, Barney12 said:

I remain of the view that there is something they are not telling us. Does the above have some form of detrimental effect on the phase change material hence their decision to impose the 50% level?

 

Exactly what I typed on the other thread, though Jeremy believed that the inbuilt sensors would protect the PCM.  With BS responses from SA, it's easy to start fearing the worst and it won't take much for us 'early adopters' (as we are seen by SA) to stick to more traditional technologies at the expense of SA.

 

 

[Ed Davies]

4 hours ago, JSHarris said:

The controller I have is the PV specific version, the UniQ_SBC_01_PV. 

 

What's the difference between that and the standard UniQ_SBC_01? Just that the 230 V in for internal power and for the heater element are separate (so the power for the heater can go through a diverter without the controller switching off every time the sun goes in)?

Edited February 26, 2019 by Ed Davies

[NSS]

Perhaps they' be better filling them with snake oil ?

 

Sorry, I'll get my coat!

[Onoff]

A great pity all this. I imagine those who have gone the Sunamp route aren't short of a few quid and are happy to pay for good tech at a slight premium. Couple that with foresight, investing in the long term and looking for self utilisation rather than export. Pity the new SA isn't really maybe aimed at them but the mass market. I'd wonder at less physical sensors maybe to keep the costs down leading to possible localised overheating of the PCM if the PV input is "rushed". The previous "wet" heat transfer system allowed for a more gradual, distributed heating of the PCM without killing it. That there is no quick fix suggests SA are sh!t scared of if they did that they'd have a whole lot of new, peed of customers with completely buggered units. With nothing of worth coming out of them this conjecture will only continue.

 

So...you're all digging out for these grand designs...how big a hole would be needed for a simple, heavily insulated thermal store, heated by whatever means available, to equate to the efficiency of a SA unit? The Yanks seem to do it all the time on their solar sites.

[Triassic]

Knowing what I know now, I would have probably saved my money and rather than a Sunamp bought something else.

[newhome]

32 minutes ago, Onoff said:

So...you're all digging out for these grand designs...how big a hole would be needed for a simple, heavily insulated thermal store, 

 

What about something like this? 

 

https://mixergy.co.uk/about-howitworks/

 

 

[Jeremy Harris]

8 hours ago, Ed Davies said:

 

What's the difference between that and the standard UniQ_SBC_01? Just that the 230 V in for internal power and for the heater element are separate (so the power for the heater can go through a diverter without the controller switching off every time the sun goes in)?

 

 

I don't honestly know for sure, but I don't think so, as the fitting instructions I have only refer to the UniQ_SBC_01, there is no mention at all of there being an SBC_01_PV model at all, yet that is the label on ours.  I had just assumed that the difference was that the PV option is set in ours, and may not be set on the UniQ_SBC_01.

[Onoff]

43 minutes ago, newhome said:

 

What about something like this? 

 

https://mixergy.co.uk/about-howitworks/

 

 

 

Think bigger, like part of the basement!

[newhome]

5 minutes ago, Onoff said:

 

Think bigger, like part of the basement!

 

People don’t want bigger though. That’s one of the main attractions. 

[le-cerveau]

I am shooting from the hip but I suspect that there are basically only two UniQ (physical) models!

 

Agree this should now be a separate thread.

 

They come in five (5) sizes (3, 6, 9, 12, 60) and 3 PCM fillings (34, 58, 73).  The two models are with and without the electric heating elements, the Heat 60 is not available with heating elements I believe.  Not all combinations are available, the PCM 34 & 73 are not available in size 3 or with heating elements.  So, for an example if we take a size 9 in standard PCM 58 there is:

UniQ HW 9, UniQ Heat 9, UniQ Dual 9, UniQ HW 9 + I, UniQ eHW 9, UniQ eDual 9

The first 3 don’t have a heater and the second 3 do, so two physical models.  I make this assumption for the following reason, design and cost, it is cheaper and simpler to have a fewer physical designs and make changes in software.

 

 

 

As detailed in section 1.1 of the design and instillation manual.  The only difference is 45mm in height (for all sizes) the electric heater element and it’s connections.

 

The plumbing connections are the same for all models, it is just how you connect them that differs:

 

From section 1 of the reference manual V2.0:

 

A = High Power feeding the top of the heat exchanger.

B = Low Power feeding the top of the heat exchanger.

C = Low Power feeding the bottom of the heat exchanger.

D = High Power feeding the bottom of the heat exchanger.

 

High Power is typically used for the potable water and Low Power for primary Water.

The order A – D varies throughout the reference manual! I will stick with this demonination.

 

Controller details from section 3.1 of the reference manual:

 

(there is inconsistency between the two manuals)

For all but the e__ units they are designed for an external heat source, so charging direction is top to bottom, therefore Heat source flow goes to B and return to C.  Potable water (DCW) feed to D and (DHW) to house to A.  This is all detailed in the reference manual and also in the design and install manual.  This is what I would consider normal, you pump heat into the top of the cell/tank with the return at the bottom and you feed in cold water to the bottom of the tank an d take out the hot water from the top.

 

For an e___ unit there is confusion, the reference manual shows paralleling the HP and LP circuits (makes sense as all potable) but feeding the cold water into the top of the heat exchanger and taking the hot water out of the bottom, whereas the design and install manual does not parallel the circuits (omission) but does feed the cold water into the bottom and take the HW from the top, so again inconsistencies.

 

 

 

I suspect this is down to the thoughts in the previous table that normal units are heated top to bottom but that the e__ units are heated bottom to top (because of the heater element), however that heat will migrate to the top of the tank so it should still be discharged bottom to top (flow) as per normal.

 

The so-what is if you have a standard unit (NO e or I) then it can be used as any HW/Heat/Dual functionality, if you have an e or I unit it can operate as any unit an e only unit a normal unit, just ignore the heater or an I unit, it is just plumbing and wiring.

 

So in theory (at least anyway) Jeremy can wire up his unit as a HW+iPV unit using the correct controller and it should accept charge anytime!

 

It is all just a controller issue.

 

Ready to be shot down in flames!

[le-cerveau]

14 hours ago, JSHarris said:

How many people on this forum that have a Sunamp (one of the newer models, not the older Sunamp PV) are 100% happy with it, I wonder?

 I don't have UniQ's but rather an interim (pre UniQ) dual port (UniQ technology) units, 2 x PCM34 and 2 x PCM58.  There is no casing bulging issue but the cases are remarkably solid.  I don't have internal heaters (I wasn't available) so control is rather simple, when cool (what level I don't know but suspect 50%) they call for heat.  apart from an initial issue which was resolved (custom controls) I haven't had any issues with them.  They are effectivly 2 x UniQ Heat6/9 (PCM34) and 2 s UniQ HW 6/9 (PCM58).

[Onoff]

1 hour ago, newhome said:

 

People don’t want bigger though. That’s one of the main attractions. 

 

Space rich, cash poor people like me do!

[Jeremy Harris]

38 minutes ago, le-cerveau said:

 So in theory (at least anyway) Jeremy can wire up his unit as a HW+iPV unit using the correct controller and it should accept charge anytime!

 

It is all just a controller issue.

 

 

Sadly this is not correct, although it is a controller/sensor issue, for sure. 

 

Mine is wired as a PV unit, checked, double checked and checked with Sunamp themselves. 

 

Sunamp have confirmed that it will not charge until the cell is ~50% depleted, but have also separately stated that owners should not get hung up about the nominal 50% threshold.  The latter comment annoyed me more than a  little, as when you have a cold shower in the morning, just because the damned thing has refused to charge, it's hard not to get "hung up" about it!

 

This is the scenario that creates the problem, and one that anyone who wishes to use a Sunamp to store heat from excess PV generation may encounter.  We use about 4 to 4.5 kWh of hot water most days, usually as two showers early in the morning (before the PV array is exporting, so these usually rely on stored heat).   I've confirmed many times now that after running off two showers there's about a 30% chance that the Sunamp won't call for heat afterwards.  When the sun comes up and we start generating, the Sunamp will then not accept any charge, unless manually reset.  The result is that we could not utilise excess PV generation to heat the hot water for ~30% of the time, as the Sunamp will sit there, fat, dumb and happy, with its contactor firmly turned off.

 

Come the next morning, and if the Sunamp hasn't been manually reset, then the hot water will run cold towards the end of the second shower, leaving us with no hot water until such time as the PV puts enough charge into the thing.

 

The old Sunamp PV only had around 4.5 to 5 kWh of storage capacity, but this could all be used, all of the time.  Anytime there was any spare charge capacity it would accept power and charge.  As a consequence, even though it was a smaller capacity unit (and I thought it might have been marginal, even though we never ran out of hot water, ever) all that capacity could be utilised all of the time, unlike the larger (and significantly more expensive) Sunamp UniQ 9, where it seems it struggles to work at half of it's nominal capacity.

[ProDave]

Reading this continuing saga makes me glad I fitted a conventional unvented cylinder.  SWMBO does not take well to cold showers and if I had spent lots of money on a new high tech piece of kit and it was not working, there would be calls to "get rid of that POS"

[ToughButterCup]

Just now, ProDave said:

Reading this continuing saga makes me glad I fitted a conventional unvented cylinder.  SWMBO does not take well to cold showers [...]

 

I've got one of those too Dave.  And I was just about to decide on which unit to order. I'm not known for being decisive, but this thread causes me to do more than dither.....

[newhome]

1 hour ago, ProDave said:

SWMBO does not take well to cold showers 

 

No one takes kindly to cold showers least of all me! 

 

I bet @JSHarris regrets selling you his instant water heater too! 

 

[Ed Davies]

2 hours ago, JSHarris said:

I don't honestly know for sure, but I don't think so, as the fitting instructions I have only refer to the UniQ_SBC_01, there is no mention at all of there being an SBC_01_PV model at all, yet that is the label on ours.  I had just assumed that the difference was that the PV option is set in ours, and may not be set on the UniQ_SBC_01.

 

Looking at the PDF UNIQ HEAT BATTERIES REFERENCE MANUAL_V2.0 version 2018_07_19_v2.0 page 19 (section 6.1, figure 6.1) the UniQ_SBC_01 seems to have only one 230 V input (16 A) with the constant supply going to the board via an internal 3 A fuse. Yours, though, has two separate 230 V inputs, doesn't it?

 

My assumption is that the controller board for the SBC_01_PV is the same as for the SBC_01 (though, as you say, maybe with different factory settings) but with wiring a bit more like the SBC_02 (figure 6.3) with separate terminal blocks for the constant supply (6 A) and the heater supply (16 A) but without the relay R2 for the pump and associated wiring and terminal blocks.

[Jeremy Harris]

22 minutes ago, Ed Davies said:

 

Looking at the PDF UNIQ HEAT BATTERIES REFERENCE MANUAL_V2.0 version 2018_07_19_v2.0 page 19 (section 6.1, figure 6.1) the UniQ_SBC_01 seems to have only one 230 V input (16 A) with the constant supply going to the board via an internal 3 A fuse. Yours, though, has two separate 230 V inputs, doesn't it?

 

My assumption is that the controller board for the SBC_01_PV is the same as for the SBC_01 (though, as you say, maybe with different factory settings) but with wiring a bit more like the SBC_02 (figure 6.3) with separate terminal blocks for the constant supply (6 A) and the heater supply (16 A) but without the relay R2 for the pump and associated wiring and terminal blocks.

 

 

Yes, there are two separate supplies.  One is an always-on, low current supply that connects to the left-most mains terminal blocks inside the controller, the other is the 16 A (nominal) heater supply that comes from the excess PV diverter.

 

Inside the unit it's clear that the 16 A power only connects to the contactor, and then goes back out to the heating element.  There's no connection from this supply to the control board.  The low current, always-on, supply connects only to the fuse and control board inside the unit.  It's only the low power circuit that needs to be interrupted in order to reset the unit.

 

The contactor is switched on and off with a low power relay on the control board, which just seems to switch power from the low-power supply to the contactor coil.  This low power relay is controlled by the chip on the control board (a PIC 16F1789), and the only sensor inputs to that seem to be three thermistors that are connected in a chain and which run down inside a tube in the centre of the cell.  It looks as if the only parameters that can be sensed are temperature at the bottom, centre and top of the cell. 

 

The fact that resetting the PIC resolves the sensing problem suggests to me that the control logic is flawed.  The PIC is presumably waiting for one or more of the sensors to show a temperature drop, before turning on power, following a charge period.  However, if turned on after a charge period it presumably uses a different logical test before turning on the heating element.  I suspect it's the difference between the "I've just charged and am looking for a discharge indication" test and the "I've just powered up and am looking to see if it's OK to charge" test, that is creating the problem.  I'm not sure why these two logical tests should be looking for a different condition.

[Ed Davies]

14 minutes ago, JSHarris said:

Yes, there are two separate supplies.  One is an always-on, low current supply that connects to the left-most mains terminal blocks inside the controller, the other is the 16 A (nominal) heater supply that comes from the excess PV diverter.

 

Ta. So it seems reasonable to assume that the “_PV” suffix means that wiring difference plus perhaps some other configuration change on the board.

 

15 minutes ago, JSHarris said:

I suspect it's the difference between the "I've just charged and am looking for a discharge indication" test and the "I've just powered up and am looking to see if it's OK to charge" test, that is creating the problem.  I'm not sure why these two logical tests should be looking for a different condition.

 

It sounds like they've made an attempt to introduce some, quite sensible, hysteresis but overcooked it. It's difficult to know the state of charge with PCMs but they've got enough temperature headroom between the whole lot becoming liquid (e.g,, I imagine you can be pretty sure of this by the time all the sensors read, say, 65 °C) and cooking the gunk. E.g., stop charging when any sensor gets to 75 °C, start charging when all have reduced to 65 °C would seem to me to be safe but use a much larger proportion of the capacity. You'd still get the behaviour where resetting the controller might cause it to start accepting charge but only over a much narrower band of SoC.

 

And WTF, in 2018, did they build a controller without at least a web interface to allow you to see what's going on?