rule of thumb -- watts for 3 ton AC
#1
Member
Thread Starter
Join Date: Nov 2006
Location: USA
Posts: 62
Upvotes: 0
Received 0 Upvotes
on
0 Posts
rule of thumb -- watts for 3 ton AC
Hi:
I'm looking for a guesstimate or rule of thumb to give me an idea of how much current is drawn by a 3-ton 220V central AC unit (outside compressor and condenser).
Eventually I want to install a 3 ton unit, and am wondering if a 40A 220V circuit will be sufficient.
I can't seem to find any manufacturer on the web who will divulge this info without getting involved with a dealer.
Thanks,
s/Mike
I'm looking for a guesstimate or rule of thumb to give me an idea of how much current is drawn by a 3-ton 220V central AC unit (outside compressor and condenser).
Eventually I want to install a 3 ton unit, and am wondering if a 40A 220V circuit will be sufficient.
I can't seem to find any manufacturer on the web who will divulge this info without getting involved with a dealer.
Thanks,
s/Mike
#3
They are rated per unit, so it will depend on the manufacturer. What is so difficult in getting a contractor involved? Just asking the question because I've seen many 3 ton units all with different size breakers needed. It also depends on the efficiency rating of the a/c. Best to get a contractor involved. The breaker also has to be HACR!
#4
Member
Join Date: Jan 2011
Location: usa
Posts: 82
Upvotes: 0
Received 0 Upvotes
on
0 Posts
rule of thumb -- watts for 3 ton AC
If you want to run the wire now, why don't you just leave the breaker
out for now until you get your unit. If you ran a #10 wire than you are covered for up to 30 amps, and the never run more than that, but you can always put a smaller breaker in. paul
out for now until you get your unit. If you ran a #10 wire than you are covered for up to 30 amps, and the never run more than that, but you can always put a smaller breaker in. paul
#5
Member
I am a homeowner, with a 3 ton 11 year old unit, and I'll tell you straight up what my outside unit pulls. The compressor pulls about 11-12A, and the fan pulls about 1-2A. That totals about 14A (max steadystate, not including surge) @ 240v. But I can tell you that the circuit is protected by a 50A breaker both at the garage box, as well as the outside disconnect.
I had an AC tech over recently, and he made a comment that a 50A breaker was a bit higher than necessary. Since the house was built in 1974, I assume AC was less efficient back then and subsequently pulled more power, but I don't know for sure the exact reasoning for my 50A breakers.
I bet if I replaced one or both of the breakers it with a 30A breaker, that would more than cover the circuit, assuming the high startup surge of the compressor wouldn't trip it. I may do this myself just for kicks and grins.
I had an AC tech over recently, and he made a comment that a 50A breaker was a bit higher than necessary. Since the house was built in 1974, I assume AC was less efficient back then and subsequently pulled more power, but I don't know for sure the exact reasoning for my 50A breakers.
I bet if I replaced one or both of the breakers it with a 30A breaker, that would more than cover the circuit, assuming the high startup surge of the compressor wouldn't trip it. I may do this myself just for kicks and grins.
#6
Member
This topic got me thinking. On the way home I purchased a 20A breaker and replaced the 50A breaker for the outdoor unit with this one. I put the 20A breaker in at the main panel in the garage, and left the larger breaker outside next to the unit. The outside unit started fine and so I am going to keep this configuration unless the 20A breaker starts tripping under normal use. It is definitely safer this way.
#7
ensure your new breaker is HACR. Also, instead of just putting a breaker you think will work in (even though you are probably correct about the size) check the data plate on the A/C for a recommended breaker or a max fuse.
#8
Member
Thread Starter
Join Date: Nov 2006
Location: USA
Posts: 62
Upvotes: 0
Received 0 Upvotes
on
0 Posts
thanks for responses
Howdy:
Sure do appreciate the responses that have come forth.
The main reason I am asking is I had a 40A breaker in a 4-T (maybe only 3 1/2T) unit back in the early 70's. I was thinking that a 40A circuit would be more than enough for a modern 3T unit; however, one vendor (who will remain anonymous) says that I will need a 60A breaker for a 3T 14 SEER unit--and I find that to be ridiculous.
What say, you experts ...
Sure do appreciate the responses that have come forth.
The main reason I am asking is I had a 40A breaker in a 4-T (maybe only 3 1/2T) unit back in the early 70's. I was thinking that a 40A circuit would be more than enough for a modern 3T unit; however, one vendor (who will remain anonymous) says that I will need a 60A breaker for a 3T 14 SEER unit--and I find that to be ridiculous.
What say, you experts ...
#10
Member
Join Date: Jan 2011
Location: usa
Posts: 82
Upvotes: 0
Received 0 Upvotes
on
0 Posts
rule of thumb -- watts for 3 ton AC
Howdy:
Sure do appreciate the responses that have come forth.
The main reason I am asking is I had a 40A breaker in a 4-T (maybe only 3 1/2T) unit back in the early 70's. I was thinking that a 40A circuit would be more than enough for a modern 3T unit; however, one vendor (who will remain anonymous) says that I will need a 60A breaker for a 3T 14 SEER unit--and I find that to be ridiculous.
What say, you experts ...
Sure do appreciate the responses that have come forth.
The main reason I am asking is I had a 40A breaker in a 4-T (maybe only 3 1/2T) unit back in the early 70's. I was thinking that a 40A circuit would be more than enough for a modern 3T unit; however, one vendor (who will remain anonymous) says that I will need a 60A breaker for a 3T 14 SEER unit--and I find that to be ridiculous.
What say, you experts ...
#12
Member
Update: I've been running on a 20A breaker on my 3 ton outside unit for the last few weeks and it is working perfectly.