Anyone with experience of these, please? I am interested in fitting one of the small DIY split units to heat a conservatory.
This kind of thing:
http://www.dry-it-out.com/PMSF09
Thanks in advance for any advice.

Have AC units like that in our house and apartment in Thailand. Also had one in our rented house in Korea along with underflood heating.

Only thing I remember from the one we had replaced in the house was that we went for a larger sized one than we needed to make sure it didn’t get overstrained trying to cool 40 degree air all the time. IIRC we went 1000BTU over for negligible cost, but at least we knew the room was always cool.

We have a Daikin heat pump in our house they are pretty common here. Works very well unless it gets really cold, which it tends not to here. I’d avoid if you get lots of minus weather, we rarely even see frost so it heats all winter and is very efficient – is on 5-7am then 5-10/11pm and costs maybe 100 bucks a month if that inc weekends etc. Only issue is the way it wafts air around. Never use the a/c function but then i live in Wellington ha ha ha

In principle, they are an ideal solution – spec’d up a few over the years. Didn’t realise they came as DIY units – last I heard, you needed an F-gas certificate.

The one you linked to is 2.5kw – have you done/got the heat loss calcs done? Ensure 2.5 is enough? Worcester do a similar unit at 6kw for approx £1150 plus installation, and valiant do some cracking units as well.

I would definitely check the install regs and make surre you can DIY it.

Don’t buy a self install “no name” system. The lines leak terribly and someone will charge you a fortune to regas it. Also you won’t be able to get parts for it and the tech support for anyone trying to fix it will be non existant. If you’re going to buy one get a mitsubishi electric and have it properly installed with copper pipe an 1/2″ wall insulation. Let me know the size of your conservatory and i’ll tell you what size to buy. The “watch it” with these is ensuring you can get sufficient heat out of it in the colder ambient temps. I have a lot of experience in these so let me know if you want any help. The worcester and vaillant ones are just generic chinese systems with a sticker on (similar to the one you have linked to).

They use a lot of Toshiba and Fujitsu ones here in Sweden. It is a very common way of providing hot water and heating.

I’ve got 2 mitsubishi electric ones. My house is 150m2 and i have a 5.8 in the lounge and a 3.2 in the master bedroom. I’ve got it on air-con at the moment as it’s roasty here tonight 8)

They are awsome, way better than my gas central heating in the UK. However they only work down to -14 i think, and the colder outside the harder they have to work. Dead economical to run though. every 1kw of energy used they put out about 3kw in heat.

rule of thumb. go for bigger than you need, and only ONLY get a decent brand ie Panasonic, fujitsu or Mitsubishi etc. No name ones are shitty in my experience.

hope that helps

1kw of energy used they put out about 3kw in heat.

This is correct although they can go to COP/EER of 4.5, conditions dependent. Electricity is more expensive than gas though.
You really want a unit which uses refrigerant gas R410a and is inverter driven.

Try the “green building forum”
http://www.greenbuildingforum.co.uk/
Usually some good advice there on stuff like that

I stayed in philly for a couple of years and our 3 bed detached house was heated with an air to air heat pump. The heat it supplied was blown around the house with a forced air heating system. It worked very well I have to say. In the summer you reversed the system and it was an A/C unit.

I cannot comment on cost of running since the electricity rates were different.

Disadvantages is when it got very cold outside, you are trying to get heat from ambient air of less than -20, and is its snowing the heat exchanger can get choked with snow and ice. I would put in a different heat source such as sunken pipes in garden, pond or well

Very useful information, thanks.
I have a couple of decent sized rads in the conservatory already. With a bit of sunlight, once things heat up, it is comfortable even in winter. However, early morning and late at night it is unusable in cold weater, and I thought that a heat pump with blown air would be a good solution to top up. The bonus would be the AC for the relatively rare occasions when it gets uncomfortably hot in summer.
The conservatory is probably 20-25 square metres.
My understanding was that you can DIY fit the units with quick connections (no gas cert required) because there is no release of refrigerant involved. Interested in the comments above if they genuinely don’t provide a reliable connection.
I’ll check out the green building forum

Slightly off topic but I work with air to water heat pumps for the swimming pool and fish pond markets.

R410a is the best gas out there at the moment but within 2 years there will not be a drop in the COP levels when the temp drops like it does currently.

where do the pros think the COP will go for ground source heat pumps? Is it pump efficiency and coolant dependant only or will it be pipe dependant too? i.e. if one were to sink some pipes when the opportunity came along could one benefit from improved tech fully or would legacy pipe systems hold one back?

Also what is the theoretical maximum COP of a ground source heat pump assuming massively efficient heat transfer and pump rate?

GSHPs are around COP of 3 I think. They are not by any means perfect and electrical resistance heaters are commonly used as a boost for high heat demands. I don’t need to tell you that resistance heating is highly inefficient and expensive to operate. There are currently 2 choices for pipe layout; a slinky (horizontal) which requires a lot of land or borehole, which is very expensive. I don’t think pipe tech will change to the degree that it will have massive effects on performance, certainly not as much as the mech (compressor, refrigerant gas etc) side could.

I would also go for the Mitsi electric ones as they are quieter and alot more reliable. We use these systems on all the buildings we manufacture at work and they have been very reliable over the last 4 years. To be honest though unless you want the cooling for the conservatory in the summer it will be way more expensive than a panel or convector heater and alot more hassle to instal.

cheers BH.

Ive got to landscape around the barn in the new year. We currently have a wood pellet/log boiler operated system to which I shall add a ground based solar water array (prob about 5sqm/2.5kW) to indirectly heat the 700l thermal store.

Was wondering whether whilst ive got a man moving earth around (and we have enough horizontal space to put slinky out) to drop in some pipes, whether I use them or not? I dont see a COP of 3, 4 or even 5 as being relatively efficient compared to wood since elec prices are only going to go north.

Be careful there stoner, I think that the heat from a GSHP is relatively low grade and may not be able to heat your water to above 60degC, which is the legionella min temp. This means using resistance heating and regardless of what the salesmen will tell you, the system will not be efficient. In actual fact a COP of 1 would considerably more efficient than a wood burner, just more expensive in fuel costs. The ideal use for a GSHP is for underfloor heating where lower temps can be used. How are you getting on with the wood burner? Have you managed to find a local FC approved fuel source?

BH – you misunderstand my setup.

I have a boiler heating a thermal store into which I shall also be feeding a heat coil from a solar array. I can also, if I want to run a second indirect heating loop from a GSHP (theres spare ports on the thermal store)

all DHW is indirectly heated through 2 further coils so theres never any risk of legionella.

Temperature levels are immaterial as the thermal store is the stratifier and simply collates energy inputs – the energy being extracted at different points in the store for different uses and the pellet boiler being the on-call additional heat.

In terms of efficiency I speak in £ terms. My wood fuel supply costs around 4p/kWh whereas an average COP of, say 2.5 in a GSHP and an electricity input cost of around 12p/kWh gives 4.8p/kWh equivalent which isnt enough to make it a financially preferable energy source.

Ah, Ok I get you. By thermal store, you mean a well insulated tank?
In such case then it may be an option but I’d also consider an air-air system. Neither the HP nor the solar are going to give you much heat energy when you need it most (winter) but the air-air will give you the most in the summer months.
I read efficiency as energy in vs energy out. Cost is a different aspect in my profession!
Any joy with the wood burner? C’mon I’m interested!

wood burner? as in log stove is schweet.

The biotriplex has been really good to. this fella:

the log boiler on the left hand side of the boiler (the big grey box has two chambers, one for logs, the other as you can see for the red pellet burner) has been a godsend when Ive forgotten to order more pellets. I now have a two ton stash in dry store for the rest of winter.

Thermal store is this “energy battery”.

there’s another indirect coil out of shot at the bottom of the tank specifically for a solar link. There’s also another two ports for another energy source link – potentially GSHP/ASHP. I can also connect to the boiler iteself instead (theres spare ports and an indirect coil in that too). The boiler is connected to the tank via two pumps which balance the temp diffs between the two (theres a 200l tank in the boiler as well as the 700l whit thing)

In summer a 2.5kWh panel should be sufficient for all our DHW. Thats not when we’d need a HP. In winter though a GSHP would make sense if I could et the effective fuel cost below the wood cost and keep it below the wood cost.

A thermal store is opposite to a traditional hot water tank. Your hot water passes though the thermal store rather than a heat exchanger from the heat source heating your hot water.

oops too late

Wow, I’m impressed. I take it the delivery system for the woodchip is a vacuum affair? Has reliability been OK so far?
I’ve had issues with biomass previously as they are quite maintenance intensive, the delivery systems can get clogged by the dust from the pellets/chips but by far the worst problem has been sourcing the fuel. There is apparently little profit in the supply so many suppliers are living off of subsidies (which may dry up soon). In many instances the fuel is not from an approved (sustainable) source which defeats whole the object of biomass and many people are importing fuel from eastern europe. Many commercial buildings seem to have installed them just for the BREEAM credits and many have never used them!
The thermal store is basically a calorifier, can the coil handle DX (refrigerant) without having to have a secondary water circuit? You’d get better efficiency if it can.
Loving the log burner, looks like an lovely home I’m very jealous. What do you do for a living? maybe time for me to give up engineering!

its wood pellet not chip, so its a refined, homogeneous fuel. 8% moisture, low dust and ash etc etc. Its augured up the black pipe fomr the bottom of the hopper. Auger screw is in the red housing at the top. Very reliable and simple to maintain. Its a swedish burner and finish boiler thats been used for years over there.

Its a lovely simple system. Even if I had a problem with the pellet burner I can switch to logs as back up and apart from an electrical supply for the pumps there’s nothing complicated to go wrong. As a back up Im considering an switch over to an inverter/battery (with a periodic generator charger that I have already) to keep the hot water going in a power cut.

There’s a number of suppliers round here (Worcs). I currently get mine from delivered on ton pallets (2t at a time) from Travis Perkins. Balcas Brites from ireland. Theyre a large supplier so supply reliability isnt such a problem.

As I understand it the coil can handle pretty much anything and specifically solar water. Whether that includes refrigerant I dont know off the top of my head.

I crunch numbers for a living. Freelance.