Residential grade furnace to heat shop and office

It's more difficult than it sounds.

I am HOPEFULLY going to closing within a couple of weeks on the new house.

Shop is 24 x 24 and has a 12 x 24 efficiency apartment on the back. Right now it has a simple wall furnace. I want central air in the shop, and the shop will get bigger in time. I also want central air in the apartment.

Is it possible to set up a dual zone residential grade forced air furnace? Or should I say, is it cost effective. Or am I better off just throwing in the window AC, a cheap reznor in the shop, and stick with the apartment (office) heat the way it is.

Beyond excited!

Id go ductless mini split all day. You can get a 2 zone unit fairly affordable these days. Ive installed both LG and mitsubushi units myself and they both are great.

Keep the IRS man happy and put separate systems in the apartment and shop. And if you rent out the apartment the renter can pay his own heat / cool.

The apartment will be office space...I will not be a landlord!

What kind of temperatures are we talking about here? Is the heat more important than the A/C? Outside of Houston our weather is mostly hot and humid with moderate temps in the winter. A/C and moisture control is the most important thing for me.

I personally think the window units with AC/Heat are the simplest way to go. Ease of install, low price and ease of repair, just slide a new unit in place, are a few of the reasons I like them.

I have three in my shop, all 699.00 at Home Depot. Total area of the shop is 60 x 40 with a 20' tall roof, in the main area, and 10' average height ceilings in the two machine rooms. All three units can be switched to another area if a critical unit fails simply by removing the front cover and sliding them out of the enclosure.

The first unit I put in the 16 x 14 machine room 9 years ago. It ran fine until last year when I replaced the fan motor and a run capacitor for 165.00. When it went out I purchased a new unit and slid that one into the already installed cabinet and was back up and running in less than a day.

The repaired unit is now going to be installed in the main shop 40 x 25 and I will run it until it fails again. I have three areas of the shop that are used for different types of work. The two machine rooms are well served by their units and I can always open the doors, between the areas, if extra cooling is needed in the larger area.

The second unit I installed two years ago is in the new machine room that is 20 x 40 with 12' ceilings. It runs continuously and keeps the machines dry and around 73 degrees.

In your climate I would probably consider window units for the A/C and the most efficient heaters for your fuel sources. For me the fuel is either electricity or propane so the window unit heaters work well enough for our climate.

back to your question - a friend has a zoned system in her house, she is not happy with the set-up and plans to convert to two separate systems as funds allow.
HVAC guys I work with aren't much in favor of them either.
Could it be one system that is balanced by air flow to put the correct percentage of air where you want it?
The mini-splits are nice, but you pay for it. Cheaper to use a conventional compressor/air handler system if you have room to place the air handler inside, or use a package system (all in one) outside and duct it in.

First off you are located in Michigan, a heat pump may not be the right choice for heating in that climate. If you go that route make sure the outside unit is installed on a stand.

Also a lot depends on load of the spaces. The Mitsubishi splits to my knowlege will only run in one mode ie: if the shop needs cooling and it is the master zone, the unit will stay in cool mode and vice versa as to the master area.

Also Mitsubihi's indoor units have a shit filter expect it not to work well and to clean it frequently, not good for a shop environment, and the thing is plastic, bash it once and done.

JR

jlrii said:

First off you are located in Michigan, a heat pump may not be the right choice for heating in that climate.

Also a lot depends on load of the spaces. The Mitsubishi splits to my knowlege will only run in one mode ie: if the shop needs cooling and it is the master zone, the unit will stay in cool mode and vice versa as to the master area.

Also Mitsubihi's indoor units have a shit filter, not good for a shop environment and the thing is plastic, bash it once and done.

JR

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I have a residential type gas forced air furnace with air conditioning in my shop. No troubles with it at all. One thing to think about is if you will have any flammable fumes. You may need to use a furnace with closed combustion and outside air intake. I hung mine on the wall about 30" off the floor. It is 80,000 BTU propane and has no trouble heating or cooling my 36' x 36' shop.

There is no reason residential HVAC cant be used. You should check your local codes. The apartment and shop/garage, you might be required to keep the air separated.

If you are married or have a family, that may be a real reason for keeping the air separate. I have my shop in my garage and have a separate system there; a window unit. My wife gets headaches easily and would never put up with the odors of even "nice" smelling solvents and paints and lubricants in the house. And no HVAC system that I have ever seen will filter out those odors.

I went through a couple of window units. Even with extra insulation, a small window unit was totally helpless in the face of south Texas summer heat. One died after just a year. I finally wound up with a Friderich, which is one of the few good brands of window units left. It has been going strong for several years now. Change the filters and hose down the outside coils occasionally. Probably due for some coil cleaner by now.

Even with the separate systems I have a painting booth set up in the separate lawn shed and try to use only low odor products in the garage/shop.

mach2 said:

There is no reason residential HVAC cant be used. You should check your local codes. The apartment and shop/garage, you might be required to keep the air separated.

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See if California Economizer is still around. They make conversion kits to change single zone into multizone by using motorized dampers. It works on a round-robin principle, checking each thermostat in turn and heating or cooling zones as needed, using a bypass in the main trunk to limit airflow into the rooms. I've successfully used them in office settings.