Dirty Coils?


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Old 06-05-06, 06:55 AM
R
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Dirty Coils?

I have a 4 ton Rheem A/C w/ gas heat. about 10 yr old.
Last summer my electric watt usage doubled. I have never used over 1350 watts. It jumped to 2600 last June. The compressor comes on and runs about 50 to 55 minutes and cycles to off for 15 min.If I set @ 76, it takes forever, and 72 is out of the question as we had a party recently and I set it @ 72 when I got up at 6 inthe morning and it took nearly 5 hours to cycle. In the past we have had 20 plus people in the house and it did a perfect job. We are cooling 1800 sf. I keep therm. set @ 80, it has a 1 deg. swing. I have several thermometers throughout the house, so I know the temp. is holding correctly. I replaced the thermastat. I had 2 different service companies check it last year. They checked outlet air @ 59 deg & return air at return vent @ 67 degree. One of the techs(?) said every thing was ok. The second one added a drop of freon (he said it didn't need it) and installed a quick start. My question is, does my cooling coils need to be cleaned? What would happen if I got a water hose and sprayed a fine mist on them (with unit turned off)? I looked at them last year and what I could see, they appeared clean and shinny, but I know looks are deceiving. I had a new pan installed about 3 years ago. I wasn't here at the time, so I don't know if he removed the coils or worked the pan in some way. Thanks in advance for any help. I checked the vents in the attic and could not find any leaks in the duct work.
 
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Old 06-05-06, 07:44 AM
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Dirty Coil?

I presume you are talking about the indoor coil. You need to look at them from the incoming air side. This is where most of the dirt, hair, lint, etc. will build up. They can be cleaned with Simple Green (or something similar) & a soft brush (be sure to brush in the direction of the fins), then rinsed with water.
If your thermostat has an adjustable temperature swing, you might want to increase it to 2º. Also the outdoor unit should be cleaned from the inside out. To do this, turn off the power at the breaker, remove the fan, dampen the coils with water, & using a garden sprayer, spray the coils with simple green from the bottom up then rinse well with a course spray from a garden hose from the inside out.
 
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Old 06-05-06, 11:29 AM
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Your power consumption is not out of line. In fact I think it's a bit low. Figure your first 1000 kwh are used for running the refrigerator, lights, small appliances, etc.
If in fact, your consumption was 1350 kwh for a particular month, then that would leave you with 350 kwh for air conditioning. Certainly not very much. A 4 ton unit of that vintage would use about 5 kwh in one hour, possibly a little more. This would equate to 2.3 hours per day of actual running time.

2600 kwh is a far more realistic figure especially for Texas. This would equate to 10.6 hours per day. I suspect the meter was misread (happens more frequently than you think) for that month.
 
 

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