Central Air Conditioning

F Reynolds

My father has a building that was a duplex. There is a furnace for the right and one on the left, in the basement. He is considering putting AC in, and had talked about installing it on one side only, which services the upstairs (right) and downstairs (right), cost about $3500. It has since been converted into one big house, a business on the bottom and one big apartment on top. Here is my question. Will one compressor service two furnaces, or do you have to have two compressors? Thanks

Paul Mitchell

need two

Need a condenser and coil per furnace.

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Paul Bock_2

and hopefully when

it was converted it was re-zoned floor to floor. If it is still split top to bottom on both sides,"aint nobody gonna be happy" with its performance, even with two condensors. Paul

F Reynolds

You got that right

No, it has never been split. It is right side, left side, top to bottom. Ugh, I was hoping we could use two coils and one compressor. But you answered the question, it must have two coils and two compressors, right?

Paul Bock_2

Yes, and probably

zone dampers or a re-work of the ductwork. the cooling requirments of the business space vs the living space are going to be incompatible the way it is currently divided. Paul

Mike T., Swampeast MO

There is a device

that will let one condensing unit serve multiple evaporator coils:

www.rawal.com

Don't know if it would be suitable to your application.

They're rather expensive and I haven't used one yet.

Only knowledge regarding performance came from head engineer at Unico who said "they do what they say" and "work extremely well on our systems".

JimGPE_3

Codes?

Someone should check with the local jurisdiction having authority and see if there is a problem having a business and a residence sharing airflow from the same furnace.

Even if not, if the resident cooks cabbage, the business isn't going to like having the odors cycled through his floor.

Just my $0.02.

Paul Bock_2

generally, fire dampers

are required between floors,and at chase wall openings when there is a change of use floor to floor. Paul

Dean

Single Condensing Unit

Depending on the size (primarily air flow capability of each furnace) you could use a 2 stage condensing unit with an evaporator on each furnce. One furnace would always be stage one, the other stage two. Lennox has a High Efficient two stage unit that with the right controls (available from Lennox) can do just that. The model is an HSXA19 available in 3,4 and 5 ton sizes. It uses environmentally friendly R-410a refrigerant, can achieve up to 19 SEER with certaon match-ups.

Check with your local Lennox dealer about this. I am a territory manager with Lennox Industries in the Indianapolis market, and we do this type of application on occasion.

Thanks,

Dean Meece

F Reynolds

Codes

Thanks for the information. Just to settle the one questions, the business downstairs and apartment upstairs have been used in this configuration for over 30 years. There is no cabbage cooking going on there. The business and local area are zoned residential commercial. It is inspected yearly and is absolutely up to code, inspections, and safety issues.

F Reynolds

Lennox

Thanks for the information. I will make the connection and see if it is appropriate for us.....

Boilerpro_3

Sanyo Ductless Split Systems

may be set up this way with multiple units on a single compressor. If not Sanyo, I am almost sure one of them does. I'd look at the various ductless manufacturers on the market.

Boilerpro

Unknown

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S Ebels

The way you describe

The building seems as though it will lead to problems running it left and right. What you'll wind up with is the upper thermostat controlling heat in half of each floor and the same with the lower thermosat. I don't know how it works presently with heat but typically A/C is a little tougher to regulate and control.

What you really ought to look hard at is your duct system. If you could install a zone damper for upper and lower floors for each side, a total of 4, you may be able to make one unit work correctly. You would have two zones off each furnace, four t-stats, four dampers, maybe some by-pass duct and if your A/C guy is sharp, only one condensing unit.

You would have to evaluate the total A/C load of the building, the present duct system, and the furnace blower capacity also.

A mini split system might be the best alternative for you in any case. Check out Sanyo, Mitsubishi and Carrier. They are the best ones on the market. It might sound expensive but doing it right is always cheaper than spending less and winding up with problems that can't be fixed.

Earthfire

utility billing

Here in Pa. state law requires that the property owner must pay the utility bill if any tenants utilities are utilized for more then the tenants space, even if the electric, for example, is used to power a light in a doorway or hall.If your father is not paying the utilities for both tenants he may have an expensive can of worms waiting to burst open, besides the other code related considerations.

F Reynolds

Ahhhhh, off the topic

Ok, just to make eveyone happy, he (THE OWNER) lived upstairs and the business (his business) was downstairs. Now, he is going to use the total building for the business. Ok, next code question?