Air Conditioners

[Kev Williams]

So yesterday I come in from the fairly cool garage and notice the house is warmer- usually it's the other way 'round..

The furnace blower is running but it's blowing 79° air. So I check the AC unit and it's not running. But it's warm so it HAD been-

Short version, the fan wasn't working, and the compressor would kick off shortly after kicking on. So I pulled the fan out and took the motor apart. All motors should be like this, nothing but a big round magnet on a shaft surrounded by electromagnets. Obviously not the brushes ;)...

Felt stiff to turn, so I cleaned the bushings out best I could with some Scotchbrite, added a little moly lube and she freewheeled nicely.

Put it back and worked great-- for a few minutes. But after a few minute wait it worked again, and so far so good. I'm assuming the capacitor hiding in the wire box may need to be changed...

Anyway, this thing is a 36000 btu Amana, at least 20 years old I think. So I start looking up specs for it, AND specs for newer units. I would think newer units should be more efficient...

While running I put my amp tester around the wires in the breaker box, and the AC was using between 16.8 and 17.2 amps. The tag, and specs, say it's RL amp rating is 13.8. So maybe it's a little tired?

So looking at new units. Huh. Trying to find actual "full specifications" is a joke. Lennox only publishes "seer" ratings, no 'tons' or btu ratings, no power usage ratings...

One I DID find was a Goodman, almost a twin to mine, 3 ton, 13 seer, 36000 btu-- but it's RL amp rating is 16.6, more than my tired old Amana?

AND, I just found data on a Lennox 13acx 36000 btu unit, RL amp rating is identical to the Goodman, 16.6...

Now I'm not sure what tons or seer's do, but I believe 36000 btu's is 36000 btu's, and those btu's are what's actually entering my home trying to cool it, yes? and one machine putting out those btu's at 13.8 amps is going to use less power than one using 16.6 amps?

Am I missing something? I know this, the Amana seems to work great, and I see no reason to change it until it doesn't, especially if I won't see any reduction in power usage...

[Michael Weber]

Kev, there are 12000 BTU per ton of air conditioning. Seer is a seasonal energy rating and the higher the better. High seers are achieved by having lots of coil area in the condenser that allows the use of a smaller compressor. I have two 2 ton units that have a seer of 19 The use so little energy they could have been wired with 12 gauge wire. Higher seer units are more expensive. Hard to believe companies don't publish the capacity of their units. Thats real odd. I'm not sure what that RL rating is you refer to as applies to air conditioners. You are correct a higher seer initial reaction f the same BTU capacity will draw fewer amps. You don't say if the compressor was coming on along with the fan after you worked on it but another thing that will cause the compressor shut off and then work for a shot period is a low pressure safety cutout operating due to a low charge.

[Brian Elfert]

Running amps is a poor way to judge anything unless it runs 24x7. The new air conditioners maybe don't run as often as the old ones. I got burned by running amps on a fridge once. I bought a fridge simply because the running amps were low. Problem is that it ran a lot. I had issues and replaced it with a larger Energy Star model. The newer model had higher running amps, but took less power than the old one as it ran less often.

[Lee Schierer]

Your best bet is to get quotes on a replacement A/C unit from several reputable dealers who actually come to your house and size the unit appropriately for your house, taking into consideration the amount of insulation, type of windows, air infiltration, etc. That way you will get a unit that is properly sized for your house and needs. Getting a unit that is too large or too small will cost you in comfort and utilities. Just because you have a 36,000 BTU unit does not mean that it was properly sized for your house.

[Kev Williams]

RL is the Running Load rating, the amount of electricity being used in normal operation. There's also an LR rating, meaning 'Locked Rotor'- it's simply the amount of amps needed in the split second you kick on the unit before things get moving. Pretty high number in most case- My Amana is 86 amps I think--

As for judging something that runs intermittently based on electric usage, that is a good point. Haven't had this one checked in awhile, but the last guy who checked it said it was working as well as any. But it just may well be taking more power to put out those btu's... ;)

This Amana is actually quite large for this house- however, we have a bunch of engraving machines and computers running all day (and I counted 66 4' fluorescent light tubes in this place!) and they all do put out the heat. The installers took that into consideration, thankfully!

[Kev Williams]

Thought I'd bring this back, just had a new unit installed, an ICP 3 ton 13 seer unit, pretty much identical as the old Amana in cooling stats--

However, one glaring difference between the two:

The Amana was burning thru 17.4 amps of power when I tested it, the new one, 9.6 amps... wow...

Probably helps explain why my power bill's equal pay went up $160 a month last year...

Good timing too, it's 98° outside! House feels good... :D

Should've checked the power usage long ago, amazing....

[Michael Weber]

How much bigger is the outdoor condenser than your old one?

[Kev Williams]

The old Amana is 29" all 3 ways, new one is 27 x 26 x 31" tall.

New one is a snick smaller physically but I think it makes better use of space for the coils.

Seems to work great, yesterday was near 100° and it was shutting down at times with the stat at 76.
Old one pretty much ran non-stop if temps were in the mid 90's.

I just wonder how long it's been eating up 7600 watts of power while doing it...

Clamp meters are the bomb :)

[Michael Weber]

Interesting it's actually smaller. Amana must have really utilized the coil space. I worked for an AC company and the condensers just kept getting bigger and bigger as seer increased.