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TazinCR 09-05-2008 05:47 AM

Two Central units
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Has anyone ever encountered a system that has 2 air handlers using a common duct work system and one thermostat? Cold air goes in the bottom of the AirHandlers
My guess is the first unit was under sized so a second was added.
I did not see them but was told there are 2 condenser units. This is in a single level 1900sf. condo.

TazinCR 09-06-2008 10:11 PM

I hope someone knows

8 Ball 09-07-2008 02:31 AM

Its called twinning, I see it all the time, Carrier and Lennox even have a kit for it. Sometimes it not practical to use a built-up air handler so two units are twinned together to satisfy the need.

Twinned, as in twins.

TazinCR 09-07-2008 05:59 AM

Thanks 8Ball but what is the purpose in such a small area? I could understand if it was a large two story?

8 Ball 09-07-2008 08:56 AM

Its hard to say why, you would have to ask the architect or mechanical contractor, but normaly its one of three things;

1.) Space, could you imagine trying to work on an air handler in such a small space.

2.) Load requirements, they may have wanted staging that a single air handler could not provide, is the condo zoned, or have VAV or VVT. Remember that when the units are twinned, measure total CFM for smoke detector requirements.

3.) Money, in some instances it is less expensive to instal two small units vs. one large air handler.

Normaly both fans operate together and the heating and cooling are staged. Rarely does everything come on together. One unit will be the "master", the other the "slave".

If you have access to the Carrier Portal, or the Lennox site search "Twinning Kit".

I would be more than happy to come down and help you with this, even more happy to come down in January! Thats from the heart dude.

TazinCR 09-07-2008 11:50 AM

2 Attachment(s)
Come on down. The weather is hot and windy here in Jan.
Units work OK. There is no VAV or VVT control. It is not zoned.
The part I omitted by old age is the is a cold air return built in the condo but not in use. The return is through the bottom of the AH.
You would have to see the way they do things here to believe it.
Here is picture of a split system install. Price of home $699K
Pic 40 is the wall unit Pic.41 the refrig. lines and drain. Missing 7 more feet of line.

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