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Sunamp Thermino Heat Battery

Toodles · 2024-09-22T20:04:40Z

We opted for this Sunamp design as we just don’t have a suitable space anywhere in the house for a conventional DHW tank of the capacity required by the MCS, and I didn’t much fancy enlarging the loft hatch to fit a tank up there. This siting would have required all the attendant strengthening work to fit a 250-litre tank that bristles with pipes, sensors and pumps. Thus, we avoided any possible source of noisy motors too! (Not to mention the additional wiring and pipework!) We would also have lost the low-level heat source that we regard as always useful heat in the airing cupboard (which is too small to accommodate a conventional 250-litre tank). There is an LED panel on the front face of the Sunamp Thermino, providing indications of Power Connected and status of charge. Though very granular, three LEDs indicate full charge, half charge and low charge level. In addition, one LED indicates when the unit is charging. Our unit sits sideways in the airing cupboard, as the depth of the unit dictated this orientation; the LED display is still viewable sideways without much of a problem, though there is very little need to consult it anyway. We are able to monitor consumption via the Myenergi app, where we set our preferences for charging. The unit is VERY HEAVY, and the installers had three attempts with progressively more powerful methods of stair-climbing sack trucks to take the unit upstairs! The unit sits over two floor joists, and the load is spread by sitting on two 25mm thick boards as a sandwich. During installation, the top cover is removed, and several layers of vacuum foam insulation are lifted out to access the pipework. The connections to the water supply and hot water feed are made with solderless swivelling joints that may be set to exit to pipes on the left, rear or right of the cabinet. On the day the old water tank was removed, we were only without hot water for a few hours while the existing pipework was modified, the Thermino placed, and the pipes and wiring connected. Within 30 minutes of powering up via the Eddi, we had hot water on tap again – there are comparisons with a combi gas boiler in that sense. Now as to the working – well… it just works. Powered via a Myenergi Eddi, that once set, will provide either PV or grid power as required. The unit is ventless and silent in operation, has no pumps, and heats the cold water as it progresses through a few metres of internal pipework that is surrounded by the Phase Change Material storing the heat. It then exits through the hot outlet and goes straight to a tempering valve for safety. Expected life? As yet unknown, but tested to the equivalent of 20 years and still good, I’m told. I did hear of a failed unit once, and Sunamp replaced the whole system for the owner without a quibble. I considered several models but opted for the ePV version, as the one that runs from a heat pump input requires a high-temperature heat pump plus electrical ‘top-up’ to ensure the required minimum temperature. There is also a version for thermal solar panel heating in the range. Please see the website link, which provides dimensions, weights, capacities, and the various models available to match different energy sources. The Sunamp model we have loses less than 0.75 kW of heat in 24 hours, and what is lost is made good use of as it sits on the floor in the airing cupboard. The total heat loss in the whole heating system is less than when we had a gas boiler and 99-litre DHW tank in there, so the airing cupboard is just a little cooler than it used to be. Our system has a 210-litre capacity, so it isn’t imperative that it is charged every day just for the two of us – we could (and have) left it for 2-3 days and still had sufficient hot water as and when it’s required. Currently, our daily charge consumes ~3kWh, but will rise to about ~4-4.5 kWh in mid-winter. I think a full charge for our unit capacity is ~11.5 kWh. Would I recommend the system? Absolutely, every time!

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asoksevil

(@asoksevil)

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Joined: 1 year ago

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07/08/2025 8:42 pm

I am thinking on installing this as well given space constraints.

Is it actually better to let the solar PV or the battery charge the sunamp

for hot water and use the ASHP entirely for heating? (Underfloor heating). Or would you go about this?

This post was modified 5 months ago by Mars

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JamesPa

(@jamespa)

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Posts: 3969

09/08/2025 7:58 am

Posted by: @asoksevil

↑

I am thinking on installing this as well given space constraints.

Is it actually better to let the solar PV or the battery charge the sunamp

for hot water and use the ASHP entirely for heating? (Underfloor heating). Or would you go about this?

Depends on your electricity tariff and in particular your export tariff, also on time of year.

So for example my import tariff is 7p midnight-7am, 25p the rest of the time. My export tariff is 16.5p. So for me it makes sense to do DHW heating at night on the heat pump (and as a result export more), even though the heat pump will be less efficient than if I did it during the day.

If I didn't have an export tariff then self-consuming as much solar as possible makes sense. In this case there is an argument for a solar diverter (which I guess but dont know you can use with a sunamp) precisely to match the load to the available excess, or alternatively play the numbers game by scheduling the ASHP to do the DHW/sunamp heating from noon-2pm or thereabouts, reckoning that, on average, this will work out better.

In winter all of your solar will be consumed by the ASHP anyway most days, so best just to use the ASHP to heat the sunamp at a COP of 2, rather than the resistance electric element at a COP of 1, whatever your export tarrif.

The other calculation that might be worth doing is payback time for the additional cost of the sunamp with the facility to be heated by the ASHP, relative to an electric-only one. Its probably a long time! An electric-only sunamp would invalidate the BUS grant, however, so may not be an option.

This post was modified 5 months ago 4 times by JamesPa

4kW peak of solar PV since 2011; EV and a 1930s house which has been partially renovated to improve its efficiency. 7kW Vaillant heat pump.

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Toodles

(@toodles)

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Topic starter 09/08/2025 8:12 am

@jamespa Just for clarification, yes the Myenegi Eddi can be used to supply the Sunamp thermino. We have the Sunamp Thermino ePV210 version which is heated from solar or grid energy; by the way, we did get the £5000 BUS grant, perhaps that is because the solar energy may be used to heat the water. Our ASHP does not heat the DHW at any time - but we do have some space in our airing cupboard!😉 Regards, Toodles.

Toodles, heats his home with cold draughts and cooks food with magnets.

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JamesPa

(@jamespa)

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09/08/2025 9:55 am

Posted by: @toodles

↑

We have the Sunamp Thermino ePV210 version which is heated from solar or grid energy; by the way, we did get the £5000 BUS grant, perhaps that is because the solar energy may be used to heat the water. Our ASHP does not heat the DHW

Interesting, I must reread the BUS rules for this combo....

....Ok the relevant rules are below. I can't see how a heat pump with electric only sunamp meets condition (c) unless previously your dhw was heated on immersion only, which may be the case, but then it falls foul of (b).

Of course that's all a bit academic!

A heat pump meets the suitability criteria in relation to the eligible property, or a property to which regulation 14(1)(b) applies, for which it is installed where—

(a)it provides heating—

(i)solely to that property, or to both that property and any related property, and

(ii)for the purpose of both space heating and hot water heating, using liquid as a medium for delivering that heat,

(b)it is capable of meeting the full space heating and hot water heating demands of that property, and

(c)it replaces the heat generating components of the original heating system installed in that property (where applicable), other than any—

(i)supplementary electric heater, including any immersion heater,

(ii)circulation pump, or

(iii)solar thermal collector.

This post was modified 5 months ago 3 times by JamesPa

4kW peak of solar PV since 2011; EV and a 1930s house which has been partially renovated to improve its efficiency. 7kW Vaillant heat pump.

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Toodles

(@toodles)

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Posts: 2457

Topic starter 09/08/2025 3:11 pm

@jamespa A few days after the installation had been commissioned, I had a ‘phone call from someone within the hallowed temples (AKA MCS) to enquire if my system had been installed to my satisfaction and if everything was fully operational. The enquiry included a reference to my DHW and was everything working fully? I assured the gentlemen who rang from the hallowed temples that yes, all was working fine. His paperwork will (I suppose) have shown the details of the heat pump and the DHW arrangements; he made no further mention nor did he ask any more about the Sunamp system and my installer received the grant on my behalf. Regards, Toodles.

This post was modified 5 months ago by Toodles

Toodles, heats his home with cold draughts and cooks food with magnets.

🤩

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