Taking the plunge Daiken Altherma HT

maelstrom

Hi, after weeks of thought and research I am taking the plunge and am about to install the Daiken Altherma High Temp air source pump.

It's an old stone cottage, with acceptable levels of insulation and 10mm microbore.

I have been quoted for an 11Kw unit (cottage is 3 bed, 2 bathrooms) plus water tank plus buffer. The latter apparently should compensate for the microbore. Is this right? It's going to cost over 12K. Then I still need to add a couple of radiators over and above.

I also considered biomass, but reputable brands are very expensive.

Any thoughts?

Cardew

Have you read the other ASHP threads on this forum - including this:

https://forums.moneysavingexpert.com/discussion/2968958

Frankly to pay over £12,000 for a heating system seems to be a huge sum. If you borrow the money, or lose the interest on savings that is anything from £400 pa upwards before you start paying for electricity. That sort of money would go a long way to off-setting Oil CH/storage heating/normal electric bills.

Cardew

jeepjunkie wrote: »

i'm not interested in debating pointless facts and figures with the usual forum crowd.

The OP asked 'any thoughts'

Why are facts and figures 'pointless'?

You have made your decision - others might want discussion!

grahamc2003

maelstrom wrote: »

Hi, after weeks of thought and research I am taking the plunge and am about to install the Daiken Altherma High Temp air source pump.

It's an old stone cottage, with acceptable levels of insulation and 10mm microbore.

I have been quoted for an 11Kw unit (cottage is 3 bed, 2 bathrooms) plus water tank plus buffer. The latter apparently should compensate for the microbore. Is this right? It's going to cost over 12K. Then I still need to add a couple of radiators over and above.

I also considered biomass, but reputable brands are very expensive.

Any thoughts?

It would be great to have some real data on how these things perform in the cold. From what I can gather, the achille's heel is ice formation on the outside unit. Of course, they have strategies to deal with that, but they are very much a compromise - the longer the heating of the outside unit to melt or prevent ice, the lower the cop at that time. If the strategy is wrong, then you get the situations which have been posted on these forums smewhere where the coils ice up, and are not cleared, so ice up even more and have the heat sucked out further which leads to colder ice and more deposition.

If I went down this route (and I must say i think it's lower risk to have multiple air to air units each with an outside unit), I'd make sure no snow or rain could fall on it, and probably have a camera pointing at it so I could easily see the outside unit and shut the whole system off if it got iced up a lot (since it wouldn't be doing anything useful at that time). (and there's the rub, it could be off quite a long time till it thawed out). (btw, this is just what i would personally expect to do with the info i have at the moment, so would buy a systemn with that expectation in mind - when it's really cold, the heating would be off). I'd look in detail at the de-icing strategy.

Having said all that, I expect Daiken are about as good as you can get and work well 99% of the time. I expect the other 1% (in the coldest winters) the performance is very much a function of how and where it has been installed.

Don't want to put you off btw, just giving my personal view, based on web reports I've read.

Swipe

Let's hope we don't get another cold winter. I'm looking forward to a mild one this year. My heat pumps work great when the daytime temp stays above 4C, at least any ice build up gets chance to thaw. They even worked great at -15C but, as Graham said, it's the ice build up that's the problem.

Cardew

jeepjunkie wrote: »

As long it is installed properly and matched to the property I doubt you will have issues.

There are horror stories on the internet about everything....

Have you read the exaustive 12 month trial report carried out by the Energy Saving Trust - in the link above.

By any standard the results were very disappointing.

The difficulty is knowing that " it is installed properly and matched to the property".

You shouldn't have to spend over £12,000 on a gamble that it will work correctly - and there is no way the customer or installer can check if it running correctly.

rogerbanana

i have just installed a husky ASHP using a daiken scroll compressor which seems to be the standard unit for most ASHP set-ups.

it provides 13.5 KW and does my house, four bed, detached dormer, CW ins. and twelve rads.

mine cost no where near twelve grand, it seems you are paying way too much!

suggest you google "husky heat pumps" for an alternative consideration.

grahamc2003

rogerbanana wrote: »

i have just installed a husky ASHP using a daiken scroll compressor which seems to be the standard unit for most ASHP set-ups.

it provides 13.5 KW and does my house, four bed, detached dormer, CW ins. and twelve rads.

mine cost no where near twelve grand, it seems you are paying way too much!

suggest you google "husky heat pumps" for an alternative consideration.

Unless you are mcs qualified, then you've waved goodbye to the RHI and also the interim cash payment.

Of course, whether the premium you have to pay to get an mcs installer (and equipment) is worth the unknown value of the rhi is debatable. If the scheme is expected to be as generous as fits for solar, then I expect it won't be long before companies will spring up offering free systems in exchange for the rhi payments.

Googling around Daikin systems, it appears, they now recomment no floor mounting of outside units. Probably related to snow/icing I expect - so it looks like things are changing as more experience is gained.

Reading the installer forums, even they opften disgree about how and where the units should be installed, and the setting made for them. So how anyone can know whether it is set up in an optimal manner is anyone's guess, and I'd say those things are critical when ice formation is a possibility.

On another point, on the charts of cop vs ambient temp, does anyone know whether the cop akes account of defrosting at the lower temperatures, or are the cops derived from just steady state, non-defrost running?

At low temperatures, I'd be wary of running these things since the published cop can drop to around 1.5, meaning you're pulling 10kw from the mains to run a 15kw system - which, at that time, would be expensive heating, typically twice the cost of gas ch. (and much worse if the cop doesn't take into account defrost cycles).

BTW, to pre-empt some expected replies - these are the typical sorts of things engineers talk about and explore - it isn't anything negative. Seems pointless to me to simply sit back and say everythings great with heatpump systems and simply ignore possible problems, even if they only rarely occur (like when it's cold).

Cardew

grahamc2003 wrote: »

On another point, on the charts of cop vs ambient temp, does anyone know whether the cop akes account of defrosting at the lower temperatures, or are the cops derived from just steady state, non-defrost running?

No the COP doesn't take into account defrosting.

The technical forums frequently state that it is defrosting that 'kills the COP'

http://www.energysavingtrust.org.uk/...heat-pumps-PDF

The study was a year long and had 29 ASHP systems from a number of manufacturers.(who installed the systems)

It is quite a long report but of the 29 ASHP systems the annual COP for 19 of the systems was 2.2 or less(the highest number had a COP of 1.6). So if that is an average spread across 12 months - little wonder systems are struggling in this current weather. In fact with the requirement for wasteful defrosting cycles, it is quite easy to envisage a situation with some systems where there will be a COP of less than 1.0 and people would be better to switch off the ASHP and rely on Granny's old 1/2/3 bar fire!!!!!!

lovesgshp

maelstrom wrote: »

Hi, after weeks of thought and research I am taking the plunge and am about to install the Daiken Altherma High Temp air source pump.

It's an old stone cottage, with acceptable levels of insulation and 10mm microbore.

I have been quoted for an 11Kw unit (cottage is 3 bed, 2 bathrooms) plus water tank plus buffer. The latter apparently should compensate for the microbore. Is this right? It's going to cost over 12K. Then I still need to add a couple of radiators over and above.

I also considered biomass, but reputable brands are very expensive.

Any thoughts?

Price seems about right. Yes the buffer tank will help on the defrost cycles. Suprised they only give a 3 year warranty though, as they are a long established company.

lovesgshp

rogerbanana wrote: »

i have just installed a husky ASHP using a daiken scroll compressor which seems to be the standard unit for most ASHP set-ups.

it provides 13.5 KW and does my house, four bed, detached dormer, CW ins. and twelve rads.

mine cost no where near twelve grand, it seems you are paying way too much!

suggest you google "husky heat pumps" for an alternative consideration.

The Husky is a hybrid, just like many of the Chinese imports that are now coming in everywhere. I would rather stay with a well established manufacturer as service backup would probably be far better.