We deal with this every winter, how to keep the shop warm. I will heat the shop when I am in it, but turn it off when I am done. I have a wall mounted heater that's on a 30 amp line and my shop is 25' x 25' with 10' ceilings. Takes about an hour to raise the temp 10 degrees. I have been toying with the idea of these ductless heatpumps like the mitsubishi units. I can definitely do the install myself, though I don't know if I have the tools to charge the system. BUT, before I do this, anyone use one of these systems in their shops, I would really like to keep the shop at a consistent temp overnight and then only raise it when I'm in there working. The walls and ceiling are all insulated 2 x 6 walls. Thanks for you input.
Assuming you're referring to what they call "mini split" units, they are probably the most efficient and economical units out there today. Mitsubishi makes one of the best quality available.
The good thing with the mini splits over standard heat pumps is you won't need to worry about dust clogging things up as much. Also, on the plus side, you will have a cool shop in the summer months.
One word of advise is install an inline surge protector. It will protect the costly circuit boards inside the outside unit from power surges during lightning storms and such.
Where are you? It's makes a difference as to whether you can use a heat pump at all. You should know if you are in "heat Pump" territory or not. They fact that your shop has 2 x 6 walls makes me wonder. Where I am that would be considered a lot of insulation. (VA).
If you are in a climate that is suitable for heat pumps, the mini split systems are excellent. They may have been born in Japan, but my understanding is they are very popular in the rest of the world. The US is behind the times on these.
Look for "ductless" or Mini split systems. You do want to set up excellent filters for the indoor system but other than that they would be great for a shop. They may be 50% more efficient than builder grade ducted systems.
My son had the Mitsubishi mini split installed in an unfinished upstairs conversion this summer. He was very pleased with the cooling portion of the system this summer. It was able to maintain the temperature in the new space very efficiently He said it only added about $10.00 a month to his energy bill. It was a hot summer in Virginia this year and he is cooling most of the upstairs with this new unit.
This winter he said the unit was not keeping up on the heat side and the compressor has been icing up. He has not had a chance to call the installer to check it out due to the fact he has been averaging six 24 shifts a week. He did go to the Mitsubishi web site and researched the problem. The web site indicted either low Freon or the wrong type of wire between the controller and the compressor. Mitsubishi indicated the wire had to be a braided wire. When he looked into getting the unit he considered buying the components and installing himself, but found out that Mitsubishi will not honor the warranty unless installed by a licensed installer. You may want to keep this in mind as I understand the Mitsubishi warranty is one of the best in the industry.
Maybe things have changed a bit, but I have a friend who has one in a cold spot in his house. He said the cooling cycle works well, but doesn’t provide much useful heat below 30F.
My shop is attached to the house and the ground source heat pump heats the house and the shop. We live in northwestern PA and if works fine even on the coldest days. To prevent dust from getting into the house, I installed merv 11 filters on the air returns from the shop.
May want to rethink the dust. We have one in the house and we clean the filter every six to eight weeks. It pulls air in from the top, then over the coils inside the wall unit, then blows it out the bottom. Ours works down into the middle teens. Much cheaper than baseboard heating. Ours is a Fujitsu.
I've talked to several HVAC guys about these units because I have a couple of friends who use them in the river homes. I was trying to do some first hand research to understand how they worked so well, since I might consider going that route on my own cottage.
As I understand it these mini split units deliver heat from lower outside temperatures during the winter by several innovative improvements. They utilize variable speed fans, and now variable speed compressors, coupled with the latest refrigerant to get the job done. The industry borrowed this technology for their standard heat pumps, making them much more efficient than what was available years ago.
The advantage the mini split has over standard ducted systems is they're ductless and can be installed easier in existing structures. Another cool thing is you can get them sized so one outside unit controls up to four inside units.
Last year during a very cold day (VA eastern shore on the Potomac River) I was standing in front of one unit and the air blowing was actually very warm. I asked my buddy if those things had electric strip backup like the larger standard units do. He said as far as he knew they didn't. I found that impressive.
In a moderate climate a mini split system will perform as well as a ground source HP. There are lots of variables, but the cost of installing the "ground source" part of the system is usually huge, more than it would cost to heat your shop any other way for the rest of your life. Especially since you use it intermittently. If you wanted to heat your house AND your shop with the same ground source system and you are in a severe climate where an air source system would not work or struggle and you had an easy inexpensive way to install the ground source it might be a good idea.
I have looked into installing one of thee more elaborate mini splits in my house and some of the rentals I own. The Ductless part of it makes it sound easy and inexpensive. Not so much. No ducts to install, but you have to run refrigerant lines to each indoor unit and a power supply to each and a control wire to each. And Each indoor unit must have a condensate drain. It adds up.
They are efficient in moderate climates though. My understanding is they can be 18 SEER and maybe as high as 24. Typical units now are 14 SEER.
Most heat pumps are very efficient if the source is above 45 degrees and the ground temp is usually higher than that if you go deep enough. Unlike the air temp it does not plummet in winter and is terrific in summer.
Four years ago we had a 525 sq. Ft bedroom suite added to the Wesr side of our 1st floor in Maryland, north of Baltimore about 20 miles. We used a Mitsubishi “mini-split” system, however, rather that hang an air handler in the bedroom and the bath, we had installed a single air handler in the crawl space under the bedroom. One return air duct and 6 supply ducts are located throughout the suite.
The variable speed fan circulates air almost continuously resulting in an even comfortable temperature throughout the area. On sub-zero days ( 2-3 per year) we supplement the heat pump with a small electric wall unit (4,000 BTU). The Mitsubishi unit is vibration and noise free. You can not tell it is running unless you put your hand over a register. In summer, the cooling is equally quiet and comfortable.
I looked at the Heat pumps about 12 ~ 14 years ago when I built my shop. I didn't look at the units you are discussing however. I installed conventional furnaces, gas and fuel oil, Boilers, and central air systems for several years as a second job.
In my area (central / northern Indiana) unless you have a ground loop or water (deep ponds etc.) system installed, the heat pumps rely on a secondary source of heat for much of the winter.
I did the next best thing, installing super insulation as I built my 30' X 30' shop, then installing a high efficiency natural gas furnace and a central air unit in the ceiling. I had the trusses built for my shop that gives me a upstairs room about 10-12' wide X 8' high (with sloping sides).
My son and I installed the duct work above the shop ceiling and insulated over it. The furnace has a sealed combustion system and uses outside air for combustion and has 2" PVC pipe vent / intake.
My average cost for 24/7 heating and air conditioning is about $50 in the winter and $30-$40 /month in the summer. I keep the thermostat set at about 60 Deg. (winter) and 75 (summer) when not in the shop, then set for comfort when using the shop. I do this to prevent any condensation / damage to my cast iron tables and tools.
I feel this is the most economical way to heat and cool in my region as I could never have recouped the cost difference in system cost and installation of a heat pump system VS my conventional system from fuel savings!
Our 1992 model heat pump operated at "break even" at 20 degrees. Below this temperature the equipment could not extract more heat from the outside air than the energy required to extract it. Our 2017 model break even temperature is 10 F. The auxiliary resistance heating will seldom be required in our E. TN climate.
Hello, If you want to do it yourself look into the Mr.Cool DIY units, they come precharged and you turn valves on for the gas after you have finished the install.
However much depends on the "fuel" costs IE: Electricity KWH VS CF of natural gas. Tennessee is (or at least was) blessed with quite low electrical rates. It is not the same in many other places.
I haven't calculated the cost in Btu's for either gas in a High efficiency furnace or cost for heat pumps, but do know in the past (several years ago) I removed the entire electrical baseboard heating system from a four year old electrical heated home and installed a forced air system. The owner later told me he recovered the entire cost of conversion in less than 2 years!
Granted this is not near the same as heating with a heat pump but at some point the electricity cost does enter the equation!
I'm not sure where you obtained your data on ground loops, but just last year due to issues with our open loop system, I had 4,000 feet of ground loop installed on my property for $4,000, including connecting the loop to my existing heat pump. My house was originally heated with baseboard electric and we added 1/3 more area to the house and converted to a geothermal heat pump over 30 years ago and our electric bill was less than heating with the baseboards. We have no access to gas, propane is costly and when we converted there was a moratorium on getting oil heat, so electric was our only option. My system sees 45 degree ground temperatures year round so it is operating in the range of 3:1 or 4:1 as compared to resistance heating.
We are total electric with no auxiliary heat source, I heat and air condition about 2,000 square feet of living space (not counting the full basement) for under $2500 per year.
Re: Thank You All - I am Going to Get The Mitsibis
Tony - Memphis
Thanks...I have a 16x20 shop in Memphis. I use a wall unit. I am on my third in 20 years. I have thought about the mini splits for the next one. I'll be interested in your experience. Lowe's has units that come pre-charged. Not sure about the brand. I like the idea if installing it myself.
4000 LF for $4000 is amazing. I would have thought the pipe alone was close to that. Are you using high density PE?
I have not checked lately, but I would have expected it to be double or triple that. And the equipment cost would be about the same as an Air to Air HP, so I would think the ground source unit would cost more than the A to A unit by about the cost of the loop. In a mild climate it would take a LONG time to recoup the cost of the loop.
It is not a simple comparison but worthy of being careful about. For example, Many people would not have room for a 4000 LF loop or would not want to suffer the disruption to there landscape.