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Harvest Thermal - ASHP with a smart thermal battery

Air Source Heat Pumps (ASHPs)

Last Post by springswood 1 hour ago

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springswood

(@springswood)

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Joined: 11 months ago

Posts: 17

Topic starter 15/06/2026 6:11 pm [#3063]

I thought people here might find this interesting, even if it is a new US company so probably not available here for a while, if ever. I need to think about it for a while to decide on the pros and cons compared to using electric batteries.

The idea is to use the ASHP to heat a large water tank. The minimum they work with is 300 l, so roughly 10kWh. The ASHP feeds hot water in at the top so it's stratified and stores a variable amount of heat energy. The new bit, called the Harvest pod, connects to the heat store to deliver hot water, there's also a heat exchanger to transfer heat to radiators or underfloor heating. Diagram below.

The claim is it can cut bills by 30%.

The smart bit is that it looks at your usage patterns for heating and hot water and the weather forecasts to determine how much energy you need and when. It then supplies that heat into the tank by running the heat pump at the most efficient times taking advantage of higher air temperatures, time of use tariffs and solar PV where it can.

It was developed by a married couple of engineers in California when they put in their own heat pump. Though one of the advantages they have is that their renewable electricity has a lot of solar, meaning electricity is cheap when the air is comparatively warm.

I found it on YouTube here Harvest Thermal at Amply Energy It's an exceptionally clear discussion with an amazing lack of waffle. The designer really knows her stuff and the podcast hosts are good on both heat pump technology and the needs of installers. A word of warning though, it's very American full of unfamiliar terms and archaic units, Fahrenheit, BTU's, Gallons (presumably US not imperial).

Their website it pretty good too Harvest Thermal Amongst other things I found this general schematic. They did mention it also works for 'European style radiators'.

I'd be interested to see what anyone thinks. I suspect it may seem dangerously similar to the dreaded buffer tank...