Sunamp and SAP

[Guest Alphonsox]

I am trying to update my "as built" SAP ready for sign off but have hit a problem with regards to the use of Sunamp heat storage for hot water. Has anyone looked at how these can be described to SAP (I'm using stroma2009). The only choices seem to be "Electrical instantaneous point of use" or "electrical immersion". The former doesn't really apply and the latter assumes a water storage cylinder. 

If I use real numbers for the water storage volume (<15lt) and daily losses (0.6kw) I get a SAP failure. The only possibility would be to use an "equivalent" water storage capacity - 140lts if I remember correctly, but I am not sure SAP allows this as an option. Anyone been through this or got input from Sunamp themselves on this ?

[Jeremy Harris]

This is a good point, that does need sorting.  We still had the thermal store fitted when we did our as-built SAP, so avoided the problem.

The sensible solution would be for the Sunamp PV to have certification as a thermal store, rather than as an instant water heater that uses stored thermal energy.  The problem is that I'm not sure that the standard thermal store test procedure would work for the Sunamp PV.  It's perhaps something that Sunamp need to look at, if they feel that there is a serious market for their device in new-build low energy homes.

Logically I think it should be treated as an equivalent water volume thermal store with the measured heat loss data from their tests, but I'm not sure how valid that data has to be for SAP.  SAP is never checked by anyone, which is why there are so  many rubbish new homes with SAP EPCs that are wildly optimistic, and there doesn't seem to be any reason why you couldn't use the equivalent volume (140 litres, I think) thermal store with the certified standing heat loss (around 0.6 kWh/24 hours) in SAP.

[Guest Alphonsox]

A thermal store sees to be the most logical description, i'll use that for the moment along with a "water equivalent" storage volume. As you say no-one seems to check SAP but the very low standing loss value may set off an alarm somewhere.

[Jeremy Harris]

I'll probably be talking to someone at Sunamp in the next week or so, about something else, and if I get the chance I'll raise it as something they might want to look at.

[Guest Alphonsox]

I need to talk to them this week as well - I need to get some details on the 4-battery unit and see how it compares to the two 2-battery setup we were going with.

[Stones]

I spoke to them briefly this past week trying to confirm configuration possibilities for a 4 cell - side by side or stacked.  I await the response but will likewise be chasing next week.  Didn't get as far as asking about cells being in series vs in parallel.

[Jeremy Harris]

It looks very much as we're all asking about the 4 cell unit, or the 2 cell add-on box.

[volcane]

Sunamp appear to offer the Stack as a solution in combination with a heat pump but without consideration of PV. The Sunamp PV is aimed at users who have a combi with PV. They don't seem to natively consider PV plus ASHP, the solution many arrive at especially away from the gas network.

I know JSH has arrived at a solution, but this isn't 'out of the box'.

 

[Stones]

They are working on offering a direct electric charging facility as per the sunampPV, to the sunamp stack. This year sometime apparently. As is often the case with new products, it was developed with a particular purpose in mind but they have since realised the other ways in which it can be used and are refining their product line accordingly.

Edited May 30, 2016 by Stones

[Jeremy Harris]

19 minutes ago, volcane said:

Sunamp appear to offer the Stack as a solution in combination with a heat pump but without consideration of PV. The Sunamp PV is aimed at users who have a combi with PV. They don't seem to natively consider PV plus ASHP, the solution many arrive at especially away from the gas network.

I know JSH has arrived at a solution, but this isn't 'out of the box'.

 

Mine is a "straight out of the box" Sunamp PV, with no mods.  I just fitted it as per the standard instructions.  It works just the same whether there is a combi boiler fitted or not.  As long as it's charged up it will deliver hot water at big combi type flow rates.

[Nickfromwales]

Very encouraging to hear they're following demand / varying solutions so quickly. 

My sales pitch may soon be swaying to off grid PV and Sunamps / stacks. 

I'll be watching this intently and may soon break radio silence with them myself for the tech side. 

[Nickfromwales]

2 minutes ago, JSHarris said:

Mine is a "straight out of the box" Sunamp PV, with no mods.  I just fitted it as per the standard instructions.  It works just the same whether there is a combi boiler fitted or not.  As long as it's charged up it will deliver hot water at big combi type flow rates.

What litres per min are you getting at 38/40o J ?

[Jeremy Harris]

I've not measured it, Nick, but IIRC, the Sunamp PV is rated at 35 kW, which is up around the same rating as a pretty good combi, I think (I think our Vaillant can only deliver around 28 kW, again IIRC).

[volcane]

23 minutes ago, JSHarris said:

Mine is a "straight out of the box" Sunamp PV, with no mods.  I just fitted it as per the standard instructions.  It works just the same whether there is a combi boiler fitted or not.  As long as it's charged up it will deliver hot water at big combi type flow rates.

What I meant was a solution that is available from Sunamp (along with data) that takes into account the use of their product in combination with PV and an ASHP.

Also some form of ready reckoner would be great, where I could input the estimated heating and hot water energy requirement and be given a solution e.g. 'You will require a 6kW heat pump, (the following models have been tested etc) along with a 4 cell Sunamp. 4 kW PV panels* will typically offset xx direct electrical consumption. Annual electrical use will be xx kWh. Then I could up the level of PV decrease the heating energy requirement etc and try to arrive at an optimal solution

I am hoping to build a larger than normal very low energy house that has a slightly higher than normal water use (due to additional needs of occupants).

 

[Jeremy Harris]

It's clearly not where the bulk of their target market is, as so very few low energy houses are built when compared to existing houses fitted with PV and combi boilers, so their focus on their core market is understandable.

However, it is pretty easy to just install a low temperature "warm water" tank, heated by the ASHP, then use that to feed one or more Sunamp PV units.  It doesn't need any complex fittings and the capacity and performance calculations are dead easy, well within the ability of any heating engineer.  The only slightly out-of-the-ordinary requirement would be an immersion and time switch set to run an anti-legionella cycle every couple of weeks.

A standard UVC, run at an efficient ASHP temperature of, say, 40 deg C, would have pretty low losses, around half the normal standing loss I would think.  This could provide the bulk of the hot water requirement, with one or more Sunamp PV units only being used to add an additional 5 to 10 deg to the warm water to bring it to a usable temperature.  The Sunamp PV would be, in effect, a boost heater, used only on demand.

[Nickfromwales]

8 hours ago, volcane said:

What I meant was a solution that is available from Sunamp (along with data) that takes into account the use of their product in combination with PV and an ASHP.

Also some form of ready reckoner would be great, where I could input the estimated heating and hot water energy requirement and be given a solution e.g. 'You will require a 6kW heat pump, (the following models have been tested etc) along with a 4 cell Sunamp. 4 kW PV panels* will typically offset xx direct electrical consumption. Annual electrical use will be xx kWh. Then I could up the level of PV decrease the heating energy requirement etc and try to arrive at an optimal solution

I am hoping to build a larger than normal very low energy house that has a slightly higher than normal water use (due to additional needs of occupants).

 

Low energy means ideal candidate for an ashp. To that, couple up a large low temp pre- heat TS and then to a secondary instant heater such as a Sunamp. Without an accurate account of the additional needs of the occupants it's hard to specify, but it sounds like a few other 'tweaks' could be made to get the extra capacity. Need to find out if it's showering or bathing first though. 

[Stones]

Had a response from Sunamp about the 4 cell.  It's not going to be available until later in the year, as they have the internal hydraulics to sort out and are currently focused on rolling out larger heat batteries. 

 A side by side arrangement of cells seems to be the most likely which would mean a washing machine sized unit (a stacked 2 cell on 2 cell doesn't seem to be viable unless they introduce a racking system).  

I asked about treatment in SAP, and they advised they had had discussions about the various options, but currently don't have SAP points for any of their products. 

I've emailed them back and will be following up by phone again tomorrow, trying to pin down a date (as I have to make a decision sooner rather than later ready for first fix) and price of a 4 cell.

[Guest Alphonsox]

Thanks for the update

[Guest Alphonsox]

On 31/05/2016 at 16:30, Stones said:

I've emailed them back and will be following up by phone again tomorrow, trying to pin down a date (as I have to make a decision sooner rather than later ready for first fix) and price of a 4 cell.

Any further updates on this ?

[Stones]

The latest I had earlier this week, was that they couldn't confirm whether a 4 cell would be available in September / October.    I suspect the issue is one of type approval rather than technical feasibility, as it seems clear they want to add such a unit to their range.  

There may be a more 'home brew' option, where we as consumers buy the relevant parts to add on to an existing 2 cell.  From looking at a hydraulic diagram it looks fairly straightforward, although there would perhaps be certain issues to overcome, not least what the position would be on warranty.  I hope to discuss all this with Andrew this afternoon and will report back when I have done so.

[Stones]

Update here -