Why I decided against a mini-split for my garage.

[WVBrady]

I have been considering putting a mini-split in my attached garage for several years, but health problems and other things have delayed my doing so. Recently, I came across some information that has pretty much decided me against it. Basically, it was because it evidently is not a good thing to leave it turned off for much of the time.

I live in WVa, and have more of a need for heating than I do for A/C; I can cool my garage with just a window unit. I was planning on just heating the garage occasionally when I had a short project.

What decided me against it was a video in which the author tracked his energy usage for several months. He found that his Fujitsu unit drew a constant 164 watts when it was not running. He was planning on shutting it off when he didn't need it, but several commenters said that was not a good idea. One of them (Joshua Tortorello ) said: "The "Ghost Load" you are referring to is most likely due to the Crank case heater. This heater is attached to the compressor to keep refrigerant out on start-up. Refrigerant migrates to the coldest area in the circuit when off/idle. Compressors cannot compress liquid so I would not recommend cutting power to the unit. The heater is your compressors protection from slugging during startup. If you decide to cut power give the heater some time to boil off any refrigerant in the compressor before starting your system."

Any comments? How could you turn on the heater without starting the compressor?

 

[walrus]

I turn mine off all the time, its my house not garage. Dont need AC all the time in Maine, dont need heat either. When its real cold i run oil or wood. Split will sit for months, never checked to see if it draws energy when off. I suspect it doesnt.

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[Jinks]

Mine has been in my shop for just over 5 years. I use it a lot during June, July, August, but almost never outside that. I was amazed that I didn't see any increase in my electric bill after it was installed. Five years later I don't see any change between the months I use it, & the months I don't. I would suspect TV's with remotes & computers are bigger electric vampires than a mini-split, & not nearly as useful when you're uncomfortable.

 

[matt_i]

My question would be: what makes a mini-split different from a split system, when looking purely at the heat transfer equipment and process.

If the minisplit is heating, potentially the refrigerant flow could be reversed and the throttle point (where heat is absorbed) has to be in 2 different places in the system.

Also I have never read anecdotal evidence of someone blowing up a minisplit by letting it sit powered off....

 

[theoldwizard1]

If the comment you read about the crankcase heater is accurate (I am not disputing it, but it bears further research) I find it hard to believe it is not on some kind of thermostat ! I would just disconnect that heater from beginning of April through the end of November.

You don't mention what your alternative heat source.

What you are missing is how much more efficient a GOOD mini-split (SEER near or above 20) is compared to any other heating and cooling source (except wood). When the temps are in the 30s through the 60s is when they are MOST efficient.

The market for mini-splits can be very confusing. You need to learn how to read the specification. It is definitely "buyer beware" !

I will say, if your usage of the work space is less than about 20 hours a month the additional cost of a mini split gets hard to justify.

 

[theoldwizard1]

My question would be: what makes a mini-split different from a split system, when looking purely at the heat transfer equipment and process.

The basic refrigeration cycle is the same. The big efficiency gain is that most (all?) mini-splits use "inverter technology" to run the compressor. The AC power coming in is changed to DC and the "inverted" back to variable frequency AC. The variable frequency allow the compressor to run at only the speed required to heat/cool, which is usually less than 100%.

The second big bonus is no duct work. While some mini-split installation DO use very short dicts, it cuts doen on their overall efficiency.

If the minisplit is heating, potentially the refrigerant flow could be reversed and the throttle point (where heat is absorbed) has to be in 2 different places in the system.

No, not "potentially" the refrigerant flow IS reversed. This require one "reversing valve" a couple of one way valves (cheap) and an extra TXV or 2 electronic expansion valves.

Unless you are living in the "deep South" or SW, you do not want any heat pump that relies on a "heat strip" to provide heat to your space during cold weather. These are VERY INEFFICIENT !

 

[sgiss]

In Va I replaced a window unit with a minisplit and substantially reduced my energy use ( and noise level). My only concern is that I have now learned these units tend to mold up pretty bad. Leave them on, or at least run the fan only before shutting off, and be prepared to clean them - not easy- see youtube. I would love to see the manufacturers design them to be cleaned.

 

[EdT]

Hey wizard, Actually an electric heater is one of the few things that is close to 100% efficient. Every watt that goes in comes out as heat. That's not to say that they are cost effective heaters compared to some other methods, but within in themselves, they are very efficient.

 

[walrus]

Hey wizard, Actually an electric heater is one of the few things that is close to 100% efficient. Every watt that goes in comes out as heat. That's not to say that they are cost effective heaters compared to some other methods, but within in themselves, they are very efficient.

mini splits can be 3 to 1, 1 unit in and 3 units out.

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[Dagny]

The OEM parts for mini splits can be very expensive.

 

[danb35]

I find no other reason to consider one.

Energy efficiency? Granted there's a lot about the HVAC market I don't know, but I'm not aware of 20+ SEER with central air or other technologies.

 

[Jackfre]

Hmm, I have 3 Fujitsu systems in my home. One dual and two singles. When they are off they are well and truly OFF. Perhaps the load you reference is a parasitic load from somewhere. If you are simply looking for shop heat look at the Rinnai Energysaver.

 

[WVBrady]

Thanks for the responses. I heat my house with oil; natural gas is not available in my area.

I remember reading in this section that people complained that they could not set the heating temperature as low as they wanted. I just read this about a Pioneer unit:

"Vacation (Low Heat) Mode
Available vacation mode keeps your home above freezing point, using very little amount of energy during any unoccupied periods, to avoid frost damage to the mechanical structures and the contents."
This would be an important feature for me.

Does anyone know of this feature in other makes?

 

[PoorOwner]

If you go with Mitsubishi they don’t have a draw for the smaller I think 18k or less units.
For multi zone or larger units they do have a low ambient pre energize function on the compressor so not all the liquid refrigerant collects near the compressor during cold days.
The threshold is 61f outside and it turns on draws about 50w. Remember only on the larger units. And also can be turned off via jumper at your own disgression.

 

[Dagny]

There is such a thing as a self regulating crank case heater the colder it is the more current it draws.

 

[Jackfre]

“Natural gas is not available.” Look at the propane version of the Rinnai. The built in programmable stat will allow temps as low as 38*

 

[TangoFoxTrot]

I will say 164 watts in the off mode seems to me to be a pretty terrible design, I'd like to see more documentation on that than a random YouTube user. I'm not an expert, but somehow I doubt that's a 24/7 type thing. I would think it has some sensor to turn on only when temps dropped below a certain level.

But if that is the case, I would think there's an easy workaround depending on the season. Like maybe flipping a breaker 9 months out of the year.

I've never heard of anyone NOT using a mini split because it was deemed an energy hog.

Even if there is a standby loss like that, you're probably talking about an extra $100 a year in energy use. So like putting a refrigerator in your garage or something like that.

I would do more research but mini splits are about as cheap a way possible to heat or cool something, the issue usually is the initial cost and installation, not the energy use.

 

[cupcakemike]

Energy efficiency? Granted there's a lot about the HVAC market I don't know, but I'm not aware of 20+ SEER with central air or other technologies.

Huh? Most central air stuff, except the low end units, is 18-20 SEER...I replaced my central air in my home 5 years ago, got a middle of the road unit 4.5 ton heat pump from frigidaire that was 22 seer...they had 3 tiers, 16, 22 and 26...

 

[bobbyjean]

There is such a thing as a self regulating crank case heater the colder it is the more current it draws.

i use a self regulating heat tape to stop gutter ice build,and have seen them used on compressor's many time's-read up on them for an hour one day to try and figure how they work....works well

 

[danb35]

I replaced my central air in my home 5 years ago, got a middle of the road unit 4.5 ton heat pump from frigidaire that was 22 seer...they had 3 tiers, 16, 22 and 26...

Interesting--today, the highest they're listing is "up to 19 SEER": https://www.frigidairehvac.com/product-category/central-heating-cooling/heat-pumps/

 

[theoldwizard1]

Hey wizard, Actually an electric heater is one of the few things that is close to 100% efficient. Every watt that goes in comes out as heat. That's not to say that they are cost effective heaters compared to some other methods, but within in themselves, they are very efficient.

And heat pump are actually more than 100% efficient ! Remember, they are not "making heat", just moving it from one place to another. Hard to believe, but there is "heat" in 0F air that can be moved to inside of a building.

 

[theoldwizard1]

mini splits can be 3 to 1, 1 unit in and 3 units out.

True, but this is a "buyer beware" situation. Mini-splits with multiple outlet have much lower SEER rating (i.e. they are more expensive to operate). If you run them a lot, it actually may be cheaper in the long run to buy 2 smaller, but higher SEER, mini-splits.

 

[WVBrady]

Vacation mode

Has anyone seen any other Mini-split with a "Vacation (Low Heat) Mode" as I mentioned in #13 for the Pioneer unit? That's the only one that I have come across, but that doesn't mean that there are not others.

That feature might change my mind about getting one for my garage.

 

[bbee383]

Re: Vacation mode

Has anyone seen any other Mini-split with a "Vacation (Low Heat) Mode" as I mentioned in #13 for the Pioneer unit? That's the only one that I have come across, but that doesn't mean that there are not others.

That feature might change my mind about getting one for my garage.

I ordered a Pioneer 18,000 Btu 20.8 seer for this exact reason. Being able to set it at 46 Deg is what made up my mind on the pioneer. I should receive my unit next week and hope to install next weekend.

 

[FlaGman]

April Wilkerson (of YouTube fame) just recently posted a video installing a 42 seer Carrier mini split in her new workshop, so there are super high efficiency units available

 

[aunsafe2015]

April Wilkerson (of YouTube fame) just recently posted a video installing a 42 seer Carrier mini split in her new workshop, so there are super high efficiency units available

42 is crazy.. wow.

Her video also says the Carrier unit has a true dehumidifier mode that will dehumidify without cooling. That sounds nice. "Dry mode" on my Mitsubishi definitely seems to overcool the space.

 

[justinjoyal]

April Wilkerson (of YouTube fame) just recently posted a video installing a 42 seer Carrier mini split in her new workshop, so there are super high efficiency units available

That unit is made by Gree.

We sell it as our top-of-the-line model. It is very efficient!

 

[cupcakemike]

Interesting--today, the highest they're listing is "up to 19 SEER": https://www.frigidairehvac.com/product-category/central-heating-cooling/heat-pumps/

Well, thats fucked up...I wonder if they were being less than truthful with the marketing of their models back then? The current models are not the same as mine...I'll have to see if I saved the literature

 

[bzinsky]

164 watts of continuous power is 4kwh/day about just over $20/month where I'm at and we have pretty cheap electric. (11cents for supply and 7 cents for distribution)

That parasitic load just simply cannot be true unless he has a problem.

So when I was rehabbing my apartment building, I had (20) 9kbtu 27 seer LG splits set on hold at 74 degrees all summer long. They were all separately metered. My average bill per unit was about $18-$23.

There is no way the parasitic load of that unit costs the same to run as my splits on hold in the summer.