Shop Heating and Cooling

[Steve Rowe]

I am about to make the jump into heating and cooling my shop and am interested in experiences folks have on this. My shop is a 1000 sq ft insulated 3 car garage (except for the doors) with 10 ft ceilings. I am located in central Arkansas so cooling is the primary consideration. I had planned on putting in a central H&C system during construction but ran short of cash. I am considering going with a thru-wall heat pump and am interested in any experiences you may have on these units in a woodshop environment.
Thanks,
Steve

[Bill Simmeth]

I work in a 600 sq ft 2-car garage. This spring I installed a "mini-split" heat pump system made by Sanyo. It has a wall-mounted air handler (evaporator) and a separate compressor unit outside. A line set connects the two.

So far, I am thrilled. My shop is now a constant 74 degrees and the humdity is much lower, and more importantly, fairly constant (~45%). These units are very efficient and the effect on our power bill has been negligible. I am running an 18K btu unit. It easily handles my space and has been running only about 40% of the time during this stretch of 90+/high humidty weather we've had lately. I still get a thrill out of watching the water run out of the condensate drain! Hey, that stuff would've been on my jointer's tables!!

The downside is the maintenance on the air handler's filter to remove dust. I have both a cyclone and a JDS 750ER air cleaner, but still, I am religiously removing and washing the filters at the end of every day I work in the shop. They're easy to get to, so it's not a hard chore. It's worth the effort and I'm not about to complain! I highly recommend this type of system. (Can't vouch for the heating side yet, but based on the cooling performance I think I'm gonna like it!)

Bill in Delaplane, VA

[Bob Marino]

I work in a 600 sq ft 2-car garage. This spring I installed a "mini-split" heat pump system made by Sanyo. It has a wall-mounted air handler (evaporator) and a separate compressor unit outside. A line set connects the two.

So far, I am thrilled. My shop is now a constant 74 degrees and the humdity is much lower, and more importantly, fairly constant (~45%). These units are very efficient and the effect on our power bill has been negligible. I am running an 18K btu unit. It easily handles my space and has been running only about 40% of the time during this stretch of 90+/high humidty weather we've had lately. I still get a thrill out of watching the water run out of the condensate drain! Hey, that stuff would've been on my jointer's tables!!

The downside is the maintenance on the air handler's filter to remove dust. I have both a cyclone and a JDS 750ER air cleaner, but still, I am religiously removing and washing the filters at the end of every day I work in the shop. They're easy to get to, so it's not a hard chore. It's worth the effort and I'm not about to complain! I highly recommend this type of system. (Can't vouch for the heating side yet, but based on the cooling performance I think I'm gonna like it!)

Bill in Delaplane, VA

Bill,

The Mini-splits is something I had not considered. Can I ask the price? How big is the compressor?

Bob

[Bill Simmeth]

The Mini-splits is something I had not considered. Can I ask the price? How big is the compressor?

Hi Bob... I bought the unit off that well-known auction site (think "sanyo mini split"). It cost about $1500 delivered. I was able to do the install by myself, but paid the local HVAC guys to flair the copper joints and "purge" the system. That cost me about $100.

The compressors on these units are really neat -- very compact. Mine measures 34" wide x 24" high by 11" deep. And it is sooo quiet -- not even close to the noise level of the 1 yr old Trane heat pump (that does the house) it sets next to. In fact, if I'm more than 10' away, I can only tell if it's running by looking at the fan. Here's a link for specs... http://www.sanyo.com/industrial/HVAC...ed/Heat_Pumps/

Again, I am sold on these. I installed a battery of them in an old Victorian we renovated last year and turned into office space. The Japanese use these as their primary HVAC systems and we all know how they are about space utilization, operational efficiency and noise.

Bill in Delaplane, VA

[John Renzetti]

Hi Steve, I put a Mitsubishi split system in my daughters new bedroom bathroom addition. Works great. It was $1800 installed.
For the shop I have a Heater that I got from Northern. It's 220v and warms up the shop quickly. I think it cost around $200. For cooling I have a portable A/c unit that I bought from MSC. This is a Fedders unit. Works fine. It cost around $500. Later on I may have to replace the wall unit heat/pump a/c that is in the in law suite over the shop. When I do that I'm going to install a large dual zone split system to handle both the shop and the upstairs room.
take care,
John

[Keith Hooks]

Those split systems seem really slick. Are the "outside" units weather proof? Are they ok out in the elements?

[Bill Simmeth]

Those split systems seem really slick. Are the "outside" units weather proof? Are they ok out in the elements?

Hi Keith... yes, the outside unit is designed to be out in the elements, just like the compressor unit on a typical central a/c system or heat pump.

Bill in Delaplane, VA

[Steve Rowe]

I looked briefly at the mini-split systems and based on your responses, perhaps I should look again. This could be very beneficial since I wouldn't have to cut through a brick wall for a thru wall unit. I already have a pad for the compressor unit.

I was real concerned about the filter clogging or worse letting the fine stuff coat the coils in a dusty environment. Perhaps I am dating myself but, remembering a window air conditioner my dad had in the 60s, the filter was a very coarse and thin foam that was pretty useless. Hopefully, they have made some improvements in that last 40 years.

Thanks,
Steve

[lou sansone]

how do these split systems compare to oil for cost per btu?

[Bill Simmeth]

how do these split systems compare to oil for cost per btu?

Well, of course, it depends tremendously on where you're located. Here in Virginia, we're lucky enough to be in the bottom half of states for the cost of both oil and electricity. Compared to coastal Connecticut, where you are, our winters are also much milder. Therefore, here, a heat pump is still quite an effective source of heat. On a sheer $/BTU basis, where I'm located, oil is slightly cheaper. But, (and this is entirely subjective) having lived in NW Connecticut for a few years in a house with oil heat, I'm happy to be back in a home in Virginia without the oil "smell". Plus, the mini-split provides a/c quite effectively, which our oil burner in CT did not do.

Bill in Delaplane, VA

[Thomas Canfield]

Steve,

You might consider installing the air handler on a raised pedestal to allow installing additional filters in front of the stand filter at the unit. I built a plywood box about 42" high that now has two 25 x 25 initial filters about 1' above the floor with space for third on front face. Doing it again, I would raise the filters higher because of floor dust, but it does catch the dust. I change the unit filter about every 3 times I change the initial filters. My air conditioner is a standard house 2 ton unit with electric strip heat. I did not run ducts and only have 3 registers on an outlet plenum to direct air. The heat cost is what I have to watch, but my normal temperature range is 60F heat and 80F cooling. With insulation in the shop, the utility bill is not that bad.

[Phil Maddox]

The "mini-split" systems that have been described above do work very well. We install anywhere between 4 and 12 of them per school to keep the I.T. equipment cool. The Sanyo and the Mitsubishi systems both seem to be of high quality.

That being said, a mini-split would not be my first choice for a shop. The problem is the air handler, it is very small and has almost no capacity for additional static, like when you don't clean the filters. It is pretty easy to freeze a coil because the filter is clogged (lack of airflow will allow the coil to get too cold and freeze the condensation on it). The unit should shut down under these conditions but it can be a pain. You also cannot add any ductwork to them so the heating/cooling is very concentrated.

I would suggest a fairly conventional split system with a fan that has a bit more oomph. That way, you can add additional filters if you want, add some ductwork to direct the flow where it is needed and don't have to change the filters as often.

A mini costs more to buy and less to install, a conventional system is the other way around.

Good luck.

Phil

[Steve Rowe]

Steve,

You might consider installing the air handler on a raised pedestal to allow installing additional filters in front of the stand filter at the unit. I built a plywood box about 42" high that now has two 25 x 25 initial filters about 1' above the floor with space for third on front face. Doing it again, I would raise the filters higher because of floor dust, but it does catch the dust. I change the unit filter about every 3 times I change the initial filters. My air conditioner is a standard house 2 ton unit with electric strip heat. I did not run ducts and only have 3 registers on an outlet plenum to direct air. The heat cost is what I have to watch, but my normal temperature range is 60F heat and 80F cooling. With insulation in the shop, the utility bill is not that bad.

Thomas,
I had given some thought to that possibility. Does your box block or otherwise interfere with the flow coming out of the air handler? Thanks.
Steve

[John sexton]

Hello Steve,



<O:p< p O:p<>
I am located in Benton Arkansas. I have a 1,300 sq ft shop and I was thinking of doing the same thing but did't want to spend to much money.


I looked at a window unit on Sam's Club web site it has 24,000 BTU cooling and 16,000 heating for $509.00<ST1:p< p> <?XML:NAMESPACE PREFIX = O /><O:p></O:p>

<O:p></O:p>

John

<O:p></O:p>



<O:p< p O:p<>

</O:p<></ST1:p<></O:p<>

[Thomas Canfield]

Steve,

The box is for the inlet air and provides additional mounting surface for filters to reduce the velocity and improve the filtering of dust ahead of the primary air conditioner filter located under the unit. With multiple primary filters, the dust load can be fairly heavy and not create too much pressure drop.

The outlet plenum is a vertical section with cap and registers on three sides directed out to the shop. The unit is located on a side wall a little to one side in my 22x24' hobby shop and provides fairly uniform temperature. I do use additonal fans to create air movement at 80F to give a cooling feeling. I do have a very high ceiling and no restricted on height, but 10' ceiling should allow for doing something similar. You may need some outlet duct in a larger shop, but portable fans do wonders at very little cost.

My wife had to encourage me to do a good job with the air conditioning. My initial plan was a wall unit, but the initial cost, operating cost, efficiency, and dust problems made me look a different systems. It has been one of the best decisions made after deciding to build a free standing shop and get out of the garage.

I tried to post a picture, but could not get the right extension to load. Sorry. I need to work on that.