Taking the plunge Daiken Altherma HT

albyota

cultsmill wrote: »

I installed a Daikin Altherma HT unit 16kW to replace the oil fired heating we installed when the house was built. The oil fired system worked a treat but was getting on for 15 years old so we opted to have an ASHP installed. We have underfloor heating throughout the property.
So far it has not been the best, when the temperature goes down to -15 as it did last yer you might as well shut it down as it generates no heat, even after defrosting the ice build up. The biggest issue we have is the electricty bills last year £2500 this year £3600, neither economic to run or energy efficient. Having paid £16000 to have it installed just adds to the feeling that this is not a technology that has been fully proven.

What is the square meterage of the property?, where in the UK are you? And how are you running it? I think you need to get the company back to check the settings, firstly, why was a High temperature system specified for UFH?, when a low temp system would have been more than adequate for UFH. I also think, the system must have either incorrect settings, or has lost refrigerant gas, you don't specify whether the bill is purely for the heating and hot water, or if that is the whole house bill, I find it difficult to believe that last year, I assume you refer to 2012 a very mild year! Compared to 2011 much colder, that the costs went up by £1100
Please respond to this post, I would like to get to the bottom of this and help or advise.

calypso_rhapsody

Thinking of installing a Daikin Altherma HT system in our 23 year old barn conversion. Was rather put off by the EST field trial, but having spoken to them this seems to relate only to LT systems so not sure whether it is applicable. We are currently on oil and using 2500-3000 litres a year, depending on weather etc. Have looked at wind and solar but rejected both (on aesthetic/planning grounds - building is listed). Can't retro fit underfloor heating so an HT ASHP seems to be the route to go.

Property is reasonably well insulated - conversion was done 1990 so has roof insulation (snow does not melt too quickly on the roof compared to neighbouring properties) and we think there may be some cavity wall insulation but not sure. Double glazed.

We are speaking to an MSC approved installer and awaiting his final quote/spec following a visit by surveyor. Was feeling pretty comfortable about the plan but now getting cold feet.

Any advice - things to look for etc? Or alternatives that we might consider?

Cardew

calypso_rhapsody wrote: »

We are speaking to an MSC approved installer and awaiting his final quote/spec following a visit by surveyor. Was feeling pretty comfortable about the plan but now getting cold feet.

Any advice - things to look for etc? Or alternatives that we might consider?

The question to ask yourself is any installer ever likely to say your property is unsuitable and thus lose a customer; or indeed give any guarantee of performance.

I take it you have read post #70?

Swipe

calypso_rhapsody wrote: »

We are currently on oil and using 2500-3000 litres a year, depending on weather etc.

If your property requires that much oil to heat it then I'd be very wary of spending thousands on an ASHP without any guarantees it will be up to scratch. Are you sure it's as well insulated as you think?

nande2000

calypso_rhapsody wrote: »

Thinking of installing a Daikin Altherma HT system in our 23 year old barn conversion. Was rather put off by the EST field trial, but having spoken to them this seems to relate only to LT systems so not sure whether it is applicable. We are currently on oil and using 2500-3000 litres a year, depending on weather etc. Have looked at wind and solar but rejected both (on aesthetic/planning grounds - building is listed). Can't retro fit underfloor heating so an HT ASHP seems to be the route to go.

Property is reasonably well insulated - conversion was done 1990 so has roof insulation (snow does not melt too quickly on the roof compared to neighbouring properties) and we think there may be some cavity wall insulation but not sure. Double glazed.

We are speaking to an MSC approved installer and awaiting his final quote/spec following a visit by surveyor. Was feeling pretty comfortable about the plan but now getting cold feet.

Any advice - things to look for etc? Or alternatives that we might consider?

Wood Pellets ?

calypso_rhapsody

Thanks for replies folks - am certainly getting cold feet! (not literally of course). Re insulation - well it is probably insulated only to whatever were the standards in 1990 ... anyone any idea how i can find out what those were? We think the walls must have some cavity insulation and there certainly is loft insulation on those parts of the house that have loft (about 60% of the roof area).

If I could get to it, would the planning application file tell me more do you think?

albyota

Hi, 1990 building regs were pretty poor IMO, even houses built / converted by builders / developers up to 2006 were bear minimum they could get away with, you need to find out the U values of the walls, get a test done to see if there is insulation in them, check that the double glazing is 20mm gap, NOT 10mm, and draught free, quality doors, there needs to be 270mm min roof insulation, ideally 300mm, your floors will be uninsulated I suspect, only then should you be thinking about heat pumps. If you install the Altherma HT WITHOUT UPGRADING, If you are using 2500 Litres of oil per year, (approx 23,000kWh /yr) depending on how efficient the boiler is, then at 60p / L that is circ £1500, the Altherma HT has a seasonal COP of 2.88, so at best you would use c 8000 kWh electric which at 13p /kWh is £1,040 / yr, ....... Not worth it IMO, however, if you could get the buildings heat losses down, then a lower temperature system would be much more efficient. You have some more researching to do, hope this helps.

Cardew

calypso_rhapsody wrote: »

Thanks for replies folks - am certainly getting cold feet! (not literally of course). Re insulation - well it is probably insulated only to whatever were the standards in 1990 ... anyone any idea how i can find out what those were? We think the walls must have some cavity insulation and there certainly is loft insulation on those parts of the house that have loft (about 60% of the roof area).

If I could get to it, would the planning application file tell me more do you think?

I believe the planning application will refer to the extant Building Regulations in 1990.

Would a barn have cavity walls? If it originally did have a cavity, or a cavity was part of the conversion, then building regs in 1990 would have required cavity insulation. I converted a(non-listed) outbuilding in 1989 and the walls were 'drylined' - i.e. wooden battens, plasterboard and insulation inserted between.

If your boiler is 1990 vintage it is probably about 65% efficient, so whilst you are using 25,500kWh to 30,600kWh of oil, it will be producing 16,500kWh to 20,000kWh of useful heat.

That is a large amount to expect an ASHP to deliver in cold weather.

Another aspect is the cost of installation. The poster in post #70 paid £16,000. Well even if you have that sum of money, and with today's very low interest rates, you can still get 3+% in a long term bond - so you are giving up £500ish(gross) in lost interest.

If you replaced the oil boiler at a cost of £3,000? what would be the difference in running costs per year compared to an ASHP.

A successful heat pump installation with an overall COP of, say, 2.5 would price heat produced by electricity at approx 5p/kWh.

You also need to consider what will be available under RHI

With oil at 60p/litre a modern boiler - assuming an 85% overall efficiency(the 90+% claims are rarely achieved in practice)would cost approx 7p/kWh.

So using those 'back of an envelope' estimates a reasonable estimate of saving with an ASHP might be anything up to £400pa.

That will take a long time to recover your outlay + lost interest!

Food for thought?

Edit.
hadn't seen Albyota's post - got called away from PC. However we are in the same ball park.

calypso_rhapsody

Thanks both for those helpful replies - your sums are along the same lines as mine (hence cold feet). My calcs suggest that actual cop of 2.5 is about the breakeven point. Though we are still awaiting final quote and calcs from potential installer .... will due diligence as much as i can.

The barn was stripped back to its wooden frame on restoration so we believe we do have cavity walls and it probably has some insulation. Roof insulation is about 100mm we think - though would be easy to increase this in respect of those parts that have loft - some doesn't so would not be easy.

The last gas analysis of our oil boilers said that it was 85% efficient - though i have some doubts as to how reliable or relevant that is ....

Cardew

calypso_rhapsody wrote: »

The last gas analysis of our oil boilers said that it was 85% efficient - though i have some doubts as to how reliable or relevant that is ....

How old is your boiler?

You can look up the efficiency of your boiler(when new) in the SEDBUK tables

http://www.boilers.org.uk/cgi-local/result1.cgi

If it is indeed 85% efficient then I suggest it weighs the odds in favour of just plodding on with oil with the same boiler.

It means that from the 25,500 to 30,600kWh content of your oil, 21,700 to 26,000kWh is used for heating and less going 'up the flue'.

Would a single ASHP unit provide that much heat?