Sunamp heat battery

[newhome]

3 minutes ago, PeterW said:

 

 

ASHP ..?? I’d consider it ..! Set it to 42 and put it into the bottom of the tank and then let the boiler just do the top up ... 

 

Yes ASHP. Like you say I was thinking more of getting the water to a reasonable temp rather than it not needing the boiler at all. Would it work with the ST (assuming that is fixed and working)? Would need advice on what to get and getting it installed mind and am vaguely worried about the thing getting wrecked by the wind here. Not sure how robust they are in mega windy conditions. If I had a time machine I would have chosen PV and ASHP, and now be looking at Sunamp. Ain't hindsight great! 

[PeterW]

You could put it round the back where the store thing is and it would be sheltered. You would probably want an 8kw one just because of the size of that TS

[Russdl]

10 hours ago, le-cerveau said:

Use a PCM34 UniQ fed from Genvex as a buffer for UFH and DHW pre heat, the cells take water at 45C.  (This is what my ASHP does).

The PCM58 cells do the hot water top up.

 

That makes sense. Thanks for that. 

[Jeremy Harris]

We're really impressed with our very first generation, pre-production, SunampPV.  It's performance is really very good indeed, and most impressively the heat losses from it are negligible - the case doesn't even feel warm when it's fully charged.  It's made a tremendous difference to the temperature in our services room.  When we had a thermal store in there it used to get exceptionally hot, hot enough to damage the oak door, and that was with loads of additional insulation around the store to try and stop it wasting heat.  Now the services room is barely warmer than the rest of the house, and that's all down to the very low heat losses from the SunampPV.

 

Bearing in mind that our SunampPV is "old technology" compared to the current versions; we were most definitely early adopters (I think the first on here to get one).  I have no doubt that the performance has improved a great deal since our unit was made, which bodes well for anyone thinking of getting one now.

[Moira Niedzwiecka]

I have a 4kw PV array & under floor heating installed on the ground floor only, about 90 sq mtrs.

No tank installed at the moment for DWH & underfloor heating.

What sunamp would I need if I went down this route & would I still require a cylinder of some sort.

I have an Iboost to connect but it is still in the box & could be returned if not needed.

There will be only 2 people living in the house.

[Gone West]

7 hours ago, Nickfromwales said:

Does the space heating suffer whilst the hot water is regenerating?

As I think has been said, it prioritises  hot water over space heating. For the Combi LS it takes nine hours to heat the water tank fully from 15C to 55C when the outdoor temperature is 15C. So the time taken increases as the outdoor temperature decreases.

[Nickfromwales]

7 hours ago, PeterStarck said:

As I think has been said, it prioritises  hot water over space heating. For the Combi LS it takes nine hours to heat the water tank fully from 15C to 55C when the outdoor temperature is 15C. So the time taken increases as the outdoor temperature decreases.

Wow, thats a long time to be dedicated to DHW priority. Very long indeed.

 

[Russdl]

14 hours ago, PeterStarck said:

As I think has been said, it prioritises  hot water over space heating. For the Combi LS it takes nine hours to heat the water tank fully from 15C to 55C when the outdoor temperature is 15C. So the time taken increases as the outdoor temperature decreases.

 

7 hours ago, Nickfromwales said:

Wow, thats a long time to be dedicated to DHW priority. Very long indeed.

 

@PeterStarck as Nick say's "thats a very long time" but does it present any issues in use? How was living with the Genvex through the winter?

[Gone West]

2 hours ago, Russdl said:

 

 

@PeterStarck as Nick say's "thats a very long time" but does it present any issues in use? How was living with the Genvex through the winter?

It's not something we have noticed nor has it affected us. There are two of us in the house, the tank is 185l and it's a low water usage house. We heat the water to 45C and there has always been plenty of hot water, with the tank reheating quickly after a shower. It will be interesting to see the first years electricity bill.

[Nickfromwales]

7 hours ago, Moira Niedzwiecka said:

I have a 4kw PV array & under floor heating installed on the ground floor only, about 90 sq mtrs.

No tank installed at the moment for DWH & underfloor heating.

What sunamp would I need if I went down this route & would I still require a cylinder of some sort.

I have an Iboost to connect but it is still in the box & could be returned if not needed.

There will be only 2 people living in the house.

You have some choices.

 

Cheaper ( capital cost )  cylinders ( buffer and UVC ) which will typically have higher losses, larger physical footprint, and annual service / maintenance costs ( G3 ) etc. 

 

More expensive SA units ( combined kW heat energy storage ) with far lower losses, 1/3 the physical size by comparison, and zero service / maintenance requirements.

Quite expensive if you need the PCM34, which you only need if you have an ASHP, but in a passive standard / other equally low energy dwelling and PV I am finding myself recommending SA heat storage and ditching the HP. The money saved on the HP goes towards more kW of SA storage and it is, to coin a phrase, "a very elegant solution".

 

You could certantly go for an ASHP to drive your UFH, with it also giving you DHW from an UVC. That would all be at a reasonable CoP and be "free" when the PV can support it, but then you also have the capital cost of the two cylinders, the glycol in the primary water circuit ( brine ), the costs when the glycol needs disposal and replacement, the lifespan of the ASHP and then the 'ugly factor' where do you put it and would you hear it, the latter consideration more so only when its providing DHW in reality as when driven softly these are quite quiet. 

16 hours ago, Moira Niedzwiecka said:

What sunamp would I need if I went down this route

You could use the cheaper and higher performance PCM58 eDual. 'e' tells you it has immersions so you can hook it up to the PV, but more importantly you can also then run off grid electric when a) the suns not out, or b) you have guests / higher DHW demand just by using the Boost button on your solar device. The idea would be to max out on SA size vs the amount of PV ( and PV performance ) that you have and rely on the grid as little as possible. The mention of some PV being able to export limit is a very interesting thing as you could chuck much more PV on ( if you have the opportunity / funds ) and really utilise the SA's to their fullest potential. 

As for sizing that would be specific to the property and hugely affected by your DHW demand. Given your above, I would say a pair of 6kW eDual PCM58's, or if you wanted to purchase sooner the sale price is still available and then its seriously worth jumping up to 2x 9kW units. Big question is, what standard have you built to ? Ultimately the sizing of the units is dictated by your kW heat loss figures for space heating, and then your DHW is added on after that. Your DHW is easy to estimate but space heating would need to be stated as a figure to work on. 

[Nickfromwales]

1 minute ago, PeterStarck said:

It's not something we have noticed nor has it affected us. There are two of us in the house, the tank is 185l and it's a low water usage house. We heat the water to 45C and there has always been plenty of hot water, with the tank reheating quickly after a shower. It will be interesting to see the first years electricity bill.

Forgive me if your repeating yourself Peter, but do you have PV? I am very much interested in the concept of the Genevex, but I think it becomes the wrong choice in a medium to large dwelling, particularly when you are using it as to fortify the space heating. Its clear that auxiliary heating mediums are required when you use UFH, ( towel rads and UTH in bathrooms / walk-in-wardrobes / dressers etc ) so you then could consider the SA as a device to provide wet heating to either those ( so you stay in phase with solar PV generation eg storing for nighttime use rather than consuming on demand from the grid ) or a wet duct pre-heater. I am however still not sold on the Genevex as a stand alone unit and am currently looking to fortify one ( in a medium sized dwelling with no ufh ) with a SA but finding it a bit off a brain teaser.

I assume the Genevex will boost daily off the 1kW immersion for legionella purge so the DHW temp of 45^oC you state is probably the base figure, and it regularly resides hotter than that ? Question is, do you preheat with that by scoffing heat out of the Genevex's additional coil so Genevex > SA > DHW where I see the problem being that the Genevex will be the first device to drop off and, as its a DHW priority device, the space heating would suffer considerably, or do 'we' circulate heat from the SA unit/s into the coil and go for cheaper heat only SA units with DHW only ever coming from the Genevex, but with the Genevex then only ever kicking over tho DHW when the SA/s have been depleted.

I think the former is a no-go for sure, so then I ask would it just be easier to leave the Gnevex out, have a generic MVHR with passive heat recovery, fit a wet duct heater ( energy for which would be primarily from solar ) and use the SA's for DHW and space heating energy. Please do post your estimated electricity usage. 

Also good point about the heat recovery after showering, as that residual heat would certainly help things out. 

My head hurts now. ?

[PeterW]

17 minutes ago, Nickfromwales said:

glycol in the primary water circuit ( brine ), the costs when the glycol needs disposal

 

Glycol is only needed in GSHP... ASHP can run with standard Sentinel products and don’t tend to degrade as much. 

[Nickfromwales]

3 minutes ago, PeterW said:

 

Glycol is only needed in GSHP... ASHP can run with standard Sentinel products and don’t tend to degrade as much. 

Does anyone actually know how long the different anti-freeze solutions 'last'? ASHP's will still be subject to freezing conditions, so how effective are the Sentinel products vs a proper Glycol mix? Makes you scratch your head as to why a pipe buried 1.5m down would be better protected against freezing than surface mounted / exposed ASHPs and pipework   

[PeterW]

Glycol in GSHP is used to transfer the heat - it is a more suitable medium for low grade heat transfer as you are talking about changing the liquid temperature from 6-8c repeatedly. 

 

ASHP fluid run at higher temperatures and usually only require the standard antifreeze levels although the short lengths of pipe properly insulated shouldn’t need antifreeze. The units themselves potentially need protection however using a frost programme to fire pumps would solve that anyway. 

[Nickfromwales]

20 hours ago, JSHarris said:

We're really impressed with our very first generation, pre-production, SunampPV.  It's performance is really very good indeed, and most impressively the heat losses from it are negligible - the case doesn't even feel warm when it's fully charged.  It's made a tremendous difference to the temperature in our services room.  When we had a thermal store in there it used to get exceptionally hot, hot enough to damage the oak door, and that was with loads of additional insulation around the store to try and stop it wasting heat.  Now the services room is barely warmer than the rest of the house, and that's all down to the very low heat losses from the SunampPV.

 

Bearing in mind that our SunampPV is "old technology" compared to the current versions; we were most definitely early adopters (I think the first on here to get one).  I have no doubt that the performance has improved a great deal since our unit was made, which bodes well for anyone thinking of getting one now.

The dust has now settled ( I hope ) on the range of SA products. They will add to it ive no doubt, but the core PCM34 and PCM58 units are now at least marketed and 'fixed' so sizing and quoting can now be reasonably definitive. 

For the benefit of this thread, I am currently in very close contact with AndyT of Sunamp so I am a little further ahead of the curve than others may be. The info about the SA's is slowly filtering down to me, still a brain-frying amount to learn and digest, so I'll answer as many of the enquires here as I can to the best of my current knowledge.

 

Firstly the range has now settled and the most important bit of info for the immediate is probably on sizing. The units have been referred to as 3kW / 6kW / 9kW etc etc, but they are now "sizing numbers". The reason for that has been that the units have been found to out-perform their rating, eg a 9kW PCM58 when fully recharged actually holds closer to 10.5kW and so on. It is also relative to the PCM, as in the PCM34 is temp / performance relative. For eg a PCM34 run off an ASHP that is delivering 36^oC will see less stored energy accumulate in the PCM, whereas a PCM34 heated by an ASHP at higher temps would see more storage and better kW yield. Hopefully I will be getting my promised training and accreditation soon so I will then hopefully be privy to the calculators that are needed to work that ? out. For now I remain blissfully ignorant and factor for the worst case  

 

Ill add any other fundamentals as I become aware of them. 

 

[Jeremy Harris]

17 minutes ago, Nickfromwales said:

Does anyone actually know how long the different anti-freeze solutions 'last'? ASHP's will still be subject to freezing conditions, so how effective are the Sentinel products vs a proper Glycol mix? Makes you scratch your head as to why a pipe buried 1.5m down would be better protected against freezing than surface mounted / exposed ASHPs and pipework   

 

 

Our ASHP requires antifreeze that can protect the external pipework and PHE down to at least -15 deg C, so it uses a combined inhibitor/glycol mixture.

[Gone West]

14 minutes ago, Nickfromwales said:

Forgive me if your repeating yourself Peter, but do you have PV? I am very much interested in the concept of the Genevex, but I think it becomes the wrong choice in a medium to large dwelling, particularly when you are using it as to fortify the space heating. Its clear that auxiliary heating mediums are required when you use UFH, ( towel rads and UTH in bathrooms / walk-in-wardrobes / dressers etc ) so you then could consider the SA as a device to provide wet heating to either those ( so you stay in phase with solar PV generation eg storing for nighttime use rather than consuming on demand from the grid ) or a wet duct pre-heater. I am however still not sold on the Genevex as a stand alone unit and am currently looking to fortify one ( in a medium sized dwelling with no ufh ) with a SA but finding it a bit off a brain teaser.

I assume the Genevex will boost daily off the 1kW immersion for legionella purge so the DHW temp of 45^oC you state is probably the base figure, and it regularly resides hotter than that ? Question is, do you preheat with that by scoffing heat out of the Genevex's additional coil so Genevex > SA > DHW where I see the problem being that the Genevex will be the first device to drop off and, as its a DHW priority device, the space heating would suffer considerably, or do 'we' circulate heat from the SA unit/s into the coil and go for cheaper heat only SA units with DHW only ever coming from the Genevex, but with the Genevex then only ever kicking over tho DHW when the SA/s have been depleted.

I think the former is a no-go for sure, so then I ask would it just be easier to leave the Gnevex out, have a generic MVHR with passive heat recovery, fit a wet duct heater ( energy for which would be primarily from solar ) and use the SA's for DHW and space heating energy. Please do post your estimated electricity usage. 

Also good point about the heat recovery after showering, as that residual heat would certainly help things out. 

My head hurts now. ?

We don't have PV yet but hopefully will later this year.

The larger of the Combi 185s the LS, in my view, would struggle to provide space heating in a PH larger than around 130m2.

My view has always been to keep all aspects of the build as simple as possible. So in a PH larger than 130m2, without wet UFH, I would use electric UFH run on E7 or E10.

In the Genvex the DHW can be set to anything between 0C and 55C with an optional weekly immersion boost of up to 65C if wanted. We keep the DHW at 45C because to heat it higher than is needed is a waste of energy and 45C works well for us.

I'm not sure a Sunamp and Genvex are the best combination and wouldn't be my choice, but then as I said I like things simple and try not to make my head hurt if I can help it .

[Nickfromwales]

Yes, im currently getting a headache from it. Time to summarise on the Genevex / SA arrangement and get the hammer down. Ho-Hum.

[Jeremy Harris]

On 07/07/2018 at 09:31, PeterW said:

Glycol in GSHP is used to transfer the heat - it is a more suitable medium for low grade heat transfer as you are talking about changing the liquid temperature from 6-8c repeatedly. 

 

ASHP fluid run at higher temperatures and usually only require the standard antifreeze levels although the short lengths of pipe properly insulated shouldn’t need antifreeze. The units themselves potentially need protection however using a frost programme to fire pumps would solve that anyway. 

 

 

Not sure about this.  Gycol is a fair bit poorer at transferring heat than plain water, as Rolls Royce found out when trying to get the cooling system on the Merlin to work - that ran initially on 100% glycol to give the protection needed, but they ended up creating a mix that had less glycol in order to allow the engine to cool more efficiently.

 

The antifreeze/inhibitor I used in our ASHP was a standard product, can't remember whether it was Sentinel or Fernox branded, but did give the required protection down to -15 deg C at the dilution I used.  Expensive stuff, and I was glad I didn't have a direct buffer tank to fill with the stuff.  Our ASHP primary circuit is the ASHP, the UFH and the indirect coil in the buffer tank, so I only needed one 5 litre can of concentrate (it's expensive stuff).

[PeterW]

27 minutes ago, JSHarris said:

Not sure about this.  Gycol is a fair bit poorer at transferring heat than plan water

 

Funny you say that as I thought the same but the info I’ve got from a GSHP supplier seems to indicate this is the requirement as their FAQ states the ground can never freeze so it’s not for that ..! 

 

I’ve considered using mono propylene glycol and an inhibitor mixed as I’ve got to sort a 60 litre buffer too so have close to 25 litres needed ... 

[Dreadnaught]

1 hour ago, PeterStarck said:

My view has always been to keep all aspects of the build as simple as possible. So in a PH larger than 130m2, without wet UFH, I would use electric UFH run on E7 or E10.

 

@PeterStarck, why do you say "in a PH larger than 130m2"?

 

Wow, Peter, you have really got me thinking! I am thinking whether I really need wet UFH. How about simple electric UFH instead across the whole house as you also reminded me of something @TerryE said a while ago.

 

Until your comment my plan was wet UFH and SunAmp eDual with E7/E10. But @TerryE's reasoning, which I have just remembered, is (to invent a quote) "don't store heat energy in a Sunamp and later transfer it into the slab. For a Passive House, where the diurnal temperature fluctuation is minor so the time of day of heating doesn't matter much, just put the heat straight into the slab according to the E7/E10 timetable, the slab will release the heat gradually in to your home." 

 

Thus, if I went with electric UFH then this would make my system even simpler. Just E7/E10, a SunAmp for DHW, and electric UFH for space heating. Simple as can be. Like you, I like simple. (However, with no wet UFH I would lose the chance to add an ASHP later if my heating demand turned out to be higher than I expected.)

 

(Mine will be 117m2 TFA Passive House*. I can't have PV because its behind a huge tree . I am currently at the stage of PHPP modelling.)

* hopefully certified, am working on it.

Edited July 7, 2018 by Dreadnaught

[Jeremy Harris]

45 minutes ago, PeterW said:

 

Funny you say that as I thought the same but the info I’ve got from a GSHP supplier seems to indicate this is the requirement as their FAQ states the ground can never freeze so it’s not for that ..! 

 

I’ve considered using mono propylene glycol and an inhibitor mixed as I’ve got to sort a 60 litre buffer too so have close to 25 litres needed ... 

 

Here's some data:

 

Fresh water:

Thermal conductivity = 0.609 W.m^-1.K^-1

Heat capacity = 4.1813 J.g^-1.K^-1

 

Ethylene Glycol:

Thermal conductivity = 0.258 W.m^-1.K^-1

Heat capacity = 2.74 J.g^-1.K^-1
 

Note this sentence from the Engineering Toolbox site about cooling systems that use ethylene glycol:

 

Quote

Note! The specific heat of ethylene glycol based water solutions are less than the specific heat of clean water. For a heat transfer system with ethylene glycol the circulated volume must be increased compared to a system only with water.

 

The problem with GSHP systems isn't the ground freezing, it's the pipes above ground and the PHE that might freeze, especially if the GSHP is mounted outside, as is often the case to reduce noise in the house.

[PeterW]

So from the Kensa site, this is interesting..!!

 

“...it is important that a sufficient quantity of glycol antifreeze is added to the cooling and heating circuit fluid to avoid freezing of the fluid in cooling mode...”

 

So this seems to indicate it’s a cooling issue rather than a freezing in use issue. 

 

[Jeremy Harris]

2 minutes ago, PeterW said:

So from the Kensa site, this is interesting..!!

 

“...it is important that a sufficient quantity of glycol antifreeze is added to the cooling and heating circuit fluid to avoid freezing of the fluid in cooling mode...”

 

So this seems to indicate it’s a cooling issue rather than a freezing in use issue. 

 

 

 

Makes sense, as the return line on a GSHP will often run at around -4 to -6 deg C, so ordinary water would definitely freeze. 

 

I've often wondered whether adding one of the "water wetter" additives, as used in motor sport cooling systems, might improve heat transfer effectiveness.  I remember using it on the (very marginal) cooling system on my Imp Sport engined Clan Crusader and it made a very significant difference.  The stuff works by reducing surface tension, I believe, so allowing the liquid to make more intimate contact with the pipes etc.

[Moira Niedzwiecka]

2 hours ago, Nickfromwales said:

You have some choices.

 

Cheaper ( capital cost )  cylinders ( buffer and UVC ) which will typically have higher losses, larger physical footprint, and annual service / maintenance costs ( G3 ) etc. 

 

More expensive SA units ( combined kW heat energy storage ) with far lower losses, 1/3 the physical size by comparison, and zero service / maintenance requirements.

Quite expensive if you need the PCM34, which you only need if you have an ASHP, but in a passive standard / other equally low energy dwelling and PV I am finding myself recommending SA heat storage and ditching the HP. The money saved on the HP goes towards more kW of SA storage and it is, to coin a phrase, "a very elegant solution".

 

You could certantly go for an ASHP to drive your UFH, with it also giving you DHW from an UVC. That would all be at a reasonable CoP and be "free" when the PV can support it, but then you also have the capital cost of the two cylinders, the glycol in the primary water circuit ( brine ), the costs when the glycol needs disposal and replacement, the lifespan of the ASHP and then the 'ugly factor' where do you put it and would you hear it, the latter consideration more so only when its providing DHW in reality as when driven softly these are quite quiet. 

You could use the cheaper and higher performance PCM58 eDual. 'e' tells you it has immersions so you can hook it up to the PV, but more importantly you can also then run off grid electric when a) the suns not out, or b) you have guests / higher DHW demand just by using the Boost button on your solar device. The idea would be to max out on SA size vs the amount of PV ( and PV performance ) that you have and rely on the grid as little as possible. The mention of some PV being able to export limit is a very interesting thing as you could chuck much more PV on ( if you have the opportunity / funds ) and really utilise the SA's to their fullest potential. 

As for sizing that would be specific to the property and hugely affected by your DHW demand. Given your above, I would say a pair of 6kW eDual PCM58's, or if you wanted to purchase sooner the sale price is still available and then its seriously worth jumping up to 2x 9kW units. Big question is, what standard have you built to ? Ultimately the sizing of the units is dictated by your kW heat loss figures for space heating, and then your DHW is added on after that. Your DHW is easy to estimate but space heating would need to be stated as a figure to work on. 

Hi Nick,

Thank you for your advice.

So, if I had the 6kw eDuel PCM58's would I still need any sort of a cylinder or IBoost?

I would not be able to increase the PV array as no further room on the roof & nowhere else to install.

I have attached the initial SAP worksheet.

We have built out of a different construction than originally planned when this was produced but values are largely the same, improved on in some areas.

We haven't had an airtightness test done yet but I am expecting well to be below 0.6.

Sorry to be so dim but not really sure what I am doing in this area & not sure I fully understand the SAP figures.

Sap Worksheet - Pickwell.pdf