HELP!! HVAC Problem

[mlincoln]

also the flow of air is less in two of the rooms.

[pushkins]

Is your house a ranch house with an attic or does it have two levels ?
If it has two levels, is down stairs AC temps OK ?

One thing to do would be to place a thermostat on top of one of the ducts, leave it there for 10 minutes and then tell us what the temp. was.

[mlincoln]

No, this is not a ranch house. A friend advised a cleaning of the ducts. I had the ducts cleaned and my tenant complained that the house got even hotter. Does this sound right? If so, how can cleaning the ducts cause the temp in the house to be higher then before the cleaning? If the issue is with venting the attic, how much lower will this bring the air temp? The current unit is a 3 ton unit that seems to be fine with the exception of the elevated air temp flowing into the home. As mentioned, the problem is not with the ac, but with the air temp getting hot from the ac to the attic. The repair man said the attic was around 130 degrees. This house does not have attic fans but attic vents that are suppose to circulate the air. I have some more questions. This is the first year that the tenant has had an issue with the AC. Last summer, she never indicated that the air was too hot. What would cause this change in the ducts from one summer to the next? Also, do you think an upgrade to a 4 ton unit would help the temp flowing into the home? Or would I still need to address the issues with the ducts? If I did get a new unit, would the utility bill go up? My tenant feels that the temp in the house should reach 68-70 degrees. Is it possible to cool the house to this range when the outside temperature is around 97-100? Thank you all again for sharing your expertise and responding to all of my questions.

[pushkins]

Ok, so let me get this straight.....the property is a two level home, the lower level seems to be fine with the heat and cooling, the upper level has plenty of air moving in the ducts but there is a discrepancy of 10-15 degrees between the AC unit and the end run of the ducts as they enter the rooms. One room has a much reduced flow of air to it.
Have you, yourself, put a thermometer at several ducts where they enter the home?....this would help to find out if it's just one or two duct runs, upper and or lower level only. If you find out that it's only in the attic run ducts then the attic heat would be a real issue. (Attics should never be allowed to reach 130 degrees regardless, it for one dramatically shortens shingle life).
Another approach to take would be to place a thermometer under the attic duct insulation, find out what temp. it is reaching there.
Cleaning of the ducts will change the temp. very little if any, what cleaning does (other than reducing particulate matter and all the other pollens etc...) is help keep air flow up.
Changing to a bigger unit doesn't mean that you get colder air, a bigger unit is able to pump larger volumes of air to cover larger areas. As a rough guide for approximately every 600 sq. feet you need 1 ton....this is a very rough guide as there is a whole system of figures to working out exact sizes, but it gives you a good ballpark.

From experience I've found that in many cases when a tenant see's a landlord having problems with a particular repair sometimes the line between "it's never done that".....to "oh.....it's done that the whole time lately"......becomes blurred. That's why I think you need to work on an elimination approach, if you actually find that there is a big drop in temps. in all rooms upper only then it's an attic insulation/airflow issue.

Regardless of this issue you would be very well advised to have a powered roof vent installed, ideally you should be able to keep your attic temps. down around 90 degrees in mid summer, remember though if your sucking air ou of the attic you need to make sure that the soffits can allow fresh air in.
The foloowing link is a great explaination of roof venting and while it is from Texas A&M University, the same principle applies anywhere.
Attic Ventilation

[mlincoln]

Well the home is a single story home. It's approximately 1,400 sq ft. I will measure the temp of the ducts when I get to the house this upcoming weekend. I thought it would have been solved by now. I'm traveling from California to address this issue.

I definitely appreciate the link about ventilating the attic. I think I'm going to have some sort of ventilation method installed so that I can preserve the construction of the home.

I hate to ask, but suppose it still doesn't solve the issue, can you think of what the problem might be?

[pushkins]

Single story homes are commonly referred to as "Ranch".
If your AC is producing the correct amount of conditioned air (cool), and there are no major air leaks (main trunk line, you'd know if there were any, your attic would be much cooler...lol), then it is purely an insulation around the ducts and or attic ventilation issues.

[mlincoln]

Ok I have finally made it out here to TX. After getting the attic vented with attic fans (2) and having a digital thermostat installed, I am still perplexed. the thermostat is set at 65 and room temp is 78? The air pressure coming out of the vets seem low and the line (small metal pipe) from the AC unit to the home is freezing up? can you help please as to what the issue could be. Thanks. Upload pics attached of the line freezing over. Thanks

[pushkins]

The lines from the outside unit are, (large line- suction)(small line- liquid). The large line is supposed to be covered with black insulation. If the line is not covered it will freeze up. Get some Armaflex refrigeration insulation & re-cover it. Use 3-M electrical tape (33+) to seal the insulation over the pipe. You have to seal out the air from touching the pipe.

I also looked around and found this web page with an explanation and some ideas to help alleviate technician costs (by you being able to give him as much info. as possible).

Air conditioning freezing? Let's check out your unit and find out why.

[mlincoln]

any additional advice on why ac is not cooling? vented the attic, new compressor, no visible holes in vents or excessive cooling in attic, had ducts cleaned to remove any debris, but still not cooling house. had to buy two window ac to cool house. what could be the problem? the home warranty company says its the ducts, but also said ducts look good they are perplexed! Another independent ac guy says just replace the unit. But everyone agrees unit is fine.its only 10 yrs old. help please! Oh thanks for the infor rearding freezing up:-)

[HayZee518]

low freon will freeze the suction line - but unless you are an epa rated technician, don't touch it! r-12 and r-22 require epa licenses.

[HandymanTrainer]

I would use a laser thermometer to check duct temp at as many as thirty places along the duct....also, look for a humidifier which is running in cool mode instead of heat, or a UV sanitizer with the wrong bulbs installed...

HandymanTrainer

[HandymanTrainer]

any additional advice on why ac is not cooling? vented the attic, new compressor, no visible holes in vents or excessive cooling in attic, had ducts cleaned to remove any debris, but still not cooling house. had to buy two window ac to cool house. what could be the problem? the home warranty company says its the ducts, but also said ducts look good they are perplexed! Another independent ac guy says just replace the unit. But everyone agrees unit is fine.its only 10 yrs old. help please! Oh thanks for the infor rearding freezing up:-)

Assuming the indoor coil is not dirty or frozen, if air flow seems to be slow, it is possible that the incorrect fan speed wire is connected to the cool terminal on the control board. Under normal conditions the BLACK wire should be energized in cooling mode. If indoor coild is freezing but high side pressure is high, you may have a line restriction which usually occurs at the orifice fitting filter screen. This will cause high high side readings and low low side readings despite a clean coil.

All of this should have been checked by a reputable technician who was not just trying to sell a new unit.

HandymanTrainer

[mlincoln]

Found the problem

I since had to leave TX but they finally found the problem. First, the condensor coil was filthy, however this was not the sole problem. The Pistons, according to the technician, were put in backwards and when he switched them the unit miraculously began to work. Well needless to say, I am ecstatic! Have you guys heard of this before? my tenant didn't know what pistons or where can someone educate me on this?