Hi

I installed a Mitsibushi Ecodan air source heat pump system last August. I have had a miserable winter.

First the system does work, heat is collected from the outside, even at sub-zero. However, the good news ends there. It is a new technology and a chose a local installer from those approved by Mitsibushi on a list they supplied. The dealer also featured in their publicity brochure and video. I am a pensioner and have no heating knowledge and had to rely on the installer, particularly with the Mitsibushi recommendation behind him.

I now appreciate how important it is that heat loss calculations are carried out on the property for a retro fit. It has become very clear in hindsight, that this was not done and that the heat pump is under size. My house is well protected with cavity wall, double glazing and well insulated loft, but the installer failed to do the basics, although I gave him all the room sizes when he surveyed the property. The heat runs through the system (assuming a correct size Ecodan) at 55 degrees, instead of around 70 for a oil/gas installation. Therefore, all radiators have to be changed to increase the surface area by about a third.

In addition to an undersized system - the warmest the lounge has got through the winter is 17, on coldest days 14 - the Ecodan comes packaged with a Gledhill tank. This has been nothing but a problem. It is difficult to program times, but more importantly we have had trouble with elements of it, including needing new printed circuit boards and being without any heating or hot water for a week while they were replaced.

My advice, is look very carefully, if it is a retro fit. Check out the installer (I thought I had since Mitsibushi featured them so strongly) and be very careful to look close at the unit which comes with the air pump. This unit drives the whole process and is the 'brains' of the system. Additionally, since it will become a sealed system under mains pressure, you have to be very sure of all joints etc in the existing system – we found this out the hard way!

Despite visits from the installer and Mitsubishi (supposedly their top man on Ecodan/Gledhill) no significant improvements have been achieved – though some tinkering with the system has gone on to very minor effect. My wife and I have suffered chest colds all winter and have been ill, we are now seriously looking at facing the cost of replacing the Ecodan with oil during the summer. We cannot have another winter like the last.