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

Martyn1981

Transit van in driveway, and two guys merrily drilling holes in wall, in conservatory. Looking good, fingers crossed for evening heat top up if needed.

If all goes well, I'll have a super quiet LG 3.5kW ASHP, and be down approx £1,100.

Martyn1981

Many thanks to Z and ASavvyBuyer for maintaining my interest despite the many failures to obtain any call backs from companies. I finally hit the jackpot with a S. Wales company whose website simply states prices (inclusive of VAT and delivery) and also a standard install price.

The reduction in overall gas consumption (even allowing for gas burnt to replace leccy) for domestic heating, and a further reduction by directing heating only to one or two rooms during the daytime, will hopefully reduce my carbon footprint a little bit more.

Martyn1981

All done, now 'cooking on gas'.

Lots of sun (damn shame) so perhaps not best example, but set to 30C, in 20 mins the conservatory went from 19C to 26C and the living room (with hallway door wide open) went from 18.9C to 20.1C. Now dialed back to 25C to find the balance, but could of course close the living room door and trap more heat if necessary.

Will turn off GCH burn this evening, but TBH such a nice day, and so much solar gain, that probably not needed anyway, so might have to wait for a colder day next week, or October, to test properly.

zeupater

Martyn1981 wrote: »

All done, now 'cooking on gas'.

Lots of sun (damn shame) so perhaps not best example, but set to 30C, in 20 mins the conservatory went from 19C to 26C and the living room (with hallway door wide open) went from 18.9C to 20.1C. Now dialed back to 25C to find the balance, but could of course close the living room door and trap more heat if necessary.

Will turn off GCH burn this evening, but TBH such a nice day, and so much solar gain, that probably not needed anyway, so might have to wait for a colder day next week, or October, to test properly.

Hi

Decent amount of sunshine here today so guess you've been playing with getting free heat into the house too; so how's the learning process going ? ... :cool:

Z

Martyn1981

zeupater wrote: »

Hi

Decent amount of sunshine here today so guess you've been playing with getting free heat into the house too; so how's the learning process going ? ... :cool:

Z

Hiya Z, loads of mistakes, so excellent learning process.

Firstly, and I bet you spotted this mistake, no need to set the temp higher than needed, it's going to get there regardless, so now use 21C and let the open door from conservatory to living room (and open door to hallway) do all the work.

Secondly, way too much sun. Never thought I'd complain about that. Deliberately left heating off completely Saturday, so Sunday morning popped on the ASHP and warmed things up lovely in no time, and switched off ....... then the sun heated the conservatory to 27C and I had to open a window! Not a stupid mistake, just a wrong weather day to have a play.

Popped it on about 7.50 this morning as it's sunny and generation went 1kW+, but the forecast says grey all day from 10am, so both rooms sitting at 21C already with hallway door wide open. Today won't be cold, so I'll probably stop it soon and export the leccy, rather than waste any.


Forgot to say, went for the conservatory install in the end due to a small surprise. After the room was renovated it was very wet as it had rained during the roof install, so I wiped it down then put the 170W de-humidifier in it.

Perhaps you could tell me if I've got this wrong, but the temp went up far more than I expected:

Room 2.4m by 2.4m with ceiling also 2.4m (2.1m-2.7m). DG roof, two brick walls, one wood and DG wall to living room, one DG UPVC doors/window to garden.

Outside temp was a constant 10.5C, sun constant(ish) with grey cloud and 600W generation, no direct sunlight. The room went from 14C to 18C in just over 2hrs, then the sun came out and gen shot up to 2kW+ so experiment ended.

Is that possible a 4C temp rise in a 2.4m3 room 'just' from 170W for 2 to 2.5hrs?

Lastly, I'm shocked how well it tracks temp, I put a monitor on the opposite wall and they seem to match perfectly. Also the indoor unit is very quiet, unless fan speed dialed up high, but the outside unit is quite a shock, it's relatively pleasant, and I 'lost it' at about 10m, so happy with that.


Next stage, we have insulating honeycomb blinds being installed next week to all external glass. Hopefully these will greatly reduce heat gain/loss as required.

Like ASB, I'll be monitoring gas consumption across the heating months, but I only have quarterly readings (bit of an oversight), but should supply some information for pondering, I'm sure.

ASavvyBuyer

Hi Mart

Good to see it is going well. We were also supprised at how quiet the outside unit is when running (compared to the comments made by a few at how noisy they could be) I expect it is because of the models of ASHP we have bought.

As our solar PV panels are West facing, we have found the programming for different times of day very useful, so that as the sun starts to shine directly on them, we automatically up the setting on the ASHP to make best use of the power available (for free). Also, leaving the door from the lounge to the rest of the house open more often now, with the ASHP still maintaining a reasonable temperture in the lounge.

With the better days, we have found our gas use, for the last few days, is now less than a quarter of what it was at the same time last year.

zeupater

Martyn1981 wrote: »

... Perhaps you could tell me if I've got this wrong, but the temp went up far more than I expected:

Room 2.4m by 2.4m with ceiling also 2.4m (2.1m-2.7m). DG roof, two brick walls, one wood and DG wall to living room, one DG UPVC doors/window to garden.

Outside temp was a constant 10.5C, sun constant(ish) with grey cloud and 600W generation, no direct sunlight. The room went from 14C to 18C in just over 2hrs, then the sun came out and gen shot up to 2kW+ so experiment ended.

Is that possible a 4C temp rise in a 2.4m3 room 'just' from 170W for 2 to 2.5hrs? ...

Hi

Don't forget that what the ~170W is providing after applying the appropriate COP multiplication is additional to the normal solar gain in the conservatory at the level of insolation at the time, with this being subjected to relatively little thermal mass in the glass or wood which is close to the heat-source, so I'm not surprised ....

It may be counter-intuitive, but when sitting in same room as the heat-pump you'll find it may actually 'feel' warmer if the fan speed is reduced ... although this may result in a lower heat provision & space temperature, the reduction in air movement (no matter which direction the airflow) has a noticeable 'warmth comfort' effect which actually makes you feel warmer - think sitting in a draught! ... of course, when you need the heat to flow from the conservatory into the house it may be better to stir the air up more vigorously, but remember the impact of running the fans at full speed for extended periods on the bearings!.

Have fun ...

HTH
Z

Martyn1981

Hiya guys, cheers for all the help over the years.

Can't believe I'm going to say this, but too much sunshine here. The promised grey didn't arrive, so the conservatory is around 26C from solar gain, when I was expecting no direct solar gain but enough generation to run the HP. But I shouldn't complain.

Z, you are right about the 'stirring'. The hot conservatory does leech through the house, but very slowly, however, the HP and fan are much different. The fins are pointed towards the living room, and the door opens towards it (and past it) creating a funnel effect.

As per earlier comments, the living room temp rose much faster than I expected. Also noticed a warm draft in the kitchen, as there is a small window (old hatch now with DG unit in it) which also opens with the 'hole' facing the blower. In fact the window and door almost touch and create excellent air directors (is that a term?).

I'm still a bit unsure about 'wasting' leccy to cool the conservatory as and when A/C is needed* but have high hopes that the blinds will reflect a lot of the solar heat, and hopefully trap the worst heat. Also important to point out that prior experience seems to show that internal temps become unbearable from the early afternoon, by which time the conservatory roof will be losing direct solar gain, but my E/W PV will still be chucking out the watts.

*This is rare, perhaps one week per year, and not at all last year. Normally just opening doors and windows is enough, but if ambient is 26C (for example) and thermal mass is maxing out, then AC will be enjoyed, very much.

Wifey is very pleased, partly because the living room is far more friendly when open to the conservatory, and the garden can be enjoyed (Magnolia in full white bloom), but mostly because she hopes (?) that I'll stop going on about it now!

Martyn1981

Hooray hooray for a heat pump day. Might get lucky today, it's pretty cold outside (10C) and forecast is a coldish grey day, but the sun is threatening to break through now ...... damn!

[Update - 7:30am Piggin sun has come out, conservatory already 20C from solar gain. Just can't catch a break! ...... ;-) M.]

Long term forecast suggests coldish and grey from next Tuesday for 3 or 4 days so one can only hope! Otherwise it'll be a 6 month wait unless we get a monster hot summer, though I've noticed a dry sunny April seems to lead to poor summers?

@ASB, been meaning to tell you this, if it helps with your year on year comparisons, our 1st qtr gas consumptions here have been:
2016 352 units
2017 357 units

suggesting the two years are roughly comparable.

ASavvyBuyer

Martyn1981 wrote: »

@ASB, been meaning to tell you this, if it helps with your year on year comparisons, our 1st qtr gas consumptions here have been:
2016 352 units
2017 357 units

suggesting the two years are roughly comparable.

Multiplying those figure by an average of 11.1 to get kWh that equates to about 3,940kWh of gas.

Our figures for the same quarters (Jan-March) were:
2016 6,423 kWh
2017 2,804 kWh

So through those colder months, a saving of just over 56% by using the heat pump.

This month is forecast to be an even greater % saving, as currently forecast to be less than 200 kWh of gas, compared to just over 900 kWh last April.