Ecodan heat pumps

[toscal]

Does any one have any experience of the Mitsubishi Ecodan Air Source Heat Pump. And are they any good. I have a client who wants to get one.

http://www.airtech.co.uk/mitsubishi-air-conditioning/mitsubishi-ecodan-air-source-heat-pump/

http://www.mitsubishi-heating.com/

[Crabby]

I use a Nibe 11kW air source heat pump (ASHP) to heat a swimming pool. The only thing I would suggest is that you check the performance figures for the Mitsubishi, which should show, for different air temperatures, the Coefficient of Performance (COP) of the heat pump at different supply temperatures. The COP decreases as air temp. drops. I'd just be sure that your client realises this, because most of us want most heat when the air temp. is low , which will be at the lower end of COP. We only use the swimming pool in the summer, so COP is about 3.5. If we'd wanted year round performance, we would have gone ground source. (Apologies if teaching grandmother to suck eggs.)

[drawdog]

Ecodan Unit

Hi folks, I've had an Ecodan 14kW unit installed since Oct 08 and been very impressed indeed. The unit is giving COP's of between 3.0 & 4.5 when heating the house throughout the cold winter period, it also does the hot water and connects to the normal house controls (timeclock, stats, etc)

Of interest, I've tried running the heat pump on both timeclock and 24/7 and the results we're impressive. I've done the maths and reckon it's roughly 2/3 the cost to run the house 24/7, so now the heating never goes off.

Looked into ground source, no advantage in performance compared to an inverter air source and very much cheaper to install

If you need more info let me know

[toscal]

What did you have before, as my client would really like to know will it be cheaper than his present system. He uses 4 propane bottles. Currently around the 180 euros mark to replace which is every 20 to 30 days.

[drawdog]

Ecodan vs LPG

I was on LPG, my rate was 31.45p per litre and current electricity rate is 10p per kWhr.

[pollardspark]

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.

Drawdog did not mention if he had a Gledhill tank, or some other system, or whether he had to enlarge his radiators. I would be grateful to know the answer.

[JohnnyP]

That's a very depressing story. You've certainly been let down. I have two suggestions which you may like to consider before ripping out your Ecodan and reverting to oil.

1. Add a second ASHP unit to increase your kW output. There are two caveats: first, it would clearly be irritating to hand more money to the people who stitched you up with an undersized system; second, I'm only experienced with Nibe ASHP which can definitely be linked up, you'd have to check with Ecodan.

2. Improve your heating control system, that is, try to be more efficient with your existing, but limited heat output. You could try Honeywell CM Zone or Hometronic (for larger houses), or the HouseHeat system, which are wireless and suitable for retrofitting.

Alternatively, could you persuade Mitsubishi and the installer to replace the existing heat pump with a bigger, more powerful unit?

[SensibleHeatUK]

I'm re-posting this as my original reply does not seem to have made it to the forum!

If the heat pump is achieving 50-55 degrees water flow temperature in the colder weather then it is not undersized but rather the problem is that it has been specified as a boiler replacement for use with radiators which normally require much higher flow temperatures to meet the heat losses in colder weather i.e. flow temperatures of around 80 degrees. This means there has to be one of two approaches taken to make heat pumps work effectively with radiators, the first is to increase the size of the radiators so that the heat losses for each room can be met with the reduced flow temperatures or secondly use another heat source to boost the flow temperature in the colder weather (this requires the heat pump to have the correct fittings or a thermal store and also on-board controls to co-ordinate the use of top-up heat). Neither are a simple quick fix and if the heat pump was sold as a direct replacement for an existing boiler then in my view it has been mis-sold. Unfortunately there are a lot (if not all) heat pump companies promoting their units for use with radiators (I guess they do not want to limit their potential market) but unless the heating system can run effectively at these lower flow temperature then they simply will not work in cold weather.

If the heat pump was stuggling to achieve 50-55 degrees in the cold weather then it sounds like they have compounded the roblem by undersizing the unit as well! Does this unit include an immersion heater to top up the output when the compressor is struggling? If so has it been commissioned?

If your radiators are not sized to take account of the lower temperatures from the heat pump then adding more heat pump capacity will not solve anything long term, you might be a bit warmer of the current unit is undersized but you will still be way down on the heat capacity of the system due to the lower temperature.

If the package was sold as a full boiler replacement the I would suggest contacting Consumers Direct, Trading Standards and Citizens Advice to find out what rights you have against the supplier as the heat pump will not be fit for purpose. If you do not pursue the suppliers (and assuming the heat pump is correctly sized) then you are left with the choice of replacing your radiators with suitably oversized radiators (again assuming that the main distribution piping is then large enough for the increased radiator sizes) or look at re-fitting a boiler in place of the heat pump.

[toscal]

Try contacting Mitsubishi direct to see if they can help. Especially as you got the name of the installer from Mitsubishi.
Are you able to contact anyone else that this installer has done work for. Maybe they have similar stories.

[drawdog]

Ashp

Suggest you hassle the installer, then contact Mitsubishi direct as they approved them and no doubt want to protect the brand.

The design of ASHP systems relies on many factors when retro-fitting and if any single factor is ignored the whole system fails to work properly. This includes ASHP output (at winter temps), defrost allowance, water flow rate, rad sizing, controls/thermostats, etc

As I stated earlier my Ecodan is working superbly so the unit itself is probably not at fault. To confirm : I don't use the Gledhill option, just a standard vented indirect tank with 'S Plan' valves. My rad's are all unchanged, although I have had to add an additional one to one room which wasn't un-expected.

Good luck with this one, sorry to delay you but I've been away.