Posted by: @etchedpixels

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@ashp-bobba I thought England now allowed 2 on a detached house ?

That is true for the last few months when they updated the rules for permitted development but its not just detached homes that have A2A, also many homes including non detached have more than one and hope they never get caught.

Posted by: @escapist

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Newbie and my brain hurts.

1970s detached extended bungalow, initially working towards air to water, calculated heat loss 5.37.

Two distinct zones  between original building older cavity wall insulation and good loft insulation, and extension/living area which has underfloor insulation new cavity wall insulation and a lot of glass and solar gain(it’s a vaulted garden room with velux and two mostly glass walls ).

Eleven rooms all with rads mostly doubles all on microbore with the garden room rads piped under the concrete floor.

Heating is oil, grant blueflame + OSO cylinder all 4 years old and pretty efficient.

We want to get rid of oil and until recently thought air to water(vaillant7/8kWh). Cost to us between £7/8k using BUS including re pipe on all but the stuff in the concrete, pump, new cylinder(which pains me) and all controls etc.

However by chance I came across several YouTubers with actual living experience of air to air and I’m very interested and due to have a survey in 2 weeks.

...

We are having a 12/13kWh solar array +11/12kWh storage installed in a few weeks.

We live in Pembrokeshire so other than the occasional Beast from the East event, very temperate climate.

At the moment air to air looks the firm favourite.

Thank you for sharing all the details.

Oil is the obvious one needing quicker replacement given the price hikes and the gov is hiking the BUS grant for it. Microbore is bound to be the one pushing your estimate higher.  

I would challenge the new cylinder, assuming yours is mains pressure.. Heat Geek can provide their own 5 yr warranty (with their own tanks, but maybe worth enquiring). I could be wrong but Vaillant apparently reduce the warranty cover if other cylinders are used. I found Mitsubishi R290 would also fit our requirements and they seemed less fussy. 

The 11/12 kwh energy storage capacity you are having seems tight (in the coldest days) but it should help if you use a Cosy type TOU tariff with a typical 3 lower cost periods.

In any case, with an ASHP and properly sized pipework and rads, you should expect a much more evenly heated house!

Personally, in case the electricity supply has been reliable, I would take the BUS grant and remove the oil boiler. And I could always have it ready to use a generator for extra peace of mind. 

Curious to know what the price would be for A2A in an 11 room bungalow, will they be able to run pipework to the internal units around the loft?

Hope that helps! 

An interesting discussion that is helping stimulate my thoughts on ADDING A2A....to existing A2W.

1. For summer cooling

2. For boost/quick heating that could be useful in shoulder months and also on coldest winter days. 

I have had A2W for 6 years - generally very happy with it especially once weather compensation correctly setup to reduce cost.

I believe my LG Therma ashp could be set to allow cooling but I'm doubtful its sufficiently useful in my case with retrofit to previous oil system. U/f heating & rads. Dewpoint likely to be an issue.

So thinking about adding A2A. Grants irrelevant as previous heat pump grant already.

My thoughts 

- outside unit near heat pump

- inside unit(s) might be

- single unit on landing  would cool bedrooms if doors open? Without too much noise impact? 

- single unit downstairs .. might be sufficient if internal doors opened...  

- those positions probably not too disruptive to install....near outside unit... near elec...near drainage etc

ChatGPT thinks 2 indoor units + 1 outdoor multi-split condenser with a good brand that is efficient & quiet might cost £5 to 6k installed....up to £7.5k? for premium

It suggests Daikin & Mitsubishi....maybe Worcester Bosch 

i would be interested in any thoughts to save me reinventing the wheel!

@editor you might move this to standalone/new topic? New thread?

Hi @ashp-bobba when you said, "Only Multi units do not modulate down as low as A2W, I think at the time our example was a multi system covering multiple rooms, splits will do the same as A2W modulation but you cannot have multiple outdoor units without planning permission so multi systems are much more popular for multiple rooms." I'm afraid you lost me. I could be all the different multis.

I think you're saying a system with one outdoor unit and multiple indoor units can modulate down as well as an A2W system, but if you have more outdoor units each with one indoor it can't. Is that right?

Posted by: @tim441

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An interesting discussion that is helping stimulate my thoughts on ADDING A2A....to existing A2W.

1. For summer cooling

2. For boost/quick heating that could be useful in shoulder months and also on coldest winter days. 

I have had A2W for 6 years - generally very happy with it especially once weather compensation correctly setup to reduce cost.

I believe my LG Therma ashp could be set to allow cooling but I'm doubtful its sufficiently useful in my case with retrofit to previous oil system. U/f heating & rads. Dewpoint likely to be an issue.

So thinking about adding A2A. Grants irrelevant as previous heat pump grant already.

My thoughts 

- outside unit near heat pump

- inside unit(s) might be

- single unit on landing  would cool bedrooms if doors open? Without too much noise impact? 

- single unit downstairs .. might be sufficient if internal doors opened...  

- those positions probably not too disruptive to install....near outside unit... near elec...near drainage etc

ChatGPT thinks 2 indoor units + 1 outdoor multi-split condenser with a good brand that is efficient & quiet might cost £5 to 6k installed....up to £7.5k? for premium

It suggests Daikin & Mitsubishi....maybe Worcester Bosch 

i would be interested in any thoughts to save me reinventing the wheel!

@editor you might move this to standalone/new topic? New thread?

1)  absolutely and of course

2) you should not need this for this application, if your A2W is set correctly your home will be 21 DegC from October to May and never need any further input form any other heat source, set up correctly your A2W would technically be cheaper to run as they are best run very slow and low, until A2A gets going and idles the same as the A2W it is still reactively heating the home rather than a steady state. Try no to think reactively like the good old thermostat on off days, set up right your home will never drop below 20 Deg C when using an A2W. I do not turn any of our 5 A2W systems off or on all year, they just work it out for themselves, set and forget designs, this is what we install. 

The issue with asking your A2W to do the cooling is the emitters and non vapour sealed circuit design, if you do not have force draft convectors with condensate drains and a vapour sealed pipe circuits you can not remove the latent heat from the air and you are unable use a lot of the sensible cooling power the system has. Even connected to UFH is only 50% effective and no latent is used, feels cooler but no moisture removed. A typical radiator that produces 500w of heating to the living room, ran in cooling above the dew point would only transfer around 100w, now if you imagine, what you are trying to offset is 2000w and the power of the solar effect on your building.

We have designed installations for customers that cool the landing and they have doors open, if you cant afford or do not want units in every room then we advise use pedestal fans in doors ways to help push the air in the right direction, the air will not bleed into rooms as easy as you think.

Price wise you are very close, £1700 - £2,300 for single split. £1,900 - £2,400 multi per indoor unit is average.

Mitsubishi, Panasonic, Toshiba Midea are outstanding systems, all of the boiler manufacturers are very new to the AC Market, we do not have any history on them and IMO the 4 brands I listed here have more than 50yrs in the market and support their warranties much better than some other leading names not mentioned from your list.

Posted by: @springswood

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Hi @ashp-bobba when you said, "Only Multi units do not modulate down as low as A2W, I think at the time our example was a multi system covering multiple rooms, splits will do the same as A2W modulation but you cannot have multiple outdoor units without planning permission so multi systems are much more popular for multiple rooms." I'm afraid you lost me. I could be all the different multis.

I think you're saying a system with one outdoor unit and multiple indoor units can modulate down as well as an A2W system, but if you have more outdoor units each with one indoor it can't. Is that right?

 

Sorry, I am not the best at being clear, Im just an engineer so forgive me.

The outdoor unit that has multiple pipe connection all on one unit (called a Multi) might be able to operate at say 10KW of cooling to 4No 2.5kw indoor units, this system can modulate down to 2000w so that works nicely until only one room need running at 1000w. Now 4No splits so 1+1 outdoor and indoor so 4X 2.5kw systems. These systems can operate 500w - 2500w and modulate down further.

This is what i was trying to get across.

@ashp-bobba many thanks for useful inputs & sanity check!

I'll continue to look into options and your brand comments are helpful. I guess reliability, efficiency, noise are key... controls as well maybe.

@etchedpixels Thanks for your comments I found them interesting and helpful. Up to a point anyway.

Good point about hot water. I have an EV charger and cheap overnight electricity so a simple immersion heated tank will be my most economic choice.  Plus it means I'm not limited to the Daikin Multi+.

The question then is the one you raised, will need lots of indoor units or not? I have a modest 2 bed terrace built in 1911 with high ceilings and one of the bedrooms is in the attic. I can't tell whether the heat would circulate or not. 

Also how much I'd really use cooling.

I suppose it's also about why I want to make the change. Getting rid of gas seems a good move to me. First I'm so well insulated that the standing charge is over 35% of my gas bill. Second is about emissions, not just the CO2 but the methane in production and distribution. I'm fortunate to be able to make the change now. As a bonus getting the boiler off the kitchen wall will add space where I need it most. 

I suppose I'll just have to talk to some installers for answers.

Posted by: @springswood

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The question then is the one you raised, will need lots of indoor units or not? I have a modest 2 bed terrace built in 1911 with high ceilings and one of the bedrooms is in the attic. I can't tell whether the heat would circulate or not. 

If you leave the doors open very likely not.  Rooms share heat anyway, with open doors more so.  One unit on each floor may well do the job.  Electric mats or small radiant heaters are good for small closed off spaces (eg a WC)

Posted by: @etchedpixels

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Definitely air to air (and we did)

We have a big solid stone 1860s victorian pile with 18" thick solid walls. It's grade II listed so a lot of insulation is simply not possible and would wreck the building.

Why do you think it impossible?

Posted by: @etchedpixels

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Posted by: @batpred

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A2A would only work in smaller properties (and I think there's a consultation running to eventually allow more people in flats to have them).

That's possibly the most bogus heatpump comment I've heard this week 8)

The context of my comment is retrofit cost effective installs for heating, looking to leverage BUS. As far as I am aware, the main goal of the government push for A2A heating is to decarbonise at a large scale. The announcement indicated it could be most cost effective than what A2W is delivering for flats and small houses. 

I agree there are other cases where A2A can be user to remove a fossil fuel boiler. But how many millions of dwellings could be in scope? 

@jamespa That's interesting and would bring cost down a lot.

I realise what's holding me back is that without experience I have no feel for how warm air heating will spread through a house. 

There's a saying I picked up when studying physics. An ounce of experiment is worth a pound of theory. It was a long time ago. So if it was the winter I'd play around with a couple of fan heaters to see what positions might work. Maybe I'll be better off waiting...

On the ground floor there's the living room and kitchen. Would heat from the living make it to the kitchen or would it escape up the stairs, which can't be closed off? 

Upstairs is probably OK for heating. Just one bedroom and the bathroom. I can see heat spreading there OK. Up to the spare bedroom in the attic as well.

Would the attic be cooled by a unit on the floor below though? I imagine not and naturally it overheats most (and gets used maybe 20% of the time).