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

rogerblack

WestonDave wrote: »

Its also the case that these systems aren't easy to retrofit to existing homes as you need to get the air ducting into most if not all rooms. However as a concept (coupling a MVHR system to an ASHP) it seems to have some legs - it needs someone to make a unit which is more designed for supplementary heating coupled to solar than the current offerings from Genvex which seem to be designed as total heating solutions.

This is basically what passivehaus almost is.
Though there is even more emphasis on insulation.
Insulate, air-seal, proper heat recovery ventilation, and you go a long way - even before the heatpump.

WestonDave

I agree Roger - however in a 1950's house the chance of getting air tight and insulated enough to be Passivhaus isn't great so hypothetically getting as close a possible and having a bit of a free boost from the spare solar might just push it over the edge.

In our case the drivers are somewhat different my OH and we think at least one of the kids gets quite bad hayfever, plus we get a bit of condensation due to lack of ventilation at present. As we are going to instal a new ensuite which will need ventilation the option of improving the whole house ventilation and providing air filtration at the same time seems sensible to at least investigate. In financial terms though its far from clear whether paying another £5k for an ASHP equipped system is worth it compared to a couple of hundred quid for a small conventional after heater in the ducting that we can use for surplus solar. (We don't have an immersion to dump to)

zeupater

WestonDave wrote: »

... we think at least one of the kids gets quite bad hayfever, plus we get a bit of condensation due to lack of ventilation at present. As we are going to instal a new ensuite which will need ventilation the option of improving the whole house ventilation and providing air filtration at the same time seems sensible to at least investigate. In financial terms though its far from clear whether paying another £5k for an ASHP equipped system is worth it compared to a couple of hundred quid for a small conventional after heater in the ducting that we can use for surplus solar. (We don't have an immersion to dump to)

Hi Dave

On the MHRV/condensation front, you might find that a small trickle heat recovery ventilation unit which recovers ~50%/70% of extracted heat and is priced at around £300 would be an alternative, especially if you're looking at changing a bathroom around anyway ... they're not whole house, but I know someone who has installed one in a bathroom and it stopped all window condensation upstairs, so it might work for you too ....

We have both a mobile aircon unit (which can be used in dehumidifier mode) and an old dehumidifier for the times when internal humidity becomes high, which is pretty rare anyway because of the effect of the log-burner - during the recent warm period we were running the aircon and removing somewhat over 10litres of water from the air inside the house each day .... at least MrsZ has plenty of water which wont clog the iron up with scale ...

Anyway, £5k for a combined MHRV/Heat-pump unit looks very expensive ... an alternative would be ~£1000 MHRV, ~£800 for an Air/Air heat-pump and whatever the installation cost would be (£500-£1000?) ... you'd likely get much better quality/brand kit and achieve better overall performance ....

Have you thought about these options ?

HTH
Z

WestonDave

Hi Z - All options are in play at the moment!

We're pretty set on the full house system because we have one off chance during this work to make it possible in a retro fit and we'd get the filtration benefits.

I agree that with a relatively recent mains gas CH system a Genvex system doesn't pay because the free solar that we could use would struggle to pay the opportunity cost on the capital outlay. Separated systems would be better financially but you'd lose the aesthetics of the Genvex which has all the heat pump gubbins hidden in the loft unit rather than an outside fan unit with the planning requirements and noise nuisance to neighbours.

That being the case the simple MVHR with a cheap after heater on the duct that we can dump solar to is looking the best option at present all considered with maybe a combined unit coming back into play if we have to change the gas boiler and the economics make it worthwhile at that point. Of course if I can track down a loft based heat pump unit to sit on the ducting then I might well be back to seperated systems again.

We've got to clear the junk from the room we'll be using and the loft before we can actually start so there's time for new options to hit the market.

Thanks for the help - its useful to bat things about to clarify thinking!

Martyn1981

Hiya Zeup, just read this on the other thread:

zeupater wrote: »

We'll be going down the route of a high COP (/SCOP) air/air heatpump for soaking up excess generation in the shoulder months of the year, effectively multiplying the excess by a considerable factor .... the only issue at the moment is trying to convince MrsZ that the efficiency of some models outweighs the aesthetics of others .... :D ... but that's a story on another thread ...

HTH
Z

Can I ask what you've found out so far? My progress has fallen flat as nobody got back to me, and I bust some ribs trying to get fit (ironic!). Last stage I got too was that the kit will probably cost about £500 per system, with dual systems costing more than double (probably due to production numbers). Not sure how much install will be, have you any figures, is £200 too low an estimate?

Regarding aesthetics have you heard of the LG 'Cool Art' range, where you can put pictures in/on them? (Just an example link, not a company recommendation.)

http://www.youtube.com/watch?v=Lv04hyNmeJA

Really should get back to this little project. I believe it's more efficient, and greener, but doubt it will work out profitable for me, but think it's worth doing anyway. Happy to mooch off of your research though!

Mart.

zeupater

Martyn1981 wrote: »

Hiya Zeup, just read this on the other thread:



Can I ask what you've found out so far? My progress has fallen flat as nobody got back to me, and I bust some ribs trying to get fit (ironic!). Last stage I got too was that the kit will probably cost about £500 per system, with dual systems costing more than double (probably due to production numbers). Not sure how much install will be, have you any figures, is £200 too low an estimate?

Regarding aesthetics have you heard of the LG 'Cool Art' range, where you can put pictures in/on them? (Just an example link, not a company recommendation.)

http://www.youtube.com/watch?v=Lv04hyNmeJA

Really should get back to this little project. I believe it's more efficient, and greener, but doubt it will work out profitable for me, but think it's worth doing anyway. Happy to mooch off of your research though!

Mart.

Hi

Seems like you're starting to sound like MrsZ as those LG units and the mirror version are on her aesthetics list (pretty near the top !), but they're not on my efficiency list ....

After quite a bit of research, I'm tending to steer towards something like the Panas0nic / T0shiba high spec units at the moment. Looking at the performance specs, T0shiba seem to have the lowest low power setting, around 160W, with better COP & SCOP and what seems to be a better industry reputation, but Panas0nic has a decent corporate image to protect and their units have the potential for WiFi control via android and some other 'geeky stuff' which could be useful at a later date, or maybe not as the case may be ... but stay clear of their flagship range as they're about 3x the price for very little additional benefit ....

I've looked at multi-split unit combinations which, according to manufacturer's configuration modelling S/W claim to raise a SCOP of ~5.x for a single unit to ~6.0 for multi, but they work out substantially more expensive than I believe they should (market demand, margins, and all that stuff !). Initial prices for a decent spec setup fully installed & commissioned single split unit seem to be pretty consistent, with the installers I've talked to targeting around £1200-£1500 (inclusive), with install only prices coming in at £300-£500 for between a couple of hours & 1/2day ... of course, they're basing everything on what they want as a margin, not what I am willing to pay .... ..... but that's for the negotiation stage, not now - a couple more weeks and the time to negotiate on an aircon unit might be about right

The problem with talking to anyone in this sector seems to be that they really don't want to bother with the domestic sector and just want to concentrate on commercial .... you can't even get anyone to ring back on a sales enquiry without waiting for days, or weeks ....

A couple of months ago I spoke to a friend who lives in Spain for at least half the year ... I know that the air conditioning market in the UK is comparatively small, but, considering that the equipment would go through the same distribution chain, the margins in the UK must be huge ... you can get one fully installed there for less than one installer claimed to pay his wholesaler .... yes, either he's a mug or he thought I was !! :cool:

Let you all know what we decide, but the way it's going aesthetics currently has the 'upper hand' and that's why the going is slow !! ...

HTH
Z

1961Nick

For the past 10 years we've been heating the conservatory with 2 electric heaters, a combined 5kW. Since installing pv & the accompanying energy monitor, it became apparent just how much this arrangement was costing to run!

Last November I had a Fujitsu split system heat pump installed. It's output is 5.2kWh for an input of 1.3kWh so 4x. Most of the time it runs around 400w to maintain a temperature of 22C. With the conservatory doors to the house open & the kitchen door into the hall, it manages to keep the daytime temperature of the rest of the house above 19C & prevent the CH coming on. It's clearly saving gas as well as electricity. Even at this time of year when generation is low, it often runs free.

The only downside is that it's not aesthetically pleasing to look at, particularly as the pipework is in some pretty heavy duty trunking. Not really a problem for a conservatory but anywhere else in the house, you'd want the pipes going straight out of the back & possibly a smaller unit (4kWh).

Including installation it cost just less than £1000. Energy savings are hard to calculate because I hadn't banked on saving gas & also the conservatory is now open to the house all the time we're at home.

tunnel

Hmm, looks like Mart may be dipping his hand in his pocket sometime soon me thinks!!
Go on Mart.....you know you want to...lol

zeupater

Hi All

There's a strong rumour that a shiny new arrival is expected at the Z household before the weekend .... I wonder what it will be ? ... :think:

HTH :shhh:
Z

theboylard

Pics please Z!