I'm new here although I have been an avid reader for years.
I need to determine how to proceed with an inefficient a/c situation.
Top floor loft condo. 1650 sq. feet. open concept. double pane builders windows. Located in Baltimore, MD.
Air handler located in exterior balcony closet. Thru-wall Aerosys 3 ton condenser. 4 years old. All ductwork is located in the attic.
1 central return duct in the living room which is fabricated from chip board inside a drywall partition with the return grill at floor level. The ceiling in the living room is 18 feet high and is open to a second level loft.
There is a sheet metal trunk line in the attic that runs from an upflow air handler for approximately 10 feet and then it transitions to a flex duct which turns 90 degrees up to the roof peak and turns 90 degrees to supply flex duct for the MBR, Kitchen, Bath and Loft.
When outside temperature climbs past 85 degrees, the a/c can not maintain 74 t stat setting. When it gets to the mid to upper 90's, it can not maintain 80.
Purchased condo new in 2004. it had a 2-1/2 ton a/c unit. In 2005 the builder said they were going to install an attic fan. Then they found out they could not because of the HOA rules. So they replaced the a/c with a 3 ton unit. No help.
My electric bills are running extremely high. The a/c does not cycle off until late night every night.
I just discovered that there are identical condos being built and the loft units now have 2 systems! I am not allowed to put in a second system because of the HOA rules on exterior alterations.
Any thoughts would be greatly appreciated
Ductless mini split. Sanyo, Mitsubishi.
Has the system ever cooled properly under those conditions?
Have you had the system serviced since it was installed?
Does the fact the builder is installing two systems in identical condos being built tell you anything?
With your chrome heart shining in the sun, long may you run.
An attic fan may not have helped your situation. If not done correctly, attic fans can actually draw air you paid to cool out of your condo. Not good.
What does your HOA say about installing staple-up radiant barrier underneath the roof deck in your attic? It won't be visible from the exterior and may cut down on some of the heat gain in your attic. Question would be is there any ventilation in your attic at all?
Left to resolve this problem with the HVAC alone, it will come down to ensuring the correct amount of air is delivered to every room inside your condo. This is more challenging when one system is trying to supply two levels, but not impossible. Most residential duct systems are never checked for proper airflow, nor do they receive a proper balancing after installation. You could have way too much air flowing into one area and not enough in others, which might account for any temperature variation you experience as you move around inside.
Staying on HVAC, the other thing to check along with proper airflow is clean filters, clean cooling coil, clean blower wheel, and THEN proper refrigerant charge. If you have been good at changing the filter on a regular basis since you bought the place new, you may not have a lot of dirt building up on the blower wheel or the coil. But it never hurts to get same cleaned after eight years of operation, nonetheless.
Duct air leakage can be another challenge, as leakage can rob the quantity of air that should be supplied to each area within the structure.
- Electricity makes refrigeration happen.
- Refrigeration makes the HVAC psychrometric process happen.
- HVAC pyschrometrics is what makes indoor human comfort happen...IF the ducts AND the building envelope cooperate.
A building is NOT beautiful unless it is also comfortable.
Thank you all for your input.
The cooling problem has been going on since day one.
I have had 3 service calls. When the unit was installed both the furnace would run in concert with the a/c. The T-Stat was replaced. Then the circuit breaker would trip every night. Wrong amperage breaker installed.
Another service tech said the coils needed to be cleaned. He cleaned the coils. No improvement.
I clean the condenser once a season.
The A coil and blower are clean.
My son’s bedroom is beneath the majority of the attic space. His room was unbearable.
I had the installation company and the builder do a walk through on a typical hot summer day. They both agreed there was a problem. They proceeded to the attic. This is when they suggested the attic fan. Then a few days later the builder said he could not install it because it would alter the exterior appearance. This is when it was decided to increase the unit size. Because it's a thru the wall unit and it has to be the same on the out side, we could only go from a 2-1/2 ton to a 3 ton. I doubt its true 3 ton. Aero-Sys stopped making them.
I did discover that the duct boot in my son’s room was just laying over the penetration cut in the ceiling. It was cooling the attic more than his bedroom.
I fastened it down and sealed it with foam and metal tape.
The system is definitely not balanced. My son’s bathroom register had to be closed down as it was getting way too much supply.
The end of the run is where the master bath and master bedroom are located and there is a significant pressure drop.
As far as the new condo's with 2 units...Yes I do realize this is what they have come up with to resolve the problem.
I spoke with my Father in law who resides in Florida. He thinks I should be able to do something. His home is twice the size, he has high ceilings a smaller system and has no problems whatsoever with the climate down there.
He did tell me that he has knee-deep blown in insulation which buries the ductwork.
Does anyone think this may help? (More insulation on the ductwork?)
Thanks to ALL!!!
Oh I forgot to comment on some of your suggestions.
The attic is vented.
I can not install a mini-split. I wish I could. HOA Rules.
I could install radiant barrier.
I'm willing to have new duct work installed if it would fix the problem.
3 tons is plenty for a 3 story 1650sqft in baltimore. I would focuse of insulating and sealing the ductwork better including hte return.
Simple test. If you set the system fan to "on". Can you have "attic smell" and does it quickly get warmer and more humid? If so, you may have significant air leaks. Also take or purchase a simple little digital meat thermometer (they are a must have for grilling IMO and cost like $10 for a basic one) and measure the temperature at the return and supply with it set to fan only. You shouldn't have a significant increase. Actually, if we assume your airfow is 1200 CFM for example, every 1F temp rise you see, is approx. 0.1 tons of heating being done to the air.
You do realize even with the information you've provided, there's no way any of us can tell you what needs to be done to make your existing system more efficient. Sure, we can tell you to check this and check that, do this or do that, but without being there to physically see the system, ensure it's sized and installed properly, ensure the return air and supply duct work is sufficient, ensure the refrigerant charge is correct, etc., we'd be pissing in the wind and you could be wasting a lot time and money.
You say it's never worked properly since day one. Have you talked to your neighbors and, if so, do they have the same issues? If so, and due to the fact the builder is now installing two systems instead of one system, you all have some issues that need to be looked at by a reputable and knowledgeable HVAC contractor. That's the only way you're going to get the answers you need, not in an online forum. In fact, based on what you've told us, you may have some issues that need to be handled by an attorney. But, first, call a reputable HVAC contractor to check out your system.
With your chrome heart shining in the sun, long may you run.
Again, thank you very much for your knowledge and suggestions.
This is a common issue with all of the loft units in my community.
The builder is extremely difficult to deal with. I gave up on them a long time ago.
Thanks to all!
Call a reputable company and have a complete system performance evaluation .if they put a 3 ton unit on 2 ton duct system they did not acomplish anything