air source

[jambo]

hey guys just completed a mitsubishi ecodan air to water course went fine just wantin to know if any one fitted one in the feild yet and there opinion of the job

 

[Renewable M]

out of curiosity, what are mitsi charging for the ecodan? do you still have to use that daft boilermate cylinder with it?

 

[payney1974]

When did you go on that course Jambo? I was on it a couple of weeks ago in Manchester and a work colleague was there this week.

out of curiosity, what are mitsi charging for the ecodan? do you still have to use that daft boilermate cylinder with it?

You dont have to use their cylinder. I personally dont like air source because when we had that really cold weather they struggled! Ground source on the other hand is very impressive!

 

[quality]

Danfoss / Thermia have a new AX range of air source heat pumps - not to bad but, IMHO mitsi are way ahead of the rest with the air source equipment

 

[Renewable M]

There are dozens of heat pumps out there with a better cop than mitsi, (tested to BS EN 14511) and then theres new CO2 units with excellent low temp cop and max 65degree flow..... but few companies spend what mitsi does on marketing!

Payney - out of interest, what make was the ASHP that was struggling? If an ASHP is struggling then it's either sized wrongly or it's garbage. Same as any heat source, if sized incorrectly.

 

[unguided1]

I would like to say that if any one is considering fitting an ASHP, be careful to do your heat calcs properly for the job it is intended for. for the best cop figures out of a heat pump you want it to run at the lowest temperatures you can. this means running them on under floor heating, aluminium radiators or ecovector radiators.
You can run the heat through steel radiators but you are going to have to oversize them.
Trianco heat pumps need very carefull consideration, they are one of the cheapest on the market, but certainly not the best. They take their cop figures from 20 degrees C unlike other units that comply to EN14511 that take theirs from 6 -7 degreesC

 

[gakmonkey]

Trianco heat pumps are great when they go wrong you simply throw them away and use a decent machine..... From my experience

 

[Renewable M]

unguided is absolutely correct.

many ashp systems have a backup boiler for peak demand. some of ours have 2 x ashp's.

apart from the bad performance of the trianco activair, the controller is useless. it's a chinese water heater after all. it only allows you to set time and temp. No interface with the room stat, your heating programmer etc etc.... so how do you actually integrate it with a heating system? You can't.

Their schematics are an abomination. they have stuff like the temp sensor on the return pipe back from the heating instead of a switch from the roomstat.... so what happens there is the heat pump cycles on/off terribly.

Also, the heat pump cannot control a 3 port valve (or 2 ports) so how do you divert between heating and hot water.... you cant.

There is only one set temperature.... so if you have low temp heating for example underfloor set at 38 degrees, then the hottest your DHW can be is also 38 degrees. her indoors would love that!

Lots of people start with trianco activair, until they realise they can't do anything with them.

 

[Transcoman]

There are dozens of heat pumps out there with a better cop than mitsi, (tested to BS EN 14511) and then theres new CO2 units with excellent low temp cop and max 65degree flow..... but few companies spend what mitsi does on marketing!

Payney - out of interest, what make was the ASHP that was struggling? If an ASHP is struggling then it's either sized wrongly or it's garbage. Same as any heat source, if sized incorrectly.

Agreed RenewableM; I had an ASHP to install in new build, but the owner of the property had calculated the size of the unit required himself and had already purchased it but would not accept he had undersized it. I managed to get him to sign a disclaimer waiving any responsibility from me if it failed to achieve the performance required. It was a good decision as it proved to be the case when the system was commissioned and after he had complained to Mitsibushi who later sent a rep down.

The owner bought another correctly sized unit, which I fitted and I purchased the smaller one from him and intend to use it later in my home which is much smaller than his 8 bedroom mansion!

By the way, I put a request on the Web Suggestion forum for a renewables section/forum to be added, why not add your name to the list and help persuade the admin to do this?

 

[payney1974]

There are dozens of heat pumps out there with a better cop than mitsi, (tested to BS EN 14511) and then theres new CO2 units with excellent low temp cop and max 65degree flow..... but few companies spend what mitsi does on marketing!

Payney - out of interest, what make was the ASHP that was struggling? If an ASHP is struggling then it's either sized wrongly or it's garbage. Same as any heat source, if sized incorrectly.

I will find out which ashp it was, it was on a contract i wasn't working on. It was one our company has inherited.

Is there a mears calc or something similar to do the boiler / rad sizing??

 

[stevetheplumber]

Is there a good source of impartial advice i can read to bring myself up to speed with these air source units ? Web preferably

 

[Transcoman]

Is there a good source of impartial advice i can read to bring myself up to speed with these air source units ? Web preferably

Try the EST website Steve, they are quite impartial:

Air source heat pumps - Generate your own energy - Energy Savint Trust

 

[Renewable M]

guiding the installers 1. to the right unit and 2.to the correct install diagram is how i spend a lot of time. Anyone who wants to chance it, doesnt get to buy one, simple as that, because ultimately its our phone that rings when the homeowner is unhappy and the installer cant do anything.

I produce loads of project specific diagrams every week. time consuming sure, but better than picking up the pieces!

there is a lot of bad press about heat pumps, which a lot of it should be directed against the installers. At the end of the day, someone who buys a £1400 ebay heat pump and expects it to heat their 5 bed house is fooling themselves.... but people do it, then slag off the heat pump.

Still it keeps me in work... he he he

another common misconception.... high temp air source are better.

we have a high temp range that go up to 65 degrees, but i spend a lifetime explaining to installers that they should be installing lower temp heating....NOT cranking the heat pump up to full tilt and destroying the efficiency.

 

[quality]

Heat pumps are at there most efficient when running at full tilt the trouble is that most, not all manufacturers are very ambitious at claiming briliant cop - for the past 3 years I have worked with 3 un-named leading manufacturers to evaluate and improve the heat pump refrigeration cycle performansce - follow this link very long I know but contains very good information AWHP superheat & sub-cooling - Refrigeration-Engineer.com forums

 

[Renewable M]

huh? heat pumps are not at their most efficient when running full tilt! If you run a heat pump at 55 degrees set temp, the COP will be significantly lower at any ambient temp than at lower set temps.

Do you mean running for longer/off for longer?

Agree about some dodgy quoted cop figures. Ecodan, 3.7, our Eco Air Source, 3.85 most others in that range...... then you get completely bogus 'data' usually direct from chinese factories which claim 4.4 and stuff like that. It gives the industry a bad name. If the BS EN 14511 isnt from a european lab, like TUV that did ours, it's on shaky ground.

 

[quality]

I am not getting into a slagging match or out to put my opinion in front of any one elses - but in simple terms the largest use of electricity used in a heat pump is used by ansnycronous electric motors which are at their most efficient operation at full load. It is not all about what temp is produced but the enthalpy of rejected heat at a given electrical energy input which is down to the transfer of heat energy from the refrigerant to the water. I could or anyone could produce a heat pump to provide water at 90 degrees but the finite balance of electricity use would be huge

as I have allready said ambitious manufacturers figures are that ambitious

 

[Renewable M]

No, I'm not slagging you off, dont know where you got that one from.

You're talking about the efficiency of a motor. Yep, full tilt all the way. But it's only one factor on the efficiency of a heat pump as you know.

As you have explained, the COP is relative to other factors. I dont think i need to explain to you, I just read your post on refrig-eng-forum.

 

[quality]

think we are on the same wave length we could converse more on this as your more in the field as it were , but as I am not as such could be interesting lets keep on form
cheers

 

[Renewable M]

no probs,

regards, matt

 

[himac]

Hi,

We have taken out a few Ecodans this year as they let people down bad in winter trying to do DHW and heating.

We have just got our own pumps listed on the MCS list of heat pump products, man was that hard work, I think they only want the big boys on that list.

 

[Transcoman]

Hi,

We have taken out a few Ecodans this year as they let people down bad in winter trying to do DHW and heating.

I think this is going to be the case with quite a few air heat pumps if they are not sized correctly; I have been fitting a few Glow Worm units and they performed excellently over the winter. I would however always suggest that if people can afford to go the extra yard to go for solar heaitng on DHW and air pumps on CH, but that is a rich man's game really and until any Government actually provides a realistic financial grant towards renewable energy then that is all it will remain.