need advice: HVAC conventional or "ductless"???

[SUPERFORD]

Hello everyone,

I'm new to the site, this is my first post. I really wish I had found this board about a year ago.

I'm in the process of completing my "dream garage" project. actually it's not quite my ideal setup, but it's the closest thing my county and my budget will allow at this time.


I'm getting ready to insulate, and install HVAC equipment.

I was planning to use a standard heatpump / air handler ducted system, but one of the local installers is REALLY trying to sell me on the Mitsubishi Mr. Slim "mini-split ductless" system. he says it costs less to install, is more efficient and offers equal or better performance. I'm not familiar with this type of system. if it delivers what he says, awesome. However, I'm skeptical that such a small unit can deliver adequate climate control (especially heat) to my entire garage.

I'm also concerned about filtration with the small wall mounted unit. the contractor says it's not an issue. at worst, he says I can clean the washable filter out more frequently.

I am located in central Virginia, we have summers with 100 degree heat and VERY high humidity. We have winters with 30 and below temperatures occasionally in the teens.

my garage has 2x6 walls (plenty of room for insulation), it has one area with 10foot ceilings with attic storage and one with 13 foot ceilings. there are no walls dividing anything except for the bathroom. I used insulated doors.

any tips or advice would be greatly appreciated.

thanks,
Chris

 

[gesoffen]

While I don't have a mini-split yet, one is in the plans for my future garage renovation. I've had second hand experience with them through my father-in-law (for a living area) and his has been completely reliable, up to the task and dead quiet. Appropriately sized, you shouldn't have any concerns with the units themselves. Are you considering the heat pump version or just the AC?

Your uninsulated doors will complicate things as those will be a HUGE heating/cooling loss and depending on material and humidity levels, a potential source for moisture/sweating problems. Any plans to update those in the future? If not, I'd consider putting a layer of foam on them if you can. You may also consider adding a ceiling fan to help cut down on the moisture and cooling demands.

 

[cw_racefan]

I have a ductless mini split in my garage and am very happy with it. I think you may get a little more even air distribution with a ducted heat pump, but for my use it's been great. I only heat/cool it when I'm out there, so it's not running 24/7, which is one reason I couldn't justify the cost of a ducted system. Mine has no backup heat, but if it's that cold, I have my trusty torpedo heater. Also interesting to note, while it was a mild winter (MD here so similar to you), my garage (2x4 so less insulation than yours) never got below 40 deg the entire winter.

The installation of the mini splits is super easy. One electrical line, and one 3 inch or so hole in the wall to run refrig. and condensate lines outside.

 

[SUPERFORD]

Are you considering the heat pump version or just the AC?

Your uninsulated doors will complicate things as those will be a HUGE heating/cooling loss and depending on material and humidity levels, a potential source for moisture/sweating problems. Any plans to update those in the future?

I plan on a heatpump version of whatever I do. it gets HOT & HUMID here in the summer (it's expected to be 102degrees today + NASTY humidity), but it gets cold in the winter, occasionally in the teens.

so I need HEAT and A/C. I want the garage to be just a comfortable as the house.

About the doors. I do have well insulated doors from "Overhead Door". If I remember correctly, they are an R-17 value.

 

[JohnZ]

I have a 42,000-BTU Mitsubishi "Mr. Slim" mini-split in my super-insulated 2600 sq. ft. garage (cooling-only, I have separate heat), and I'm very happy with it; cools very well and makes virtually NO noise, inside or outside. It's been in the low-to-mid 90's here for the last four days, and I'm nice and comfy.

http://www.villagephotos.com/pubbrowse.asp?folder_id=1411059

 

[Red'n'WhiteRebel]

How big is your shop? You say you want to be as comfortable as your home. If that's the case and it's a large space there's no way a ductless will do it. It will work but the temp won't be balanced. It will come down to how picky you are and how much green you want to spend.

 

[SUPERFORD]

How big is your shop?

1060sq ft.

13 ft cielings in half, 10 foot cielings in the other.

 

[Ron Lombardo]

My advise .. I;m a DAIKIN Dealer and the Mini splits save a lot of time and money on install cost. If you give me your sq footage I could quote the unit that fits your application. Also the beauty of the DAIKIN Unit is you can have multiple Ductless units and one condesnor outside. Basically you can zone it.

Email me if your interested [email protected]

Ron

 

[gesoffen]

I plan on a heatpump version of whatever I do. it gets HOT & HUMID here in the summer (it's expected to be 102degrees today + NASTY humidity), but it gets cold in the winter, occasionally in the teens.

so I need HEAT and A/C. I want the garage to be just a comfortable as the house.

About the doors. I do have well insulated doors from "Overhead Door". If I remember correctly, they are an R-17 value.

Oops - for some reason, I read "insulated" as "uninsulated" - you should be in good shape then!

 

[speed bump]

Only thing I can think of not to like on the mini splits is that the seer ratings arent as high as what you can go with a full size unit.

Also make sure whatever unit they install is R-410a instead of r-22.

 

[SUPERFORD]

Only thing I can think of not to like on the mini splits is that the seer ratings arent as high as what you can go with a full size unit.

Also make sure whatever unit they install is R-410a instead of r-22.

See that's what I don't get, my contractor is telling me that the Mr.Slim is MORE efficient than a standard heatpump.

He has actually told me several times that the unit is a 21 SEER!

He keeps telling me that the unit has NO drawbacks for my application.

He says it's:

1. CHEAPER INITIALLY
2. MORE EFFICIENT TO OPERATE
3. HE EVEN SAYS that it will put out 135 degree heat at the register where a heat pump will only put out 90 or something like that.
4. QUIETER etc.

This guy is really hyping this product. I'm not sure why he would be trying to misguide me as he is also a TRANE installer, surely he'd make more money on the trane system with ductwork too???

He flat out says the MR SLIM will be BETTER than a standard heatpump with ducts. I called another Mitsubishi Mr.Slim dealer in my area but they haven't returned my call.

 

[Red'n'WhiteRebel]

That's a good sized space for a split unit. I'm not saying that it won't do it but you won't balance the temp as well as a ducted system. I'm not sure why he's pushing you on the split, maybe he bought several of them at a decent price and needs to unload them or he could just prefer the simplicity of installing the split?????? I don't know.

 

[DRRummel]

I am in the process of building a 890 sq ft garage in Baltimore, MD. Soit should be about the same climate as you. I have R-10 insulation around the foundation and under the slab. Walls are 2x6 and should get R21 insulation. Ceiling should be R38. The garage doors are Overhead Door TheraCore R-17 doors. I have 12 foot walls with a scissor truss roofline that gives me about 15.5 feet at the peak. Sound familiar?

I just bought a Mr. Slim M-Series 23,200 BTU unit. It will heat and cool. While the unit is good, it sounds like your sales man is overselling the unit. If you want PM your number and we can compare facts. I also have a seller that WILL talk to you about the unit capabilities.

Mr. Slim Split-ductless:
M-Series Heat Pump 23,200 BTU's
16 SEER - $2,051.55
15 foot line set - 65.00
Power Disconnect and wire whip - 00.01
Wall mount brackets for Condenser – 112.37
Total to my door = 2229.00

While there are cheaper units. I don’t know how well they work or how long the parts will be available. Make sure you get a R-410, not a R-22 unit.

 

[SUPERFORD]

Sound familiar?

haha, I was just saying to myself, this guy seems to be describing my garage!

FWIW, I had a second HVAC contractor come out today to give me an estimate. This was THE largest residential contractor in my city, and supposedly one of the largest on the east coast? anyway, this contractor is a Mitsubishi "Diamond dealer" whatever that means. this guy also felt that the MR. Slim would be ideal for my application, however he said that I should use a dual setup with two indoor units due to my square footage. He said a single would probably do it, but it would be borderline with my 13ft ceilings. unfortunately the dual setups are substantially more expensive.

 

[MyDomain]

Mini-split units are generally more efficient, very quiet, excellent at dehumidifying and destratification, space-saving and reliable. There are no duct losses so you get out what the unit is rated for. An "inverter" style unit will provide up to 110% of rated cooling and will heat at rated amount down to 14 degrees. My company sells LG, they are very good. I would recommend LG, Mitsubishi, Fujitsu or Sanyo...whichever is in stock locally and has good parts and service availability.

The LG unit http://us.lge.com/products/model/detail/home appliances_air conditioners_art cool_LA245HV.jhtml

 

[DRRummel]

Mini-split units are generally more efficient, very quiet, excellent at dehumidifying and destratification, space-saving and reliable. There are no duct losses so you get out what the unit is rated for. An "inverter" style unit will provide up to 110% of rated cooling and will heat at rated amount down to 14 degrees. My company sells LG, they are very good. I would recommend LG, Mitsubishi, Fujitsu or Sanyo...whichever is in stock locally and has good parts and service availability.

The LG unit http://us.lge.com/products/model/detail/home appliances_air conditioners_art cool_LA245HV.jhtml

What does the LG unit cost with a 15 foot line set? Heating and Cooling.

 

[DRRummel]

haha, I was just saying to myself, this guy seems to be describing my garage!

FWIW, I had a second HVAC contractor come out today to give me an estimate. This was THE largest residential contractor in my city, and supposedly one of the largest on the east coast? anyway, this contractor is a Mitsubishi "Diamond dealer" whatever that means. this guy also felt that the MR. Slim would be ideal for my application, however he said that I should use a dual setup with two indoor units due to my square footage. He said a single would probably do it, but it would be borderline with my 13ft ceilings. unfortunately the dual setups are substantially more expensive.

If you are looking to buy next year, I will be glad to tell you how it preformed over the summer and winter. I should have mine hooked up this weekend.

 

[SUPERFORD]

If you are looking to buy next year, I will be glad to tell you how it preformed over the summer and winter. I should have mine hooked up this weekend.

I'll keep in touch.. I'm not sure when I'm going to buy. I did go with the dealer trying to sell me on one of these to look at another garage with a Fujitsu mini-split. I was impressed with the performance. The garage was slightly smaller than mine, but was extremely comfortable on a day that had a high of about 100 degrees. I'm still curious about the heating capability though. the dealer is supposed to be getting back to me with a quote for a 30,000btu unit, and also a commercial "P" series unit that has higher heat ratiings.

-chris

 

[MyDomain]

I could only give you list prices...I can only sell a/c stuff to licensed contractors. There should be a locator on the LG web site.

 

[DRRummel]

I'll keep in touch.. I'm not sure when I'm going to buy. I did go with the dealer trying to sell me on one of these to look at another garage with a Fujitsu mini-split. I was impressed with the performance. The garage was slightly smaller than mine, but was extremely comfortable on a day that had a high of about 100 degrees. I'm still curious about the heating capability though. the dealer is supposed to be getting back to me with a quote for a 30,000btu unit, and also a commercial "P" series unit that has higher heat ratiings.

-chris

I understand the commercial unit are significantly more money. When I asked what was the difference between he units I was told "It is made for commercial environments." You can guess how well that went over. If you find out how the residential unit and commercial unit differ, please post.

 

[chase0803]

I love it when i hear about people saying this unit is 21 seer and blah blah blah.
How much is the unit alone? 8 grand? LOL. Your sales guy is full of ****!

Tell him to prove that its 21+ seer(standard energy efficiency rating). Better yet, give me his number and ill ask him to prove it to me.... No on (to my knowledge) makes a 21 seer yet!

Mr. Slims are computer room units. Applications where they need the room 68* constant. Oh and these rooms are usually small. I just worked on 3 of these on thursday. Wanna take a guess where? A server room. A small room with no windows and one door!!!

Dude, if you can afford it do a ducted system. Try and get a higher seer rating. And do some research online. Carrier, trane, york ect ect. And dont use some rat *** company like warner or B&B.


Dont be bullshited about a ductless doing a better job! A/C is A/C! All direct expansion coils are only capable of a 18-22* split across the coil! The seer rating only gives you an estimate of its cost effectiveness to do said cooling.

I just put in a 2 1/2 ton straight a/c for a friend of mine(carrier). And that thing was pretty bad ***. The only noise coming from the outdoor unit was the sound of the fan blades cutting the air!

If you dont mind me asking, how much was the quote for the ductless system?

 

[chase0803]

I understand the commercial unit are significantly more money. When I asked what was the difference between he units I was told "It is made for commercial environments." You can guess how well that went over. If you find out how the residential unit and commercial unit differ, please post.

There really is no difference. Only application. Commercial units are more "fancy" so to speak. With that being said, bells and whistles that may be applicable for commercial vs residential.

 

[MyDomain]

Chase:
Mr. Slim 23 seer unit http://mrslim.com/Products/itemDeta...oryID=140&ProductCategoryID=24&ProductID=1721

"Mr. Slims are computer room units." Yes, mini splits are used in computer rooms because they are small, efficient and have built-in low ambient capability however that is far from their main market.

Your ductwork is notoriously inefficient. Between leakage and ambient infiltration the losses are estimated up to 40%.

I am not saying minis are great for 100% of the applications out there but your total disdain for them says to me that you do not know much about them and therefore are quick to shoot them down. For reasons I have already posted they are great for garages.

 

[chase0803]

Chase:
Mr. Slim 23 seer unit http://mrslim.com/Products/itemDeta...oryID=140&ProductCategoryID=24&ProductID=1721

"Mr. Slims are computer room units." Yes, mini splits are used in computer rooms because they are small, efficient and have built-in low ambient capability however that is far from their main market.

Your ductwork is notoriously inefficient. Between leakage and ambient infiltration the losses are estimated up to 40%.

I am not saying minis are great for 100% of the applications out there but your total disdain for them says to me that you do not know much about them and therefore are quick to shoot them down. For reasons I have already posted they are great for garages.

Remember where i said dont get some rat contractor to install it? That means they will take care of your said 40% air loss and seal, wrap the duct....

 

[chase0803]

And im shooting them down because i see mini vs ducted systems everyday. And i have to work on them. Salesmen dont know **** except some number someone told them.

 

[MyDomain]

About mini splits http://www.fujitsugeneral.com/learn_about.htm

 

[MyDomain]

It helps to be a salesman that has had 10 years of experience as a technician prior to sales. Best of both worlds.

 

[chase0803]

About mini splits http://www.fujitsugeneral.com/learn_about.htm

Wow, an unbiased opinion from the company that makes them....

http://www.fujitsugeneral.com/case_studies.htm i found that to be pretty humorous. Again, look at the application!

Do you work for or own stock in these unit?

 

[chase0803]

Have you been properly trained to work on them? They are exceptionally simple to repair when needed.

It helps to be a salesman that has had 10 years of experience as a technician prior to sales. Best of both worlds.

Well, i've been doing this for ten years and the fact that i have a union card from one of the best 5 year mechanical engineering trade schools in the country kinda helps.

I never said they dont work well given the proper application.....

 

[Vicegrip]

SEER is an average of many variables. Google it.

The *only* way to compare electrical efficiency is with the EER ratings. That gives you the number of Btu's output per watt of power consumed.

Not only do ducts need to be sealed, they also need to be designed properly to reduce airflow restrictions as much as possible. It is difficult to get a contractor that does both, much less one or the other.

SEER also assumes that the air conditioner is chaged properly... and that takes time.

Contractors know that homeowners shop by dollars, so a contractor that prices the job done correctly won't be very busy competing with the hacks out there.

It will be difficult to get a traditional split system with ductwork at the same price point as a mini-split.

By eliminating the ductwork (ductwork leakage and low bid residential cap-n-tap metal/flex work), you pick up some SEER points.

The variable speed motors and compressor(s) in the mini-split unit also add SEER points.

You would need a top shelf air handler with a variable speed motor plus a 2 stage or ECM compressor to come close to matching the efficiencies of a mini-split.

Well said. The mini splits are nice if they are an option. Shops with the off and on use profiles and single room shape are often a good candidate for a mini split. I am still amazed at how quiet they are both inside and out. The variable speed units can be oversized to a good degree too. This gives the fast pull down that an oversized unit gives and as temps get close to set point they still pull the humidity out properly while maintaining the high SEER. Best of both.

 

[chase0803]

Another thing to take into consideration is the filter media use in the two units. One will have a HI-E pleated and the mini will have a cheese cloth type that about 1/16" thick. Again, i really dont see any advantage of having a ductless system in a garage!

 

[chase0803]

Well said. The mini splits are nice if they are an option. Shops with the off and on use profiles and single room shape are often a good candidate for a mini split. I am still amazed at how quiet they are both inside and out. The variable speed units can be oversized to a good degree too. This gives the fast pull down that an oversized unit gives and as temps get close to set point they still pull the humidity out properly while maintaining the high SEER. Best of both.

Wrong.....

 

[Vicegrip]

Wrong.....

Do you care to explain why?

 

[Vicegrip]

Another thing to take into consideration is the filter media use in the two units. One will have a HI-E pleated and the mini will have a cheese cloth type that about 1/16" thick. Again, i really dont see any advantage of having a ductless system in a garage!

Consider how easy it is to clean/change a mini split filter and for that matter the relative ease of cleaning the entire air handler. A ducted system will get lined with the dust and dirt generated in the shop over time. The ducted system's filter only helps prevent the dust from getting on the system after the filter. The ducts before the filter will get dusty and are far harder to clean than a right in front of you mini split air handler. Also keep in mind that none of the residential air filters have 100% capture rates. some of the dust that gets past the filter will remain in the ducted system as well.

 

[Ron Lombardo]

Most residential HVAC contractors dont do much calculations because its too costly ... but in the commercial world my shop re checks and re sizes ductwork based on the CFM spec by an engineer ...things like the use of vains and the proper takeoffs on a branch duct all contribute to the TEST and BLANCE report at the end of the job submitted to the engineer proves the system is performing at each diffuser and return grill as it was designed also 15% outside is required for air changes ..yes even in the winter. Some times a shieve size needs to be changed for the Blower to meet the required CFM specs.

When was the last time you seen a HVAC contractor TEST & BALANCE your HVAC system.

With that said AIR FLOW is king in AC systems. SEER ratings translates to efficiency ... so buying a high SEER rating and then having some RESIDENTIAL HACKER install it CHEAP ... your throwing your money in the garbage.

Take a look at LEED requirements for HVAC systems ..this is fairly new GREEN requirement on some jobs we do ... it elevates quality, performance and requires the systems to be commisioned properly.

Ron

 

[SUPERFORD]

If you dont mind me asking, how much was the quote for the ductless system?

I got 4 quotes, three from local Mitsubishi ductless installers. all companies also install ducted systems from Trane, Carrier, Lennox, or York. here are the results:

1. (small "one guy" name on the truck company) recommended a 24,000 btu single indoor/outdoor unit. his price was something like $3300 installed

2. (largest company in town) recommended same 24,000 btus, but wanted to use a single outdoor unit with two indoor wall mounted units for better air distribution. wanted something like $7300 installed!


3. (mid size company) did not advise using Mr. Slim for my space, instead offered a York ducted system for $5000

4. (non mitsu dealer mid size company) also did not advise using mini split ductless although they offer carrier ductless systems. suggested lennox ducted system for $6300

so I'm as confused as ever.

out of 4 quotes:

50% said use ductless, 50% said go ducted

of the two that recommended ductless, both claimed that they would work great for the space. while the other two said they wouldn't be adequate.

the two that recommended ductless agreed on sizing, but disagreed on if I need one or two indoor units.

and to make matters worse, the 3rd mitsu dealer that recommended a ducted system said that they had seen multiple compressor failures on mitsubishi systems that were using multiple indoor units. none on single indoor units, but problems with mr.slim running multiple zone indoor units off of one outdoor heat pump...
???

 

[Vicegrip]

Most residential HVAC contractors dont do much calculations because its too costly ... but in the commercial world my shop re checks and re sizes ductwork based on the CFM spec by an engineer ...things like the use of vains and the proper takeoffs on a branch duct all contribute to the TEST and BLANCE report at the end of the job submitted to the engineer proves the system is performing at each diffuser and return grill as it was designed also 15% outside is required for air changes ..yes even in the winter. Some times a shieve size needs to be changed for the Blower to meet the required CFM specs.

When was the last time you seen a HVAC contractor TEST & BALANCE your HVAC system.

With that said AIR FLOW is king in AC systems. SEER ratings translates to efficiency ... so buying a high SEER rating and then having some RESIDENTIAL HACKER install it CHEAP ... your throwing your money in the garbage.

Take a look at LEED requirements for HVAC systems ..this is fairly new GREEN requirement on some jobs we do ... it elevates quality, performance and requires the systems to be commisioned properly.

Ron

Well said. I have seen some real junk tin and tube work stuck to good units.

 

[Vicegrip]

Well, i've been doing this for ten years and the fact that i have a union card from one of the best 5 year mechanical engineering trade schools in the country kinda helps.

I never said they dont work well given the proper application.....

And a garage is likely one of the proper applications.
Well I have been doing this and more since the 1970s and some of what you say is not true at all. I don't mean to sound harsh but you don't seem to want to discuss rather than spout hard "facts". I have been paid to work on everything from $50 window shakers to ammonia absorption systems to the metro bus sized RTUs I like to walk around in order to cool off. I do not profess to be an ex-purt but I do like to understand and learn new systems and methods. I get the feeling that you have little experience in range, with variable drive systems and or were trained by a very opinionated instructor.

You never did explain how a fully triple variable system will not work slightly oversized other than to say "wrong" All 3 motors, evaporator, condenser and compressor are frequency driven and computer controlled. As the room temps close on set point the system adjusts all 3 to keep the optimal evaporator and condenser temps and air flows over the coils.

 

[Ron Lombardo]

SUPER FORD wasnt your application for a 2 story garage or barn ? How would one ductless unit work for that ?

If you can get ducted units for those prices ... send them up to NY I will sub my work to them ? LOL

 

[SUPERFORD]

SUPER FORD wasnt your application for a 2 story garage or barn ? How would one ductless unit work for that ?

If you can get ducted units for those prices ... send them up to NY I will sub my work to them ? LOL

Ron,

No, my application is for a single story "one room" garage that has two different ceiling heights (one "bay" has 10' ceiling and the other area has 13').

I can get ducted systems for those prices here in VA, however I don't think they are willing to make the 5 hour commute to NY to subcontract!