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More detail required on air source heat pumps

Dear Sir,

With reference to your article “Back to school on air source heat pumps” in H&V News 23 February issue there are some points that need clarifying.

When talking about heat pumps and when providing training courses on the benefits of heat pumps it is absolutely essential that you clearly differentiate between the monoblock type and the split type of heat pump. The Ecodan system is, as I understand it, a monoblock system whereby the refrigerant circuit is entirely built in the factory and the only field connections required are flow and return water connections and the electrical supply. These systems are clearly built for and marketed towards the plumbing and heating market where no specialist refrigeration skills are required. The split type systems, however, have a separate outdoor unit that requires refrigeration pipes to be connected and properly pressure tested, evacuated and leak tested on commissioning.

There is the very real possibility of causing confusion with end users or the uninitiated. The reason this is important is that the quote from Mr Rusling that “the units are not currently affected by the F-Gas regulation…” is factually incorrect. Where a split type heat pump is being installed it is illegal for the pipes to be installed by non qualified refrigeration technicians regardless of the charge weight of fluorinated gas. The charge weight refers only to leakage checking frequency and the necessity for keeping log books and records. On that point Mr Rusling is correct when referring to the monoblock systems but I feel the article is misleading.

Further, the quote from Mr Rusling where he gives an extremely simplistic explanation of the expansion valve’s role in the compression cycle and then states that understanding the expansion valve will put you “ahead of quite a few people in the AC industry” is patronising to all good engineers.

Surely, if Mr Rusling and Mitsubishi truly believe this to be the case, they would be better serving the industry they make their millions from by helping contractors to raise their knowledge and standards by providing real incentives for their customers to learn the real skills necessary to become a proper engineer rather than engineering systems that seem to encourage a general “dumbing down” of the trade. Admittedly Mitsubishi are not the only company guilty of this practice, nor is the ACR sector alone in undermining real skills development. But I have always been proud to have been trained as a proper engineer in a highly technical sector and I resent the proliferation of semi or part skilled people undermining the industry and giving nothing back.

Graeme Fox

Specialist Mechanical Services

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