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weemer
08-25-2008, 14:01
So our a/c unit is not doing so well. We have been in the house for 7 months. Got a great deal because it was trashed to hell. LOTS of time and money later it is our dream home. But little things keep coming up to take care of.

Previous owner had 4 kids, birds, 4 dogs, and cats. It looked and smelled terrible. We took the carpet out ourselves because contractors wouldn't touch it. Kilzed the entire house, fresh paint, 3 new interior doors, new front door, 5 new closet doors, 3 trashed ceiling fans, multiple sheetrock repairs....... it goes on and on. I couldn't believe what I had to pay for a new patio screen door.

House:
7 year old 2 story 3000 sq ft, 1500 up and 1500 down, plus basement. Open floor plan.
2 a/c units and furnaces. The 2nd one is in the attic.
2.5 ton a/c units.......2 ton coils....

Symptoms:
1. Hardly any air coming out of supply vents (both units) Although 2nd floor unit seems to work OK
2. Water leaking at base of coil (both units)
3. Considerable amount of air felt coming out of base of coil (both units)
4. With 5 tons of a/c the house should stay pretty cool, but it doesn't
5. Blower was completely packed with gunk. I doubt previous owners EVER changed, or even had a filter in the units based on the rest of the house.
6. Did not heat well last winter

What I have done for the HVAC so far:
1. Warranty replaced one compressor
2. Warranty charged systems
2. Warranty replaced [b]1/2 HP blower. It was completely packed and burned out from the gunk. The tech that replaced it almost pucked when he pulled it out.
3. Cleaned both a/c units
4. All ducting blown and cleaned out. Dirtiest they had ever seen.
2. Went to the cheap blue filters rather than the thick ones to get better air flow
3. Taped shut the 2 vents in basement, lots of air coming out of them. Was told we were losing 10-20% out of them.

I do not have another $4-6000 for a new system, but am willing to pay around $1k to make it work.

What we know now:
1. 2.5 ton a/c to 2 ton coils are not good
2. Current venting is on the cusp of being too small for the system

What 4 contractors have told us:
1. Just get a new system for $6000. Replace all ducting, a/c and furnace systems.

2. Make current air return vents bigger, and add 1 ea return air vent to the up and down units.

3. Add return air vent to first floor. Increase size of return air conduit in basement. $1400+.

......NONE of the above contractors went outside to check the a/c units, or climbed into attic to look at unit........

4. Looked at everything and took measurements: Replace both 2 ton coils with 3 ton, and upsize trunk lines $2800, or $1400 each. Current 5 tons of a/c are plenty for house, and they should last for another 7 years, it's the coils that are undersized. With the 3 tons we will be half way to a new system in the future. Wants to reduce drag in supply ducting above coil by angling out the T.

What should we do? We are tapped out from this house.....remember the movie "The Money Pit"???
-I suspect the coils are filthy as well considering the state of the home. I have not done that before. Easy DIY? #4 will not clean the coils because they are undersized, only replace.
-Will just cleaning/servicing, $100-250, the coils be enough? Or should I just get them replaced, $2800 for now?
-Will the 1/2 HP blower be under powered if the coils go to 3 ton?

To top it off I found the attic unit venting to the roof is leaking rain......another item added to the list....

HunterCO
08-25-2008, 19:31
From what you described it sounds like the A-coils are plugged not allowing air to flow through. When that happens they freeze up.

The other option is the A-coils are too small in which case they will freeze up causing the same problem. If the furnace can not send enough air through the A-coil that can also make them freeze up.

Sounds like you need somebody that has a clue to help you. I am just giving my .02 from what I have learned when the HVAC system was installed in my house.

My brother is a mechanical engineer who designs HVAC systems, He is also who installed my system while he was still in college working as a tinner to get his masters. I can ask him or if you want I am sure he would be willing to look at it.

Tim

Great-Kazoo
08-25-2008, 20:04
make all duct 6" supply and 8" return. how many return vents back to unit??
start there. NEVER close off any supply lines. this can cause icing of the coil.
a 2.5 ton condenser is under powered and over working for your sq ft. i'm runing a 2.5 on a 1600sq ft total home.

bryjcom
08-25-2008, 21:27
Sounds like the A-coils are plugged.

The reason you are not getting air flow is because the are plugged and/or frozen up.

If the blower wheels were gunked up then your coils are also. Why didn't the first technician realize that when he replace the blowers?

Need to pull the coils and hose them off which requires pumping down refrigerant, cutting lines and removing and after cleaning, reinstalling them, brazing lines back together and vaccumming system and opening service valves.

Sometimes they can be cleaned in place by pulling them out from furnace and combing them but in your case sounds like cutting the lines and getting a garden hose on them is the best route.

I would really have to take a look at them to tell you "officially" what needs to be done but screwing around with the duct systems are usually a waste of time.

PM sent also

weemer
08-27-2008, 13:40
Thank guys. The last contractor wants $477 to clean the coil. I'm going to pull the cover off and see what I can see. Good news is I contacted the home builder about the 2.5 ton a/c going into the 2 ton coils, and they are having an HVAC company contact me. We'll see if they can help.

weemer
08-28-2008, 09:15
I pulled the cover off. It is filthy on top as well as inside. There is a lot of trash on top of it. Must have fallen in through the vents.

I was able to peek inside the coil after getting the screws out, but there are 2 little plastic peices holding the cover on the bottom. Anybody know how to get them out? should I cut them?