Ductless Mini Split Air Conditioner Heat Pump

[chester7]

I just built a 1248 sq ft shop I am looking to put A/C and Heat in about 624sq ft of it all insulated and plywood on the walls
and im considering using a 24000 BTU 15 SEER Inverter Ductless Mini Split Air Conditioner Heat Pump 2 TON system.
Anyone have any suggestion or thoughts on this?
Im in WI were it gets real cold and Hot.
Any info would be great Thanks

 

[theoldwizard1]

Mini-splits are perfect for "one room" heating and cooling !

You need to become "informed" on heating performance. The top brands will produce heat at 100% efficiency down to below 10F. Performance drops off after that. You have to learn how to read the spec sheets or just buy a Mitsubishi HyperHeat.

If there is anything in your room that would get damaged from freezing (plumbing) then you better have a backup plan for when the power goes out for an extended period. Portable propane heater with 2-4 20lb tanks should do the job.

You may need your alternate heat source on super cold nights (-20F) unless you have extremely good insulation.

 

[chester7]

The shop will only be Cooled & heated when im going to be working in there eh. If it gets below 10F how bad does performance drop? I only need it to be 50 or 60 degrees in there to work eh
What are the spec I would be looking for?
This is the unit I was thinking about eh
http://www.ebay.com/itm/252234535308?_trksid=p2060353.m1438.l2649&ssPageName=STRK:MEBIDX:IT

Mini-splits are perfect for "one room" heating and cooling !

You need to become "informed" on heating performance. The top brands will produce heat at 100% efficiency down to below 10F. Performance drops off after that. You have to learn how to read the spec sheets or just buy a Mitsubishi HyperHeat.

If there is anything in your room that would get damaged from freezing (plumbing) then you better have a backup plan for when the power goes out for an extended period. Portable propane heater with 2-4 20lb tanks should do the job.

You may need your alternate heat source on super cold nights (-20F) unless you have extremely good insulation.

 

[nick2010tundra]

In Canada ( Yeah its cold) you either buy a Fujitsu or Mitsubishi. The New Fujitsu is king though

 

[tomroblee]

Your link to the listing had expired. If you go to the original listing there is a link to manuals--including the specs.

http://www.bonterrahomeandgarden.com/content/15 SEER Specs.pdf

It says that the ambient (outside) temperature range for heating is 19 to 75 degrees. That doesn't sound too promising for heating when the temperature is 10 degrees.

I'm not familiar with the Air-Con Inc. brand.

 

[fastjohnny]

The shop will only be Cooled & heated when im going to be working in there eh. If it gets below 10F how bad does performance drop? I only need it to be 50 or 60 degrees in there to work eh
What are the spec I would be looking for?
This is the unit I was thinking about eh
http://www.ebay.com/itm/252234535308?_trksid=p2060353.m1438.l2649&ssPageName=STRK:MEBIDX:IT

A minisplit IMHO is not the best for occasional use for a large delta T. They are best used at efficiently maintaining a set T.

 

[justinjoyal]

Where are you located ?

You say 624 sq ft.. How high is the room ? What kind of insulation is in the walls (R values?) ?

 

[derkperk]

First post says Wisconsin.
A 2 ton system is going to be way oversized. You won't get the humidity out in the summer. Being in MN, I know you'll want that. Do you really need ac? If not, just run a low profile unit heater. With good insulation and building on concrete, it shouldn't get too hot in there.

Sent from my XT907 using Tapatalk

 

[theoldwizard1]

If it gets below 10F how bad does performance drop? I only need it to be 50 or 60 degrees in there to work eh
What are the spec I would be looking for?
This is the unit I was thinking about eh
http://www.ebay.com/itm/252234535308?_trksid=p2060353.m1438.l2649&ssPageName=STRK:MEBIDX:IT

That link takes me to a page for an Air-Con 24,000 BTU unit. Read specs is tricky, because different manufacturers use different terminology. I this case what you should worry about is



I take that to mean below 20F you are not going to get much of ANY heat !

Get your data in writing from the manufacturer. If you can't figure it out call the company and ask them, "When in heating mode, at what temperature does your unit fall below 90% efficiency ?" For example.

View media item 43975
This example is still making heat at -10F !

 

[chester7]

Hartford WI.
10'
R13 walls Kraft roolls
R49 celling blown cellous ins

Where are you located ?

You say 624 sq ft.. How high is the room ? What kind of insulation is in the walls (R values?) ?

 

[chester7]

I just thought I would get a bigger one just in case I want to cool the whole shop someday 1264sq'
A bigger unit wont work for the 624sq'???

First post says Wisconsin.
A 2 ton system is going to be way oversized. You won't get the humidity out in the summer. Being in MN, I know you'll want that. Do you really need ac? If not, just run a low profile unit heater. With good insulation and building on concrete, it shouldn't get too hot in there.

Sent from my XT907 using Tapatalk

 

[theoldwizard1]

I just thought I would get a bigger one just in case I want to cool the whole shop someday 1264sq'
A bigger unit wont work for the 624sq'???

It will work fine. It will help you warm up faster.

 

[chester7]

If the heater dont work so good I can just put a lp heater in if need be, But I like the A/C part of the mini splits cause the condensor is outside and wont get plugged up with dust, paint fumes etc eh

It will work fine. It will help you warm up faster.

 

[manwithtools]

Bigger is not always better on the AC side of things. It needs to run long enough to allow the moisture to condense out of the air, that's important in many ways. The unit sized for the smaller area is the proper way to start off unless you are certain you are soon going to cool the whole building.

 

[theoldwizard1]

Bigger is not always better on the AC side of things. It needs to run long enough to allow the moisture to condense out of the air, ...

Less true with an inverter heat pump or A/C unit. They will only run at full speed when required.

 

[walrus]

If the heater dont work so good I can just put a lp heater in if need be, But I like the A/C part of the mini splits cause the condensor is outside and wont get plugged up with dust, paint fumes etc eh

There is still stuff inside that can get plugged. In the winter the indoor unit is the condenser. There are filters that need to be cleaned.

 

[manwithtools]

Less true with an inverter heat pump or A/C unit. They will only run at full speed when required.

Maybe if it's got a smart enough control system, but why pay for something that size if one half the size would do the job and you may never need it?

It's simply best practice to size the equipment to the load.

 

[justinjoyal]

24k btu is way oversized.

Around here we have roughly R24 in walls and R41 in ceilings and for your space I would install a 12k btu inverter unit.

You can go with a 18k btu inverter which should compensate for the oversize and the less efficient insulation, but 24k is definitely too much.

I would go with a popular brand-name unit rather than some cheap knock-off.

I don't know what's the coldest temp you get in WI but there are mini-split heatpumps that can efficiently heat down to -22F.

 

[chester7]

Which ones go down to -22?

24k btu is way oversized.

Around here we have roughly R24 in walls and R41 in ceilings and for your space I would install a 12k btu inverter unit.

You can go with a 18k btu inverter which should compensate for the oversize and the less efficient insulation, but 24k is definitely too much.

I would go with a popular brand-name unit rather than some cheap knock-off.

I don't know what's the coldest temp you get in WI but there are mini-split heatpumps that can efficiently heat down to -22F.

 

[tomroblee]

As I said in my first reply I'm not a HVAC guru, but I have studied various options when I built and bought.

A two ton unit is going to be at least double the size you need to heat/cool 600 sq. ft. on a 24/7 basis. If you are going to use your shop on an intermittent basis you will need to go oversize.

The mini split you mentioned in your first post only appears to be capable of handling a single inside unit. You say that you might want to eventually cool your entire shop. This will be hard to do with a single inside unit located in a walled off room.

An AC unit will only remove moisture from the air while it is running. An oversized unit may run less, so may remove less water from the air. However, it is hard to predict your results if the equipment is only run when you are in the shop. If humidity is an issue for you in the summer, you may want to leave a dehumidifier running even when you aren't using the shop.

Just about any air conditioner will have the condenser outside and isolated from the inside dust. Just about any air conditioner will have the blower and coil inside and subject to the inside dust. Because of the small size of the inside unit, the mini split may not be as efficient in filtering out the dust as other options.

You also mentioned paint fumes. A super sealed room will require fewer btu to heat or cool, but you need ventilation or some sorts to dissipate paint fumes. This ventilation will affect your heating and cooling load as well as the humidity levels.

There are heat pumps that will produce heat at lower temperatures---but they are expensive. The efficiency will suffer at lower temperatures. There seems to be lot of differences on how manufacturers report the efficiency and capability of their systems. I tried to look at the Mitsubishi website. It appears that the "rated" capacity of the heating drops off significantly when the outside temperature drops into the teens, but the units are capable of producing more heat down to sub zero temperatures. The literature doesn't seem to dwell on how efficient the unit will be at sub zero temperatures. To me, this is similar to a car manufacturer advertising that a sporty model can get 30 mpg at highway speeds and is capable of going from zero to 60 in 4 seconds. The vehicle may get 30 mpg at 55 mph with the cruise control on level ground, but the mpg will probably be less when you are drag racing. I doubt that the manufacturer will publish the expected mpg when you are drag racing.

A well insulated 600 sq. ft. room shouldn't have much of a heating or cooling load. You might want to consider the play off between various equipment and operating cost scenarios. Buying a 12,000 btu heat pump and leaving it running 24/7 (with modest changes to the setting when you aren't using the shop) may be preferable to a 24,000 btu heat pump running only when you are using the shop.)

 

[bzinsky]

There are heat pumps that will produce heat at lower temperatures---but they are expensive. The efficiency will suffer at lower temperatures. There seems to be lot of differences on how manufacturers report the efficiency and capability of their systems. I tried to look at the Mitsubishi website. It appears that the "rated" capacity of the heating drops off significantly when the outside temperature drops into the teens, but the units are capable of producing more heat down to sub zero temperatures. The literature doesn't seem to dwell on how efficient the unit will be at sub zero temperatures. To me, this is similar to a car manufacturer advertising that a sporty model can get 30 mpg at highway speeds and is capable of going from zero to 60 in 4 seconds. The vehicle may get 30 mpg at 55 mph with the cruise control on level ground, but the mpg will probably be less when you are drag racing. I doubt that the manufacturer will publish the expected mpg when you are drag racing.

The data is tough to find but it's out there. Went through hell trying to find performance data when I installed several of them about a year ago.

They are still pretty efficient at low temps. They are certainly efficient in teens (mitsu hyper heat, lg art cool premier, etc). I found the manufacturer data was more akin to Porsche 0-60 times, and that they actually perform better than what they spec.

 

[justinjoyal]

Which ones go down to -22?

I have a Gree Crown serie that works great down to -22. Installed a few for customers as well and they're all satisfied.

I heat my whole main floor (1280 sq ft) during Quebec winter using my 1-ton mini-split. The baseboards are pretty much useless!

Most large mini-split brands have units rated for very cold weather now.

 

[tomroblee]

I'm not familiar with the Gree brand, so I looked up their website. Their submittal documents provides a fair amount of information about capacity at lower temperatures.



http://17uo7e27w1attiybs22of10v.wpe...016/01/Crown-Submittal-CROWN12HP230V1A-V1.pdf

 

[chester7]

Which one do you have exactly?? Part # etc?
Is it this one it says 350 to 500sq' only
http://www.ebay.com/itm/GREE-Crown-...053798?hash=item2ee4cbbfe6:g:7YYAAOSw4HVWCvEg
Thanks

I have a Gree Crown serie that works great down to -22. Installed a few for customers as well and they're all satisfied.

I heat my whole main floor (1280 sq ft) during Quebec winter using my 1-ton mini-split. The baseboards are pretty much useless!

Most large mini-split brands have units rated for very cold weather now.

 

[chester7]

Good Info eh

As I said in my first reply I'm not a HVAC guru, but I have studied various options when I built and bought.

A two ton unit is going to be at least double the size you need to heat/cool 600 sq. ft. on a 24/7 basis. If you are going to use your shop on an intermittent basis you will need to go oversize.

The mini split you mentioned in your first post only appears to be capable of handling a single inside unit. You say that you might want to eventually cool your entire shop. This will be hard to do with a single inside unit located in a walled off room.

An AC unit will only remove moisture from the air while it is running. An oversized unit may run less, so may remove less water from the air. However, it is hard to predict your results if the equipment is only run when you are in the shop. If humidity is an issue for you in the summer, you may want to leave a dehumidifier running even when you aren't using the shop.

Just about any air conditioner will have the condenser outside and isolated from the inside dust. Just about any air conditioner will have the blower and coil inside and subject to the inside dust. Because of the small size of the inside unit, the mini split may not be as efficient in filtering out the dust as other options.

You also mentioned paint fumes. A super sealed room will require fewer btu to heat or cool, but you need ventilation or some sorts to dissipate paint fumes. This ventilation will affect your heating and cooling load as well as the humidity levels.

There are heat pumps that will produce heat at lower temperatures---but they are expensive. The efficiency will suffer at lower temperatures. There seems to be lot of differences on how manufacturers report the efficiency and capability of their systems. I tried to look at the Mitsubishi website. It appears that the "rated" capacity of the heating drops off significantly when the outside temperature drops into the teens, but the units are capable of producing more heat down to sub zero temperatures. The literature doesn't seem to dwell on how efficient the unit will be at sub zero temperatures. To me, this is similar to a car manufacturer advertising that a sporty model can get 30 mpg at highway speeds and is capable of going from zero to 60 in 4 seconds. The vehicle may get 30 mpg at 55 mph with the cruise control on level ground, but the mpg will probably be less when you are drag racing. I doubt that the manufacturer will publish the expected mpg when you are drag racing.

A well insulated 600 sq. ft. room shouldn't have much of a heating or cooling load. You might want to consider the play off between various equipment and operating cost scenarios. Buying a 12,000 btu heat pump and leaving it running 24/7 (with modest changes to the setting when you aren't using the shop) may be preferable to a 24,000 btu heat pump running only when you are using the shop.)

 

[justinjoyal]

Which one do you have exactly?? Part # etc?
Is it this one it says 350 to 500sq' only
http://www.ebay.com/itm/GREE-Crown-...053798?hash=item2ee4cbbfe6:g:7YYAAOSw4HVWCvEg
Thanks

That's the one. Mine is white, not silver.

350-500 sq ft is plain ridiculous. This goes to show how eBay is not a reliable hvac source...

Gree is one of (if not the) world's largest air conditionners maker. It produces 1/3 of units sold worldwide.

The company has greatly evolved, and it now offers great products at a fair price, competing popular brands like Mitsubishi, Fujitsu, etc. I've installed many without problems and the warranty is good, if a problem should arise.

 

[theoldwizard1]

As I said in my first reply I'm not a HVAC guru, but I have studied various options when I built and bought.

I am not either, but I have done my "homework"

A two ton unit is going to be at least double the size you need to heat/cool 600 sq. ft. on a 24/7 basis. If you are going to use your shop on an intermittent basis you will need to go oversize.

Concur

The mini split you mentioned in your first post only appears to be capable of handling a single inside unit. You say that you might want to eventually cool your entire shop. This will be hard to do with a single inside unit located in a walled off room.

Good catch ! OP is obviously trying to "save a buck" and not having the extra ports would not help him long term.

An AC unit will only remove moisture from the air while it is running. An oversized unit may run less, so may remove less water from the air. However, it is hard to predict your results if the equipment is only run when you are in the shop. If humidity is an issue for you in the summer, you may want to leave a dehumidifier running even when you aren't using the shop.

I understand everyone concern about short run time not doing as good of a job of dehumidification, but that is with traditional A/C units, not with a variable speed inverter. I would think the lower speed would help.

If I was really concerned about humidity, I would leave the A/C running all the time set at 80-85F

A well insulated 600 sq. ft. room shouldn't have much of a heating or cooling load. You might want to consider the play off between various equipment and operating cost scenarios. Buying a 12,000 btu heat pump and leaving it running 24/7 (with modest changes to the setting when you aren't using the shop) may be preferable to a 24,000 btu heat pump running only when you are using the shop.)

Very difficult to do, even for a pro.

If OP ever wants to heat/cool the other half, buying another unit would kill any savings.

 

[manwithtools]

But if you never cool the other half that's money thrown away. We don't have enough info to make an educated recommendation. I'd like to go deeper into this but I don't think its worth our time....

 

[theoldwizard1]

Which ones go down to -22?

Not sure about -22F but this is probably one of the best heat pumps on the market.

Mitsubishi High-performance H2i™ Hyper-Heating Wall-mounted Heat Pump Systems

• Industry-leading efficiency of 30.5 SEER (MSZ-FH09NA).
• Hyper-Heating performance down to -13° F outdoor ambient.
• 100% heating capacity at 5° F outdoor ambient.

 

[justinjoyal]

Mitsus are excellent, but now overpriced IMO. But hey, they're selling like hot cakes ´cuz people find comfort in brand names..

 

[theoldwizard1]

Mitsus are excellent, but now overpriced IMO. But hey, they're selling like hot cakes ´cuz people find comfort in brand names..

Yeah, and who are you going to find to service a Gree ???

 

[justinjoyal]

Yeah, and who are you going to find to service a Gree ???

How would I know ? Ask Google for the nearest retailer/tech ? Just like any other brand out there..

It's not like Gree is the new kid on the block. They've been around for a while. However, they do not seem so popular in the US market. A matter of time, I guess.

 

[chester7]

Your prolly right but if I open the small garage door between the 2 shops I could put a fan to blow cool air in the other shop if i need to work on something in there eh
What info do you want?? I ll try to answer with what you are looking for need to get this figured out soon its driving me nutz eh

But if you never cool the other half that's money thrown away. We don't have enough info to make an educated recommendation. I'd like to go deeper into this but I don't think its worth our time....

 

[miketyler]

I am in nearly the same boat, about to install 24k BTU Mitsubishi heat pump to heat and cool my 30x40 shop in Texas. It's the single zone GE24NA model that will be mounted on the east wall (far end) of the shop. Mine is well insulated like yours and am hopeful I can distribute air using three existing ceiling fans. If necessary I may add a horizontal fan to help comfort levels at opposite end.

 

[theoldwizard1]

I am in nearly the same boat, about to install 24k BTU Mitsubishi heat pump to heat and cool my 30x40 shop in Texas. It's the single zone GE24NA model that will be mounted on the east wall (far end) of the shop. Mine is well insulated like yours and am hopeful I can distribute air using three existing ceiling fans. If necessary I may add a horizontal fan to help comfort levels at opposite end.

Before you do your install, consider placement of the indoor and outdoor units, especially if you decide you need to add a second air handler.

With good insulation and fans, you are probably good.

 

[fourstringriot]

I am in Wisconsin (Elkhart Lake) as well and just had this conversation with my HVAC guy today for a detached garage I'm finishing. I'm considering a split unit for the upstairs portion which will be an office that i'll maintain temp (~50) when not in use and ~68 when in use. We were talking specifically a Mitsubishi HyperHeat, which he said would work excellent until about -20 below, in which case he recommended I wire in baseboard heat as backup. I'm going to forego the baseboard heat and my second heat source will be a ceramic space heater if it really gets that bad. I don't have plumbing so my office equipment would be the worst thing I could lose but nothing to cause permanent damage. My quote for a HyperHeat was around $3k installed. Not sure if that's good or bad..

 

[machsnell]

3k for how many btu?

Sent from my SM-G900V using Tapatalk

 

[theoldwizard1]

I am in Wisconsin (Elkhart Lake) as well and just had this conversation with my HVAC guy today for a detached garage I'm finishing. I'm considering a split unit for the upstairs portion which will be an office that i'll maintain temp (~50) when not in use and ~68 when in use. We were talking specifically a Mitsubishi HyperHeat, which he said would work excellent until about -20 below, in which case he recommended I wire in baseboard heat as backup. I'm going to forego the baseboard heat and my second heat source will be a ceramic space heater if it really gets that bad. I don't have plumbing so my office equipment would be the worst thing I could lose but nothing to cause permanent damage. My quote for a HyperHeat was around $3k installed. Not sure if that's good or bad..

Sounds like a good plan ! I think office equipment would survive freezing if you let it warm up for 24-48 hours.

 

[fourstringriot]

3k for how many btu?

18k BTU for the split unit.

so the $3k quote was verbal, the actual written quote was $3750 for the MSZ 18,000 BTU heat pump and installation. Plus an additional $400 for the wifi capability.

They also quoted me $1835 for a Reznor 75k BTU propane heater installed with vent pipe.

That all seems high to me, but I dont price these things everyday - thoughts?

 

[tomroblee]

fourstringriot

It's hard to say much about your proposal without knowing the size of the office, how often it will be occupies, how much insulation you have, your electric rates, etc.

Just to toss out some information for comparison, I have a rural home in SW Indiana that is a 36' x 64' footprint with about half the first floor as living area and the other half as garage. It's a 12/12 pitch roof build with attic trusses so I have a finished area upstairs 18' wide x 64' long (divided into three rooms). I'm all electric with one heat pump upstairs and one downstairs (Having two separate systems solved some ductwork issues and provides a backup system in case one fails.) The systems are about 10 years old and rated at 13 SEER.

I spend most of the summers there, but turn the AC to about 80 when I'm gone. I don't spend much time there in the winter, but leave the heat at about 62 degrees when I'm gone. Over the past three years my electric bills have average just over $100 per month (I had a couple of months two winters ago when one heat pump was operating on auxiliary resistance heat full time because of a short in a wire.) My low bill during the period was $65+ in a month when neither the heat or air conditioning was running much (if at all). This $65 was the $30 per month fixed charge plus the cost of a water heater, security lights, appliances, etc. Based on this, I'm estimating that I'm spending less than $500 per year to heat and cool the house.

I mention this figure because a lot of folks like to tell me that I could save big money if I had the latest super efficient system. (one fellow who tried to sell me a geothermal system said that I could save $2000 per year with his system.)

I'm sure that the high end Mitsubishi system is great. I imagine that the installed quote includes a lot of profit, but is probably not far out of line with competition. However, there are a lot of lesser systems (such as PTHP units like you see in a hotel) that are starting to use inverter technology and the installation costs COULD be minimal. You might also want to consider if your overall cost would be lower if you spent more on insulation and less on HVAC equipment.