The World of Air Conditioners

[red-beard]

Yesterday was an A/C intense day. The unit at work went balky. The Technician looked it over and said nothing was wrong with the unit, except that it was installed poorly. And it will cost me money to make it reliable....At least now I know how to make it work: shut it off for an hour...

My parents had to spend the night at my place because both brand new, super high efficiency units failed. How do BOTH compressors seize in the same day? Seems very weird. And the tech said that the motor windings are open circuit.

Seems to me that the motors must have a fusible link someplace...

Fortunately, those units are under Warranty. Hopefully they get them replaced today. you can't really live here in July without A/C...and it isn't really even hot yet...

[GH85Carrera]

The real trick seems to be in finding the old Grey hair technician that really completely understands AC and not just the few typical things the average technician knows.

Our office AC system is a 3 phase unit. Every year when it got HOT the unit had problems. One company was pushing us to replace the compressor and condenser unit. Not cheap!

We called another company for a second opinion. The old Grey started from ground zero. Right away he found one of the legs of the 3 phase breaker box was partially fried because the connection was loose next to the fuse. We replaced the disconnect box and all is fine with the AC unit.

[CHICKS]

Things I always found as a tech:

-Poor airflow, such as dirty evap, or filter, blocked return's, and closed off supply's. Filters should be changed 1-3 months depending on how filthy your house is.
-Unrealistic expectations of temperature. Just because the stat will go to 50*, doesn't mean your house will.
-Short cycling the unit. Pick a temp and let it run, quit turning it off and on.
-Dirty or blocked condensing unit. Cottonwood seed is nasty, as is grass clippings. Dirty cond. coils cause high head pressure.

[campbellcj]

Our house has a split system and both units are down now...we're dying...waiting for the tech to come back today. I'll post the findings.

[Joe Bob]

Mine had a tech out two weeks ago. Leaking Schrader valve, tightened and gas installed......blowing hot again. Tech will be there between 2 and 6. Oi!

[red-beard]

CHICKS:

This is a cheesy setup in our office. 2.5 tons should be able to easily handle 650 sq. feet. Crap, a 1.5 ton unit should be able to handle it! Even in Houston.

1. This is a replacement unit. They re-used the R-22 lines, so they are a bit under sized.
2. The run from the Condenser to the Evaporator is nearly 100 feet, plus 20 feet of vertical.
3. The Ducting layout is PATHETIC!

Originally, there were 8 x 8" ducts with diffuser outlets. There was only 1 return, 12". A quickie calculation shows that the 8" ducts have a combined cross-section of about 400 sq. inches, while the return had about 113 sq. inches. An 8" return was added...but I don't think it was enough.

Bathrooms are very chilly, so I'm cutting one of the lines and putting on a "Y" to reduce air flow. The "extra" line will get moved to the main office area. I want to move the diffusers around to get better distribution around the office. I also want to move the second return to the outer most part of the office and increase it to 12".

To fix the re-start issue with the refrigerant, they will be installing a recirculation solenoid valve.

[billybek]

Originally Posted by Joe Bob

Mine had a tech out two weeks ago. Leaking Schrader valve, tightened and gas installed......blowing hot again. Tech will be there between 2 and 6. Oi!

Ah the leaky schrader diagnostic.
Perfect for the tech that doesn't want to do any work.

Their line of thought is that I will dump some gas in and if the leak is slow enough they will call me again next year.

[billybek]

Originally Posted by CHICKS

Things I always found as a tech:

-Poor airflow, such as dirty evap, or filter, blocked return's, and closed off supply's. Filters should be changed 1-3 months depending on how filthy your house is.
-Unrealistic expectations of temperature. Just because the stat will go to 50*, doesn't mean your house will.
-Short cycling the unit. Pick a temp and let it run, quit turning it off and on.
-Dirty or blocked condensing unit. Cottonwood seed is nasty, as is grass clippings. Dirty cond. coils cause high head pressure.

Yep. These are the places to start.
If it is a single phase blower motor on the air handler, make sure it is running on the highest speed if you are freezing the evap up due to low load/airflow.

It is amazing how much decrease in compressor performance you get with an increase in discharge pressure. The decrease in performance is also very evident when you drop the suction pressure due to low load.

Make sure that your suction line is as short as possible and well insulated. Adding heat that isn't contributing to the cooling of the building is waste heat in the system. 100 feet and undersized is begging for trouble.

[red-beard]

Update: It seems that both of us are on the same distribution line and that there were several drop outs yesterday. I think a hard start kit will help.

Do you recommend the 5-2-1 or the Kickstart units? With what I've read, I'm leaning to 5-2-1.

[asphaltgambler]

Originally Posted by CHICKS

Things I always found as a tech:

-Poor airflow, such as dirty evap, or filter, blocked return's, and closed off supply's. Filters should be changed 1-3 months depending on how filthy your house is.
-Unrealistic expectations of temperature. Just because the stat will go to 50*, doesn't mean your house will.
-Short cycling the unit. Pick a temp and let it run, quit turning it off and on.
-Dirty or blocked condensing unit. Cottonwood seed is nasty, as is grass clippings. Dirty cond. coils cause high head pressure.

OK, I know this will cause you to laugh but we live in an older 1500 sqft rambler - 1 story on a slab. It's just the wife and I so I close off the vents in the rooms we rarely use. I thought this is OK - No?

[billybek]

Originally Posted by asphaltgambler

OK, I know this will cause you to laugh but we live in an older 1500 sqft rambler - 1 story on a slab. It's just the wife and I so I close off the vents in the rooms we rarely use. I thought this is OK - No?

Fine as long as you have enough airflow to keep the suction pressure high enough to avoid freezing the moisture that condenses on the coil. For R22 over about 58 or 60 psi.
If you don't have enough airflow, the suction pressure drops resulting in a below freezing saturated refrigerant temperature. If you are freezing up, open all your vents.

[aschen]

The houston area is hard on home and automotive AC systems

It is popular lunch conversation to be whining about a dysfunctional AC system. At least it didnt get hot too early for us this year.

[CHICKS]

Originally Posted by asphaltgambler

OK, I know this will cause you to laugh but we live in an older 1500 sqft rambler - 1 story on a slab. It's just the wife and I so I close off the vents in the rooms we rarely use. I thought this is OK - No?

Originally Posted by billybek

Fine as long as you have enough airflow to keep the suction pressure high enough to avoid freezing the moisture that condenses on the coil. For R22 over about 58 or 60 psi.
If you don't have enough airflow, the suction pressure drops resulting in a below freezing saturated refrigerant temperature. If you are freezing up, open all your vents.

This ^.

[CHICKS]

The stuff I saw was when people would close off all their supplies except the bedroom, or living room. A few here and there is ok. In my house there's a few I cant close because It'll cause poor airflow.

[Hugh R]

My A/C guy said besides changing filters, make sure your system is up for the type of filter. Lots of people put HEPA filters in old systems and burn out the blower motor, and restrict airflow. He also said pull the fuse on the outside unit and hose it off at least once a month in the Summer.

[Baz]

I've certainly had my adventures with HVAC and my philosophy is install a small 110v window unit to use for emergencies in case the main unit is down. This buys you time and maintains survival.

I recently purchased a mini ductless split unit for the garage and can see one day putting one in the main house maybe with a spare for 'emergencies'.

Some good tips here - thanks guys!

[Joe Bob]

So my AC is up and running again.....was talking to the tech/owner of the service company.

Home use of R22 is being phased out like R12 was in motor vehicles? Six years from now? $600 for a 30lb canister?

[calimedeiros]

I'm a teck here in canada and since we have been installing the. R410 units as the r22 units are getting phased out we have had lots of problem leaking coils dead compressors etc
R410 runs at a lot higher pressures which I think the compressors and coils sTart to fail quicker
Best thing to keep them going is replace filter regularly and wash the outside condensor coil to help reduce pressures and save on your electrical bill

[wdfifteen]

I told her not to. Told her they don't work in humid climates, but my ex-wife once bought one of those evaporative units anyway while I was out of town. It moved a lot of air, made a lot of noise, and lowered the temp a degree or two, but we had water dripping from the ceiling.

[71scgc]

Just had our entire system replaced yesterday. They've been throwing parts at it for three years to no avail.
We rent, so it wasn't on our dime. Three years without decent heat/air is a long time.
It's a heat pump.
Wish it was a real AC and furnace...

Carter