Daikin Altherma HT running costs??

mikematic

hi all, I am considering installing a daikin altherma HT ASHP but trying to find typical running costs or at least a ball park figure has been very difficult.

Its a 1987 4/5 bed semi detached house 102m2 (although this may or may not include the attached garage with door into the kitchen) it will need 11 or 12 radiators. off grid gas

currently we are on storage heaters so have economy 7 available. there are only 4 storage heaters and we use them sensibly so our electricity bill for the year is about £1200 (not too bad considering)

storage heaters are a pain. the house is warm all day when we are at work and cold in the evenings when we really need the heat. I am an electrcian and my brother is a plumber so between us the cost of an installation would be a lot cheaper than for most people.

to be honest an oil boiler would suit the house but i'd rather be a bit greener if possible. All the sales and marketing spiel says definite savings over storage heaters etc but ive seen some horror stories on the forums. I cant afford to do this twice or get it wrong so any advice on actual running costs for similar(ish) properties would be greatly appreciated.

thanks Mike

Cardew

Welcome to the forum.

The first thing to appreciate is that to get the RHI(Renewable Heat Initiative) subsidy(which is substantial) the system needs to be certified by a MCS registered company - you need to research this carefully. In particular the level of insulation required in your house.

https://www.gov.uk/government/speeches/renewable-heat-incentive-amendement-regulations-2015

In practice this means they will install the system as I doubt you will get any firm to certify a DIY installation.(even though you and brother are qualified)

If you search this forum you will find loads of threads on Heat Pumps. Also the Energy Saving Trust(EST) commissioned two 12 month trials. The results of the first were so poor that they extended the trial for a further 12 months. This is one I started, albeit before introduction of RHI.

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

If you read the second report in detail you will see that there was wide variation on results. The installation is critical to get them operating correctly.

The average COP(co-efficient of performance) was 2.54. i.e. 1kW input gives 2.54kW output.

If you are starting from scratch, underfloor heating is best as a heat pump operates best at low water temperatures. Otherwise you need very large radiators.

The other thing to note is that a heat pump gives a low level output, so it needs to be on for very long periods, 24/7 in really cold weather.

It is impossible to check the efficiency(COP) of a Heat Pump system without expensive equipment over a long period. The COP quoted in brochures is akin to my Ferrari(I wish) doing 50mpg. It is COP in a system with defrosting etc that counts.

Some owners(not all) who have paid sometimes in excess of £10,000 for an installation can be less than objective about their results. Normally along the lines of 'My electricity bills used to be £thousands and now they are £hundreds;)' It is interesting that those reporting on MSE who are renting properties with a heat pump are far less enthusiastic.

P.S.
The navitron website is useful

[Deleted User]

mikematic wrote: »

hi all, I am considering installing a daikin altherma HT ASHP but trying to find typical running costs or at least a ball park figure has been very difficult.

Its a 1987 4/5 bed semi detached house 102m2 (although this may or may not include the attached garage with door into the kitchen) it will need 11 or 12 radiators. off grid gas

currently we are on storage heaters so have economy 7 available. there are only 4 storage heaters and we use them sensibly so our electricity bill for the year is about £1200 (not too bad considering)

storage heaters are a pain. the house is warm all day when we are at work and cold in the evenings when we really need the heat. I am an electrcian and my brother is a plumber so between us the cost of an installation would be a lot cheaper than for most people.

to be honest an oil boiler would suit the house but i'd rather be a bit greener if possible. All the sales and marketing spiel says definite savings over storage heaters etc but ive seen some horror stories on the forums. I cant afford to do this twice or get it wrong so any advice on actual running costs for similar(ish) properties would be greatly appreciated.

thanks Mike

Hi, similar size detached house here but high ceilings and 100+ years old, rural Scotland!


As Cardew rightly says running times are longer than GCH etc but house always warm unlike our previous houses on GCH which suits this old house. We had LPG previously...


To keep give you an idea on running costs it varies between mid £60s pm to mid £80s pm for total electric. Cost varies due to what deal we got for the year and how cold a winter is.


We have a mix of underfloor and fancoils. Water temp is usually in the 30c bracket unless extremely cold where it may hit the 40s.


We do have solar which when taken over a year does add a significant saving. No Fits/RHI are taken into account in the monthly figures. If it was I'd be living scot free


I've posted a lot about it previously, most of which I've forgotten as it's pretty much fit and forget...


Cheers

matelodave

I've got a Daikin LT system and I'd expect an HT system to cost more to run as most heatpump systems work best at low flow temperatures.

Ours runs an underfloor overlay system which is installed on top of the existing floor (PolyPipe Overlay) and the flow temperature sits at around 30-35 degrees increasing to 40 degrees when it's everso cold (around zero outside)

If you want to get the RHI payments then the system will need to be signed off by a registered MCS installer so you might find that that a diy approach could work out more expensive in the long run although you could probably do a lot of the actual plumbing and just get the heatpump installed by a MCS installer.

The secret with a heatpump is to not try and run them like a conventional boiler - the low temperatures take ages to heat the place but once there will keep it warm all the time. So you need to ensure that the insulation is as good as you can get it and that the heat emitters, whether they be underfloor, fan coils or even radiators are sized correctly - just bunging a heatpump onto a conventional system is a recipe for disaster and disappointment.

Likewise, don't heat the hot water more than you need. Ours is only heated to 45 degrees with a boost to 60 on Saturdays to satisfy the requirement of legionella disinfection. We get all the hot water we need from an hour or so heating every morning and the 200l tank stays hot enough from the disinfection cycle that we don't need to heat it on Sunday mornings

Our system is installed in a 140 sq.m 1980's detached bungalow out in the Cambridgshire fens and is on all day every day. Our total leccy consumption is around 6500-7000kwh a year of which the heating and hot water account for around 3-3500kw depending on how cold it is.

mikematic

Thanks for the replies, heat pumps sound like a bit of a risk. Im not sure if I can get a grant to upgrade the cavity wall insulation, I know there is about an inch or so of foam insulation board between the cavity as you can see down there through the joining hole between the house and garage loft spaces. There is plenty of loft insulation.

I would also have to get an MCS accredited installer to spec the system and install the heat pump if I wanted the RHI (if i qualify for it)

I dont mind having to sort this stuff out but what really worries me is that it sounds like I will basically have no idea of running costs until the whole thing is finshed and I've spent thousands. Also I've read that some of these ASHP's struggle if the temperature gets below about -5.

If the house was a square shape I would seriously consider renewing the storage heaters with Dimplex Quantum's, I have fitted some of these and was really impressed with their heat retention for when its needed in the evenings. The problem is that to eliminate the cold spots in the house I need more storage heaters!! Which is not at all economical to run.

Is there really still not a reliable, reasonably priced alternative to burning fossil fuels for off grid properties????

Installing an oil boiler in this day and age just seems a little old fashioned.

mikematic

matelodave wrote: »

Our system is installed in a 140 sq.m 1980's detached bungalow out in the Cambridgshire fens and is on all day every day. Our total leccy consumption is around 6500-7000kwh a year of which the heating and hot water account for around 3-3500kw depending on how cold it is.

matelodave your 3-3500 kwh/year is very interesting. Is this a guess or does your Daikin tell you how much energy it uses?? This info would be very helpful

Cardew

mikematic wrote: »

Is there really still not a reliable, reasonably priced alternative to burning fossil fuels for off grid properties????

Installing an oil boiler in this day and age just seems a little old fashioned.

Electricity generating power stations largely burn fossil fuel.

You indicate that you are out during the day. In that case you are heating an empty house, and at night, if you have a heat pump.

With oil/gas CH you can have the heating to come on 30 minutes before you return home, and get up in the morning.

matelodave

mikematic wrote: »

matelodave your 3-3500 kwh/year is very interesting. Is this a guess or does your Daikin tell you how much energy it uses?? This info would be very helpful

It's based on what I'm using when I'm not heating the house. I've got an energy monitor that measures the amount of leccy that I'm using and on average I get through about 300kwh a month when the heating isn't running and a lot more when it is - it's been known to get right up to 1500kwh when it's been everso cold.

I've also got monthly records of every kwh I've used since we moved in six years ago. We refurbed the bungalow and installed the central heating so I've got no information on the original storage heaters that were here.

It took a couple of winters to tweak it so I could optimise it's performance, so the earlier years were a bit more expensive and it was also colder - the temperature got down to -14 at one point.

If you want to PM me I can send you a chart showing my monthly leccy consumption over six years and a link to my real time energy monitor. I've also got a write up of what I did with some piccies if you are interested

The place is averagely insulated - UPVC double glazing that's 16 years old, rockwool of indeterminate quality in the cavity walls (installed when the place was built in 1986). There's none under the suspended floor and about 300+mm in the loft (which is quite large *140sq.m)

I put quite a lot of effort into understanding how heatpumps would work and did quite a lot of homework before I took the plunge. I based my decision on not getting any RHI as the government were procrastinating about what they were going to do. In the end I get around £700 a year for 7 years linked to inflation so that's around £5k which is about what the heatpump & its installation cost me in 2010. (the underfloor heating costs were on top of that)

ALtherma used to have a heatpump configuration tool which would give you some indication of the running costs - I don't know if it's still available (I might still have a copy somewhere although their equipment has changed somewhat since my stuff was installed

thozza

mikematic wrote: »

Is there really still not a reliable, reasonably priced alternative to burning fossil fuels for off grid properties????

Installing an oil boiler in this day and age just seems a little old fashioned.

The other 'green' alternative is a biomass (log, wood chip or pellet) boiler, running costs are on a par with oil or LPG (at the minute), however installation costs are rather high, and you have now missed out on the rather splendid RHI scheme payment which was in place 2 years ago for this technology, still the Government currently pay 4.68p per kWh of assessed requirement (from the Energy Performance Certificate), so this might be an option to look at.

Again MCS is required and you must have an 'acceptable' level of insulation, as determined by the regulations.

some more details on the EST website here:

http://www.energysavingtrust.org.uk/renewable-energy/heat/biomass