Heat and a/c for shop

cgraham

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Mar 6, 2011
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Interested in what others have in their shop for heat and air conditioning.  Had a used heat pump given to me but it uses the old freon. The price has skyrocketed for old freon and was thinking about getting a new mini split system instead. The old system would require ductwork and would evenly heat and cool the space.  Does anyone have a mini split and do they like it. Shop is 24x32 with 12 foot ceilings
 
For a small space like that I'd put I a wood-burning stove that would also help you get rid of your off cuts and a floor standing or wall-mounted air conditioner.
 
RL said:
For a small space like that I'd put I a wood-burning stove that would also help you get rid of your off cuts and a floor standing or wall-mounted air conditioner.
cgraham said:
Interested in what others have in their shop for heat and air conditioning.  Had a used heat pump given to me but it uses the old freon. The price has skyrocketed for old freon and was thinking about getting a new mini split system instead. The old system would require ductwork and would evenly heat and cool the space.  Does anyone have a mini split and do they like it. Shop is 24x32 with 12 foot ceilings

A SMALL SPACE!!!???  [jawdrop]
 
I don't have a mini split yet but will likely do so into my garage next year, perfect solution for my needs. Regarding burning wood, I wouldn't want to lose the floor space, nor have an open flame unless I could get its air supply from outside for greater safety and efficiency, and in my area of California the govt issues no wood burn days in the winter for air quality reasons so that wouldn't be an option for me.
 
[member=19439]Paul G[/member]

Following up on this old thread to see if you've installed the mini split and what your thoughts are. 

I'm building a 24x30 workshop that will have a second level with about 300sf of finished space.  With a total of around 1000 heated and cooled sf, I'm looking at a dual zone Mitsubishi mini split with 15K BTU for the ground floor and 9k upstairs. 

If I were staying in California I wouldn't worry too much about the cooling, but this workshop will be in Monroe, Louisiana where the summer temps are much higher. 

Would appreciate any advice on this, as the HVAC folks I've talked to are suggesting a traditional ducted system.  They argue that the systems will have about the same installed cost and that the traditional system will be cheaper to maintain in the long run.  That may be true, but I'm still leaning towards the mini split. 
 
Unfortunately no, I haven't done so yet. Need some extra power to the house and waiting until that is done. Since our utilities are underground it's a bit involved, especially since phone and gas are on top in the same trench as the direct burial electric. Thankfully hadn't yet poured concrete in the same area.
 
What kind of insulation do you have in the shop?  How tight is the structure?  How many south facing windows?

My gut tells me you're a little on the light side and even if it's well insulated, you'll have an issue with airflow downstairs.  Put the unit on the short wall pointing across the length of the shop.  A ceiling fan can help aid in circulating the air. 

I have a 24K MS in my 600 SF insulated attached garage (11 ft ceilings).  On the AC side it's completely oversized, but since these inverter units scale so well it doesn't matter.  So if you want to err on the side of caution, that's what I would do.  I oversized it to get the heating output.

Many installers shy away from these for a number of reasons, especially if they don't work with these regularly.  Installation issues can arise, but it's not rocket science.  Servicing the electronics and other parts in the indoor unit might be difficult because of the tight confines, but someone familiar with them shouldn't have any issues.  I think you need to ask them more questions to assess whether their recommendation is based on their own biases and comfort level, or something more real.  Mitsubishi and Fujitsu are two of the best as far as I'm concerned.

 
[member=21249]RKA[/member]

Thanks for the reply.  I can look at upping the BTUs for the downstairs unit, as I'm a little worried how it'll do over the 30 foot length of the shop. 

Walls will be R-19.  No south-facing windows.  Will definitely put in a couple of ceiling fans to get the air moving. 

Good advice on talking with the HVAC folks.  Looking at the hardware, I'm wondering if installing the mini split myself is an option.  Doesn't look that complicated.  Agree with you on MS and Fujitsu as reputable manufacturers. 
 
Sanyo is another quality brand to consider. I have a 1.5 ton MS in my 24x24 shop with 10.5' ceilings. But I'm near Philly so don't have as many hot, humid days as you do. We have maybe a dozen days each summer where it gets above 95°F.
You might want to bump the size and go to a 3 zone system with two units downstairs so you'll get more evenly distributed air over the large work space.
 
[member=60461]Bob D.[/member]

Also good advice.  Going 3 zone would for sure help on the ground floor.  I'm not as concerned with the upstairs, as that's for storage.  But would make a nice area for a ping pong table so want to have some cooling up there.  I'll take a look at Sanyo.  Thanks!
 
Max, you can definitely do the bulk of the work yourself.  The bulk of the work can be done without specialized tools (mount indoor and outdoor units, run electrical, run piping).  The difficulty is finding an HVAC guy to do the last 3rd of the job.  That would be adding the flares to the lines, pressure test, pull a deep vac and release the refrigerant (or adjust the fill if needed).  It's those last steps that require an investment in more specialized tools and may not be worth a DIY, but if you were to do it, figure $500-600 in tools and supplies.  You have to be careful with the warranty if you go this route.  Some manufacturers are fine as long as a certified tech does the final part of the install, some get persnickety about this.

One of the things I liked about Fujitsu is they specified a range of length for the linesets (16-60ft or something like that).  I have no idea how, as most others specific a narrow range or absolute value and provide and adjustment in oz of refrigerant to be added or pulled out.  None of this matters if you're paying someone for the final install, but for DIY, it can mean you never need to open the system.  You just connect the lines, open the valve on the outdoor unit to release the refrigerant and you're done.  But with a Fujitsu you will lose the warranty if you're DIYing. I went this route 6 years ago, no regrets, but it's not for everyone.

 
I have a 3 car garage i use for shop, about 800 SF, insulated walls, ceiling, and garage doors. I have a Mitsubishi Mr. Slim that works great for heat and AC.  It's prob about 10 yrs old now and has been flawless.  No ductwork, as it comes through an exterior side wall about 7' off the floor.
 
I originally started this post a few years back. I haven't installed a system yet but I have saved about half of the cost of the system ($6500 total). I am going with a propane furnace with an ac coil. Several reasons.  Based on square footage it would require two units for a mini split.  I don't want to maintain temperatures when there is times I won't be in there for several days. The quickest way to heat is with the fossil fuel and I already have propane at my house. A ducted system will produce an even temperature throughout the shop and circulate the air better in summertime. I am in the construction business so I consulted with several hvac companies and all three came back with the same opinion for a traditional ducted system and all three were within 2-3% price of each other

 
I originally built my 1500 sq. ft. shop in south La  (Covington) with no consideration for HVAC. In fact I installed 2 large attic fans in cupolas on the roof with an open gabled ceiling (joists at 12'). I have basically a metal building with foam in the walls, but only the rolled blankets that they typically use for the roof of a metal building. My southern exposure has a large porch the length of the building.

Later installed 3 $600 heat/cool window units, and the results are fantastic. I can have the place heated or cooled in a short time, use them to remove humidity, or turn them off and open the doors on the 6 nice days we have every spring or fall here....

AND - not needing to keep a system running 24/7 sure keeps the electric bill down.
 
I heat 5500 sqft with a 190000 btu hanging furnace. Keep it at 45 at night turn it to 55 when I am working (makes me sweat any higher) about 70 bucks a month to heat.

It's a block building so it stays pretty cool most of the time. 
 
Thanks for the feedback, everyone.  I sure hope I don't need anything near 190,000 BTU in my place!  I'm pretty settled on a Mitsubishi or similar unit with two zones.  Along with a couple of ceiling fans in the main floor, I'm hopeful it will heat and cool the 720sf downstairs.  Will post back after I have some experience with it.
 
How much can you rely on passive?
With some south wall, skylights, etc and a concrete floor one gap can get heat I out and thermal mass for storage.
Whether that costs more than power is probably the primary question.

You probably need some heat/heater, but a well sealed and insulated structure with some way to get light/heat in can do a lot of the naturally.
 
One more thing to consider for the mini splits is parts and service.

The concept is pretty new in the US, and in many areas parts and service may be limited to only a small number of dealers.
 
I am building a shop now. Looks like I will be going with the Mitsubishi Mini-Split system with Hyper-Heat etc. My shop is about 1,000 sq ft so it sounds like a 6-9,000 BTU unit will be sufficient. I am still sorting out the details so these numbers may change. I know for cost the system I have been quoted is around 8K with 12 year manufacturer warranty. But this system also includes another 1,000 sq ft above in the apartment. So I'd say the cost for the shop alone should be closer to $1,500-2,000 etc.
 
Thread is a few months old, but I have a 2 ton Mitsubishi mini-split HVAC in my garage.  I live in Houston, TX so the summer months are HOT and HUMID.  My garage is 550 sqft, it is a 2 3/4 bay garage, basically a 2 car garage with the right hand bay being 35 feet deep.  The right hand wall is non-insulated, but all other walls and the garage door are insulated.  The space above the garage is also insulated.  I spent $4k on the unit w/installation and another $250 to add a disconnect from the breaker box to the external unit.

I would not work in the garage without this thing, it is fabulous.  It is efficient and nearly silent, I think the external unit actually is silent.
 
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