Comparing LG and Fujitsu: Is LG fudging numbers?
I was looking at the specs of the Fujitsu 9RLS3H and the LG LA090HYV1, and I’m puzzled by a couple of things. The first is if you compare the COP at the various temperatures, on balance the LG looks at least as good as the Fujitsu, but the HSPF rating is significantly lower – 12 vs 14. Kind of weird.
The second, and most disturbing thing is I’m pretty sure that LG’s test data at 17F and 5F does NOT include the power of the pan heater, despite this note for that model:
“heater is always turned on from 0C down if the unit is “on” and in “heat””
I couldn’t find the power rating for the pan heater in the LG model, but for the Fujitsu it’s 150W, so it’s presumably in that ballpark. Maybe less, but certainly not something like 10W or lower.
If you look at the COP ratings for the LG unit at below freezing temperatures, they look pretty phenomenal, especially for a unit with a pan heater. At the minimum heating output at 5F, the COP is 2.7, barely below the COP at max. This is odd, because as the input power delivered as heat to the indoors goes down, the proportion of input power being used by the pan heater should go up dramatically. So what’s going on? To me, the damning evidence is if you compare the minimum input power at 47F, when the pan heater would be off, to the minimum input power at 5F, when according to their own documentation the pan heater will be on 100% of the time. At 47F, 70W. At 5F, 60W. Less total power with the pan heater on. So unless their pan heater is using dark energy or something, it seems to me that their data is fudged. They ran all their tests with the pan heater disabled, despite the fact that in the real world that pan heater will be on all the time the temperature is below 32F and severely hindering the efficiency. This is supposed to be a cold climate heat pump, and in cold climates it’s below 0C/40F a lot. Sending out 100W or 150W into the outdoors that entire time seems pretty wasteful.
I’ve attached a spreadsheet showing the pertinent data of the two units, plus data from the Fujitsu 9RLS3, which is the comparable model without a pan heater. You can see clearly that the 9RLS3H includes power for the pan heater, as the minimum input power is 0.15kW higher for it than the 9RLS3, the exact power rating for their pan heater. So we know those tests were legitimate. The LG unit, not so much. I’m a little surprised that a brand like LG would pull something like this, and I’m also surprised that they appear to have gotten away with it.
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Replies
The AHRI efficiency tests are done at +17F and +47F, and not at maximum or minimum modulation, so it's not easy to estimate the HSPF efficiency from the min/max data found on the NEEP data sheets.
Without better specs on the pan heater it's hard to estimate how much power that will chew up over the season too.
So this tells me that the HSPF number is not of much use to me, or to anyone in a cold climate and super insulated house. I don't use any heat at 47F, let alone the rated amount.
I found the pan heater specification: 120W
https://app.totalhomesupply.com/application/uploads/manualsupload/PQSH1201_Drain_Pan_Heater_Submittal.pdf
Regardless of exactly how much power it chews up, my main point is that they're not being honest about their efficiency numbers.
The form they had to fill out for NEEP is different from what's required in a formal AHRI test.
On page 3 of the NEEP submittal sheet instructions they specify:
"Do not include the power required for defrost
cycling or drain pan heater operation in the table"
https://neep.org/sites/default/files/ColdClimateAir-sourceHeatPumpSpecification-Version3.0FINAL_0.pdf
This is very interesting, because it strongly implies that Fujitsu was the one who filled out the tables incorrectly. Unless there's some other reason that the 9RLS3H would use exactly 150W more than the 9RLS3 at every single temperature and load.
The HSPF is a more useful comparision metric and it shows the LG is behind the Fujitsu, so I don't see a scandal. I bet the pan heater was included for the HSPF but perhaps they didn't bother redoing the tables with the heater.
Is the heater standard or a optional accessory? They may be describing the control algorithm even if it isn't standard. The mits FH series can be ordered with or without the heater.
It's tough to look at performance versus temperature tables and calculate real world consumption since there are so many variables. HSPF isn't perfect but it accounts for a bunch of things that are non-obvious when just looking at the table.
You can't look at Brake-Specific fuel consumption table for an engine and accurately project the fuel economy without knowing the vehicle the engine will be in and the operating conditions. So instead we have window stickers that give you a fuel economy reading that can be used as a relavent comparision point. The HSPF is similar to the window sticker fuel economy. Geeks would love to see a load versus rpm versus fuel economy chart but it's kinda anecdotal information unless you do a lot more math. https://en.wikipedia.org/wiki/Brake-specific_fuel_consumption
>"Is the heater standard or a optional accessory? "
I believe the pan heater IS standard equipment with the LAU090HYV1 / LAN090HYV1 .
With Mitsubishi cold climate mini-splits the pan heater has traditionally been an add-on accessory, but necessary to be fully warranteed in colder climates. Just as with the Fujitsu RLS3s vs. RLS3H, ordering up an FHxxNA with pan heater doesn't seem to affect the installed cost at all, but it's important to be explicit with the installation contractors about including it.
My Mits dealer here in Toronto, doesn't even stock non NA(H) FH heat pumps due to our climate. Even if you ask for a NA they will probably give you a NAH without even asking you.
I'm all for accurate numbers, but 120W when < 0C is what, $20/year?
I'd be more concerned about the misleading fact that fans often don't have the modulation range of compressors and you probably have to run a dehumidifier to get reasonable latent removal/SHR combined with low load cooling (dry mode has practical problems).
Thanks for putting some perspective on it. I ran some guesstimate numbers, and $20 doesn't look far off.
Good point Jon, but it still stings a little to think about false advertising (if that is in fact what's going on here).
Trevor, I was amused by your comment, "I’m a little surprised that a brand like LG would pull something like this...".
LG is an absolutely MASSIVE company. I wouldn't put anything past them. ;-)
Well known brands care about their image, so they don't usually risk getting caught with their pants down. In this case, it looks like they did nothing wrong.