More Renewable Shenanigans at Stinsy Towers

[Stinsy]

Right, what with roasting hot weather upon us and Nowty installing several units before I've gotten my first one installed, I thought I'd better get on with it. Hoiked the 43kg lump onto my shoulder climbed the ladder an plonked it onto the mount.

Quite stressful but it held a vacuum and seems to work.









Also I bought some good quality allen keys recently having put up with several cheap/nasty sets for many years. It was good to put them to use!

[Oldgreybeard]

Hoiked the 43kg lump onto my shoulder climbed the ladder an plonked it onto the mount.

That's pretty heroic! I struggled getting a 28kg outdoor unit up a ladder . . .

Timing looks good given we're set for a few more days of this hot weather.

[AE-NMidlands]

Hoiked the 43kg lump onto my shoulder climbed the ladder an plonked it onto the mount.

That's pretty heroic! I struggled getting a 28kg outdoor unit up a ladder . . .

Timing looks good given we're set for a few more days of this hot weather.

A baptism of fire!

[AGT]

Did you use a torque wrench/spanner, any flange oil/ locktite?

Always interested in how others achieve a successful installation

[Stinsy]

I’ve seen a few (American) YouTube videos where people use thread lock on the mating faces which completely undermines the engineering design of the metal-to-metal joint. The mating faces must be perfectly clean.

I did put a teeny bit of oil on the threads and the back of the flange so that the nut slid nicely and applied the correct amount of force to the mating surfaces. I didn’t use a torque wrench, I trust my “feel”, I’m not a “tighter is better, crank it as hard as you can” kind of person.

[Oldgreybeard]

I’ve seen a few (American) YouTube videos where people use thread lock on the mating faces which completely undermines the engineering design of the metal-to-metal joint. The mating faces must be perfectly clean.

I did put a teeny bit of oil on the threads and the back of the flange so that the nut slid nicely and applied the correct amount of force to the mating surfaces. I didn’t use a torque wrench, I trust my “feel”, I’m not a “tighter is better, crank it as hard as you can” kind of person.

I did the same, just a smear of vacuum pump oil on the thing and then tightened them up. The torque setting was a lot greater than I would have thought, TBH. I did it by feel using the length of the spanners and my calibrated arms (!), roughly checked by previously pulling a spring balance. Even then it wasn't tight enough as one joint had a very tiny leak, not enough to show after half an hour at vacuum but enough for the thing to lose about half its gas over a three year period. The suspect joint could be tightened around another half turn when checked by the guy that re-gassed it.

[Stinsy]

Right!

The AC has been running for 5 days now during an unusually hot spell so I'm in a good position to do a bit of a review. I haven't even tried the heating setting because it has been too warm and I don't think I'd learn anything.

1) Can a single "7kW" AC unit cool a 5-bed house on its own?

YES!

My unit is mounted in the upstairs hallway and it fires straight down the stairs. You can feel a slight very-cool breeze at the bottom of the stairs. this cools the living-room (open door opposite the stairs) nicely, the dining-room and kitchen notsomuch. However if you come in from the garden through the patio doors in the dining-room you immediately notice how cool the dining room is. In "whole house" mode the upstairs landing is uncomfortably cold, lovely if you've worked up a sweat sweeping the patio in temperatures over 30℃, or have been working in the loft where it is over 45℃, but you wouldn't want to spend much time there.

2) Is it noisy?

A bit.

I've seen heat pumps and AC units where the outside unit is so quiet you cannot tell it is running standing right next to it. This isn't that. Run on a sensible setting (target temperature 19℃ inside fan set on "quiet") the outside unit is about as loud as a fridge freezer with very similar sound profile, my fish tank pumps make an identical type/amount of noise. When I crank it to the max (inside unit set to 16℃ inside fan set to "turbo") the outside unit gets much louder and the sound profile changes. The sound profile is a bit like a Cessna 182 on full chat just after takeoff but quieter obviously, just loud enough to be annoying. Be aware that it is VERY quiet where I live, there is zero road noise and I can hear the West Coast Mainline trains 3 miles away.

The inside unit is pretty quiet, it shifts a lot of air. You cannot hear the fan motor at all just the moving air.

3) How much power does it use?

If I set the inside unit to 19℃ and its fan to "quiet" it uses about 750W.
If I set the inside unit to 16℃ and it's fan to "turbo" it uses about 1400W.
If I set it to "ECO" it changes the temperature to 27 and it cycles the outside unit on for 5 minutes, off for 5 minutes. (I don't think I'll use that setting).

I know a few chaps have this make of AC unit (if a different model) I'd be interested to know your findings.

[Tinbum]

I've just bought a KFR531 and fitted it on the landing and am finding much the same as you except that the outside unit is virtually silent even on full bore. I've also one the same as yours on order but it's got lost in transit!!

[Oldgreybeard]

We have a 2.5kW Toshiba that is now about 3 years old. The outdoor unit is very quiet, hard to tell it's on sometimes without checking to see if there are drips coming out of the condensate pipe. The indoor unit makes some air movement noise when on full chat, but is very, very quiet on eco mode. It's in our bedroom, and we can leave it on at night, set to 20°C and eco mode, and it's barely noticeable - I have to listen hard to hear it.

Power consumption initially is around 700W, but this quickly drops to around 250W to 300W once the room is down to the set temperature. I've been running the house effectively "off grid" this week, with all the sunny weather, and leaving the aircon on all the time increases our night time energy usage by around 2kWh to 3kWh, not enough to worry about, as it's only about 10% to 15% of the battery capacity.

I did specifically choose this Toshiba model because all the reviews I read mentioned how quiet it was, and I needed that as it's fitted in our bedroom. As mentioned before, if I leave the bedroom door wide open then the cool air flows down the stairs and cools most of the ground floor. The house is notably warmer first thing in the morning when our bedroom door has been shut all night, even with the underfloor cooling running downstairs. It seems that the hall and upstairs landing are the areas that end up with all the warm air from downstairs.

[Stinsy]

Winter update!

Those who've been following this thread will know that back in the summer I copied Nowty and installed a mini-split AC / A2A HP in my house. I went for the big boy "7kW" model intending that it cool our entire 5-bed house in summer and augment the GCH in winter. Now if you scroll up you'll see my review of it in cooling mode. However I've not been able to test it properly in heating mode until now...

Shoulder months:

October and November have been unseasonably warm this year. I benefit from the Octopus Go 0230-0630 cheap period. I schedule the A2A unit to come on at 0500 and turn off at 2000 set to 19℃ and the fan speed to "Auto". The first thing I noticed is that the A2A really doesn't "short cycle". Initially it would turn on at 5am reach temperature and turn off between 6 and 630am, then come on again at 4pm-ish. However as the weather has gotten colder it has introduced an additional "cycle" midday-ish. I'm confident that a smaller unit (eg the "3.5kW") would have been able to maintain a steady temperature running low-and-slow all day in these mild, shoulder-month, conditions.

Power consumption has been the same as cooling mode: c. 1500W for 5-10 mins followed by c. 750W for the rest of the cycle.

Cold Weather

After the aforementioned unseasonably mild October/November, 1 week into December and winter is here. Outside temperatures are -6℃ overnight and subzero all day. I've been very conscious that sucking heat out of 5-10℃ outside air and spurting out 45℃ air into your house is a doddle for a HP. The real test comes in winter!

Stuff has gotten more complex to measure because the GCH is also running and it is difficult/impossible to know how much heat is coming from which at any given moment. However the A2A is scheduled to come on at 5am along with the oil-filled rads in each bedroom and kitchen, then at 0630 (when my cheap slot ends) the oil-filled turn off and the GCH kicks in. The A2A is then set to 19℃ all day while the GCH is set to 16℃, in the evening the GCH cranks up to 18℃. Finally at 2130 everything turns off.

The most difficult thing to measure is the heat output of the A2A. Anecdotally, if you stand in front of it, you are hit by a wall of heat. And this warm air circulates nicely around the upstairs and the thermostat downstairs by the front door measures increasing temperatures even with other sources of heat turned off. The amount of heat output feels consistent right down to the lowest outdoor temperatures encountered to-date (-6℃ is as cold as it gets around here).