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Help with AC

Posted by tim_ac (My Page) on
Fri, May 29, 09 at 1:23

Problem:
I have 10+ year old Payne systems. A 3.5 ton for upstairs & a 5 ton for downstairs. The main problem is that the 5 ton unit is rated for 29.1 amps on the name plate. And it was installed on a 30 amp breaker! So .. this thing pops the breaker unless I keep the outside unit very clean. I think the units are rated about 10 or 11 SEER.

If I hose down the unit, the current draw goes down. So I've ordered a misting kit as a short term fix.

Some background. We live in the Houston area, Lake Conroe actually. The house is a 2 story box. Upstair sq ft about same as downstairs. Front entrance opens to 2 floor. Square footage is about 4600 sq ft. Heating is all electric.
The upstairs 3.5 ton definitely runs longer than the downstairs unit.

Since my house is a 2 story box, why are the units not the same size?

I'm looking at replacing the units, (preferable not all at once) with either Heat pumps or geothermal heatpumps.

With the 30% tax credit with a geothermal unit, that looks enticing. But I haven't seen any pricing yet.
For a air source heat pump, I'm looking at 16 SEER I think. What would the current draw be for say a 3.5 & 5 ton 16 SEER unit?

I haven't got unit numbers or details yet. I did get one quote for 16 SEER Goodman units. Are the any bad names to stay away from? Preferred brands?

Any help/guidance would be greatly appreciated.


Follow-Up Postings:

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RE: Help with AC

Tim... You asked are there any units to avoid? I can tell you my sister had Janitrol put in her house and she has had nothing but trouble with it. Just a thought... as for your heat pumps, let me state I am not in the hvac field, but ran into a simular situation last year. 2 story house, contemporary design, smaller than yours, right at 3000 sq. ft. had to replace 2 heat pumps. I ended up going with a brand called Air Ease ( a division of Lennox ) I got 2 18 seer units, a 5 ton and a 2 ton, that included the compressors, air handlers, either 15 or 20 kw strip heat set up in 5 kw increments, new ductwork over the den, the old ductboard plenums replaced with sheet metal plenums and 2 honeywell vision pro thermostats. The whole shootin match ended up an even 18 grand. I will tell you I also live in the south ( louisiana ) where it's hot and humid and I can honestly say these Air Ease units do a much better job than my old Carriers. On the A/C side, these things are really really quiet. On the heat side, with my old carriers, whenever the outside temp got down to around 30 or the high 20s, my carriers were only able to warm the house to around 66 degrees... this past winter I set the thermostats to 72 one night when it was 25 outside.. It took them awhile, but both units reached that temp.. Overall I am able to keep my house considerably more comfortable with my monthly bills running about 10% or so less than before. Also I belive the 16 and 18 seer Air Ease units qualify for the tax credit. Not to mention the warranty on the 18 seer is 10 years on the compressor, 10 years on parts and 10 years on labor. Good luck with your decision. One thing I learned on this forum is regardless of what brand of equipment you buy, make sure you hire someone you trust with the install. From what I've read here top of the line equipment wont work correctly if it's installed incorrectly. Good luck with your decision.

Rp


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RE: Help with AC

Your units seem to be topsey turvey. The upstairs has the higher heat load if your sq. ft. is the same up as down. So your upstairs should have a slightly larger unit for ac. Putting a sprinkler on the condensing unit is a trick used usually for undersized units on hot days to increase cooling capacity. The water lowers the temp of the condensing coil, which lowers the condensing pressure. This reduces the differential of the high and low sides of the system. This makes it easier on the compressor and lowers amperage. I have installed many janitrol and now goodman units without any more problems than any other brand. The thing is, janitrol/goodman got a bad rap due to many bad installs. This is because the company made thier units readily accessable to the public and thereby many unskilled installers. That lead to unskilled installations. Compare this with say Trane ac distributors, who put any ac company through the wringer just to set up an account to buy a unit.


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RE: Help with AC

You can put a hard start kit on the unit to help lower amps on startup. The misting system works ok but will corrode the condenser coil causing more problems. As far as Goodman units it is in the install but the housings are alot thinner and fall apart. They also tend to be noisier than other units.


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RE: Help with AC

Thanks for the input.
Yes, finding a AC service I can trust is difficult.

What amp service are 5 ton condensers normally installed on?
Mine is on a 30 Amp service and that too low, but I think with a higher efficiency unit I should be able to use my current wiring.
Any idea on the current draw of a 16 SEER 5 ton HP unit?
Any thoughts on GeoThermal?


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reply to troys

Hi troys,

The one AC service tech that I trust didn't think a hard start kit would be effective. I agree. The big problem is running current so need the breaker limit.
As for the misting kit, its a short term fix.

Thanks for the input.


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RE: Help with AC

You need to have a competent tech look at the thing. Read the name plate on the condenser and it will say "maximum HCAR breaker" or something similar. I would do the following; check the compressor windings to see how many ohms each reads, check the compressor for ohm value to ground, check the microfarads of the capacitor, check the line voltage into the system, into the contactor and out of the contactor, check the outdoor and indoor fan amp draws, check and make sure all electrical connections are tight and corrosion free, check the in rush current at the moment the compressor fires, check the refrigerant charge, superheat and subcooling, check the static pressure, check for clean outdoor and indoor coils, check for correctly sized ductwork. If all of this passes then replace the breaker. Your problem is almost certainly NOT being caused because you have a 29.1 amp system on a 30 amp breaker. If anything, you have more protection in the circuit than you need. Without being there to see the thing myself, I'd say you have a dodgy breaker. Nate Certified, HVAC Excellence Certified, National Comfort Institute Certified, heating and cooling proffesional.


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RE: Help with AC

Your problem IS definately because you have 29.1A drawing on a 30A breaker. A breaker has an error margin of 10% so max for a 30 is 27A of continuous draw. A 5 ton A/C condenser regardless of SEER rating has a minimum circuit amps of 33.2 to 35.5. Max fuse rating is 50. I am not NATE certified, I have fifteen years of being an HVAC company ownership and practical field experience. Check the size of the wire suppling power to your unit, hopefully it is #8 AWG copper wire, if so you can install at least a 40A breaker and that will solve your problem. Hopefully you didnt waste alot of time taking all of the irrelevant readings suggested by the last guy.


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