Building a real shop, Want heat pump

[Rick Huelsbeck]

Ok, it's going to be disquised as a garage, but it will be 24 X 24 or 560 sq ft I've only got 250 sq ft now. Anyway I'm going to add a heat pump, what I want to know is if anyone here has some experience with the Ductless Mini Split units. I'm looking at going with an 18000 BTU (1.5 ton) heat pump with electric back up (yes it really does get below 25 frequently here in the winter.) Does anyone regret going that route? Any suggestions on the best brand to go with? I know some of you are using them I've seen your post

[Ray Newman]

I 'dunno' about the heat pump units you recommended, but how much insulation are you installing?

I have a Hot Dawg heater in my shop, and the installer wanted to know not only the size of the building, but the am't. of insulation and type of windows to better size the unit for the heating demands.

When I had my shop built, framing was 2X6 and the contractor said that R-19 would suffice; however, I had R-21 installed as that was the maximum insulation possible. The price difference between R-19 and R-21 was not much as the labor cost and install time were the same as for the R-19. Same with the windows: he wanted to install a more economical window and I opted for double pane and insulated windows.

Energy costs will not decrease and it is always cheaper to add more insulation now than try to heat a colder shop in the winter or cool a warm shop in the summer.

[Ken Garlock]

Hi Rick. My shop is nearly the size of yours.
When mys shop was built, I had a Trane 2 ton heat pump installed. The unit has run without problems since late in 2002. I keep the shop at 75 in the summer, and 60-65 in the winter. We have temp ranges from 9 deg. this last winter to around 108+ deg. in the summer.

This doesn't answer your question, but gives you another option/opinion.

[Bill LaPointe]

Ok, it's going to be disquised as a garage, but it will be 24 X 24 or 560 sq ft I've only got 250 sq ft now. Anyway I'm going to add a heat pump, what I want to know is if anyone here has some experience with the Ductless Mini Split units. I'm looking at going with an 18000 BTU (1.5 ton) heat pump with electric back up (yes it really does get below 25 frequently here in the winter.) Does anyone regret going that route? Any suggestions on the best brand to go with? I know some of you are using them I've seen your post

Rick,

I have a 2 ton Mitsubishi split unit. It is actually a bit oversize but does a great job. I don't have the heaters in the unit as I have a ventless fireplace that I use to heat the area. I couldn't be happier with it's performance in the 2 years since I installed it. VERY quiet and super efficient. I bought mine on Ebay from a gentleman that had bought 3 truckloads of new, overstock units direct from Mitsubishi. Both the air handler and compressor units were in sealed cartons. Cost was $700 and I picked it up from his warehouse. I installed the unit myself, very easy if you have some basic knowledge of A/C. Tried to locate his info, but can't find it. If I locate it I will PM it to you.

[Scott T Smith]

Rick,

I have a 2 ton Mitsubishi split unit. It is actually a bit oversize but does a great job. I don't have the heaters in the unit as I have a ventless fireplace that I use to heat the area. I couldn't be happier with it's performance in the 2 years since I installed it. VERY quiet and super efficient. I bought mine on Ebay from a gentleman that had bought 3 truckloads of new, overstock units direct from Mitsubishi. Both the air handler and compressor units were in sealed cartons. Cost was $700 and I picked it up from his warehouse. I installed the unit myself, very easy if you have some basic knowledge of A/C. Tried to locate his info, but can't find it. If I locate it I will PM it to you.

I had a ton and a half Mitsubishi unit in my old woodshop before the fire. Worked great cooling a 24 x 32 shop.

[Mike Hicks]

I don't have any experience with the particular unit you mentioned but I have had heat pumps in my house before the one I am now in. One thing people don't realize (at least I didn't) is that once the outside temperature goes below 32 degrees there is no longer any heat transfer from the air so your unit goes to a backup resistance strip like a regular electric heater. So it is not as efficient as it is usually. Where I live in northern Texas, they claim we are borderline on how efficient the heat pumps are. I now have geo thermal in the new house I built and it works on the same principle as the heat pump. The difference is the heat transfer is taken from water that is circulated through the ground where it is a constant 65 degrees. My units don't even have the heat strips installed in them. It is more expensive initially but definitely more economical.

[Brian Cover]

We have installed a few mini splits for customers and they generally do the job quite well. Since you are adding the heat strips, you won't have the usual problem of lack of heat in the sub freezing temps.

An 18,000 btu unit should be adequate for the job provided the walls and ceiling are properly insulated. All the name brand units are well made, so durability and reliability won't be an issue IF it is installed correctly and a vacuum pump is used for at least an hour to evacuate the moisture from the tubing.

There are many close out deals on the R-22 units, so that is what I would buy if it was my shop.

(Actually, my shop is 40' x 60' with 14' walls, so I didn't use a mini split)

[Rick Huelsbeck]

We have installed a few mini splits for customers and they generally do the job quite well. Since you are adding the heat strips, you won't have the usual problem of lack of heat in the sub freezing temps.

An 18,000 btu unit should be adequate for the job provided the walls and ceiling are properly insulated. All the name brand units are well made, so durability and reliability won't be an issue IF it is installed correctly and a vacuum pump is used for at least an hour to evacuate the moisture from the tubing.

There are many close out deals on the R-22 units, so that is what I would buy if it was my shop.

(Actually, my shop is 40' x 60' with 14' walls, so I didn't use a mini split)

Ok, I'm planning to insulate the roof with R-19, and the walls are going to be block and not insulated (They are going to be painted), may one day put something on the walls (or in). Do you still think 18000 will do? What would be the average installation price? I know I could do it myself (did some AC work when I was in a previous life) but from what I'm reading the moment I do it, I've just voided the warranty. Anything you can tell me to look out for would be appreciated as well.

Thanks for the help, everyone. This place is certainly a wealth of knowledge

[Brian Cover]

The thermal efficiency of any block wall is very poor. Just adding 1x2 fir strips and plain drywall actually doubles the R value. If you used 2x2 fir strips and put the cheap white foam board behind the drywall, you will greatly improve the comfort of the space. For the small price difference, put R-30 in the ceiling instead of R-19.

Most contractors will charge about $3000 for an installed mini split IF you have the electric ready for them. If they want more than that, let me know and maybe we can work out a vacation trip in your area come hunting season. feathers or fur, no preference.

[paul cottingham]

I don't have any experience with the particular unit you mentioned but I have had heat pumps in my house before the one I am now in. One thing people don't realize (at least I didn't) is that once the outside temperature goes below 32 degrees there is no longer any heat transfer from the air so your unit goes to a backup resistance strip like a regular electric heater. So it is not as efficient as it is usually. Where I live in northern Texas, they claim we are borderline on how efficient the heat pumps are. I now have geo thermal in the new house I built and it works on the same principle as the heat pump. The difference is the heat transfer is taken from water that is circulated through the ground where it is a constant 65 degrees. My units don't even have the heat strips installed in them. It is more expensive initially but definitely more economical.

I use an air source heat pump in Victoria, BC and it works well below 32 degrees, without any electric backup. Larger units are much more efficient at lower temps.

[Gary Click]

Anyway I'm going to add a heat pump, what I want to know is if anyone here has some experience with the Ductless Mini Split units. I'm looking at going with an 18000 BTU (1.5 ton) heat pump with electric back up (yes it really does get below 25 frequently here in the winter.) Does anyone regret going that route? Any suggestions on the best brand to go with? I know some of you are using them I've seen your post

When we built on to our house several years ago, I decided to take in the area under a double garage as a storm room/man cave. The room is below grade, has 12" thick poured cell walls and a 6" poured garage floor/ceiling. To finished off the room I needed a door that could withstand 200+mph 2x4's. I found a used 8" thick solid steel Mosler Bank Vault Door (5500#) for $400 and used that.

The need for HVAC was then obivious and the HVAC guy suggested using a Mitsubishi Mr. Slim unit. Installation was easy and the preformance is outstanding. The unit is quiet and cover the area quite well. I would not hesitate to use this approach again.

[Jonathan Spool]

Hi Rick,
I am in the middle of a shop project also. I also have cinderblock walls.
I have decided to pull the lidand insulate to R30, and fir the walls 1.5" and install RMax board at R10. I will be having a ductless heat pump system installed as well. Note that some systems are rated to produce heat town to zero degrees farenheight. Others go down to 5, and the lesser ones to 32. Also, make sure you get a unit that utilizes DC inversion as it will pull much less power. I know I'll never have the opportunity to do this work once the shop is set up and running, so I'm biting the bullet and doing it now, and saving later.

[John Keeton]

I found a used 8" thick solid steel Mosler Bank Vault Door (5500#) for $400 and used that.

Now, THAT is a shop door!!!

[Chris Singletary]

U guys with the mini splits better keep your filters clean the dust from a shop will clog the coil of any ac unit. I have seen some good ones being in the wholesale ac business.

in my shop I installed a 2-1/2 ton split heat pump and ran exposed duct. 24x24 shop with 14' ceilings and will cool to 65 degrees in july in south ga. put a 4" pleated filter under unit and change or blow out every week