Taking the plunge Daiken Altherma HT

Cardew

Ally74 wrote: »

We had storage heating. I contacted the HA as we had a problem with damp and my son has asthma. They agreed to help and said they were currently carrying out a trial of 4 ASHP systems. After a survey my house was fitted with one.

Just a point. With storage heating you presumably were on an Economy 7 tariff?

If you haven't already done so, you need to consider switching to a 'normal' tariff as on Economy 7 you pay a premium for your daytime(17 hours) electricity and you will be using a lot more during the day. - and a lot less at night

grahamc2003

Ally74 wrote: »

Hi

My housing association fitted my house with an ASHP a few months ago. Are you saying they can consume up to 10kw per hour in winter?

The HP fitted is a 8.5kw (i'm sure) Mitsubishi Ecodan.

Hi Ally, no I'm not saying that. I'm saying that some (I don't know which) have very big electric heaters (which, if set up correctly, would, I assume, only come on in very cold weather, and some others don't even have such heaters. I don't know whether the Ecodan does or not. The ecodan (and the altherma) appear to be the best HPs out there, so your chance of having problems (if set up correctly) is less than other makes, judging by what I've read.

Just because this discussion is all about possible problems in cold weather, those problems seem to get out of proportion - remember we're mainly talking about performance in the depths of the very cold weather we had last year.

I'd be really interested in what owners experience this winter - I'd hope the best handle a normal winter very well (by which I mean providing sufficient heat at a cop of say above 2 at the worst of the weather). I hope someone hooks up an energy monitor to the heat pump input and reads off the power consumption at the coldest time.

With what I think at the moment, if I owned one I would look out for ice on the outside unit, and simply turn it off if I saw much at any time, since that is when the performance will deteriorate (the hp has to heat the heat exchanger to clear the ice off, and that is technically quite a hard thing to acheive generally at minimum cost). If you ever see large blocks of ice (as has been photod on these boards) on the outside unit (hopefully you never would with a mitsui or daikin), then keeping it operating would use a lot of electricity for little (or even no) heating. But please realise we are talking about very much the worst case, and hopefully, for 99% of the time at least, your HP should give cheap heating (I'm optimistic enough to believe that things have improved for the makes mentioned since the time of the mentioned survey, assuming the installation and settings are correct).

Most of the possible problems are much less for air to air HPs, and that is the type I'm considering getting (even though they don't attract the RHI subsidy of the air to water type).

paceinternet

Most of the possible problems are much less for air to air HPs

Why do you think they avoid the need to defrost?

lovesgshp

grahamc2003 wrote: »

I think what you say is necessary but not sufficient.

Even with a full thermodynamic survey and a correctly specified system and the system working as specified, some owners may not be too happy with the performance under certain conditions (in the UK).

Firstly, aiui, some whole house (air to water) systems have 8-10kw heating elements to help out when the ambient conditions are such that the HP can't extract sufficient heat from the air - and that could be for a couple of reasons (icing of the heat exchanger, or simply insufficient volume of air when cold over the heat exchanger). Obviouly this only happens in cold weather - but it certainly affected at least a couple of owners (or at least users) of these forums last winter.

So if it's cold, and the HP switched in a 10kw heater to jolly things along, then it may well be operating as the spec says, but the user is unlikely to be very happy about it when his electrcity bill comes (as some users weren't on here a few months ago).

That's one 'problem' which I see for cold weather operation.

Another one is related. Afaiui, some of the better HPs don't have resistive heating, so, in fact, can't suffer from the above problem. But, of necessity, they still have the problem of extracting heat from the air at a rate approaching 10kw, which is obviously difficult the lower the temp, and obviously more difficult still with ice deposition on the heat exchanger (which are likely to be more precisely designed and engineered the higher the model). So the defrost strategy with no other heating becomes critical. As well as operating in a domain where the cop is probably well below 2, the need to defrost would or could push the true cop well below 1 (at the low temperatures we experienced in the uk last winter). Again, the HP may well be operating within spec while doing that, but I doubt many owners appreciate it could happen (i.e. they get high electricity usage for not a lot of heat at that time).

Appreciate your comments on the above, you have control.

Thanks for the constructive comments. I agree that the COP will reduce in low temperatures. We also have to look, as you say at the model design and the company history of manufacture of the unit.
Nordic countries have obviously more experience of these types of units and yes the houses are better insulated, so gain by lower heat output models. Here in Italy, we are seeing a much larger interest in heat pumps due to the cost of LPG and oil, but obviously not against mains gas.
With reference to the electrical connectivity, you have to put into perspective that this is only when the pump needs an extra boost, so 13kw would not be running for hours on end. It would heat much faster than 3kw, so overall the cost differential would be minimal. Most modern ASHP's will operate down to -20c, so if the heater needs to activate then it will only be for a limited period. The normal scenario for this is high DHW usage, whereby if the DHW has priority,
then the pump feeds that first. I am not sure on other models, as we only use IVT. I looked up the Ecodan and saw its electrical feed for the hot water tank immersion is 3KW, the IVT 290 A/W is 13kw.

grahamc2003

paceinternet wrote: »

Why do you think they avoid the need to defrost?

I don't think they avoid the need to defrost.

I think the problem is less for air to air because, in general, air to air units, ime, are much lower powered than whole house air to water systems. Extracting say 3kw for a powerful air to air unit needs much less air blowing over the heat exchanger than extracting say 10kw for an air to water unit. Blowing much more air also means blowing much more water in the air, so much more potential for deposition of ice on the coils.

I suppose for systems which hook up 2 or 3 inside air units to one outside unit (and therefore need to extract say 10kw from the air from one unit) potentially suffer to the same degree as a typical air to water system - and for that reason I'm thinking of having just one outside unit for each inside unit, and installing them, in a modular fashion (i.e. starting with one, and if I like it, install another and possible a third at some stage). Strangely, it doesn't seem any more expensive have multiple outside units as opposed to just one.

Cardew

jeepjunkie wrote: »

From what I read you are needlessly scaring off people who are interested in these systems and that is not good... Fair enough point things out but leave it that, you don't half go on about one EST report when 00'000s of these things have been sold... There would be global uproar if they were crap...

My objection is that every advert I have seen talks glibly about producing 3 or 4 units of heat for each unit consumed - including Mitsubishi for your Ecodan - from their website:

The Ecodan air source heat pump system consists of an external box which is fitted to your outside wall. It harvests renewable, low grade energy from the outdoor air and upgrades this into useful heat to supply a home with hot water and heating. For every 1kW of electricity fed into Ecodan, you will get at least 3kW of heating energy.
It can work efficiently all year round even if the outdoor temperature should drop to -25ºC (PUHZ-W50VHA -15ºC, PUHZ-W85VHA -20ºC, PUHZ-HW140VHA/YHA -25ºC).

I suggest Mr Average reading that would take statement at face value in that you will still get 'at least 3kW' at - 25C.

The problem is that it is almost impossible for any of us to verify those claims, or even know how it is performing.

Then along comes the Energy Saving Trust, conducts a trial over a year, with manufacturers involved. At last something for a customer to see what performance he might get - and IMO the results were little short of a disaster.

As said above: 'Eight ASHPs on the EST year long trial had an overall system COP of 1.6 or less.' Well to use your expression IMO those results 'are crap'.

Yet it seems(on a money saving website) you want to discourage any publicity for the only validated performance figures for ASHPs that I have seen.

Yet even worse you dismiss the report as being 'of little use, most of the featured systems were just not right in one way or another... '

The whole point of the report was to see the performance achieved, and because it clearly demonstrated 'most of the featured systems were just not right in one way or another... ' you state the trial report can be dismissed?

I really can't see the logic of your statement! The fact that 'most of the featured were just not right in one way or another' is by far the most valued conclusion of the trial - and IMO should be given the maximum publicity!

The trial has been extended by a year to find out why so many systems were 'crap'.

You may be very happy with your system, albeit you haven't had it for a winter yet. However if the many reports on the web are true, and for those systems in that trial, there will be a lot of unhappy people; and unless the ASHP industry gets its act together there are going to be a lot more unhappy people.

As it is people can spend huge sums - and £12,000 or £16,000 is huge for a heating system - on completely unsuitable houses with absolutely no guarantee of performance, or any way of checking the performance.

Ever heard of someone selling ASHPs advise a customer their house is unsuitable?

TiredGeek

Cardew wrote: »

As it is people can spend huge sums - and £12,000 or £16,000 is huge for a heating system - on completely unsuitable houses with absolutely no guarantee of performance, or any way of checking the performance.

!!!!!!, that's me LOL

TiredGeek

jeepjunkie wrote: »

Yes I do know well respected companies that have refused to install ASHPs unless certain measures were taken. In fact all companies I have had dealings with are very professional, know their stuff and are not in the business to just chuck them in for a profit.

Wish I'd have come across these people back when mine went in, 'cos mine were ALL about the profit and sod the customer :mad:


Time will tell about winter performance and I'm happy to report back but i'm not worried it will not function as expected.

We weren't either for the first few weeks.....

I don't disagree there are badly installed system out there. I know of a system costing £9 a day in spring when it should be about £20-25 per month!!! The weather in spring was superb as well, better than summer. Something clearly wrong there and it is up to the customers to resolve this with whoever installed it...

I'll see your £9 and raise it to £12
Installer hasn't a flipping clue, totally useless, I've had more and better help on here.
Shortly they'll be discussing things with my solicitor if REAL don't pull their fingers out.....

The EST report and why I disregarded it... well that would just take to long to type out my response to that but basically they were either dodgy sounding manufactures and or systems connected to oversized rads... no no no... Or perhaps connected to UFH with the wrong loop spacing or utilising existing microbore pipes that were not insulated. I could go on for pages....

Actually, here I strongly agree with Cardew, the standard of instalation of the test systems is a critical part of the results.
If they are not performing due to poor system design, be that pipe size, rad size, water temp etc, that is how "joe public" will get their system and when you pay a big wad of money to a big company how are you as a non techy meant to know if the instalation isn't exactly right when you're being told it is?

I've said before if you are installing these things you need to reasearch and speak to installers and customers and take an interest in all parts of the install as there is no way a proper sysem will be less than £10k. If you buy one of these and connect it to existing rads and make a few bigger and run it 45-55c than no it will not be cheap to run...

The information needed to make an informed decision wasn't available when I made up my mind. If it had, I'd have probably had a different system and certainly a different company.
Most people won't know enough to realise they need to do this research, it's more easy to waste your money on these than it is to get one that works well.

Cardew, I really respect and enjoy your posts but this anti ashp stance really annoys me.

Just an alternative point of view, you can't agree with everyone all of the time, and if one person reads the posts and thinks "ooo, there's more to this than I first thought, I'd better research ASHP a bit more" then even a totally anti-ashp post is fine, not that I'm saying Cardew is anti ashp of course

Just my 10p worth on the subject

Cardew

jeepjunkie wrote: »

The EST report and why I disregarded it... well that would just take to long to type out my response to that but basically they were either dodgy sounding manufactures and or systems connected to oversized rads... no no no... Or perhaps connected to UFH with the wrong loop spacing or utilising existing microbore pipes that were not insulated. I could go on for pages....

I've said before if you are installing these things you need to reasearch and speak to installers and customers and take an interest in all parts of the install as there is no way a proper sysem will be less than £10k. If you buy one of these and connect it to existing rads and make a few bigger and run it 45-55c than no it will not be cheap to run...

Cardew, I really respect and enjoy your posts but this anti ashp stance really annoys me.

If we can turn to the EST trial and your assertion there could be ‘dodgy sounding manufacturers’ well this is the acknowledgements extract from the report.

The Energy Saving Trust would like to thank our partners, who have made this field trial possible:

Government organisations
The Department of Energy and Climate Change
The North West Regional Development Agency
The Scottish Government

Manufacturers
Baxi Group
Danfoss UK
Mitsubishi Electric
NIBE Energy Systems
Worcester Bosch

Specialist heat pump contractors
Earth Energy Ltd

Energy suppliers
British Gas
EDF Energy
E.ON Engineering UK
NIE Energy
RWE npower
Scottish Power Ltd
Scottish & Southern Energy PLC

Technical consultants
EA Technology Ltd
Energy Monitoring Company
Gastec at CRE Ltd
The Open University

Energy Saving Trust project team:
Simon Green, Project Director
Jaryn Bradford, Project Manager

“The Department of Energy and Climate Change(DECC) is very pleased to support the Energy Saving Trust’s field trials into heat pump technology. Field trials such as these are a
valuable way of establishing true performance in situ, as opposed to in the laboratory, and provide useful insights as to how performance may be improved. This is beneficial for industry, householders and the Government. DECC considers that heat pumps have an important role in achieving Government policies to reduce CO2 emissions”

In keeping with the Energy Saving Trust’s work throughout Europe and the UK, the results of this first year of the trial have been peer-reviewed by leading EU heat pump experts, including the SP Technical Research Institute of Sweden, Planair (Switzerland)
and Germany’s Fraunhofer Institute, as well as UK stakeholders including the Energy Technologies Institute (ETI).

The exact involvement of all those bodies in the trial is not clear. However the conclusions of the report were that they simply didn’t know the reasons for the poor results, hence the trial would be extended for a further year to see if lessons could be learnt.

It is all very well describing your extensive research – starting presumably with determining if your property was even suitable for installation of an ASHP! However Joe Public without any technical knowledge should be able to buy a system and expect it to work; and currently they are spending their money and just have to take pot luck!

If a firm installs, say, an Ecodan in an unsuitable house, or installs it badly, there should be some comeback – IMO Mitsubishi should take on some responsibility.

Anyway if we are to debate the pros and cons of ASHPs there has to be two sides!

lovesgshp

Could not find the original manufacturer details, from the EST trial, but came up with some other information from field trials in Germany and Switzerland from EST and another source. There you can see that ASHP's performed well. Obviously we do not know what insulation levels/ thermal loss in the properties are, but, it shows that the units can operate in temps, that can be the same or lower than the UK.
I cannot see why Earth Energy Systems could be the specialist ASHP heat pump contractor, as they are bore hole and GSHP providers, as their website says.
http://www.earthenergy.co.uk/

The other links I mentioned:
http://www.gshp.org.uk/documents/1ESTFieldTrials.pdf
http://www.all-energy.co.uk/userfiles/file/jennifer-arran-180511.pdf