Mixergy Delivers More Usable Hot Water with a Heat Pump
Independent testing from early adopters is helping us elevate performance standards, especially when it comes to what “usable capacity” really means.
In a recent deep dive, Mick Wall ran a full drawdown test on his 250 litre Mixergy cylinder when connected to a 5kW Vaillant heat pump. His goal was to test whether Mixergy’s entire cylinder volume can be heated and used effectively for hot water, as claimed.
What he found strongly supports what we have seen across our projects with local authorities and housing providers. Mixergy cylinders with a heat pump consistently deliver more usable hot water while using less energy.
Key findings from Mick’s test
250 litres of usable hot water, verified by energy input
Using Open Energy Monitor and a water heating calculator, Mick confirmed that it took 7.925 kilowatt hours to heat his cylinder from 20.4 to 45 degrees. This aligns precisely with the theoretical energy required to heat 250 litres, proving that the full volume was heated and usable.
Shower-safe temperatures all the way down to 1 percent capacity
Even at just 1 percent remaining capacity, Mick recorded 39.8 degrees at the tap. That is well within the ideal showering range. Usable hot water was maintained from 100 percent all the way to empty, without any noticeable drop in performance.
Up to 75 litres more usable hot water than conventional cylinders
Conventional cylinders with coils often fall short on usable capacity because of internal design. According to Hot Water Association standards, only 70 percent of the stated capacity needs to be usable. That means a 250 litre cylinder may deliver just 175 litres of hot water.
By contrast, Mixergy’s top-down heating and coil-free design enables close to 100 percent usability, gaining up to 50 to 75 litres more usable hot water without increasing the physical size of the cylinder.
Why this matters
These insights are not theoretical. In real homes, they translate to:
- Smaller cylinders with the same usable capacity
- Faster reheat times for high occupancy homes
- Lower energy use which reduces running costs
- Strong performance with heat pumps, with verified efficiency above a COP of 3.8
This is what innovation looks like when it is grounded in real world data. We are proud to see early adopters helping validate the Mixergy approach in practice.
If you want to dive deeper into the test results and see exactly how the data was captured, you can read Mick Wall’s full blog post here.
