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Mitsubishi Mr Slim Heat Pump


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Mitsubishi Mr Slim Heat Pump R410A.

Anybody real familiar with these

No auxillary or backup heat switch on thermostat

I was told that at the low temperature (near zero) operation they need supplemental backup (auxiliary) heat source as it is not like a standard heat pump with electric heat backup. (Area of installation can get down to zero degrees.)

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They supply minimal heat. If the building is super insulated or similarly efficient, they're OK. If it isn't, they're not.

I completely disagree. You can't compare these to American ducted heat pump systems. The split-ductless models with the variable refrigerant flow certainly provide 100% adequate heat (if sized and installed properly) in ambient temps as low as -13 degrees.
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Brand new home, R-49+ in attic, 2x6 w/ high density batts.

Marc: Don't know size of cables to inside unit, what would I look for, are you talking refrigerent lines or electric cables??

BTW this was a ducted system: There was a unit or something I thought was a duct manifold in the attic

Outside today was 40 degrees, home temp was 62, took 1/2 hour to reach 68 in home.

HVAC Guy told me they do not (normally) have auxillary heat and possibly needs to be added, so I told clients to ask installer.

How you would tell (aux heat) or test it?

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Electric cables...to see how much ampacity would be available for a heat strip. Most portable electric heaters for 120V receptacles are about 1,200 watts which is about 4,000 btu/hr so if it's a 20 amp circuit and doesn't share with other loads you might have about that much back-up heat available.

The label on the indoor units should give that info.

Marc

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HVAC Guy told me they do not (normally) have auxillary heat and possibly needs to be added, so I told clients to ask installer.

How you would tell (aux heat) or test it?

There is NO auxiliary heat. As I described above, it's completely unnecessary - unless the installer didn't size or install the system correctly.

BTW this was a ducted system: There was a unit or something I thought was a duct manifold in the attic
What is shown in the pictures is certainly not a ducted system.
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Jerry, your 1st picture is the "outdoor unit" and your 4th picture is the "indoor unit" of a mini-split heat pump. The two are connected primarily by refrigerant lines, although there is also a cable to provide power to the fan in the indoor unit. As Bill said, there is no backup or strip heat.

The indoor unit in your pic does not connect to any ductwork, although there ARE mini-splits that use short lengths of ductwork (at some efficiency loss compared to a ductless installation). If there is warm air coming out of a ceiling register then there is something else going on. There are systems where one outdoor unit supplies more than one indoor unit (again at some efficiency loss) and I suppose it's possible that your installation has one outdoor unit supplying that indoor unit AND a ducted unit in the attic, although I would not expect to see that (more likely to find multiple indoor units of the type shown in your pic, fed from one outdoor).

What you could do is shut off the breaker supplying the outdoor unit and see if both heat sources switch off simultaneously.

As Bill also said, these things work well. You can look at the specs for BTU output at given outdoor temps. Here in our moderate climate they are the bee's knees, probably 250-300% efficient a lot of the year. In your climate I would expect to see the high heat models, which are still quite efficient.

How big is the house? Is the indoor unit in an open-plan area? I might expect that to serve up to about 1000SF of reasonably insulated house.

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Kibbel over-caffeinated and telling me what I'm doing again.......I wasn't comparing them to a conventional ducted unit. I was comparing them to the hundreds I experience when I'm in China.

That particular unit supplies minimal heat. A building has to be reasonably tight and well insulated for them to work OK. 500 million Chinese know that. Apparently, Kibbel does not.

Of course size is important. But just cranking the size to overcome a minimally insulated property isn't particularly smart.

I said they work if the building is "similarly efficient". Read before you get cranky.

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heres some more labels, I could not get a good shot of air handler or whatever in attic (to big and close), it was approx 3' wide, 2 high, 4' long, wrapped in insulation, no wood platform indicating some that would be some kind of serviceable unit.???

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If there is warm air coming out of a ceiling register then there is something else going on. There are systems where one outdoor unit supplies more than one indoor unit (again at some efficiency loss) and I suppose it's possible that your installation has one outdoor unit supplying that indoor unit AND a ducted unit in the attic, although I would not expect to see that (more likely to find multiple indoor units of the type shown in your pic, fed from one outdoor).

How big is the house? Is the indoor unit in an open-plan area? I might expect that to serve up to about 1000SF of reasonably insulated house.

This is closer to home. Now that there's more pics, I suspect this is a VRF (variable refrigerant flow), where a single condenser accommodates multiple coils and air handlers. Mitsubishi's system only uses 2 pipes, so it's a little confusing; we're used to one compressor-one coil; the Asians have figured out how to put multiple coils on a single compressor.

Again, if it's not a tight house, they have a hard time keeping up. If it's reasonably tight and efficient, they work fine.

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Kibbel

That particular unit supplies minimal heat. A building has to be reasonably tight and well insulated for them to work OK. 500 million Chinese know that. Apparently, Kibbel does not.

Where the F... do you come up this this shit. What I know about these systems at first came from my manufacture-sponsored training from.... this particular manufacturer. Then I have worked with top-of-the-industry folks for 2 decades spec'ing HVAC retrofits to several historic building museums that are, guess what - horribly drafty and not insulated at all.

We chose these systems specifically to minimize collateral damage and disruption to historic materials. They work very well, with no issues keeping up with heating drafty and inefficient construction.

So Kurt, show me the research data and list your professional experience that backs up your claim. I see you checked with Mr. Google after your initial post.

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Jerry, your second group of photos... first photo... that's the Washington State Energy Code sticker, and it's showing that the house has two systems. The second one is listed on the "cooling" line but it's listed as a heat pump. Beats the sh*t out of me why a builder would put in ducted air AND a mini-split, but they did. There is almost certainly a second outdoor unit somewhere, or else maybe that thing in the attic is an electric furnace and is mis-represented on the sticker. But, you need A/C in Yakima, right? So my money's on another outdoor unit. What was in the electrical panel?

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Bill, you really got to calm down. Now you're upset that I looked at the Mitsubishi site. Are we not allowed to look up information? (you actually tracked my internet use...?!?!) You're not painting a pretty picture of yourself.

I never said they don't work, I never said they're bad, I never said anything you're foaming at the mouth about. I've lived in a dozen residences with that particular system. I've worked with the Fujitsu systems, and I think they're grand.

But, they do not crank out heat. You better have a reasonably tight and efficient structure, things that were not entirely clear in the OP. If your experience is different, that's your experience. None of it is quantified, so none of it is particularly edifying.

We had minimal information in the original post, I responded with minimal information, that is, within it's minimalist nature, not precise. It wasn't inaccurate, though; given what I could see in the OP, I thought it would provide minimal heat.

And, what is this anyway? Wipe the spittle off your computer monitor, and forget I said anything.

Pay attention to Meiland, he's providing coherent information.

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We had minimal information in the original post, I responded with minimal information, that is, within it's minimalist nature, not precise.
You responded to the post with an opinion you formed in your head. Oh, that's right, it's from your interviews with 500 Chinese.
It wasn't inaccurate, though; given what I could see in the OP, I thought it would provide minimal heat.
Okay Mr. Accurate, what exactly did you see that indicated it would provide minimal heat?
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Jerry, your second group of photos... first photo... that's the Washington State Energy Code sticker, and it's showing that the house has two systems. The second one is listed on the "cooling" line but it's listed as a heat pump. Beats the sh*t out of me why a builder would put in ducted air AND a mini-split, but they did. There is almost certainly a second outdoor unit somewhere, or else maybe that thing in the attic is an electric furnace and is mis-represented on the sticker. But, you need A/C in Yakima, right? So my money's on another outdoor unit. What was in the electrical panel?

Empty house on full basement, no outside unit. 2 attic accesses: nothing there but that large 'manifold or plenum' covered in insulation. No walkway from access points to indicate some kind of serviceable unit up there.

I'm stumped

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What (looked like) it's relatively small capacity/size. No numbers, no precision.

The opinion was formed from talks over a couple weeks (thru my wife, the interpreter) with Ming Xian, project manager for Guanghua Heating, a large heating company operating out of Wuhan, Hubei.

They have satellite offices in every major Chinese city; they're competent. With his help and engineering, we installed a hybrid system of mini-split ductless and hydronic radiant in our apartment in Wuchang District, Wuhan.

After that, I cede the floor to Kibbel. He's intent on proving.....something.

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You guys were right on with info, thanks

talked to the installer/ builder on the unit.

said it is a 2 stage hp, ductless mini split in main room, that has refrigerant lines that run to evaporator in attic (which I photoed, just didn't know what it is)

Said evaporator is all wrapped in insulation because there is nothing to view or service. (don't guess it needs outside air flow?)

The ducts come directly off attic unit that is why it looked like a duct manifold to me!

He said he has been putting them in for a couple years, and has had zero complaints even down to zero degrees. Said they are cheap to run (low amp draw) especially at low temps because there is no electric furnace backup.

He is sending me an info brochure on them which I will post when I get it.

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Got me curious enough to Google. From http://www.mitsubishielectric.ca/en/hva ... orUnit.pdf

Looks like you have a "multi-split" installation there, one outdoor unit, one ceiling unit connected to a bit of ducting, one wall unit, one stat for the whole thing.

The ceiling unit is circulating indoor air through it, no outside air connection.

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Got me curious enough to Google. From http://www.mitsubishielectric.ca/en/hva ... orUnit.pdf

Looks like you have a "multi-split" installation there, one outdoor unit, one ceiling unit connected to a bit of ducting, one wall unit, one stat for the whole thing.

The ceiling unit is circulating indoor air through it, no outside air connection.

yep.... thanks

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