Will ASHP or air-to-air be better for a 1930s detached, or storage heaters?

[Gone West]

6 hours ago, Hanksy said:

I have had 4 Mitsubishi LN A2AHP's installed roughly 2 months ago. they total 15.5kW output (2x5kW Kitchen and conservatory, 3.5kW in lounge and 2.5kW in main bedroom - we are in a bungalow 120sq/m).

 

My heat load for the property is 12,500kw and water 2000kw. Until these were fitted I was running a pellet boiler for the past 7 years typical pellet cost was £1200pa

 

I have been logging my daily running costs and room temps since the A2AHP's have been installed and comparing costs to pellets. From what I can see so far (only end Aug/Sep and uptown today) the running cost is averaging 79p a day (elec cost is19.3p/unit btw)

That's very interesting. It would be good to have updates as the colder weather comes. I have often thought about A2A HPs as a good option, thanks for posting.

[chrisgreen]

7 hours ago, Hanksy said:

I have had 4 Mitsubishi LN A2AHP's installed roughly 2 months ago. they total 15.5kW output (2x5kW Kitchen and conservatory, 3.5kW in lounge and 2.5kW in main bedroom - we are in a bungalow 120sq/m).

 

My heat load for the property is 12,500kw and water 2000kw. Until these were fitted I was running a pellet boiler for the past 7 years typical pellet cost was £1200pa

 

I have been logging my daily running costs and room temps since the A2AHP's have been installed and comparing costs to pellets. From what I can see so far (only end Aug/Sep and uptown today) the running cost is averaging 79p a day (elec cost is19.3p/unit btw)

Wow, thanks for all that useful info Hanksy!! 

 

A few questions if that's ok: 

 

What made you switch from pellets to Aircon?

 

Why did you pick Aircon over A2Water heat pump?

 

And are you in a warm part of the country?

 

How many hours are in the day you're using? 

 

The PV is covering some of the AC cost?

 

A 10kw PV array - fabulous! Do you get much from it in winter? Is it worth the initial outlay?

 

Have you been able to predict at all what your cost per day might be in mid winter (would that be possible to work out based on your existing cost and COP ratio thingame, and the manufacturers' COP for a colder temp (if they provide it?).

 

And can you recommend a good online heat load calculator!?

Thanks in advance! Please do post your monthly winter data if you have time!!! 

[chrisgreen]

Hanksy, I meant to also ask - the cost per day you've calculated e.g. 79p/day, is that figure including a saving due to having PV? Or is that the figure before taking anything off? 

[chrisgreen]

10 hours ago, Ferdinand said:

 

One option to look at is simply to upgrade heat emission is to replace your existing rads with double ones, which will fit the same space.

 

Though when I upgrade an old house I tend to switch the rads from under window - as windows no longer leak and are warmer - onto inside walls, which are closer together and keep the heat in the house.

 

F

Thanks Ferdinand! In this house we have no existing central heating: no rads no nothing! Just one logburner in the lounge...

Good point about placement of any future rads on internal walls.

[Hanksy]

16 hours ago, chrisgreen said:

Wow, thanks for all that useful info Hanksy!! 

 

A few questions if that's ok: 

 

What made you switch from pellets to Aircon?

 

Why did you pick Aircon over A2Water heat pump?

 

And are you in a warm part of the country?

 

How many hours are in the day you're using? 

 

The PV is covering some of the AC cost?

 

A 10kw PV array - fabulous! Do you get much from it in winter? Is it worth the initial outlay?

 

Have you been able to predict at all what your cost per day might be in mid winter (would that be possible to work out based on your existing cost and COP ratio thingame, and the manufacturers' COP for a colder temp (if they provide it?).

 

And can you recommend a good online heat load calculator!?

Thanks in advance! Please do post your monthly winter data if you have time!!! 

Hi Chris see below for answers as best I have so far

 

1. why switch - Brief history No gas in Village (north Shropshire) was on Anthracite boiler 2K+pa running cost. RHI came out so fitted pellet stove in place of anthracite boiler had for 7 years RHI finished in April this year. Pellets were costing me c1200pa (4 tons). Been looking at ASHPs as house is well insulated. Then we had the warm weather and house was too hot which led me to A2AHP's so we could have free cooling in summer as loads of excess PV. That really was the logic. Oh and to top it off wife has MS and so cannot fill boiler and she pointed out if I died she would have to move as cannot do the heating! using heat pump at least solves that one ?

 

2.Why A2A - Cooling in summer, If one unit fails still have 3 working so heat/cool still works, efficiency of the Mitsubishi units is really good and have a great installer in Midland Air Conditioning. Too many cowboys out there just wanting your cash without the skills and service to ensure a good solution. Didnt need water heating as solar thermal and PV.

 

3.Where - North Shropshire SY13 area not particularly warm 

 

4.Hours a day - 24/7 its just on and set to 24 degrees on every unit

 

5.PV has covered all the running costs so far apart from £1.91 if we used it all 100% for heating . Reality is it is used for other things too eg car charging water heating etc but it has definitely contributed. In my figures I have assumed zero input from PV so just raw imported energy costs The AC total cost is simply total kWs used x elec rate.

 

6. PV array - had 3.7KW at start of fit then added further 6.3kW last year. really pleased with it. Will attach a graph showing the6 kw garage array for the last year easy as on app) overall winter is generally poor but it really depends on how many dull days we get eg dull overcast day typically 6Kw day sunny winter day c16kW day (summer 60kW/h day regularly). For me well worth outlay especially if you have an EV and or battery storage (we have both).

 

7. Prediction - I only have data on temps so far lowest is 5 degrees that's averaging at £1.33, 6=£1.22, 7=£1.15, 8=£1.06 will get more accurate as number of days at that temp increases

 

8 Heat calc - Sorry no I used my EPC to estimate heat and water loads

 

Will post updates each month no problem

 

Hope that helps 

[Hanksy]

Sorry forgot to post the solar edge 6kW data as promised. Don't have an easy way to add the other PV

 

2 images 2021 to date and 2020 only installed in November 

 

 

[severnside]

@Hanksy This is interesting information, I was looking into this as well to convert whole house to A2A from Oil boiler. Could you help me with following questions

1. Does having multiple outdoor units affect startup current requirement e.g. too much load when all start at same time. Did it need planning permission?

2. How is the response time of heating? Does it heat up quickly in 1-2 hours if you leave it off for a day or two.

3. Is it noisy for bedrooms? Do you have extra pump or is it gravity drained, I have heard pumps are noisy.

4. How much did it cost, was it comparable to A2W or much cheaper?

 

Thanks,

 

[Hanksy]

12 hours ago, severnside said:

@Hanksy This is interesting information, I was looking into this as well to convert whole house to A2A from Oil boiler. Could you help me with following questions

1. Does having multiple outdoor units affect startup current requirement e.g. too much load when all start at same time. Did it need planning permission?

2. How is the response time of heating? Does it heat up quickly in 1-2 hours if you leave it off for a day or two.

3. Is it noisy for bedrooms? Do you have extra pump or is it gravity drained, I have heard pumps are noisy.

4. How much did it cost, was it comparable to A2W or much cheaper?

 

Thanks,

 

Hi severnside I will try to answer your questions below

 

1. Start up is very low they are all inverter units and as small units biggest is 5kW when running all of them consume less than 1.5kW on a cold night so far. Pp depends on where you live here no issue but supplier should investigate all that for you if it’s needed and deal with it.

 

2.not turned it off since installed it’s on 24/7 at24 degrees so can’t really answer but it can kick out some heat if required so would not see it as an issue if off for awhile

 

3.we have gravity drained needs an external wall or a corner next to external wall pumps make a noise for about3-5seconds every 15-30mins I would find it annoying in a bedroom I think.

 

4. Total cost for all 4 units (these are top of the line units) inc power supplies etc etc was just under 10k from Midland Air Conditioning a very professional outfit they travel all over as well. I did get lower quotes but was lower spec kit and cheaper brands the company’s reminded me a bit of used car salesmen if you know what I mean. Also comes with 7 year warranty. service as domestic is only every 2 years as well with them (they do a lot of commercial installs eg Birmingham Bill ring etc).

 

hope that helps

[Hanksy]

Just a quick update now data is growing a couple of charts showing average cost per day V's night temps and one that inc kWh's used.

 

General observation - still very efficient overall running costs now average £0.89p per day (up from 79p/day) pellets would have averaged at 3x this cost so very pleased.

 

 

 

 

Edited October 26, 2021 by Hanksy

[Hanksy]

Also have a nice thermal pic of conservatory unit in operation

 

[SteamyTea]

Data is so much better than speculation.

[Iceverge]

@Hanksy What thermal camera are you using. I am planning on asking Santa! 

[Hanksy]

Hi Iceverge

 

 it’s a Flir E5 unit but I got it with a tweaked firmware so it has the resolution of a much more expensive one. Flir use the same imaging chip in all the pro units they just cripple their resolution with sw.

 

ebay had some modified ones a while back but haven’t checked recently though

Edited October 27, 2021 by Hanksy
Model number wrong

[Hanksy]

Quick update on running costs so far

 

Average/Day now £1.01 over 73 days

Actual running costs chart added (aug only last 2 weeks)

Currently saved over £90 by not using biomass boiler in 73 days

 

Still rally pleased with performance and costs

 

 

 

[SteamyTea]

2 minutes ago, Hanksy said:

Currently saved over £90 by not using biomass boiler in 73 days

 

On 26/10/2021 at 10:47, SteamyTea said:

Data is so much better than speculation.

Good stuff

[Mr Punter]

Things may have changed, but it was the case that you could not have A2A heat pumps as the main source of heating so if you specified them for your new build you would not pass SAP.

[SteamyTea]

5 minutes ago, Mr Punter said:

Things may have changed, but it was the case that you could not have A2A heat pumps as the main source of heating so if you specified them for your new build you would not pass SAP.

Wasn't it electrical resistance heating that caused problems.

@TerryE only has resistance heating.

[TerryE]

Yes, you can pass SAP with electric only heating (at least the 2016 Rev), but you really need a passive-class house to make the numbers work.

[Mr Punter]

On 01/11/2021 at 08:57, SteamyTea said:

Wasn't it electrical resistance heating that caused problems.

@TerryE only has resistance heating.

 

I don't think that the air to air heat pumps like @Hanksy has will work in SAP.  Resistance heating is fine but punitive.

[chrisgreen]

Hi All and thanks so much Hanksy for keeping us updated with your figures. We've taken the plunge and bought 2 x 5kw Daiken ac units to heat our large kitchen diner. Having them installed this week - will let you know how things go...

[chrisgreen]

Our installation was delayed a bit but should be in this week. Will be interesting to see what happens in this upcoming cold weather...

@Hanksy - how have your units been getting on?

 

 

 

[Hanksy]

Quick update now turned really cold here -2 last night 0 in day £4.65 total cost for the 24hrs

 

Still pleased overall 94days in now 

 

[Mr Punter]

Tasty looking spreadsheet and charts @Hanksy.

[Hanksy]

Latest update now really cold weather has hit us and some reasonable data points now in

 

Sweet spot for heating is 4 degrees and above. Once you hit 3 for any length of time elec usage rises sharply.At zero degrees pretty much all day and night running costs are  £5.45 day pellets would be £4.48.

 

Suspect its defrost cycles causing the increased usage. Plus point however is that as they are 4 separate units they defrost at different times so you don't notice any heating drop.

 

Running pellet boiler this week now to confirm usage of pellets is as I remember

 

Overall still way cheaper to run than pellets but looking to maximise savings so hybrid running may well be the best solution overall. That said wouldn't be upset running A2A full time if didn't have pellet boiler in.