Owlman - thanks for your response. I understand where you are coming from with your idea of having two external units rather than one massive one but I don't think I will be allowed more than one outdoor ASHP unit. This is an extract from the Welsh Gov website regarding installation of air source heat pumps:

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Installation of one air source heat pump used solely for heating purposes is normally permitted, provided that it complies with the MCS Planning Standards (or equivalent standards) and subject to the following conditions:

no more than one air source heat pump can be installed on (or within the curtilage of) your property

the volume of the air source heat pump's outdoor compressor unit (including any housing) must not exceed one cubic metre

no part of the air source heat pump can be installed within three metres of the boundary of your property

if in the case of the installation of an air source heat pump, a stand alone wind turbine is installed within the curtilage of the dwellinghouse

the air source heat pump can not be installed on a pitched roof

if installed on a flat roof, the air source heat pump must not be sited within one metre of the external edge of that roof

the air source heat pump cannot be installed on a wall or roof which fronts a highway.

An air source heat pump must be sited to have a minimal effect on the external appearance of your property and the wider amenity of the area. For more details on restrictions applying to the installation of air source heat pumps, you should contact your local planning authority.

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Condition number 1 also states that the ASHP can only be used for heating purposes, so I that rules out cooling, not that I think I would ever need to use that function! Does that mean that I would not need condensate drains then? If I did need them then that would be quite a headache and means that all the indoor units could only be put on exterior facing walls!

Jeff, are those the rules for permitted development? If so, all it means is that you would need planning permission if you wanted to do more/something else.

Posted By: djhJeff, are those the rules for permitted development? If so, all it means is that you would need planning permission if you wanted to do more/something else.

Yes, but as I said in my reply to Owlman, I would not relish the idea of going for planning permission - it smacks of lots of bureaucracy and hefty LA fees! But if it has to be.....

Owlman - ok, thanks, that sounds a lot less daunting. I have had a look on the Internet and it seems that I might have to buy mini-pumps to go inside the indoor units depending on their location i.e. whether or not I can simply use gravity flow.

JeffB

I'm not suggesting you should or shouldn't apply for planning regarding a possible ASHP, but there's nothing to worry about in terms of costs/fees.

The homeowner LA fees will likely be around £200. You'll need drawings, which your LA will have a guidance document to explain exactly what's required, but a location map showing your house and 100m all around can be bought on line for about £15, and you can hand draw floor plans, roof plans, elevations, plot plan etc. I've seen some really rubbish quality drawings as planning applications, so don't worry if you think your artistic skills may not be up to it. LA's seem to go easier on homeowner applications, than when a professional applies on their behalf.

So for under £250, and a few hours measuring and drawing, you could have the application submitted.

There is a note that you need to comply with "MCS020 Planning Standards", whatever that refers to - interested parties can google that.

Hi Will, My system is ducted, I guess you're talking about the wall or ceiling hung indoor units? I can't answer that but my guess is there will be some fan noise and the only advice I could give would be to carefully compare individual manufacturers specs. I certainly will, during my next project for those types of unit.
My loft mounted indoor unit feeds the supply flow through quite large diameter rigid, spiral, insulated ductwork; similarly the return both via ceiling registers. At the dead of night you can hear the fan very faintly on speed 1 and 2 ( there are 5 ). During the day generally any noise is lost within normal household activities.
Likewise the outside compressor unit; there's much made about their noise, but mine is a well specced unit that constantly modulates, and when at it's lowest is incredibly quiet even when standing next to it.
How noisy is MVHR in comparison, I've no idea? In a bedroom I guess it depends on how light a sleeper you are, and your locality, isolated rural or urban.

Posted By: WillInAberdeenOwlman, how noisy is the indoor unit - would you have it in a bedroom?

The indoor units are often used in bedrooms in hot climates, but maybe the situation is different. A bit of noise from the A/C or from an overhead fan is preferable to stifling in still air. At any event you soon get used to them.

Posted By: GreenPaddyJeffB - link for purchasing maps (no connection, just use them regularly)

https://www.ukplanningmaps.com/" rel="nofollow" >https://www.ukplanningmaps.com/

Many thanks.

DJH, it comes from the OS. I had the same problem on a previous project, and Ukplanningmaps guys gave me a contact at OS, to whom I sent the required correction.

TBH, I've never checked to see if it has been corrected - I hand amended the map to get it into the planning system.

You might need to go via Land Registry first/aswell, since it's a boundary issue?

Resurrecting this thread as now have go ahead from 'the residential planning committee'!

We are after a split A2A with about 2.5kW downstairs and 1.5kW upstairs.

We're in the east of England and will be keeping the gas (and have a wood burner) so don't necessarily need to spec it for super cold i.e. <5C times if that compromises the efficiency. We can also heat the whole house quite happily with a 4kW wood burner so the above total sounds about right.

Touring a nearby house that had A2A we were advised to get a unit that can throttle right back (maybe 5 fold) without cycling and that has a lower baseload power - even if that means the headline CoP is a bit worse.

Being very new to this any specific advice, recommendations for models and/or installer in the south Cambridge area would be much appreciated?

I can't advise on fitters in your area, but try looking for independent aircon engineers, You'll need their "F" gas qualification for any eventual fit.
If you establish a rapport, they may be amenable to you doing some of the onerous groundwork yourself thus keeping costs down. Buying the kit through them may be wise too, to get any VAT perk.
As for manufacturers, the ones that spring to mind from my own research are Daikin, Mitsubishi, Toshiba and Panasonic. All four have a good range of models with modern modulating compressors.
Do your own research regarding ancillary kit, e.g. pipework ducting, outdoor mounting systems, insulation etc. especially from an aesthetic point of view, if that's important. Well intentioned, decent fitters aren't always fully informed of all the best kit that's available.

Thanks djh and owlman!

thanks Rob, dropped him a mail :)

Just had R32 Fujitsu split unit fitted

1.1-5.5kW exterior and 0.9-4.0kW downstairs unit and 0.9-3.2kW upstairs

It looks like he's made a nice neat job