My home has central air conditioning which is good and works fine. It does not have duct work to cool or heat the attached 2car garage. We would like to have a heat exchanger (similar to those used in motel rooms) installed in the outside wall at the back of the garage. Before contacting a contractor, we want advice on what we should ask for, in terms of type (plate or tube). Any other advice will be welcome
I think you are asking for a heat pump. When you contact a vendor, let them know what your intended purpose for the garage will be; do you just need to heat it, do you want to heat and cool, or just cool? Will the garage be used often, or just rarely? With this information, you will have more options for your specific use.
You'll want to see if the attached garage has the exterior walls insulated. You may want to consider having that done as well with the install to prevent unwanted heat loss and gains. Additionally depending on the total size of the 2 car garage you may have difficulty finding a 120 volt rated unit that is sized to serve the space. You'll likely need to have an extra breaker space dedicated at 240 volts in the panel, make sure you have room for that and that you won't have to upgrade your panel for it. As far as the AC goes I would suggest installing a unit that utilizes a fin tube heat exchanger. If you get one that utilizes a plate heat exchanger the potential for it to plug up restricting air flow is greatly increased considering the application of being installed for residential use. You likely won't find a self contained unit that utilizes this type of heat exchanger either.
You are talking about a PTAC, a packaged terminal air conditioner. They run about 11 to 1400 bucks. A two ton unit will condition about 1200 square feet. You will need a 240 volt socket to power it, mainly for the heat strips, but for the compressor and blower motor, in cooling mode. There are heat pump models, too. Friedrich makes a top of the line unit.
