Is anyone having problems with recent Daikin heat pumps?

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#3264365 25-Jul-2024 17:57

timmmay:

Does this help? I didn't leave the heat pump at the same temperature all day, I have to turn it down twice because it was getting hotter and hotter. Daikin Cora FTXM25U.

what size room and insulation level?

timmmay

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#3264370 25-Jul-2024 18:11

tweake:

timmmay:

Does this help? I didn't leave the heat pump at the same temperature all day, I have to turn it down twice because it was getting hotter and hotter. Daikin Cora FTXM25U.

what size room and insulation level?

4.2m by 3.25, sloping ceiling across the width that's 2.2m to 2.5m. Heat pump mounted high. Insulation looks to be pink batts walls and ceiling, no idea the R value, concrete floor. The little 2.5kw heat pump (that can actually pump out more heat than that) works very well in such a small room.

tweake

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#3264373 25-Jul-2024 18:54

timmmay:

4.2m by 3.25, sloping ceiling across the width that's 2.2m to 2.5m. Heat pump mounted high. Insulation looks to be pink batts walls and ceiling, no idea the R value, concrete floor. The little 2.5kw heat pump (that can actually pump out more heat than that) works very well in such a small room.

that heat pump has a max output of 5.4kw, thats why it works so well. its massively oversized. i have a similar room, single glazing, auckland/northland, and it only requires 1.5kw (heat pump is similar size but only 4.4kw max output, and it overshoots as well. funny enough it runs fine on super cold days).

one thing i can't find is daikins install height. the panasonics are actually meant for 2.7m high rooms, not 2.4's. so i suspect they are looking for a slightly hotter temp due to the extra height. one day i will get the external thermostat for them and see if thats the case.

timmmay

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#3264380 25-Jul-2024 19:18

I asked for the smallest one and that's the one I got. It works extremely well, according to the information that home assistant provides it sits on between 100 and 300W most of the time during the day in winter. In practise I don't think I've seen it use over 2.5 KW at least not in the output graphs from home assistant.

Anyway, this thread is about Daikin overheating. I provided that information in case it helps, but because I didn't leave the temperature the same all the day due to overheating it may not be that helpful.

MadEngineer

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#3264385 25-Jul-2024 19:40

Have I got this right? It's set at what looks like 23 deg c (target) at 5.30am and it reached that at around 7.15am (desk temperature). From 8am however it slowly started to ramp up and a bit after 8.30am you turned it off and dropped the set temp down to 21. I don't get what you mean by "Office Daikin heating" which is hitting 26 deg c.

You've left it at 21 deg c and it starts off with a few bumps as you turn it off n on until 10am but after that and especially from 11am it slowly ramps up to ~23deg c again before you've turned it off

Do you know if you can set hysteresis options?

timmmay:

Does this help? I didn't leave the heat pump at the same temperature all day, I have to turn it down twice because it was getting hotter and hotter. Daikin Cora FTXM25U.

It shouldn't matter but can I ask what mode it's in? eg for fan/mode, auto/auto, set speed/auto, auto/heat etc

Floor or wall model? Plain install or against an old fireplace?

You're not on Atlantis anymore, Duncan Idaho.

tweake

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#3264386 25-Jul-2024 19:49

timmmay: I asked for the smallest one and that's the one I got. It works extremely well, according to the information that home assistant provides it sits on between 100 and 300W most of the time during the day in winter. In practise I don't think I've seen it use over 2.5 KW at least not in the output graphs from home assistant.

Anyway, this thread is about Daikin overheating. I provided that information in case it helps, but because I didn't leave the temperature the same all the day due to overheating it may not be that helpful.

how is that wattage measured? if thats input thats just under half power.

they do make one smaller. the problem is many companies want to upsell.

the oversizing could very well be why they are overheating, so i think the data is very useful.

tweake

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#3264436 25-Jul-2024 19:59

MadEngineer:

I don't get what you mean by "Office Daikin heating" which is hitting 26 deg c.

i think thats the inlet air temp ie ceiling air temp. the colored part being on/off due to thermostat rather than him turning in on/off. hence the temp changes.

a thought here is that with such big heat pumps that they are sucking a lot of its own air flow back in instead of being cooled by the room air. it expecting a 5 degree difference between ceiling air temp and middle of the room temp. its jus the room temp is catching up with ceiling temp. but i have no idea why its lifted the temps at the end.

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dazzanz

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#3264441 25-Jul-2024 20:08

Here is a graph for one of my rooms with a Daikin:

I don't have the independent temp sensor on the graph but checking its logs for over the night time it was between 17.5 and 18 degrees while the Daikin target was set to 20 and the Daikin reported temp was 24 degrees.

timmmay

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#3264447 25-Jul-2024 20:37

@MadEngineer I've added information to my post with the graph.

@tweake I suspect the kwh is heat output based on the graph below reaching 2.5kW, but I'm not sure. If it was 2.5kw power consumption that would be 7.5 - 10kw heating, which that unit can't do.

The information appears in home assistant from the Daikin integration. I don't think it's overheating because it's oversized, it can ramp down really low, I think it's the Daikin logic is faulty. You can see in my graph above that the Daikin knows it's set to 21 and that the intake temperature is 24 - 25 but it's still heating anyway. It's a bit puzzling.

My 7-8kw Daikin Highwall that's 10 - 12 years old does the same thing - if I leave it on 21, on a cloudy day, by lunchtime it's heating the room to 23 or 24 degrees. I have no real stats on that because it's old and doesn't integrate with HA. I don't know why I got this model instead of the smaller one, it may have been availability, upselling, etc. It was installed by my electrician, he probably told me at the time of install but I forgot.

tweake

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#3264453 25-Jul-2024 21:09

timmmay:

@tweake I suspect the kwh is heat output based on the graph below reaching 2.5kW, but I'm not sure. If it was 2.5kw power consumption that would be 7.5 - 10kw heating, which that unit can't do.

i think the numbers are wrong. its probably an estimation based on compressor speed. but the curve is probably right. soft start, run up to max speed, then hits max temp way to quickly. drops speed back down. reducing further as room fully heats up.

at the end its running on minimum speed, like its almost about the shut off. but i wonder if its programmed to overshoot the temps a little bit so it doesn't have to come back on for quite some time. thats to avoid short cycling.

neb

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#3264459 25-Jul-2024 22:08

tweake: can you get the size of the rooms and location in nz please. edit: house insulation levels to please.

Insulation is R2.0 walls, R4.2 ceiling, double-glazed low-E argon-filled windows. The room the graph came from is maybe 3x3m. So definitely not bleeding out heat anywhere.

tweake

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#3264596 26-Jul-2024 10:14

neb:

tweake: can you get the size of the rooms and location in nz please. edit: house insulation levels to please.

Insulation is R2.0 walls, R4.2 ceiling, double-glazed low-E argon-filled windows. The room the graph came from is maybe 3x3m. So definitely not bleeding out heat anywhere.

my guess here without knowing model numbers, is a major factor is its well oversized for the room.

if there is another issue as well, i can't tell. it could be like my panasonics where they are designed for different height rooms.

timmmay

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#3264597 26-Jul-2024 10:19

The thermostat should shut it off when the room is up to heat regardless of room size.

I noticed this morning that the temperature at the Daikin was 25 but the room temperature was 21. I wonder if there's an assumption that the temperature near the heat pump is higher than the rest of the room, that's why they keep the heating going to higher than the expected temperature. That wouldn't explain why it keeps going up.

tweake

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#3264602 26-Jul-2024 10:51

timmmay:

The thermostat should shut it off when the room is up to heat regardless of room size.

I noticed this morning that the temperature at the Daikin was 25 but the room temperature was 21. I wonder if there's an assumption that the temperature near the heat pump is higher than the rest of the room, that's why they keep the heating going to higher than the expected temperature. That wouldn't explain why it keeps going up.

its going to expect the air to be hotter up at the ceiling than at desk level. higher the wall, the more difference there would be. but it seams to assume way to much given the size of the room. part of the issue is its assuming the room is bigger (taller?) than it really is. this is one of the issues with having the thermostat up at ceiling level.

however i have no idea why it keeps going up even further than that.

cddt

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#3264636 26-Jul-2024 11:54

We had a Daikin in our old house for ~4 years (from install in early 2019 to sale in 2023). No similar issues - but the unit was more appropriately sized. In fact we liked it so much we would strongly consider going Daikin again when we can afford to put a heat pump in our new house.

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