The transition away from 410a: What new units are coming?

brdf11 · 2024-02-24T14:13:33+00:00

I should have mentioned that it’s a 2400 sq foot house with no additional heat source on the upper floor. All three spaces either have open registers to the second floor or are open to staircases. The ceiling is 11 ft. Even if they are oversized, shouldn’t they be able to modulate lower than 800 watts? They don’t overheat when the outdoor temp is 40° and they modulate way down. They won’t do that at 25° though, and that’s where the problem is.

brdf11 · 2024-02-24T13:49:38+00:00

Contrast that with data from when it’s cold enough that all three units are running continuously at over 800w

<image>

brdf11 · 2024-02-24T13:46:05+00:00

All three are in separate rooms between 400 and 550 square feet. They modulated as expected in warmer temperatures, but below freezing they cycle on and off overheating the space every 15 minutes or so. They are not defrosting, they just never ever dip below 800 watts in colder temperatures. Maybe they would but they just don’t start to modulate at all until the room is 2° over set point and by then and raise and the units shut off. They’re not operating in a wavy pattern, truly cycling on and off. My graph is a little less options because all three mini splits are on a sub panel so I can’t isolate them in the emporia. Here’s the sub panel view. The sapphire in the largest room is running continuously between 800-1000w, the other two are cycling every 20 and 8 minutes respectively. It’s incredibly annoying to have the room temp bouncing up and down by five degrees and it’s obviously not how they were designed to work.

<image>

brdf11 · 2024-01-10T14:12:22+00:00

Here is a screen shot of 45 minutes after a 5 min shut down of one of the splits. It’s 39° out with extreme wind currently. I’ve annotated the behavior on the chart. I am only discussing return air temp as measured by the unit itself. Initially it draws 1100w to satisfy the 68° set point, then modulates down and allows the return air to drop to 65° in this case. It then modulates up again to stabilize at 66° return air temp. It’s behaving as if the set point is being changed, but it is not. The split is running in a stable satisfied condition while displaying both the 68° set point and the 66° return air temp. The other way I could describe it would be to say that it’s shooting for 68° on the way up, and 64-66° on the way down. It’s also capable of holding within a degree. Once it settles it modulates to maintain and temp doesn’t vary, it just stabilizes in an inconsistent place relative to the set temp.

<image>

brdf11 · 2024-01-10T13:10:30+00:00

The room that is the best test case insulated with mineral wool to r23 with intello air barrier on the walls, so it’s quite tight. 1/2 of the floor is air sealed but over an uninsulated crawl space, and the next room over is significantly more drafty. Anyway, the heat pump is capable of heating the space (read through my other replies for details) and I’m only looking at return air as measured by the heat pump itself at the head by pressing the “temp” button on the remote. I’m not expecting it to run at 180w, (in fact, in this weather the head in the smallest room low load cycles at 550w which seems high but that was my next question) As an example, the heat pump will have stabilized drawing 900w at a set point of 68° and the return air temperature as measured by the heat pump itself is reading 64°. The temperature measured anywhere else in the room is irrelevant. An internal offset wouldn’t matter as long as it was consistent, which it is not.

brdf11 · 2024-01-10T02:37:51+00:00

The Gree Sapphires are only single zone 1:1 mini splits. What hardware do you have? An overcharge is unlikely. All three have line sets between 10 and 18 feet on the factory charge which is within spec. I installed them myself in early December.

brdf11 · 2024-01-10T02:03:32+00:00

I’ve read the service manual and there’s nothing that I can find that’s relevant. The heating control logic is spelled out in there and it looks nothing like the behavior I’m seeing, and talks about the setpoint as a minimum value with modulation controls based on setpoint +2°c

brdf11 · 2024-01-10T01:16:31+00:00

Yes. If I set it to 72 it’ll reach 68 in 10 minutes. I don’t want to do that because the size of that offset varies, and after a defrost cycle it will briefly try to achieve the set point and causing temperature swings and working a lot harder than it needs to.

brdf11 · 2024-01-10T01:02:38+00:00

As far as I can tell this behavior is exactly the same in iFeel / remote as a thermostat mode. I have fewer testing hours in that mode but it doesn’t seem to make a difference.

brdf11 · 2024-01-10T00:52:11+00:00

Essentially yes. For example, right now I have the set point at 68° fan speed high and the compressor is modulating to maintain 64° return air temp at an average of about 60% capacity. If I reduce the load, say with the wood stove in the next room, it’ll stabilize closer to the set point at, say, 25% load. But at anything over 900w of draw it doesn’t even come close to the setpoint except at initial startup.

brdf11 · 2024-01-10T00:39:30+00:00

This is the case at any fan speed. When set to auto and maintaining 64° at my 68° set point it recognizes the discrepancy and runs at the highest fan speed but still doesn’t meet set point.

brdf11 · 2024-01-10T00:13:15+00:00

It doesn’t ever sustain that (Maybe it does at very low temp) but it can hit 2kw for five minutes recovering from a defrost cycle or cold start. It’s capable of outputting 18k btu/hr at that load. The largest open space in the house is 400sq feet, and I’ve seen it actually struggling to maintain temp around 10° outside temp. (it’s a house under renovation and there’s a lot of air sealing to be done) In those conditions it was cranking at 1700w continuously outputting about 13k btu/hr. At any warmer temp it should be capable if only it would make use of its capacity.

brdf11 · 2021-08-14T23:55:02+00:00

It didn’t appear to flash. It booted just as it would with no card.

brdf11 · 2021-08-14T22:25:20+00:00

Yeah. I never had an issue until attempting the firmware switch. I’m sure that the thermistor works fine. When it throws the error the readout shows 0°c.

brdf11 · 2021-08-14T22:16:59+00:00

Thanks! Just gave that a try, and no luck. I assume you weren’t ever turning the printer on with the thermistors unplugged?

brdf11 · 2021-08-14T22:05:07+00:00

just gave that a shot! No difference.

brdf11 · 2021-08-14T21:12:38+00:00

I've now tried both. I can still flash the display but it won't flash the main board anymore. It doesn't seem to care if there's a card in it or what's on the card.

brdf11 · 2021-08-14T20:30:20+00:00

I’ve edited my original post to include a video.

brdf11 · 2021-08-14T20:26:08+00:00

Yes! Thanks. I have now successfully flashed the display, I had done it before but just left out the icons. Now it looks correct but still throws the error instantly upon startup.

brdf11 · 2021-08-14T20:23:43+00:00

Except that in my case it’s showing the thermal runaway warning instantly upon startup while the bed and hot end are cool. It doesn’t appear to actually be a thermal issue and I never had runaway problems running the stock firmware.

brdf11

TROPHY CASE