Air Conditioning - Attic Air Handler

I am thinking about adding central air to my 1903 urban brick row house (1800 SF). I have very little (8' x 20') outdoor space and a pitched roof. From various sources of advice i am leaning towards an outdoor on grade condensor and an attic installed air handler feeding ductwork through the half finished attic.

I have some mechanical engineers around me to help with sizing etc however i wanted to bring this installation process to this forum for real life construction advice.

How much ventilation does the air handler require? Are there major noise or vibration issues? Is running the copper condensaste lines 70 ft to the AHU a big issue? How much electric do i need for the AHU?

Thanks for any advice as i am in the very preliminary planning stages for installing a system.

70 feet is a long way for a line set but that can be addressed. Isolation blocks and canvas connectors should be used for low noise. No ventilation required for AC. Don't know where you are at but Id look into a heat pump. If this is a three story home Id look at Two units.

I am in Pittsburgh so the climate isn't drastic for heating or cooling. how would i benefit from heat pump?

Canvas connectors? I am not familiar with this term. Is this a compressable washer or something? thanks for your input.

I am also open to the option of installing an exhaust fan in lieu of the AC. I know the cost difference is drastic...on the order of a factor of 10. This house is more of an investment property in that i am in a quickly improving urban neighborhood and am looking to sell in the next 5 years. I want to update my house to attract an upper level buyer. Many of the higher end renovations in the area include central air so i am leaning that direction. I personally would be quite comfortable with a whole house exhaust fan and ceiling fans but i know the majority of young professinals that i would be attacting can't "function" without AC.

It sounds like you are talking about a 2 to 3 ton system but that is just a guess there are window and insulation and shading issues that need to be considered if you have PE's helping you you should be able to get an accurate load calculation then consider the multi level question for comfort control if you are planning to sell in five then a whole house fan is not going to fly in the next five years buyers will be asking about seer ratings and outside air and radon and who knows what so if you can now is the time to make improvements, if not just make yourself comfortable and then plan to upgrade before you sell

Hole house fan will not be a good option because the humidity is to high in your area. If you where in a dry climate Id go for it! But in the south and up the east cost no way!

Who ever gets the job for sure have them run a AC load on this

I am thinking about adding central air to my 1903 urban brick row house (1800 SF). I have very little (8' x 20') outdoor space and a pitched roof. From various sources of advice i am leaning towards an outdoor on grade condensor and an attic installed air handler feeding ductwork through the half finished attic.


Boy with that 8'X20' there. Id sure put the condenser unit there over running that 70 ft of bigger copper line up to the coil. It takes a lot more head Psi to get the freon up there and cost $$$ in more power for the compressor. We have condensing unit pads. Then also vibration absorption mounting pads to go under the unit So you wont know its there. Put the blower coil in the attic.;)

You might be misunderstanding. The 8'x20' of on grade outdoor space is ALL i own. Putting a condensor outdoors (which i now understand is my only option) would require the unit to be in my little back yard and also require the lines to run approximately 50 to 70 to either a new attic air handler or my existing furnace.

The difference being, if i run the lines to the attic the majority of the run will be on the exterior of the house. Do i have issues with that? If i run to the basement furnace i will be running indoors through my first floor joists.

Are you susggesting to put my condensor on the pitched roof?