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Author Topic: Is the Sunamp diversion system all that?  (Read 5430 times)
NoahsDad
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« on: March 03, 2017, 03:00:20 PM »

I was recently made aware of this Scottish-based system on  that featured on 'Fully Charged' for making better use of Solar PV by diverting spare energy to a heat store for hot water - a typical quote is around 3,000 for a 5 kwh heat store, from http://www.sunamp.com/

Has anyone got one, and what do you think?

I don't think it seems like a sensible or financially viable option to be honest. The kit looks a bit hefty in size to me. I'd rather spend the money on adding more Solar PV panels, or even put it towards a proper battery storage system for excess PV to be diverted to.
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Fionn
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« Reply #1 on: March 03, 2017, 03:04:16 PM »

It depends on your priorities and existing situation. It has a high power output and is quite compact for the storage capacity.
If you wanted high output showering and were off the gas grid or if you had limited space then it could be a good option.
They may need to drop their pricing to compete with cheaper battery storage solutions in time admittedly.
It should outlast any battery storage system though.
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djh
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« Reply #2 on: March 03, 2017, 10:51:05 PM »

If you think of it as a very low loss hot water tank that happens to be able to be powered by PV then it makes a lot more sense. Whether it makes sense depends on whether you want a hot water tank or not, and on how you plan to heat the tank.

JS Harris, late of many parishes, has one that he is quite pleased with. It came out just after I bought my thermal store otherwise I might have one too.
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Cheers, Dave
regen
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« Reply #3 on: March 04, 2017, 09:57:19 AM »

Very few situations where this will be of benefit and even less at the current unit cost. Their savings are optimistic to say the least and variable within the same brochure according to them. 550pa then 500pa.

Based on supplying hot water from excess PV rather than sending back to grid then my figures for the last 4 years indicate average production of 3750kwh (bit low for UK average perhaps) average direct usage 1750kwh and average to tank of 1900kwh rest lost to power immersun etc.

1900kwh at 15p per unit =275 absolute max saving and this saving can be achieved with a 300 immersion type device.

Figures simply do not stack up!

However if you don't have a tank and are very short of space and your usage exactly matches or is less than the unit produces (which will not be the case for at least half the year) then it may be of use.

Regen
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3.92w freestanding PV with sb3300 +Imersun
21kw Stratford T70 woodburner
 300litre thermalstore with 3kw and 1kw immersions
 Wall star 25kw oil boiler
  Spring water supply with uv and ro membrane
 Sheep, poly tunnel and approx 80 sq m of raised veg beds.
camillitech
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« Reply #4 on: March 04, 2017, 04:15:19 PM »

I was recently made aware of this Scottish-based system on  that featured on 'Fully Charged' for making better use of Solar PV by diverting spare energy to a heat store for hot water - a typical quote is around 3,000 for a 5 kwh heat store, from http://www.sunamp.com/

Has anyone got one, and what do you think?

I don't think it seems like a sensible or financially viable option to be honest. The kit looks a bit hefty in size to me. I'd rather spend the money on adding more Solar PV panels, or even put it towards a proper battery storage system for excess PV to be diverted to.


This is how my totally electric 'off grid' house works, I figured as heating and DHW were the largest consumers of power then I'd have a large 'heat bank' (1500lt thermal store) and a relitively small 'battery bank' (800Ah). As soon as my batteries are fully charged all excess is diverted into the store. Works really well as the 'heat bank', unlike the 'battery bank' doesn't degrade with use.

Great if you're doing it a build/design stage or fitting it in with other upgrades but as you say, you can buy an awful lot of PV for 3K.

Cheers, Paul
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http://lifeattheendoftheroad.wordpress.com/

'Off grid' since 1985,  Proven 2.5kW, Proven 6kW direct heating, SI6.OH, 800ah Rolls, 4.75kW PV ,4xTS45, Lister HR2 12kW, , Powerspout pelton, Stream Engine turgo, 60 x Navitron toobs and a 1500lt store. Outback VFX3048 and 950ah forklifts for backup,
biff
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« Reply #5 on: March 04, 2017, 06:07:32 PM »

Everybody is different,
                    We all have different hot water requirements. I kept seeing this 4kw of pv figure all the time and eventually ended up with approx 3.8kw+. I am in the envious position of having done it all in dribs and drabs and somehow arrived at a place where everything seems to work and look after itself pretty good but it took time, However, If some one were to ask my advice on how to proceed with thermal stores or thermal battery bank, I could only spout praise for our own installation because I know no other and that is not much good. However, There are a few interesting revelations available,
1, After sticking an 18" dc immersion heater at the top of a 6ft DHWT and then having to figure out some way to get rid of the extremely hot water at the top, I discovered that by using an essex flange and  pumping it down to the bottom, through a solar coil and drawing it up to the top,to keep the water temperature under control, I was in fact getting the best of everything going.
2, The 18" immersion would provide instant hot water and the internal, indirect circulating system give a good 3 to 4  hours dumping  excess energy from the PV, before the C/H pump kicks in and starts indirectly exchanging the cool water in the C/H rads for the Hot water in the boiler coils inside the DHWT, (2 x 8mtrs=16mtrs).
3, Any more than 4kw of pv would make it uncomfortable around July/August. from mid march onwards our rads will become warm round about 2pm on most sunny days. It means that any little fire in the stove sets the rads warm because the whole system is already full of hot water.Even the boiler in the stove becomes a dump load for excess heat from the PV. Closing down the stove and shutting the valves, prevents the heat from escaping up the chimney Until the fire is lit.
  Planning something like this is best done by sitting down and jotting down all your requirements and then seeing if you can tick all the boxs and maybe gain several points with the one move. Locate your thermal stores in a central position.  Map out your pipework, looking for the most direct troublefree route and do not box yourself in. try and leave good access to your pipework, you may want to adjust or reroute them.
We got away pretty good. I wished i had used a S/S tank for the DHWT. The guy who sold me the 1800 x 500 DHWT had large S/S ones there and even had beastie 8ft tall ceramic tanks with all kinds of baubles on them,,(600.00) The Thermal store downstairs in the hall is S/S. It is all a learning curve.
                                                                                 Biff
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An unpaid Navitron volunteer,who has been living off-grid,powered by wind and solar,each year better than the last one.
ringi
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« Reply #6 on: March 05, 2017, 07:41:21 PM »

I think the Sunamp is best for people without mains gas, redo some of the calcs using the cost of LPG for water heating then the Sunamp starts to look better.

Its small size is a real benefit but only if you have little space

It is the lowest loses way of heating water with E7 as it loses so much less heat then a normal DHW, therefore it may work for someone not on mains gas, heating water with E7 and without PV.   Or someone on PV with a home that will overheat if a normal tank was used.

Clearly it works best if you dont already have a tank, as installing a Sunamp saves the cost of a tank.

Overall I think the SunAmp has its place but is overpriced for the mass market.
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regen
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« Reply #7 on: March 05, 2017, 08:29:07 PM »

Whilst the technology is good its the unit price which kills it together with their wildly optimistic savings when coupled to a 4kw PV installation- The capital cost of which does not appear to figure in their calculations.

I had  look back at 2014 where I have daily figures.

The 3.92 kw pv produced 3642kwh and the immersun diverted 2074kwh of this to the 300 litre store after it had satisfied the household electrical use. By using .. wood backup we have 24/365 hot water. -

For around 3000 I think you get a 5kwh unit so what happens to the excess electricity when the 4kw pv can divert in excess of 20kwh after household use is satisfied? Unless hot water is being used during the sunny period then i guess it sends it to the grid. So on the assumption that the tank was cold at say 08.00 each day and can be stopped from automatically retaining the 5kwh load allowing the PV to divert the full 5kwh and that is used before the next days cycle then in 2014 such a system would have put 1187kwh into the unit from the PV- just over half that diverted by a 300 immersun device and worth 178 based on electricity at 15p per unit.-So where is the rest of the 500pa or is it 550pa savings they are claiming?

Regen
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3.92w freestanding PV with sb3300 +Imersun
21kw Stratford T70 woodburner
 300litre thermalstore with 3kw and 1kw immersions
 Wall star 25kw oil boiler
  Spring water supply with uv and ro membrane
 Sheep, poly tunnel and approx 80 sq m of raised veg beds.
M
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« Reply #8 on: March 06, 2017, 09:18:02 AM »

I put a lot of calculations together for the 5kWh Sunamp model on this thread in January. I calculated annual savings for myself (on the gas grid) at around 20-40 pa. So a complete no no economically. However I stressed repeatedly that the idea seems good, and I feel guilty being so negative about it ..... but!

So whether it's about environmental or economic issues, most folk would be better off investing the money in a some type of renewables fund (like Abundance). They'd get more money, and probably do far more good.
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Just call me Mart.     Cardiff: 5.58kWp PV - (3.58kWp SE3500 + 2kWp SE2200 WNW)
regen
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« Reply #9 on: March 06, 2017, 10:10:09 AM »

Hi Mart,

I agree entirely re the technology but at the moment the quoted savings in the glossy brochure are simply not achievable by a country mile which puts it in the chocolate teapot category along with rent a roof and windmills on houses!

Regen
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3.92w freestanding PV with sb3300 +Imersun
21kw Stratford T70 woodburner
 300litre thermalstore with 3kw and 1kw immersions
 Wall star 25kw oil boiler
  Spring water supply with uv and ro membrane
 Sheep, poly tunnel and approx 80 sq m of raised veg beds.
Fionn
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« Reply #10 on: September 05, 2017, 11:26:38 PM »

Dragging this one up from the past, but the latest brochure shows that the price has been reduced to 1700 + VAT.
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pdf27
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« Reply #11 on: May 15, 2018, 09:08:40 PM »

Apologies for the thread necromancy, but I've been kicking around an idea and think it makes sense.

When providing heating & hot water with heat pumps, the 60C requirement for legionella protection is a problem. Using a thermal store gets around that problem to some extent allowing for a significant improvement in COP (to avoid scalding, DHW should ideally not be much above 43C at which point the COP is much better), but they're absolutely massive to provide any decent amount of storage at this temperature.

With Sunamp, because they're using phase change for the majority of heat storage then essentially the heat capacity of the device is independent of the temperature at which you store it - and they can customise the storage temperature by varying the ratio of chemicals stored in the cell with AIUI 43C being one of the available setpoints. Given the unit is half the size of an equivalent hot water cylinder and running at half the temperature, standing losses will be very low which is another advantage for a well insulated house. Over the course of a year, if providing hot water with an ASHP I could see the total power consumption for hot water being halved. Not worth it for retrofit, but might well justify the price differential between a Sunamp and an equivalent hot water cylinder, particularly given the internal volume saving and the lack of requirement for a G3 inspection.
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NoahsDad
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« Reply #12 on: May 16, 2018, 10:09:55 AM »

@pdf27 there is no more risk of having a HP for your heating system than there is of having a gas boiler. Any HP in the UK has to or at least should meet safety criteria for this. HP's have a Legionnaires section in the menus which any decent MCS installer will be aware of. The norm is to have the Legionnaires program to run on a weekly cycle (is an automated timer thing). In my own setup I have several hot water tank feeds other than the HP, including approx. 10kW of PV, and evacuated tubes. My tank temp is almost always around 80C. sometimes creeps up to 82C depending on what is going on.

Re Sunamp, their office is actually in my area. They don't really have a great reputation in the area, and have a somewhat unusual and confusing product at best. My renewables installer doesn't really feel they have a good value for money product. He says the best fit for it would be if you were trying to fit renewables into a very small property, with confined and limiting space. As that is what it does best, making use of small space.
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pdf27
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« Reply #13 on: May 16, 2018, 06:44:38 PM »

@pdf27 there is no more risk of having a HP for your heating system than there is of having a gas boiler. Any HP in the UK has to or at least should meet safety criteria for this. HP's have a Legionnaires section in the menus which any decent MCS installer will be aware of. The norm is to have the Legionnaires program to run on a weekly cycle (is an automated timer thing). In my own setup I have several hot water tank feeds other than the HP, including approx. 10kW of PV, and evacuated tubes. My tank temp is almost always around 80C. sometimes creeps up to 82C depending on what is going on.
Sure you can do it but in thermodynamic terms it's a really bad idea. Playing with the numbers today using UK climate data for the past couple of years and published Samsung COP curves, cutting the cylinder flow temperature from 55C to 45C reduces annual power consumption by about 40%. For a well insulated new build house where the majority of heat demand is for hot water rather than heating that's a very worthwhile saving and the price you're looking at is the difference between a Sunamp and a cylinder rather than having it in addition to a hot water cylinder. A big cylinder at 45C with a weekly pasteurisation cycle is possible, but given the cost of building floor space is about 1,000/square metre you're going to rapidly start eroding the cost advantages.
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Sprinter
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« Reply #14 on: May 17, 2018, 04:06:33 PM »

I wonder if this could be used to get hot water for our sink and bath.

Its a problem for us in the summer as we do not have a tank or thermal store (yet) but an oil powered combi boiler, and Oil will inevitably go up and up in the future, in winter its fine as it keeps the house nice and warm and supplies hot water, but in the summer it is still used for an hour a day for washing the dishes, which is almost certainly wasteful and costly with the pilot light being on all year round.

Also in the summer we have spare electricity that is going to the grid even after the batteries are topped up, it might be a good idea if i could divert that extra juice to something to supply hot water to the kitchen as well, then i can shut the oil burner down in April and leave it down until Oct.
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