Air conditioner poor performance?

[Doug Warner]

Starting to get warm in Atlanta, so I tested my 22-year-old Carrier SX A/C system. Performance is low. At 80 degrees outside, it can't cool the house lower than 74. =20

I checked the charge level: (Condenser inlet air temp, across chart to suction pressure line, then down to suction line temperature. ) It's within 2 degrees of target using a Fluke dual thermocouple thermometer. =20 (Suction line temp measured just before it enters the compressor/condenser unit)

Temperature drop across the evaporator (if it matters) is 67.0 inlet,

51.2 outlet,. with a 75 degree outdoor temp. =20

Temp difference across the condenser is about 17 deg.=20

Never had any issues with it in the past 22 years.. Any thoughts on what else it might be?

(If call a servicer, they'll probably just try to sell me a whole new system instead of fixing the old one..)

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[CJT]

Look for leaky ductwork.

[Art]

It is 22 years old. A new one will probably pay for itself in 5 years.

Starting to get warm in Atlanta, so I tested my 22-year-old Carrier SX A/C system. Performance is low. At 80 degrees outside, it can't cool the house lower than 74.

I checked the charge level: (Condenser inlet air temp, across chart to suction pressure line, then down to suction line temperature. ) It's within 2 degrees of target using a Fluke dual thermocouple thermometer. (Suction line temp measured just before it enters the compressor/condenser unit)

Temperature drop across the evaporator (if it matters) is 67.0 inlet,

51.2 outlet,. with a 75 degree outdoor temp.

Temp difference across the condenser is about 17 deg.

Never had any issues with it in the past 22 years.. Any thoughts on what else it might be?

(If call a servicer, they'll probably just try to sell me a whole new system instead of fixing the old one..)

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[Joseph Meehan]

As well they should. Putting money in a 22 year old unit is false economy. First you could put your money into a repair only to have something else go out the next day. It would not take long to invest enough in repairs to have paid for a new unit. Second the new unit will be far more efficient and the energy savings will easily pay for itself in a short time.

Still you should not want someone to sell you a whole new system, you should buy a whole new system.

[scott21230]

Find out what the SEER rating on your existing unit, so we can more appropriately evaluate it (more like point and laugh). It's probably using 2X as much electricity as a new one (or more), and you live someplace where you need air conditioning a lot. Just do the math. Plus there is a tax credit if you upgrade. Between now and your next electric bill, I'd be looking for the leaks mentioned above and check the inside coil to see if it's dirty.

[HeatMan]

yep.

A gent told me recently that a heating and cooling system definately has a limited life in the Atlanta area. 15 years for the cooling system and 20 years for the heating system.

While yours (the OP) still runs, it's lived a long and fruitful life. Retire it and get a new system. The money you save will pay for the new system.

I looked at a complete system today that was 27 years old and still running. The HX was shot and the evap coil was plugged up. Something like that isn't worth repairing.

[Doug Warner]

Agreed, it's about time. I just don't want to buy it just at the start of the season when the installers are all overworked and the prices are high.. If it lasts the summer, I'll probably have it replaced during my September vacation.

Any references on comparison sites for new equipment? =20 The only issues I ever had was the draft inducer motor seizing up due to condensate getting into the front bearing...=20

I installed a new one once, with the blower wheel that came with it. That wheel disintegrated in about 3 years.. Fortunately, I had saved the original (galvanized) one. and reinstalled it.

The only other thing was a condensate leak in the exhaust plenum. I disassembled it, re-sealed, and it's been OK since. =20

Are Carrier condensing furnaces still as reliable as they were 22 years ago?

I've considered a water source heat pump, using water from a creek / drainage ditch in the back. Unfortunately, it's about 80 feet away and 15 ft downhill, so I'd either have to pipe the refrigerant all the way down to the water, or pump the water up to a heat exchanger at the house. =20

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[Gideon]

==============

Based upon what detailed evaluation of his specific home and his particular AC usage? You're just pulling numbers our of your butt.

An 84 year-old neighbor lady recently got talked into replacing her

10 SEER unit, which was working quite well, with a 13 SEER unit. The friendly HVAC tech "explained" to her that she couldn't afford to not make the upgrade since the new unit would "pay for itself" many times over in the lifetime of the unit.

This little old lady runs the unit very little in our northern climate and when she does, she sets the thermostat to 78 since she chills so easily.

What is her payback point? What is her life expectancy. When will she move out of the house and into a nursing home?

[Gideon]

I'm curious: What reasonable assumptions are you making that would lead you to assume that: "It's probably using 2X as much electricity as a new one (or more)"

Also, what assumptions are you making with the global statement: "Plus there is a tax credit if you upgrade."

[Stormin Mormon]

two things come to mind. Dirty coils, and high indoor humidity.

[HeatMan]

Opinions are like belly buttons, no two are the same.

Here's mine.

That's a big IF. The installers may be overworked, but the prices will not go down. With the cost of the raw materials going up, the price will be passed on to the consumer. One manufacturer has had 2 increases this year so far.

The only non-partisn comparisions would be by someone like Consumer Reports.

?????

Again, ?????? Exhaust plenum?

I had a 92% Carrier furnace in my old house for 10 years and never did anything (other than regular service) to it the entire time I was there. I installed a Rheem 92% modulating, VS furnace in this one and love it.

WSHP's don't really operate like that, moving the refrigerant like that. If you want to pump the water up, you'll really need a lot of water. A lot of water.

[Art]

I guarantee you his 22 year old unit is no where near 10 SEER.

[Art]

I had a water source unit in my last house. A PIA. More stuff to go wrong. And much more expensive so upgrading until complete failure was out of question.

Agreed, it's about time. I just don't want to buy it just at the start of the season when the installers are all overworked and the prices are high.. If it lasts the summer, I'll probably have it replaced during my September vacation.

Any references on comparison sites for new equipment? The only issues I ever had was the draft inducer motor seizing up due to condensate getting into the front bearing...

I installed a new one once, with the blower wheel that came with it. That wheel disintegrated in about 3 years.. Fortunately, I had saved the original (galvanized) one. and reinstalled it.

The only other thing was a condensate leak in the exhaust plenum. I disassembled it, re-sealed, and it's been OK since.

Are Carrier condensing furnaces still as reliable as they were 22 years ago?

I've considered a water source heat pump, using water from a creek / drainage ditch in the back. Unfortunately, it's about 80 feet away and 15 ft downhill, so I'd either have to pipe the refrigerant all the way down to the water, or pump the water up to a heat exchanger at the house.

-- Email reply: please remove one letter from each side of "@" Spammers are Scammers. Exterminate them.

[Art]

Right now you can get a left over 10 Seer unit. In a few months they may all be gone and you will have to pay much more for the units that meet new gov standards. You should comparison shop now and decide which is the better choice for you. In a few months you will have no choice.

Agreed, it's about time. I just don't want to buy it just at the start of the season when the installers are all overworked and the prices are high.. If it lasts the summer, I'll probably have it replaced during my September vacation.

Any references on comparison sites for new equipment? The only issues I ever had was the draft inducer motor seizing up due to condensate getting into the front bearing...

I installed a new one once, with the blower wheel that came with it. That wheel disintegrated in about 3 years.. Fortunately, I had saved the original (galvanized) one. and reinstalled it.

The only other thing was a condensate leak in the exhaust plenum. I disassembled it, re-sealed, and it's been OK since.

Are Carrier condensing furnaces still as reliable as they were 22 years ago?

I've considered a water source heat pump, using water from a creek / drainage ditch in the back. Unfortunately, it's about 80 feet away and 15 ft downhill, so I'd either have to pipe the refrigerant all the way down to the water, or pump the water up to a heat exchanger at the house.

-- Email reply: please remove one letter from each side of "@" Spammers are Scammers. Exterminate them.

[Art]

The guy is in Atlanta, genius. I live in NC which is not as hot. Even in a small house he is using a lot of ac. My butt is smarter than yours. I do feel sorry for your 84 year old neighbor. She got ripped. Too bad you didn't do anything to help her before the fact.

[HeatMan]

A few months? They're gone NOW, at least from the reputable manufacturers...