The Boilermate A-Class Ecodan

This is complicated. The Boilermate A-Class Ecodan is an A-Class Boilermate thermal store heated by a Mitsubishi Ecodan air-to-water heat pump, rather than by a gas boiler. Very few were sold I suspect, as I’ve only ever encountered two. The Mitsubishi Ecodan air-to-water heat pump does the same job as a gas or oil boiler but runs on electricity. The advantage of using electricity to run a heat pump over using the electricity to directly heat the house, is that for every unit of electricity energy burned running the heat pump, three units of heat energy are produced by the heat pump. This 300% ‘efficiency’ broadly offsets the high cost of electricity leading to reasonable running costs and a far ‘greener’ carbon footprint due to the much lower CO2 from burning certain types of electrticity. 

(A heat pump is a device that extracts heat energy from the outside air. It uses conventional refrigeration technology to extract heat energy from outside air air blown through it with a large fan. It then raises the temperature of this energy and uses it to heat water, which is then pumped through the Boilermate in just the same way that hot water from a gas boiler is used to heat other Boilermates.)

Mitsubishi have since started producing their own brand of thermal store to go with their Ecodan heat pumps, cutting Gledhill out of the equation. If you have a Boilermate A-Class installation and the Mitsubishi Ecodan outdoor unit needs service or repair, Mitsubishi will provide technical support, and their own in-house repair service but as far as I know, the A-Class Boilermate inside will not be covered. For repair of the A-Class Boilermate repair, you’ll need to call someone like me!

Other than the fact that it is heated by a heat pump, the A-Class Boilermate Ecodan works in exactly the same way as an ordinary Boilermate A-Class heated by a gas boiler. There is one exception though. The Boilermate used with the Ecodan heat pump has an internal coil for heating domestic hot water, rather than an external plate heat exchanger. 

A drawback of this system is the Ecodan heat pump cabinet which needs to be installed in the garden. It is a large grey box about 100cm x 70cm x 40cm, and it contains a large fan which despite the optimistic claims of Mitsubishi, is simply not silent! 

Common faults with the BoilerMate A-Class Ecodan system:

1) Water scale-contamination of the internal heat exchanger.

I have to admit I have yet to see this in a Boilermate A-Class Ecodan system but this happens commonly in earlier Boilermates with an internal heat exchanger, so I expect to see it on these systems too eventually (once those installed are old enough). Chemical descaling is perfectly feasible although it is likely to take several hours and several kilograms of descaling chemicals!

2) Circuit board failure. 

The board can be interrogated for faults by pressing the buttons on it in accordance with the manual. Unfortunately although the error codes are quite easy to find on the display, the manual doesn't mention what they mean! Any parameter reporting code "29" is an "internal communications error" on the control board, for which the fix is a new control board. The main problem however is that the circuit board is designed and programmed to communicate directly with the Mitsubishi Ecodan outdoor unit and now the Gledhill/Mitsubishi partnership project has ended, the circuit board is no longer in production. So if the circuit board fails in a Boilermate A-Class Ecodan, the appliance will need to be replaced.

3) Seized water pressure regulator

Here, the symptom presents as no water at all coming from the hot taps. The regulator can be freed but on the one occasion I did this in an attempt to save the customer some money, it seized again a day or two later but in the opposite condition, too high a pressure. So I had to replace it anyway.

4) Failure of the external Mitsubishi heat pump. I've yet to see one fail but as they use refrigeration technology, I will be unfamiliar should I encounter one. Mitsubishi however, support these directly. See here: 

https://les.mitsubishielectric.co.uk/homeowners/ecodan-owners

If you'd like to discuss your BoilerMate A-Class Ecodan system, call or text me on 07866 766364.