Discussion ... ASHP(Air/Air) with Solar pv ....

Martyn1981

Coastalwatch said:

Hi Orbit, I'm interested to learn of your unfortunate experience as, prior to installing our first unit,I believe it was Mart who placed a post suggesting that installing multiple single splits was a more cost effective means of heating than precisely the setup you describe.

I had no knowledge of this until Marts post and do not know how or where the information came from. But as usual it would appear his views are well founded!

Cheers CW, you've jogged my memory. Yes, as I recall I was surprised that a multi-split option was more expensive than two singles. I had a nice chat with the company, and the larger outside units are a lot more, plus the multi-split has to be hardwired, unlike the smaller units which can plug in to a socket (up to one per ring main). So additional work, materials and costs for the sparkie.

I think the numbers look better for 3+ units off a multi-split, but that's a bigger project, and may not be something for many domestic situations.

Oh, also, you need to consider the pipework runs, which may be shorter and simpler with two units, plus a condensate pump depending on layout too. Loads of stuff that I simply hadn't considered / known / understood looking in from the outside, before things 'got real'.

ForestBluebells

im struggling to make my final decision as usual. Do I go with the installer who has lots of reviews but more expensive or the cheaper one with still good reviews but less of them.  The latter is also an electrician.

Do people use the apps for their units or just the remote? Do you set it on a schedule or just turn it on and off manually on the remote?  I am not sure the ones im looking at have a very good app but not sure how needed it is.  i did like the look of the apps which have more functionality including energy consumption figures but i guess once ive seen the data thats it i dont need it anymore and i could work it out from my daily usage anyway. 

Trying to decide between mitsubishi heavy industries, mitsubishi electric or panasonic, also had a quote for daikin but it was a lot more. argh decisions 

ispookie666

@ForestBluebells Easy - Mitsubishi electric and the installer who is an electrician 
Remote is good, but both Daikin and Mitsi have good cloud connectivity.  I have integrated mine into Home Assistant.  

Coastalwatch

@Forestbluebells, not having an App we use the remote only by setting programs as seasons dictate and switching on and off casually as the need arises. Normally winter settings are programmed in such as coming on at 4am to 9.30am  then again from 4pm to 10pm. Summer is mostly covered by cooling as and when required.

We did consider the App but doubt we should use but a couple of times a year when away on hols etc so manage quite well without. No doubt others will have different views and hopefully post to share their experience too.

Meatballs

orbit500 said:

ispookie666 said:

ForestBluebells said:

That’s great thank you. I think the ecodan is air to be water and I’m looking air to air but I’ll keep digging. Just so overwhelming trying to decide. It’s now trying to decide if the most energy efficient models are worth paying an extra £600 per unit for 

Mitsubishi would be the go to for me followed by Daikin. They usually come with 5 year warranty and preferably R32. You could look into multisplit VRF if £ is not limiting.  

I’d be very wary of multi split VRF following my experience. Pairing a large outdoor unit with multiple indoors often means the modulation floor is too high for a single unit to achieve a reasonable efficiency.
I have a 14kW outdoor Toshiba VRF and 4 indoors, 2x2.5 and 2x3.5. Running a single indoor in heat gives a measured COP of 1.7 which is dreadful. Running the whole system gets 3.1 which is just acceptable but way worse than the best 1:1 splits and I don’t want to heat the bedrooms at the same time.
Added to which the installer wasn’t aware that VRFs need indoor power to each unit rather than a feed from the outdoor.
The units are noisier than regular splits as they run oil recovery cycles regularly.
Last straw was it losing all its gas with no cause identified.
I’ve thrown the towel in and demanding he replace them with 1:1 splits. He specifically recommended the VRF for single unit efficiency. 
My cheap 1:1 in my old house ran at COP 4 for 11 years without fault and cost under half per unit.

Hmm this is a bit concerning as I'm looking to install A2A upstairs off a large multisplit (Daikin 5MXM). I doubt I could convince the wife to have multiple singles dotted around the outside of the house. 

The 1.7 COP for a single unit seems particularly poor though?

zeupater

ForestBluebells said:

im struggling to make my final decision as usual. Do I go with the installer who has lots of reviews but more expensive or the cheaper one with still good reviews but less of them.  The latter is also an electrician.

Do people use the apps for their units or just the remote? Do you set it on a schedule or just turn it on and off manually on the remote?  I am not sure the ones im looking at have a very good app but not sure how needed it is.  i did like the look of the apps which have more functionality including energy consumption figures but i guess once ive seen the data thats it i dont need it anymore and i could work it out from my daily usage anyway. 

Trying to decide between mitsubishi heavy industries, mitsubishi electric or panasonic, also had a quote for daikin but it was a lot more. argh decisions 

Hi

We used an installer I was familiar with from past work experience that has been around for years and has fitted literally thousands of units, mainly in industrial & commercial premises, but also plenty of systems in domestic setting too.

We actually know someone (socially) that owns a business that installs & services heat-pumps, the issue there came down to level of experience, willingness to fit literally any make & dealing with a 'friend' with all of the potential downside that come from it, so considered it a no-no.

The installer we used would only recommend & install certain makes and this was related to their own vast experience in servicing & repairs ... I liked the performance range of the Toshiba Daiseikai range from an efficiency viewpoint & MrsZ preferred a couple of the LG offerings at the time due to 'aesthetics', which held up the decision for a while ... when the installer said they wouldn't offer LG (for some reason based on their experience) and would price the Daiseikai unit more favourably if we were flexible around when a 1/2 day in their schedule became free (most of their installations take multiple days) it became obvious what the decision was ... she now thinks that the 'aesthetics' aspect of the LG unit would make it stand out more while the unit we have simply blends in!

On installers, if you're looking at a split unit, make sure that they're f-gas approved as well as able to sign off any electrical work.

Apps .... we decided to not bother, but if you're looking to integrate with home automation, there are some units that can reproduce various remote controls to integrate heat-pumps. I considered setting up automation between the heat-pump and PV spare generation, but after years of use we've not bothered yet and are pretty happy.

Schedules ... I set one up to attempt to ramp heat output to anticipated PV generation, but it became a pain to modify as day lengths changed etc ... tend to use the delayed/timed off function quite often, but it's mainly controlled via the remote using manual variation (fan/temperature/On-Off etc), which after a little experience becomes very simple to gauge.

HTH - Z  

zeupater

Hi

PV producing 790W, heatpump kicking out ~2.5kW.t, heavy frost still on the ground & my feet are quite toasty ... and all of this cozyness is costing ..... <drum roll>  .... well, nothing at the moment actually ....

(Sorry - Needed a break from the insanity elsewhere!)

Z

mickyduck55

zeupater said:

Hi

PV producing 790W, heatpump kicking out ~2.5kW.t, heavy frost still on the ground & my feet are quite toasty ... and all of this cozyness is costing ..... <drum roll>  .... well, nothing at the moment actually ....

(Sorry - Needed a break from the insanity elsewhere!)

Z

It was similar here.. but now dark so batteries down to 55% (about 4 kWh useable), will top them up on go faster starting at 20:30.. so not quite nothing but close.  The Air to Air which was initially bought to cool my home in summer when I have a lot of spare solar has been used more for heating in the two winters its been installed. Im sure without reaching for a calculator the ROI is not good but Im happy with my daily running cost... Dual fuel standing order less than £35 a month with a balance of over £400, yes that has been helped by the the government supplement, be smug Z ,, so am I 

Screwdriva

Sorry for the tangential question but is it possible to heat a wet underfloor heating manifold using Air-Air heat pumps?

I'm assuming hot water needs would need to be met via a cylinder with built in heat pump (Vaillant, Daiken etc.)

zeupater

Screwdriva said:

Sorry for the tangential question but is it possible to heat a wet underfloor heating manifold using Air-Air heat pumps?

I'm assuming hot water needs would need to be met via a cylinder with built in heat pump (Vaillant, Daiken etc.)

Hi

Possible? - depending on your engineering/DIY skillset, yes in theory, but have to be pretty insane or have plenty of time on your hands to try to design & build a heat exchange unit from scratch in order to strip the heat from the warm airflow and dump it into water in anywhere near an efficient way ... effectively what you'd be trying to do is invent an ASHP, problem is that it's already been done, that's what ASHP's are - there are also small integrated units just for DHW & bathroom UFH  etc ... random example ...

HTH - Z