2 ton or 3 ton

joe_mnAugust 20, 2011

my old 3 ton central air system died. compressor is shorted. i have a 2 ton external unit that i can swap out. both systems are same age, and r22. my donar unit has been sitting in heated garage for 15yrs. looks very nice. found a tech who will do swap with my parts. but he thinks both units are 3 ton. i just found out today it is 2 ton. so, is it a no go? how would system work with original sized evap and 2 ton comp/condenser? tech likes that i have entire external unit so all parts match. contactor, cap, fan, comp.

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veesubotee

Sitting around for 15 years!! I wouldn't do it. Actually, I wouldn't do it if it was just removed from service.

Assuming your original unit was sized correctly, you should be concerned about losing 1/3 of your rated capacity (assuming the unit will deliver its rated capacity).

    Bookmark   August 21, 2011 at 7:44AM
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energy_rater_la

there are lots of theads about installing used units
not many have happy endings.
on another forum one of the hvac guy's tag line
refrences the money from fixing these botched installs.
lots of money in it..for the one who makes it right.
not many reputable hvac companies in my area will install
an old used unit. and warrenty it..LOL!

15 years ago..unit at BEST would be 10 SEER that is
30% LESS efficient than the least efficient unit produced today. (13 SEER) the hvac industry jumped from 10 to 13
seer for a reason, simply that 10 seer was so inefficient.
you may save money on equipment but the cost to install
and get it right plus the cost to operate are the drawbacks.
the dollar you save today will cost you every day the
old unit operates.
I've seen these older units installed on bldgs that have part usage..churches etc that use the unit for less than 50 hours a week. and still the utility and repair costs
are ongoing and expensive.

also to consider is that you are installing a smaller unit
so it will run longer and perform less. ductwork would also be a concern as you will now be moving less air through ducts sized for more air flow.

best of luck.

    Bookmark   August 21, 2011 at 9:27AM
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joe_mn

Groan! Well I knew it was a dumb question. Furnace/blower/evap is not changing so airflow is unchanged. Just less cooling at evap. I would love new system but am short funds.

    Bookmark   August 21, 2011 at 10:53AM
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veesubotee

The maximum airflow of the 2-ton unit may NOT be the same as you're current unit runs. In any event, it would be set to run at about 800 CFM, (where you were running around 1200 CFM). So, not only would you be short on BTUs, but also airflow.

V

    Bookmark   August 21, 2011 at 1:37PM
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joe_mn

So guy on CL has a 3ton unit for sale. Says he got it and found he needed a smaller unit. Maybe we could swap?

    Bookmark   August 21, 2011 at 3:34PM
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veesubotee

Was it installed--then he discovered 'it was too big', then cut it out? GOOD LUCK.

    Bookmark   August 21, 2011 at 3:55PM
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mike_home

Joe,

If you are short on funds then you should not be taking a gamble on a used unit. My advice would be to buy some fans and wait until spring to have a properly sized unit installed by a good contractor.

    Bookmark   August 21, 2011 at 5:20PM
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heatseeker

Cheap never pays off period

    Bookmark   August 22, 2011 at 8:51AM
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