THERMflow Provides The Replacement Solution For Discontinued Flowmax

Thermal store replacement

When a homeowner was looking to replace his original Flowmax unit, the THERMflow thermal store provided the perfect replacement solution.



The homeowners property had the Range Flowmax combination style thermal store installed, which had been in situ for many years. However, when it came to replacing the product due to a leak, they discovered that Flowmax had been discontinued.

A number of plumbers attended the property to quote for a replacement, with most offering an unvented cylinder solution. This would mean that there would be major disruption to the plumbing within the property, as the cylinder would only provide hot water with the heating coming directly from the boiler. This appeared to be the only option until research on thermal store solutions on the internet brought up the McDonald Water Storage thermal store ranges.


Flowmax ReplacementTom, the homeowner from Rugby, contacted McDonald to discuss the requirements for a thermal store. The specific requirements highlighted the benefit of the bespoke design flexibility, enabling to incorporate the relevant heat sources of gas boiler and solar PV, but also deliver wet central heating and mains pressure domestic hot water, as the existing system did.

The 180 litre thermal store also needed to be located in the same installation space, therefore space and accessibility to the connections were critical. The replacement THERMflow was designed to meet these requirements, which in turn simplified the installation process as the pipework configuration throughout the property could remain the same, reducing the installers time onsite.

The performance of the thermal store will be greatly improved compared to the old product, with the white casing and 50mm of injection foam insulation, providing a much improved heat retention than the spray foam insulation of the Flowmax.


Tom S., Homeowner

“Having had a thermal store originally, I was keen to replace with a like for like unit to maximise the benefits but also simplify the installation process. Although being quoted for an unvented solution, I researched thermal stores on the internet and McDonald Water Storage were able to meet my requirements.

The whole process was professionally handled, from specification and quoting to the delivery.”

Paul Barnes, Phoenix Services Plumbing

“The installation was extremely straight forward, made possible by the bespoke design of the connections, allowing for minimal work to connect into the existing pipework”

See our range of thermal store solutions and discover the benefits for your next project.


Wayne Hyde

Product and Marketing Manager

Having been in the cylinder industry for nearly 20 years, in both product and marketing roles, I have extensive knowledge of all aspects of hot water storage, from domestic through to commercial applications, including vented, unvented and thermal store solutions.

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