Heating and cooling an enclosed patio

Factual Questions
1

We’re planning on replacing our old 8x13 enclosed patio with a new insulated one, which we’ll be able to use year-round, and will also serve as a greenhouse. We’ve consulted with salesmen from two companies. Their products and prices are comparable, but there’s a big difference in what they told us about heating/cooling.

The guy from Company A said that we only need to run a duct from our furnace (forced air with central AC), and that solves the whole problem.

The guy from Company B said that would cause an imbalance in the heating/cooling of the entire house. Plus, the furnace’s humidifier would cause excessive dampness, especially without a return air duct. He said we had to have baseboard electric heating elements installed on the patio. And in the summer, we’d leave the windows open, supplemented by a ceiling fan.

We’re hoping the guy from Company A is right. We’d love to have air conditioning out there as well as heat, and just leave the windows closed. We could even leave the door between the living room and patio open, to help the air flow and equalize the temperature.

So which guy is right, and are there any further complications they haven’t mentioned?

2

The gentleman from Company A is full of soup. Without performing a heat loss calculation of the entire dwelling, it’s not possible to accurately determine if your present furnace and air conditioning evaporator have sufficient additional capacity to handle another room, but it’s highly unlikely. A return duct would be required for proper system operation, even if the present unit has adequate capacity.

Whenver people convert a garage into a living space or insulate a Florida room and wish to use it year round, I advise them to invest in a ductless mini-split heat pump. The interior unit hangs on the wall near the ceiling, the exterior unit sits on the ground, or can be located on a roof, and a wall penetration of ~3" is needed to feed the lineset and low voltage cables through.

A buddy of mine finished his garage and turned it into a family room last winter. His wife noodled around on eBay and found a 1 1/2Ton mini split at a great price. I installed it for them and it’s keeping the room quite comfy.

3

How about going with a gas stove? Very comfy.