Mitsubishi Ecodan Control Question

[aa44]

I am building a new house and intend to use an air source heat pump to provide the domestic hot water and the underfloor heating. Top of the list so far is the Mitsubishi Ecodan. (It's cheap and I live in the Shetland Islands so getting an engineer in for something that isn't available locally is a big expense).

My question is about the controllability of the Ecodan. I have read the installation guide and the manuals for the controller that come with it. Mitsubishi seem to recommend that to keep the electricity bills down the controller is set to run the machine during the night when electricity is cheap rate. All very sensible but what about the times when a boost to the DHW is required? As far as I can see there is no "boost" button anywhere to run the machine for, say, an hour to boost the hot water tank. The only way to do this would be via a traditional immersion heater boost function. This seems a waste as the heat pump would obviously be cheaper than the immersion heater, particularly during the day.

Am I right or have I missed something?

Thanks
Andrew

[sedgy]

hi aa44, yes there are a lot of questions about your situation
dose your area have cheep lectric at nite?
you say there is no boost button , that would use an electric heater, so why not use an aditional heater tank to complement that hot water you may need? obviously this could be added later. but the best of luck in your veture. sedgy

[aa44]

Hi Sedgy, Yes we have cheap rate electricity mainly at night so the timer on the Ecodan would be set to run the unit at night.

Why would the boost function have to use an electric heater? What I want is a boost button that runs the Ecodan for an hour, probably in the afternoon or evening.

Thanks
AA

[rob75]

Hi aa44 - I have an Ecodan up and running in my property.

I think what you are looking for is covered my the programmer. I am using a Honeywell ST9400C. With this you can program your heating DHW with 3 different on/off periods per day over 7 days. There is also an "extra hour" button to boost your hot water if required or you can simply override any programs and switch things "on".

I program the hot water from 8-8.30am and just 30 mins gives me a decent amount of hot water. In the afternoon, say around 2-3pm it is still warm - but not piping hot. I can't vouch for the volume because I only have a 75litre tank and I do not use if for showering or baths (yet).

Apologies if this was not what you were asking.

Rob.

[rob75]

I forgot to mention, the cylinder does have a thermostat feature but this is only to eliminate legionela via a timer set to come on once a week I believe. The timer obvious allows you to set it to run during the small hours to keep costs down.

[aa44]

Hi aa44 - I have an Ecodan up and running in my property.

I think what you are looking for is covered my the programmer. I am using a Honeywell ST9400C. With this you can program your heating DHW with 3 different on/off periods per day over 7 days. There is also an "extra hour" button to boost your hot water if required or you can simply override any programs and switch things "on".

I program the hot water from 8-8.30am and just 30 mins gives me a decent amount of hot water. In the afternoon, say around 2-3pm it is still warm - but not piping hot. I can't vouch for the volume because I only have a 75litre tank and I do not use if for showering or baths (yet).

Apologies if this was not what you were asking.

Rob.

Hi Rob, Thanks for that. Is that controller in addition to the Mistsubishi one or instead of it?

Thanks
Andrew

[TiredGeek]

Hi aa44, I'm in Sutherland and I have 2 X 14kw ecodans.

The DHW is controlled by a seperate timer that you fit. A simple Honeywell unit that switches it on/off to the times you program in. It overrides the heating side of things and switches the unit into DHW mode which heats the water temp higher, then once a week an immersion heater kicks in (controled by yet another timer unit) and takes the temp over 60'c for an hour or so to sterilise the tank.

It sounds complicated but for a heating engineer / plumber worth his salt it's actually quite easy to figure the circuits out

I'm having very significant problems with mine though. They ice up very badly all the time and then cannot defrost properly. I think it's because of the humidity where I am, but nobody seems to know what's happening right now. They are also using far more electric than we were led to believe they would.

To be honest, if you have room for GSHP and can be bothered with the trenches, stay well clear of ASHP, I don't think it's a sensible choice for northern Scotland.....

[Oakgreen16v]

Ecodan uses standard central heating controls so a 2 channel timeclock and a room termostat are all the end user needs as an interface. If the cylinder is sized for a typical days hot water usage then the 1 hour boost on the 2 channel programmer will not need to be used frequently.

ASHPs can work well in northern scotland if the system is correctly designed and installed. The same applies to a GSHP (or any other form of heating), but if you have issues with one of these it can be even more difficult to rectify.

[sinewave]

Oakgreen is correct, the Mitsi FTC2 control box can be controlled via the supplied OEM controller or any third party 2 channel controller plus a room stat.

I have wired up 20 or so Ecodans now for another company who use a Honeywell T/C and roomstat wired directly to the Mitsi FTC control panel.

the Mitsi controller is only used for initial programming and setup and is hidden away in a cupboard with the pumps and 2 port valves.

The customer controls the system with the Honeywell T/C and separate room stat in a hallway.


You can have demand heating or DHW at anytime of the day at the push of a button.

The Legionella boost to +65C can be done two ways, one with a mitsi supplied contactor that plugs in to the FTC (about £75) that triggers a 3kW Immersion heater on the tank or with a stand alone T/C (£20) doing the same.

Only downside with the stand alone T/C is when it fails no one will notice unless it's mounted in full view and the customer notices.

No fault signals will be generated by the FTC!

[frank]

Only downside with the stand alone T/C is when it fails no one will notice

Unless they all die from Legionella

[sinewave]

Most of these jobs are council owned bungalows in rural area's with no mains gas so are being converted from storage heaters under some grant assisted EU Green/Renewable energy thingy!

Virtually all have retired folk living in them.

Don't miss a trick some of these owd timers with their energy monitors and eagle eyed surveilance of how things are working!

[sweeney948]

HI aa44
just a wee bit of advice stay away from mitsubishi when it comes to air source heat pumps we had 4 systems fitted last year and none of the systems are working properly PM me and i will fill you in on details before you go ahead

[frank]

Are you technically qualified to determine if it is the equipment at fault or the design, application and installation that is at fault?
Or do you just have a gripe with Mitsubishi?

Please stop posting your phone number as this is not allowed