Sunamp container bulging

[Jeremy Harris]

21 minutes ago, scottishjohn said:

If it is as you suggest that there are lumps of solid in the liquid ,then that probably why they don,t want it be charged untill it s below this 50% level ,so you don,t end up locally heating the fluid too much  and at worst case end up with some liquid close to changing state to a gas with solid lumps which have not managed to absorb the heat from the liquid parts quick enough .

and the latent heat could cause that ,as all materials have a  latent heat range where you need to put alot of energy in to make them changetemperature + state

Ice has a larger volume than water ,then as you cool it even more it shrinks ,now not sure how much of this is to do with "free gases " in the ice ,but if same occurs  in this medium ,then theres your reason for  bulging cases,

and we all know that ice can split pipes + rock .

 So possibly the cases are just not large enough to accomodate these possible situations of excessive localised heating from an immersion heater + solution is just make more space   in the case ?

do the first type of sunamp units have same case problems?

I am not slagging the unit --just trying to get a handle on how it works  and its limitations

 

I'm pretty sure the refusal to accept charge until below 50% problem is a side effect of trying to protect the PCM, but given that it can be bypassed by simply interrupting the power supply, something that must have been considered during the design stage, I'm inclined to think that it's just a nuisance factor that results from the control algorithm they are using.  The PCM must be protected from over-heating, as it breaks down at around 125 deg C. I believe the unit limits the maximum temperature to something below 85 deg C to be safe. 

 

The case problem is unrelated, it's two separate issues.  Firstly there is too much closed cell neoprene insulation in the top of the unit, and this physically pushes the lid up.  This has nothing to do with the cell underneath, that seems to stay flat and doesn't move - it's just a design flaw that should be dead easy to fix (I've fixed it on mine by just trimming the insulation very carefully, so I know it can be done).

 

The other slight case problem is just because the new units have a less rigid case than the old Sunamp PV.  The Sunamp PV had a case that was bolted together, with return flanges on every edge, and was very stiff.  The cells were also smaller, so there was less outwards force from the weight of the PCM within them.  As I understand it (from a comment from @Nickfromwales) Sunamp are in the process of changing the case design to make it stiffer, so that it doesn't bulge.

 

The side bulging has nothing to do with the operation of the unit, AFAICS, it seems to be purely a mechanical thing, related to the design of the welded box case.

[Jeremy Harris]

7 minutes ago, scottishjohn said:

I certainly feel that if sunamp made a statement as to why you cannot do what you want and the technical reason why it would actaully make people much happier 

and knowing there is technical reason why would then be accepted by most ,especailly fi they said it will shorten the life of the unit

Just like the EV cars --everyone now knows ideally you do not keep charging them up to 100% or let them drop below 20%    ,cos it will shorten battery life

 

I agree about needing a statement from Sunamp, it would help a lot if we knew just what is going on.

 

EV's don't give a damn about how users charge them, BTW, they have a BMS that will always protect the cells in the battery no matter what the user does.  I've been charging mine up to 100% twice a day, every weekday for about 4 1/2 years, and the battery range now is the same as it was when I bought it (if anything it's a tiny bit better now).  I've also completely discharged the battery in my car many times, arriving home with less than 1 mile of range remaining on a pretty regular basis.

 

The manufacturers build in to the BMS a bit of leeway when it comes to usable SoC versus actual SoC, so that the usable SoC range is often around 10 to 15% lower than the nominal battery capacity would suggest.  Some models allow this capacity buffer to work as a sort of emergency reserve, by allowing the car to be driven at a low speed for a short time if the car runs out of usable battery capacity, rather than have it just stop.

[scottishjohn]

1 minute ago, JSHarris said:

 

I agree about needing a statement from Sunamp, it would help a lot if we knew just what is going on.

 

EV's don't give a damn about how users charge them, BTW, they have a BMS that will always protect the cells in the battery no matter what the user does.  I've been charging mine up to 100% twice a day, every weekday for about 4 1/2 years, and the battery range now is the same as it was when I bought it (if anything it's a tiny bit better now).  I've also completely discharged the battery in my car many times, arriving home with less than 1 mile of range remaining on a pretty regular basis.

 

The manufacturers build in to the BMS a bit of leeway when it comes to usable SoC versus actual SoC, so that the usable SoC range is often around 10 to 15% lower than the nominal battery capacity would suggest.  Some models allow this capacity buffer to work as a sort of emergency reserve, by allowing the car to be driven at a low speed for a short time if the car runs out of usable battery capacity, rather than have it just stop.

first ones didnt, have that sort of back up --it makes sense to not tell the driver the REAL battery states as customers will always ignore things unless the onbaord elctronics control what they can do --as you suggest sunamp will be doing the same with the 50% charge limit.

 

[scottishjohn]

one thing i have learned for sure over 40 years of being in the motortrade running dealerships 

and something i used to tell all my staff 

"how do know if the customer is lying ?--his lips are moving "

 

 

[Jeremy Harris]

6 minutes ago, scottishjohn said:

first ones didnt, have that sort of back up --it makes sense to not tell the driver the REAL battery states as customers will always ignore things unless the onbaord elctronics control what they can do --as you suggest sunamp will be doing the same with the 50% charge limit.

 

 

I have a very early plug-in car, a 2013 model, and it 100% protects the battery from the user.  Cars even older than mine protected the battery to an even greater extent, and one thing that has changed a lot over the past few years (with the exception of the Nissan Leaf 40 kWh battery fiasco last year) has been that the usable capacity of battery packs has been gradually improving.

 

My first hybrid, in 2005, only used about 60% of the available battery capacity, primarily because Toyota played very safe to ensure that battery failures didn't mar the reputation of the car.  They got this right, as battery failures were practically unheard of, and the cars quickly gained a reputation for longevity, as so many were used (and still are) as taxis.

[Nickfromwales]

13 minutes ago, JSHarris said:

I agree about needing a statement from Sunamp, it would help a lot if we knew just what is going on.

I am discussing this with SA this week. They have already approached me re a membership here so watch this space basically.

WRT the 50/90 settings, I'm also awaiting an update on that. Whether that comes from SA or me will be up to them basically. Hopefully it will come from them ( so I can get on with some work lol ).

[Jeremy Harris]

Thanks Nick, it will be very helpful to have some definitive news on both the case bulging and the failure to accept charge issues. 

 

Personally I'm not the slightest bit fussed about the case, as mine now looks fine, and the fact that the sides bulge out a small amount really isn't noticeable unless you put a straight edge across the thing.

 

My main concern is being able to maximise the use of excess PV charging, especially during the winter months.  If that means I have to adopt a means of turning the thing on and off ever day in order to get it to accept charge, then it's no great hardship, just a bit of a bodge.  I'm pleased to say that our Sunamp accepted 3.5 kWh of charge from PV this morning and has now shut off as being fully charged.  That means that me turning the power off and on again saved us a bit over 50p today, but that saving would add up over the year.

[Declan52]

24 minutes ago, scottishjohn said:

one thing i have learned for sure over 40 years of being in the motortrade running dealerships 

and something i used to tell all my staff 

"how do know if the customer is lying ?--his lips are moving "

 

 

Same saying goes for  car sales men. 

[scottishjohn]

1 minute ago, Declan52 said:

Same saying goes for  car sales men. 

LOL --especially the irish ones

[Declan52]

Just now, scottishjohn said:

LOL --especially the irish ones 

Think its just the ones that sell cars. 

[Jeremy Harris]

Last week I reported in this post just how much of our excess PV generation the Sunamp had utilised as stored heat for DHW:

 

On 03/12/2018 at 09:14, JSHarris said:

 

As an example, this is the data for the past week, the first week of energy monitoring that has included measuring the energy used to charge the Sunamp from the grid, the energy used to charge the Sunamp from excess PV generation and the PV generated energy we have exported to grid:

 

Energy exported to the grid = 18 kWh/week ( mean ~ 2.6 kWh/day, but very patchy)

Excess PV generated energy used to charge Sunamp = 6 kWh/week (mean ~ 0.86 kWh/day, but very patchy)

Grid energy used to charge Sunamp = 28 kWh (mean ~ 4 kWh/day)

 

The maximum energy exported in any single day last week was 7 kWh.

 

Total DHW energy used for the week = 34 Kwh, of which 6 kWh came from excess PV generation.

 

~ 18 kWh of PV generation was "wasted" by being exported to the grid rather then used to charge the Sunamp.

 

In terms of cost saving by using self-generation to heat our hot water, it looks like the Sunamp has only managed to use around 25% of our available self-generation, which is pretty crap.  There may have been one day when it couldn't have absorbed all our self-generation, last Friday, when it would probably only have been able to use around 5 kWh of the 7 kWh we exported (it didn't utilise any self-generation at all on that day).

 

Overall I think we could have utilised around 22 kwh out of the 24 kwh of excess generation had the Sunamp been able to do what it's supposed to do.  This would have reduced our grid import for DHW  last week from 28 kWh to about 12 kWh at a guess.

 

 

We've now had a whole week of the Sunamp operating at the 50% setting, rather than the incorrect 90% setting, and these are the results for the last week:

 

Excess PV generated energy exported to the grid = 19 kWh

Excess PV generated energy used to charge Sunamp = 12 kWh

Grid energy used to charge Sunamp = 17 kWh

 

Total DHW energy used for the week = 29 Kwh, of which 12 kWh came from excess PV generation.

 

in simple terms it looks like the Sunamp has managed to utilise around twice as much excess PV generation than it did the previous week, but it still allowed an estimated 8 to 10 kWh of excess PV generation to go to the grid, when there was almost certainly spare capacity within the Sunamp to have stored that energy.

 

It's certainly an improvement, but still disappointing, IMHO.  Next Monday I should have a full week of performance data with the Sunamp Qontroller being switched off for a short time every morning to "reset" it.  It will be interesting to see how this improves its effectiveness at utilising excess PV generation; I suspect it will make a significant difference, probably a bigger difference than having corrected the erroneous Option 1 setting just over a week ago.

[Nickfromwales]

I’ve just pre ordered 30,000 of these. 

 

 

 

 

I’ll be rich beyond my wildest dreams. 

Just don’t tell anyone ok   

[Ed Davies]

9 hours ago, JSHarris said:

(this really, really annoys me). 

 

Really? We wouldn't have guessed from your comments. ?

[Jeremy Harris]

4 minutes ago, Ed Davies said:

 

Really? We wouldn't have guessed from your comments. ?

 

This morning was close to the last straw  About half an hour after two showers had run, I looked at the energy monitor and were were exporting about 3 kW.  I rushed upstairs to find that the damned Sunamp wasn't charging (again).  Not sure why, but I just decided to see what would happen if I turned the Sunamp off and on again.  I didn't expect anything to change, so hearing the click of the main contactor coming on, confirmed by the "charge acceptance" indicator I fitted. 

 

I was overjoyed to see 3.5 kWh of free charge go into the Sunamp and top it up,  be interesting to see how much difference this makes in the longer term.  Ideally I'd like to get our winter export down to as close to zero as possible.

[Ed Davies]

8 hours ago, Nickfromwales said:

I suppose the voodoo is a well kept secret but I think the issue is that the PCM freezes upon first activation and the heat just simply sits there waiting to be used in the super insulated cell. Based on a domestic situation, it would get recharged in any 24 hour period so not an issue. Once charged, it would just sit there until the first / next activation event.  

My thoughts, may be wrong.

I just cant see how they could stop / start the reversal tbh.

 

I'm supposing, too, but my supposition is the opposite one: there's no particular voodoo in the Sunamp PCM to stop or start the phase change, it just happens with temperature. The voodoo there will be to do with not having the liquid in contact with the heat exchangers which turns solid when the first batch of cold water flows through not immediately sticking to the exchanger and insulating the rest of the liquid. This is the classic problem with all phase-change heat stores.

 

My assumption is that, unlike the hand warmers, the contents of the Sunamp are at around 58°C so the liquid-solid phase change doesn't spread in the way it does in the super-saturated solutions in hand warmers which are stored and used at much lower temperatures.

 

If all the latent heat turned to sensible heat on the first use then there'd be little point in having the PCM in there in the first place. Also, the temperature would rise a lot (at least 75 °C) yet the water comes out at pretty much the same temperature throughout most of the discharge.

 

[Russdl]

28 minutes ago, JSHarris said:

I rushed upstairs to find that the damned Sunamp wasn't charging (again).  Not sure why

 

Had you already switched it off and on once before that?

[Jeremy Harris]

11 hours ago, Russdl said:

 

Had you already switched it off and on once before that?

 

No, I'd kept it powered up since it was installed, with the exception that I turned off briefly when I added the neon indicator to show when the charge acceptance relay is on or off..  It only occurred to me to turn it off and on again as an experiment this morning.  I have a time switch sorted out now, so will turn it off for a minute and then back on gain every morning and see what sort of difference this makes to utilisation of PV.

[willbish]

10 hours ago, JSHarris said:

No, I'd kept it powered up since it was installed, with the exception that I turned off briefly when I added the neon indicator to show when the charge acceptance relay is on or off..  It only occurred to me to turn it off and on again as an experiment this morning.  I have a time switch sorted out now, so will turn it off for a minute and then back on gain every morning and see what sort of difference this makes to utilisation of PV.

Will there be any effect if you draw hot water during that power off minute?

Just a glug of cold or preheat water through your hot pipes?

[Russdl]

13 minutes ago, JSHarris said:

so will turn it off for a minute and then back on gain every morning and see what sort of difference this makes to utilisation of PV.

 

I for one will be really interested in the result of that experiment.

[Nickfromwales]

2 hours ago, Ed Davies said:

The voodoo there will be to do with not having the liquid in contact with the heat exchangers which turns solid when the first batch of cold water flows through not immediately sticking to the exchanger and insulating the rest of the liquid

I can promise you that that does not happen  

[Nickfromwales]

2 hours ago, Ed Davies said:

If all the latent heat turned to sensible heat on the first use then there'd be little point in having the PCM in there in the first place. Also, the temperature would rise a lot (at least 75 °C) yet the water comes out at pretty much the same temperature throughout most of the discharge.

From my direct experience, the water comes out noticeably hotter at the start, hence the requirement to fit a TMV to the hot outlet of every unit delivering DHW as a measure for anti-scald.

[Hecateh]

10 hours ago, scottishjohn said:

one thing i have learned for sure over 40 years of being in the motortrade running dealerships 

and something i used to tell all my staff 

"how do know if the customer is lying ?--his lips are moving "

 

 

heard that said a lot lot more about car salesmen than about the customer.  

[Nickfromwales]

2 hours ago, Ed Davies said:

My assumption is that, unlike the hand warmers, the contents of the Sunamp are at around 58°C so the liquid-solid phase change doesn't spread in the way it does in the super-saturated solutions in hand warmers which are stored and used at much lower temperatures.

The PCM doesn't start to melt until 58oC or above. They accept 65oC as the chosen injection temp when using a wet external source for heat input. You can go as high as 70-75oC if its delivered in a stable flow, but the advice ( requirement ) is that it never gets near 85oC. An ASHP, for eg, chucking out 55oC is totally useless with a PCM58 unit as it will not melt it. Heat will be absorbed, but the PCM will not phase change until 58oC or above is achieved. 

[Jeremy Harris]

9 hours ago, willbish said:

Will there be any effect if you draw hot water during that power off minute?

Just a glug of cold or preheat water through your hot pipes?

 

No, none at all.  The unit still delivers hot water in exactly the same way when powered off or on, as the Qontroller has no way of knowing that hot water is being drawn off, even when powered on, other than by monitoring three temperatures within the heat cell, near the bottom, centre and top of it.

[joe90]

I am surprised that SA have not come back about this, there is plenty of feedback info on this site alone?