Air to Air heat pump. ASHP for space heating only

semo
semo Posts: 44 Forumite
edited 23 January at 3:24PM in Heat pumps
I've read quite a few articles on ASHP around here but it seems a lot is being discussed about air to water, units installed in lofts, old stone houses and generally less than optimal scenarios.

As far as I can understand, air to air systems with high-wall mounted indoor units are probably the most efficient option. I plan on using something else for domestic hot water (advise on that subject welcome too). I plan on insulating and draft proofing the house as much as financially possible.

The things that worry me are:
1. How much will it cost? I'm looking to install the system in a 3 bedroom house (around 4-5 in door units needed). I've heard figures from £4K up to £35K.
2. Installers/dealers... I contacted a few EST recommended companies but no one got back to me for 3 working days. I can only imagine how bad things will go and how badly the company will handle it if they can't even be bothered to quote me! I plan on communicating by email where possible, take lots of photos and use a voice recorder for whenever I speak to someone in person. Too much, not enough, any other advice?
3. In the ASHP sticky, the author mentions that some Sanyo systems can defrost using hot gas. Can someone elaborate on this technique? Is it heated air, LPG, etc... and do I have to top it up? Winters seem to be getting harsher and I don't want to have to drive to B&Q one day to buy a bunch of oil radiators in a hurry...
4. What does the installation involve? I imagine the indoor units connect to the outdoor one using a flexible pipe + electric wires. Is there a limit on how far away the indoor and outdoor units have to be?
5. Servicing?
6. Can you top up the number of indoor units at a later time and can you mix and match (say 3 high wall mounted and one floor units).
7. How long would it take?
8. Does retrofitting a house with such a system get easier if you are doing work on the house to begin with (I’m planning on doing an extension and a few other things).
9. Multi-split or single(?) split. It seems that initial cost is similar but I always thought that mini-split is the most efficient method but it may not be the case according to the sales person I spoke to.
10. How do Fujitsu compare to the likes of Sanyo and Daikin?
11. Can any make/model have humidity control?

All advice very much appreciated of course
I've come across a lot of jargon when reading up on this topic so I made myself a cheat sheet. Please define abriviations that aren't included below as I'll probably get very lost very quickly :)
ASHP: Air-Source Heat Pump
CH: Central Heating
DHW: Domestic Hot Water
EST: Energy Saving Trust
GSHP: Ground Source Heat Pump
Sometimes called Geothermal heat pump

HVCA: Heating and Ventilating Contractors' Association
MCS:
Microgeneration Certification Scheme
An EST recognised scheme and using MCS installers can qualify you for an RHI grant.
R410A: A type of refrigerant gas
RHI: Renewable Heat Incentive
A government grant to promote use of energy conserving technology. Repaces the discontined Low Carbon Building Programme. Likely the result of the UK's Kyoto protocol agreement
UFH: Underfloor Heating
VRF: Variable Refrigerant Flow
VRV: Variable Refrigerant Volume (same as VRF)

Comments

  • semo
    semo Posts: 44 Forumite
    I just spoke to a salesman finally who gave me some food for thought. He didn't know about the hot gas thing I read from the sticky but assured me that at even -15 degrees C, the unit will still be able to cope with heating the house. I was initially quoted for a single split Fujitsu system but I know even less about them than the other makes. I'm also not sure now whether to go for single or multi split. The main advantage of single split is that you can set one room to be cooled while another to be heated... I'm not sure if I care much about this convenience considering I'll be forced to have condensing units dangling all around the house.

    I've added those questions to the original post. I'd appreciate any help on any of the questions. I'm sure someone around here can answer at least one of my questions :)
  • Cardew
    Cardew Posts: 29,034
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    As I see it, the big disadvantage of air to air(apart from the water heating you mentioned) is that you have to leave doors of rooms open unless you have units in every room - including the 'small room'.

    Is it possible for you to have ducting incorporated in the house when you are 'doing work on the house'? As you are probably aware ducting is standard in the USA for houses designed for aircon/ASHP.

    I also think that there is a tendancy to worry too much about the ultra low temperatures we suffered last December. Frankly for those rare occasions a few pounds spent running some £10 fan heaters from Argos is better than 'over-engineering' at great cost a system to cope with the -15C you mention. With defrost cycles in those temperatures your overall COP(co-efficient of performance) is not likely to be much higher than unity(1.0) anyway.

    There are quite a few videos on You Tube that will answer some of your questions.
  • semo
    semo Posts: 44 Forumite
    Thanks Cardew.

    I do plan on having an indoor unit in every big room so leaving doors open won't be a big issue. If I was to go with an air to water solution, I'd still have a water heating problem if I wanted 60+ degreec C on demand.

    I thought that the way to go nowadays was a ductless multi split system. Is ducting preferable? Is it more expensive?

    So now I'm split (ba-dum ching) between ducted, single split or ductless multi split (I think also called mini split?).

    I think I may buy one or two £10 fan heaters just in case...
  • peat
    peat Posts: 481
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    I think that air to air is less likely to qualify for RHI than air to water
  • semo
    semo Posts: 44 Forumite
    peat wrote: »
    I think that air to air is less likely to qualify for RHI than air to water

    RHI is not a consideration for me on the subject of heating. I'll be looking for grants for insulation and possibly PV solar later on.
    Air-source heat pumps
    Air source heat pumps will not be supported from the outset because more work is needed to better understand the costs associated with the technology and, for air to air heat pumps, work is ongoing to develop a robust methodology for measuring heat delivered in the form of hot air. Subject to successful conclusion of this work and other factors (such as the role of cooling as opposed to heating in such systems) we intend to extend eligibility to this technology from 2012.
    http://www.decc.gov.uk/publications/basket.aspx?filetype=4&filepath=What+we+do%2fUK+energy+supply%2fEnergy+mix%2fRenewable+energy%2fpolicy%2frenewableheat%2f1387-renewable-heat-incentive.pdf&minwidth=true
  • Cardew
    Cardew Posts: 29,034
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    peat wrote: »
    I think that air to air is less likely to qualify for RHI than air to water

    That is understandable as it would mean people could be paid under RHI for air conditioning!!!
  • albyota
    albyota Posts: 1,106 Forumite
    semo wrote: »
    I've read quite a few articles on ASHP As far as I can understand, air to air systems with high-wall mounted indoor units around here but it seems a lot is being discussed about air to water, units installed in lofts, old stone houses and generally less than optimal scenarios.

    are probably the most efficient option. I plan on using something else for domestic hot water (advise on that subject welcome too). I plan on insulating and draft proofing the house as much as financially possible.

    The things that worry me are:

    1. How much will it cost? I'm looking to install the system in a 3 bedroom house (around 4-5 in door units needed). I've heard figures from £4K up to £35K.

    Fujitsu J series, (Multi-split) would probably be your best bet and can accomodate mixing L/L floor, high-wall, ceiling, cassette, ducted and floor mounted options, Mitsubishi, Sanyo, Daikin, LG, Panasonic all have various similar combinations. Try to steer clear of the cheaper brands IMO. Costs for such an installation would be around £6K to £8K

    2. Installers/dealers... I contacted a few EST recommended companies but no one got back to me for 3 working days. I can only imagine how bad things will go and how badly the company will handle it if they can't even be bothered to quote me! I plan on communicating by email where possible, take lots of photos and use a voice recorder for whenever I speak to someone in person. Too much, not enough, any other advice?

    HVCA would be place to look.

    3. In the ASHP sticky, the author mentions that some Sanyo systems can defrost using hot gas. Can someone elaborate on this technique?

    Hot gas Defrost is where the 4 way valve reverses the refrigerant gas flow to be circulated around the evaporator coil to melt frost build up.

    Is it heated air, LPG, etc... and do I have to top it up? Winters seem to be getting harsher and I don't want to have to drive to B&Q one day to buy a bunch of oil radiators in a hurry...

    Refrigerant gas, usually R410A, sealed in the system pipe work.

    4. What does the installation involve? I imagine the indoor units connect to the outdoor one using a flexible pipe + electric wires. Is there a limit on how far away the indoor and outdoor units have to be?

    For a multi-split system, one outdoor unit with two pipes (liquid line and gas line (1/4 & 3/8th copper pipe) for each indoor unit. For the mini VRF* type (J series) two pipes from outdoor unit to branch pipe to feed upto eight indoor units.

    *VRF. Variable Refrigerant Flow

    5. Servicing?

    Normally and now a legal requirement for systems containing more than 3.5kg of refrigerant gas, annual inspection, leak test prevention/monitoring. service and maintenance contract.

    6. Can you top up the number of indoor units at a later time and can you mix and match (say 3 high wall mounted and one floor units).

    see 1 above

    7. How long would it take?

    five indoor units, depending on pipe work route, location of outdoor unit, ducting, 1st/2nd fix? between 4 and 7 days ish.

    8. Does retrofitting a house with such a system get easier if you are doing work on the house to begin with (I’m planning on doing an extension and a few other things).

    If the system can be designed and/or built in to the project, can be easier although this would not necessarily alter the cost of the installation.

    9. Multi-split or single(?) split. It seems that initial cost is similar but I always thought that mini-split is the most efficient method but it may not be the case according to the sales person I spoke to.

    How much room do you have for multiple outdoor units.....? one multi-split outdoor unit is better if you can stretch to it.

    10. How do Fujitsu compare to the likes of Sanyo and Daikin?

    All three, Very good, very reliable kit.

    11. Can any make/model have humidity control?

    Not entirely sure, Ill find out.

    All advice very much appreciated of course
    I've come across a lot of jargon when reading up on this topic so I made myself a cheat sheet. Please define abriviations that aren't included below as I'll probably get very lost very quickly :)
    ASHP: Air-Source Heat Pump
    CH:Central Heating
    DHW:Domestic Hot Water
    EST:Energy Saving Trust
    GSHP: Ground Source Heat Pump
    Sometimes called Geothermal heat pump
    MCS:Microgeneration Certification Scheme
    An EST recognised scheme and using MCS installers can qualify you for an RHI grant.
    RHI: Renewable Heat Incentive
    A government grant to promote use of energy conserving technology. Repaces the discontined Low Carbon Building Programme. Likely the result of the UK's Kyoto protocol agreement

    Hope that helps.
    There are three types of people in this world...those that can count ...and those that can't! ;)

    * The Bitterness of Low Quality is Long Remembered after the Sweetness of Low Price is Forgotten!
  • semo
    semo Posts: 44 Forumite
    Thanks very much albyota... I’ve update my cheat sheet from your post.

    Could you please elaborate on some your answer please.

    1. I did a quick search on this system and I found this:
    [FONT="]Energy Ratings B for cooling & C for heating[/FONT]
    [FONT=&quot]Not that I pay much attention to such things but still wondering how that compares to other makes/models. [/FONT]

    3. From what I’ve been reading, most reputable systems on the market do this as standard as part of their defrost cycle. I.e., can I assume that the Sanyo’s defrost cycle is not unique and I can expect to get the same from other good systems.

    4. So the Fujitsu J series is a multi-split, mini VRF type system. Does the VRF bit mean that each indoor unit (zone) can be set to its own individual temperature as long as the system is either heating or cooling but not both? I assume VRF is not unique to the Fujitsu system

    5. Ballpark figures on annual service costs or maintenance contract costs?

    8. As long as it doesn’t impact on the extension project much (money and time wise) then I’d be interested in doing that.

    9. It is an end of terrace so plenty of room behind the house and some on the side (behind garden entrance).

    11. I just found out about that the Daikin quaternity can control humidity but I don’t know how effective it is. It also purifies the air but again, not sure how effective it is or if it is worth the potential price increase
  • albyota
    albyota Posts: 1,106 Forumite
    edited 27 April 2011 at 8:15PM
    semo wrote: »
    Thanks very much albyota... I’ve update my cheat sheet from your post.

    Could you please elaborate on some your answer please.

    1. I did a quick search on this system and I found this:

    "Energy Ratings B for cooling & C for heating"

    [FONT=&quot]Not that I pay much attention to such things but still wondering how that compares to other makes/models. [/FONT]

    ......Mitsubishi M series are 'A A' rated


    http://www.mitsubishi-aircon.co.uk/default.asp?url=http://www.mitsubishi-aircon.co.uk/mitsubishi_electric.asp?id=152713

    3. From what I’ve been reading, most reputable systems on the market do this as standard as part of their defrost cycle. I.e., can I assume that the Sanyo’s defrost cycle is not unique and I can expect to get the same from other good systems.

    Yes

    4. So the Fujitsu J series is a multi-split, mini VRF type system. Does the VRF bit mean that each indoor unit (zone) can be set to its own individual temperature as long as the system is either heating or cooling but not both? I assume VRF is not unique to the Fujitsu system

    Correct

    5. Ballpark figures on annual service costs or maintenance contract costs?

    Ballpark, £170/yr, depending on amount of units, UK location,

    8. As long as it doesn’t impact on the extension project much (money and time wise) then I’d be interested in doing that.

    OK

    9. It is an end of terrace so plenty of room behind the house and some on the side (behind garden entrance).

    OK

    11. I just found out about that the Daikin quaternity can control humidity but I don’t know how effective it is. It also purifies the air but again, not sure how effective it is or if it is worth the potential price increase.

    quite a bit more money if thats whats needed, not normally an issue in the UK.

    http://www.daikin.co.uk/product/for-your-home/ururu_sarara/humidification.jsp

    did I miss anything?
    There are three types of people in this world...those that can count ...and those that can't! ;)

    * The Bitterness of Low Quality is Long Remembered after the Sweetness of Low Price is Forgotten!
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