New Trane Split System Not Sufficiently Cooling

[24SevnLibrarian]

Hi, all! I bit the bullet and decided to replace my HVAC split system since my outside compressor died last fall and the furnace under the house (almost 20 years old) had started making the living room floor vibrate this winter. I had a Trane system installed and kept the existing ductwork. The problem is now that it has gotten hot (low 90's), the fan is blowing (cool air) constantly but even with that and the thermostat set on 69 or 70, the indoor temp on thermostat and another thermometer are sitting between 74 and 76 degrees in the afternoon. I went from a 3 ton unit to a 2.5 since my house is just shy of 1200 sq. ft. and the humidity levels in South Carolina are pretty high most of the time. The furnace is model S9V2B060U3PSBB. It has a variable speed blower motor, 96% AFUE, and 3 multiport inshot burners. The outside air unit is model 4TTX6030J1000BA. It is 16.5 SEER when combined with the new furnace. It has a variable speed fan and a 2-stage scroll compressor. I have more product data; I just don't know what anyone might need (if anything) to help me.
My old unit never had a problem keeping the house cool even though it didn't have the bells and whistles like the new one. Also, inside the house, with the blower running full force, it sounds like the dull roar of a train going down the tracks in the distance. Never had that problem before either. Any ideas? The installer already thinks I am crazy for calling him about the inside air noise (but it is loud enough that I hear it over the TV!).

 

[Fitter30]

Pick up a pocket thermometer measure temperature between return grill and supply grill closest one to furnace difference 18*-22*. They go to the condensing unit feel the copper pipe that is insulated should be cold. If temperature difference is less than 18* and or the copper pipe isn't cold unit could be short of refrigerant or blower speed is to high. Have you looked at install air handler in crawl space?

 

[Sponsor]

 

[24SevnLibrarian]

If by supply grill and return grill you mean the two floor returns, they are both blowing 71.5-72* with the thermostat set on 69. I have added some pictures in case that helps.

 

[Fitter30]

Return grill sucks supply blows. So if the return air temp is 76* supply should be around 56* thats 20* difference. Since condenser has a two speed compressor wonder if it not running on high speed . What temperature is the thermostat reading compared to return temperature?

 

[Dana]

When retrofitting higher SEER equipment onto existing ducts it's pretty common to find that the return plenum is undersized for the air flow, even when dropping a half-ton in capacity.

There could also easily be high duct leakage issues undercutting performance. I'm assuming the ducts and air handler are in a VENTED crawlspace? If yes, any air drawn in to the return plenum is going to be high humidity outdoor air. Both the supply and return ducts need to be well sealed, and preferably insulated and RIGH SIZED for the application.

The fact that it's noisy is a clue that either the ducts are leaking or undersized, resulting in high duct velocity & high static pressures. Whenever possible it's best to keep all duct velocities under 400 feet per minute, which will usually have a HUGE benefit on reducing noise (even in somewhat leaky ducts), whereas many systems are running north of 600 feet per minute.

It's highly unlikely that a 1200' house has a design cooling load of 2.5 tons, even when allowing for a half-ton of duct losses from having the ducts & air handler outside of conditioned space. If there are doored off rooms with supply registers and no dedicated return path the rooms become pressurized, using "The Great Outdoors" as part of the return path, bringing in copious quantities of humid air whenever the air handler is running. This can usually be fixed (methods vary by the particulars)- take a look at your supply & return register layout, see if that could be contributing factor.

A typical 1200' house in the southeastern US would have a 1% design load of about 1 ton (not including duct losses) and would be better served by a 1.5 ton AC fully inside both the pressure and insulation boundary of your house to all but eliminate duct loss issues. This plot of square feet per ton from real Manual-J calculations was put together by a consulting company in Decatur GA, not all that far from you:

Note that literally all ten houses <2000 square feet had a ratio no worse than a ton per 600', with the average being about a ton per 1000'. Unless your house is the crummiest house in SC a 2.5 tonner is going to be sub-optimally oversized for your home. Shooting for a 1.2x oversize factor on cooling, and 1.4x oversize on heating usually provides the best comfort, though with multi-stage equipment 1.5x isn't going to be an efficiency or comfort disaster. So if you're at the typical ton per 1000' range your load would be 1.2 tons, and (1.2 tons x 1.2x=) 1.44 tons would be ideal, and (1.2tons x 1.5x = ) 1.8 tons might still be OK. If it's not cutting it at 2.5 tons you almost certainly have excessive duct losses &/or high air handler driven outdoor air infiltration.

The S9V2B060U3PSBB furnace is also CRAZY oversized for a 1200' house at SC style +22F to +31F 99% outside design temps in that state. Assuming there is a bit of fluff in the walls & attic, glass in the windows and doors that shut, a reasonably air tight 1200' home would come in under 25,000 BTU/hr @ +20F, and could easily be less than 15,000 BTU/hr (if not right now, could be with some modest air sealing and insulation upgrades.) My 2x4 framed sub-code antique house is twice that size, in a much colder climate and has a design load of less than 40,000 BTU/hr @ +5F (the local 99% design temp), and could be fully heated even at the 37,800 BTU/hr LOW fire output of that furnace! The ~58K high fire output would be good down to about -30F (yup, central AK type winter temps.) My house is on top of a reasonably sealed & insulated but not directly 1600' basement (in addition to the 2400' of above grade), so the duct losses in the basement are true losses. But even if yours are in a vented crawlspace or pier foundation it's unlikely that your design load + duct losses add up to my load numbers.

So where do you go from here?

#1: Assess and fix any duct leakage and return path issues. Again, see if the return paths need improvement. It may be "worth it" to design and implement an all new duct system based on a room by room Manual-J.

#1a: Don't count on HVAC contractors to get it right. Run your own room by room load numbers using freebie Manual-J-ish tools such as CoolCalc or LoadCalc. Take your time, and be somewhat aggressive on the air leakage & R-value numbers, even though we know your ducts and house are probably leaky, since the big leaks can probably be fixed pretty quickly & cheaply. Look at your coldest-month gas bill and run a fuel-use based load calculation logging heating degree-days against gas use as a sanity check. Unlike Manual-J, that is a direct measurement (using the furnace as the measuring instrument), and will automatically include duct losses & air handler driven infiltration loads. In many cases the Manual-J numbers using those tools will come in higher than the fuel-use numbers, but if you have major duct leaks or a horribly unbalanced duct system.

If biting the bullet on all new ducts, insist on a target duct velocity of 400 - 500 fpm on all ducts, not the typical 700-1000 fpm. If the crawlspace were sealed and insulated you could safely go even slower than 400 fpm, but if currently outside the insulation & pressure boundary of the house <400fpm could result in unacceptably high wintertime duct losses.

#2: Get serious about air sealing the house, including air sealing the duct boots to the sub floor, and all electrical & plumbing & flue penetrations of the subfloor and attic floor.

#3: Consider putting down a ground vapor barrier then air sealing and insulating the perimeter foundation wall (if crawlspace) or skirting (if pier foundation.) When the house & ducts are reasonably air tight, and the ducts & air handler all reside inside the pressure & insulation boundary of the house the ability of the systems to control heat & moisture flows in the house become radically improved, enhancing indoor air quality, and increasing comfort, even when the systems are 2x-3x oversized for the 1% & 99% cooling/heating loads (which is where you would be in the "after reasonable upgrades" picture of the house, if not already.)

 

[Dana]

Mind you, the ability of the AC to keep up could be due to improper refrigerant charge. When they installed the system did they weigh-in/out the refrigerant charge based on the condenser, the air handler coil and refrigerant lines? (Some installers are pretty sloppy, and overcharge system on day 1.) A competent AC tech might be able to tell from the subcooling & superheat numbers and measuring the air flow, but doing the math then pumping it down and installing the correct amount of refrigerant would eliminate that as a cause. (In California a system won't pass inspection unless the initial charge is calculated and weighed in, but most states are pretty loose about that.)

On recently installed complicated multi-zone systems with multiple air handlers pumping it down and weighing in the refrigerant charge often the best starting point, but not usually with single zone single air handler systems.

 

[24SevnLibrarian]

Dana, thanks so much for the detailed responses! I'm going to read them again in the morning when my brain is fresh (I teach and we are in the final week stretch before summer break - insane days right now). But I can at least share with you that my house was built around 1945-50, and yes, it is a vented crawlspace. Some fluff in the attic but none in the plaster walls. I have two air returns, one is ~ 8" x 22" in the hall floor and the other is 12" x 24" toward the other side of the house.
Definitely not air tight and it is past time to go back and recheck the ducts for tears and tape them up tight. Most of the crawlspace has a ground vapor barrier of 6mil plastic that extends about 8-10" (more or a little less) up onto the brick foundation walls. The part of the floor that doesn't have a barrier is where the height is drastically lower (~30-40% of the area) and the thought of crawling on my stomach and not being able to get out quickly should I come across a critter is a fear I haven't yet forced myself to face (especially having already replaced one knee ACL and not wanting to re-injure it).
Needless to say, this is why I try to do what I can do myself. Finding people who not only know what they are doing but care enough to actually do their job correctly and still be reasonably affordable is practically impossible these days. I absolutely hate to pay people to do something wrong or halfway. But I can't be an expert at everything either so....
I will work more on this tomorrow! Thanks, again, for your valuable help!

 

[Fitter30]

Contact your electric company see if a offer a energy audit with a blower door test. Usually low cost and supply you with some information on windows,doors and insulation.

 

[Dana]

Dana, thanks so much for the detailed responses! I'm going to read them again in the morning when my brain is fresh (I teach and we are in the final week stretch before summer break - insane days right now). But I can at least share with you that my house was built around 1945-50, and yes, it is a vented crawlspace. Some fluff in the attic but none in the plaster walls.

It's almost always worth blowing insulation in the wall cavities even if it means needing to do some cosmetic patches on the plaster when blown from the interior side. If you have brick, stone or stucco siding it would have to be from the interior, but clapboards, shingles, board & batten etc can usually be done from the exterior. Some analysis of the material stack-up of the walls needs to be done first, as well as inspecting (and rectifying where necessary) bulk water management details such as window flashing, etc. In rare instances you would have say, stucco on lath nailed directly to the studs, which would make it too risky, but if it's something like wood siding | tar paper | ship-lap plank sheathing | studs | lath & plaster it's usually good to go. Installing cellulose (any density) in the walls would dramatically tighten up air leakage and infiltration through the walls, and at 3lbs per cubic foot or higher it's nearly as tight as foam insulation(!). Blown fiberglass at 1lbs per cubic foot brings the R value up to about R13, but does almost nothing for air leakage. At 1.8lbs density fiberglass is as tight or tighter than cellulose, and would run about R15 in standard 2x4 framing.

I have two air returns, one is ~ 8" x 22" in the hall floor and the other is 12" x 24" toward the other side of the house.

I'm assuming that's the size of the return grilles, not the size of the ducts(?). That's only about 3 square feet at the return grille boots, the duct cross sections are probably only about 2 square feet(?) at most. Looking at Table 5 of the manual, the blower would be delivering over 1000cfm at medium speed, even at 0.9" water c0lumn (=high static pressure, ducts too small & noisy). Even if it's fully 2 square feet all the way back to a larger plenum that's north of 500 feet per minute duct velocity on the return. If the combined cross section of the return ducts or return plenum is only 1.5 square feet (200-225 square inches) it's pushing 700 fpm velocities at the high speed.

In your area AC is usually set up for ~400 cfm per ton or a bit less to provide adequate latent cooling. At 2,5 tons that would be 1000 cfm total, so you'd probably want to set it up to run at the lowest blower speed where it's only delivering 837cfm (/2.5 tons= 335 cfm/ton) for maximum humidity removal , or at most medium low where it's delivering a hair more than 400 cfm/ton. If it's running at the higher speeds in cooling mode it'll have a higher SEER, but a less favorable sensible heat ratio (less humidity removal.) Care has to be taken that it's not so slow as to cause icing on the air handler coil though.

Are there filters in the return grilles, or is it only filtered at the air handler?

Definitely not air tight and it is past time to go back and recheck the ducts for tears and tape them up tight. Most of the crawlspace has a ground vapor barrier of 6mil plastic that extends about 8-10" (more or a little less) up onto the brick foundation walls. The part of the floor that doesn't have a barrier is where the height is drastically lower (~30-40% of the area) and the thought of crawling on my stomach and not being able to get out quickly should I come across a critter is a fear I haven't yet forced myself to face (especially having already replaced one knee ACL and not wanting to re-injure it).

It's hard to deal with it DIY, but it may still be worth paying somebody else to deal with it. In your area (IECC climate zone 3) as little as 3/4" of foil faced polyiso (seams taped with any UL188 rated tap) or an inch of closed cell polyurethane spray foam on the foundation walls, overlapping and sealed to the ground vapor retarder would bring that up tp current code minimums. See TABLE N1102.1.2, the right-most column labeled "Crawlspace R-value", on the climate zone 3 row. (The climate zone is indicated on the left-most column.)

In a tight crawl space the spray foam approach is probably going to be easier than cut'n'cobbled foam board. The foam should extend all the way from the vapor barrier up & over the top of the foundation sill & band joist right up to the subfloor above. There are DIY kits for this, so if you can figure out the approximate square footage that would need to be covered, at 1" depth can be done for about $1.25$1.50 per square foot as a DIY, including the Tyvek suit and spare tips. Be sure to actively ventilate your working area when spraying the foam in tight spaces and wear both a respirator and a mask- you don't want to be breathing in the blowing agent & foam component gasses, and inhaling droplets of expanding foam can do real damage.

Use a hammer drill & plastic cap fasteners to hang the foam on to the foundation, drilling at least 1.25" into the masonry (so for 1.5" foam use 2.25-2.75" fasteners.), eg the Rodenhouse Plasti-Grip series, found at some box stores. There are others.

The alternative is to install 1.5" of EPS board foam on the exterior of the foundation down to a depth of 6-12" below grade and protecting it with a cementicious product such as Quikrete Foam Coating or other similar stucco base coatings designed for application to EPS foam. Where the exterior is paved right up to the foundation it's fine in your area to insulate only down to the pavement. When taking this route it's important to install Z-flashing to take bulk water that may have gotten behind the siding out to the exterior side of the foundation insulation. In termite zones use copper flashing, since termites will sometimes tunnel through foam insulation unseen- copper leaching kills the gut flora that wood boring insects need to digest wood cellulose.

With any unvented crawlspace code requires either active dehumidification, or a small amount of active ventilation to keep ground moisture & gases well controlled. (Duct leakage might already be doing that ventilation for you, but not in a well controlled fashion.) Active ventilation spelled out in the code can be either exhaust-only (preferred, if the ground vapor retarder isn't super tight), or actively ventilated with conditioned space air (like what's leaking out of your ducts.) The minimum rate is 1 cfm for every 50' of floor area, so for a 1200' crawlspace that's ~24cfm, less than switch operated bath fans. A 20-30 cfm continuous mode bath fan should do it.

From an indoor air quality point of view it's important to stop the "stack effect" infiltration, which means the most important leaks are at the bottom of the house and the top of the house. A vented crawlspace is a big hole at the bottom of the house, most easily treated by air sealing and insulating the crawlspace walls. The fact that the ducts and air handler are in the crawlspace puts it higher on the priority list.

Installing insulation in the exterior walls also slows down stack effect infiltration, but the upper floor ceiling/attic floor plane has higher priority, since it's usually cheaper and easier to get to. When both the bottom and top of the stack are air tight the amount of 24/365 infiltration from that source goes way down, but until the walls are tightened up too there is still a lot of potential for air-handler driven infiltration, which is probably what's killing the AC performance right now.

 

[24SevnLibrarian]

I'm working my way through what you have written. I don't close off rooms in the house and almost every interior door (including closets) have 1-2" of space between the bottom of the door and the hardwood floors. The return grills do have filters and I change them often (~3o days, maybe sooner, maybe a week longer depending on how they look). I went in the crawlspace to start mapping out the ductwork and unsurprisingly, found condensation all along the insulated pipe from outside to the air handler. There is also condensate dripping from the air handler (see pictures). I'm not happy to say the least. I do not think the drain line is clogged - I had that experience last August and the drain line is dripping outside and there is not a pool of water under it like last time (hopefully I am correct about this).
The smallest ductwork in the crawlspace is the branches that lead to the bedrooms and bathroom which are ~7" in diameter. They feed from a duct ~11" in diameter. I could not get super close to the biggest ducts, but they seem to measure around 16-17"?
I have thought about drilling small holes in the plaster walls and spraying foam insulation in the cavities. I don't have a problem with repairing the plaster, but I believe there is asbestos siding behind the vinyl siding currently on the house. My fear is that at least 1/3 of the light and wall outlets still have knob and tube cable running to them which the electrician who checked out the house and installed a 200 amp breaker panel when I bought the house in 2013 did not tell me.
I need to continue reading, but maybe the pictures will help until I absorb what you have shared with me thus far. Thank you again!

 

[Dana]

Filtered duct return grilles in common areas need to be at least one square inch per 2 cfm of air handler capacity. So in your case at high speed you're looking at ~1300 cfm, which would need a filtered grille area greater than 1300cfm/2cfm= 650 square inches (bigger is better, especially if you want to keep the noise down). The 8" x 22" in the hall floor is < 176 square inches of free area, the 12" x 24" in the other location is <288 square inches- so best case you're looking at ~450 square inches when you really want 650+.

Door cuts of even 2" (big enough for a kitten to crawl under!) aren't an adequate return for any but the SMALLEST heating & cooling cfm requirements. A 7" round duct has a cross sectional area of about 37 square inches. A 6 inch duct is about 28 square inches. The return paths from individual doored off rooms need to be 1.25-1.5x the cross sectional area of the supply.

At 1 inch clearance from the floor a 32" wide door is at best 32 square inches, 0.22 square feet of cross section, a 30" door 30 square inches, or 0.21 square feet. A relatively modest 4" x 14" supply register over 50 square inches (~0.35 square feet) of free flow area. It might be fed by a 6" duct (~37 square inches), or maybe even an 8" duct (~50 square inches), but you want the return path out of the room to be at LEAST as large (and preferably 1.5x) as the supply register. In rooms where you can feel the air moving through the door cut with your bare hand (not the best method, and well short of a reading with a dual port micro-manometer) it's worth considering using one or two stud bays of a partition wall as a jump duct, with a grill near the floor on one side of the wall, another at the top on the other side:

In new construction stud bay jump ducts would use sealed sheet metal ducts, but in your case that's not possible without ripping open a large section of wall. When using the studs and wall coverings as the duct walls it's important to install well sealed air barriers above the top grille and below the bottom grilles, caulked in place with a high quality long-lasting sealant such as polyurethane caulk. The air barriers don't need to be anything special to work (even corrugated carboard would get you there in a pinch) but using 2x4 blocking would provide a bit of protection against fire spread. Without adding the air barriers using the stud bay as a jump duct introduces new air leakage paths.


Condensate on the exterior of an insulated duct is an indication of very low temperatures (possibly due to very low air flow) inside the duct, and a high dew point of the surrounding air. Since the air in the crawlspace is essentially at the same humidity level of the outdoor air, the quantity of condensation will rise and fall with the outdoor dew point. This is common with ducts in vented attics too, though somewhat less due to the higher temperatures of attic air causing higher surface temps on the outside of the duct (or duct insulation.) If the crawlspace get converted to an UNvented SEALED crawlspace the dew point of the air in the crawlspace will track that of the air conditioned indoor air in the rooms above. Barring huge air leaks to the outdoors the duct condensation should then stop happening.

Spraying or pouring foam in closed walls is very hard to do well , since as it expands it can created blockages that prevent it from being fully filled, and with slow-rise pours can even blow out the lath from the studs, making for a very difficult repair. Once insulated with foam re-wiring also becomes much more difficult. In gutted rooms where the studs are open it's much easier to fill around obstructions in the stud bays with spray foam.

With blown fiber insulation asbestos shingles are best fully removed, but don't present a serious hazard to the indoor environment or even the outdoors when blowing fiber insulation, especially if going for low density (not dense packed) cellulose, since the pressures aren't high enough to move a lot of air out through the exterior sheathing & siding. Wind exposure alone would move more friable fiber from the shingles into the house & stud bays over the course of a year than filling the cavities with cellulose using "2-hole method".

In 2-hole method holes are drilled a foot or so above the bottom & a foot or so below top of each stud bay. The installer (possibly you, with a single stage rental blower) starts filling from the bottom hole with the blower nozzle or hose pointed down, and blows until cellulose begins flying out of the top hole, then switches to the top blowing down first until the blower begins to tall, packing it out a bit, then up into the short remaining section of stud bay. With a cheap rental blower that would reliably hit north of 2lbs density, usually in the mid-2s, which is fine. That blocks MOST of the air leakage in the stud bay, and it will get around lots of obstructions that foam would have problem with. It may settle as much as 6-8 inches at the top of the stud bays over the next decade or it may not settle even as much as an inch (depending on humidity cycling). No matter what it will be a LOT more air tight and higher R than what you're currently looking at.

State codes about insulating over K & T wiring have been relaxing since the initial legislation going back to the 1980s. The theoretical hazard that prompted those code prohibitions have proved largely theoretical, and in states that have pulled back it has been allowed if inspection shows that the condition of the wiring splices are not corroded. Like asbestos shingles it's best to just get rid of it to avoid the problem, but that might prove cost-prohibitive if it isn't already in the budget. As a DIYer/ homeowner inspecting each stud bay with a boroscope and only insulating the stud bays that have NO wiring in them would be safe.

 

[Chuyue]

If I were you, I would focus more on the refrigerant side first and make sure the system is properly charge. You can't do anything with air side at this point anyway. If your old system was a 3-ton unit and you did not have any issue, then your existing duct system should be able to handle 1000~1200 cfm air flow. I may be wrong on this but I thought normally 300~400cfm per ton by rule of thumb. Your new unit has this ( per catalog at least 400 CFM/ton at 0.5 in. H20 external static pressure; setup airflow options down to 290 CFM/ton). If this is not much different from your older unit, then you need to check your equipment. BTW. you said your outdoor condensing unit is a 2.5-ton, but the furnace per the catalog says 3-ton. so you might have an slightly oversized indoor coil so you might be ok even if you have slightly lower airflow. Since you are suffering the symptom of not having enough cooling, then your system might be either under charged or undersized or a combination of both. One of the signs of not charged properly is system sweating (a lot of condensation) BTW.

 

[Dana]

If I were you, I would focus more on the refrigerant side first and make sure the system is properly charge. You can't do anything with air side at this point anyway. If your old system was a 3-ton unit and you did not have any issue, then your existing duct system should be able to handle 1000~1200 cfm air flow. I may be wrong on this but I thought normally 300~400cfm per ton by rule of thumb. Your new unit has this ( per catalog at least 400 CFM/ton at 0.5 in. H20 external static pressure; setup airflow options down to 290 CFM/ton). If this is not much different from your older unit, then you need to check your equipment. BTW. you said your outdoor condensing unit is a 2.5-ton, but the furnace per the catalog says 3-ton. so you might have an slightly oversized indoor coil so you might be ok even if you have slightly lower airflow. Since you are suffering the symptom of not having enough cooling, then your system might be either under charged or undersized or a combination of both. One of the signs of not charged properly is system sweating (a lot of condensation) BTW.

YES! Refrigerant charge is the first place to look, once you have verified that the ducts are still all connected. When it's not cooling well enough shortly after installation it's as likely to be overcharged than undercharged. Sadly, there are a lot of installer hacks out there who never calculate or weigh in/out the refrigerant, and never fully commission the system. After visually ruling out gross errors like disconnected ducts improper refrigerant charge moves to the top of the suspect list.

But there are still things worth taking care of on the air side such as jump-duct returns on doored off rooms, verifying that the flex ducts are all stretched reasonably tight (they seem to be in the pictures provided so far), are still connected, and are not collapsed. The flex installation looks about average to slightly better than average in the pictures- definitely not a "ball of mating snakes" so often seen in crummy attic installations.
Getting the room to room pressure differences down with better return paths is important for both efficiency and comfort, since air handler driven infiltration increases both latent and sensible loads. Newer higher SEER units usually need more air flow than an old SEER 10 unit, but even if somewhat restricted should be able to keep up with the sensible load, but might not always keep up with the latent load in a super-leaky house in the Carolinas.

 

[Reader90]

Pick up a pocket thermometer measure temperature between return grill and supply grill closest one to furnace difference 18*-22*. They go to the condensing unit feel the copper pipe that is insulated should be cold. If temperature difference is less than 18* and or the copper pipe isn't cold unit could be short of refrigerant or blower speed is to high. Have you looked at install air handler in crawl space?

Good advise. Another idea, which helped me after installing a new set of units (I have two systems) and used existing duct work. After a summer with the same problem, I looked my closer at the ducting and other areas for airleaks. I ended up finding many opportunities in existing ducting and ceiling to seal better. I ended up sealing with Mastic airduct sealant (available at any big box store):

1. up and around all of the furnace/blower areas and anywhere there where seams that I could get to in ducting as all of my upstairs supply vents are in the attic
2. Sealed an recessed lighting, supply/return vents -- anything that breached the ceiling with a foam type sealant
3. In all of the supply vents, took off vent covers and sealed with mastic all around the metal I could. Also, sealed with either foam or cauking between the vent sheet metal and wallboard.

I did not do an official airflow test, but I noticed a difference on two of the vents that confirmed that airflow now is much better. I have two ceiling fans almost directly under two of the supply vents. After sealing, they now both spin from the air from the two vents, as they did not before.

Two other areas I tackled was :

1. I added return vents in 3 rooms of my home back into the system as there were none
2. On my west facing side of home, I added seasonal solar screens to reduce heat load from the windows.

All maintenance items above have made a huge difference to comfort and energy bill (lower).

 

[sajesak]

Hi, all! I bit the bullet and decided to replace my HVAC split system since my outside compressor died last fall and the furnace under the house (almost 20 years old) had started making the living room floor vibrate this winter. I had a Trane system installed and kept the existing ductwork. The problem is now that it has gotten hot (low 90's), the fan is blowing (cool air) constantly but even with that and the thermostat set on 69 or 70, the indoor temp on thermostat and another thermometer are sitting between 74 and 76 degrees in the afternoon. I went from a 3 ton unit to a 2.5 since my house is just shy of 1200 sq. ft. and the humidity levels in South Carolina are pretty high most of the time. The furnace is model S9V2B060U3PSBB. It has a variable speed blower motor, 96% AFUE, and 3 multiport inshot burners. The outside air unit is model 4TTX6030J1000BA. It is 16.5 SEER when combined with the new furnace. It has a variable speed fan and a 2-stage scroll compressor. I have more product data; I just don't know what anyone might need (if anything) to help me.
My old unit never had a problem keeping the house cool even though it didn't have the bells and whistles like the new one. Also, inside the house, with the blower running full force HVAC Contractors Greensboro, it sounds like the dull roar of a train going down the tracks in the distance. Never had that problem before either. Any ideas? The installer already thinks I am crazy for calling him about the inside air noise (but it is loud enough that I hear it over the TV!).

Got 4-5 quotes and decided on a Trane dealer that was recommended to us by our neighbors. Didnt get load info (not sure whether they tested or not but guessing not since they didnt give us info) but didnt think it was necessary since a 23 yr old 2.5 ton was doing just fine heating the same space until it died (so surely a brand new 2.5 ton could handle it right???) Anyways, they came out to do the install of a XR14 yesterday (which included replacing coil in attic with a compatible coil unit)...seemed to go just fine. Upstairs temp was registering in the mid 80's when they left around 1 PM since there had been no A/C for almost a week. Around 11 PM (when temps were in the low 70's/upper 60's), the upstairs thermostat was still registering 76 (set to 74). Today with warm temps, the upstairs reading started going up this morning. Called contracter and he said to shut off unit and he was sending someone out ASAP. Tech comes to house and says that the unit is low on freon...installers must not have put enough in (seems quite strange). He filled it up and said we should be good to go. 3 hours later after the tech left and the upstairs temp is still at 78 and not budging. Im starting to get a really bad feeling about this....luckily we havent made payment yet. Cooler air is blowing but thru vents doesnt seem as cold or as powerful as downstairs. Any advice on how to deal with this? Feel like even if they fixed it at this point, I would still want a new unit as I feel like I got a lemon...is that a reasonable request?

 

[Fitter30]

They haven't been paid ball in your court.They need to find the leak it shouldn't be to hard to find. The pic 124242jpg what am i looking at cloth wires? Since they didn't put a safety overflow pan might what to put a couple of water detectors under the unit since it in the crawl space.

https://www.amazon.com/Topvico-Flood-Sensor-Detector-Security/dp/B07311Z536/ref=asc_df_B07311Z536/?tag=hyprod-20&linkCode=df0&hvadid=198068550617&hvpos=&hvnetw=g&hvrand=441103179594915874&hvpone=&hvptwo=&hvqmt=&hvdev=t&hvdvcmdl=&hvlocint=&hvlocphy=9023802&hvtargid=pla-353322384856&psc=1

 

[Richard Crowder]

If your new Trane split system is not adequately cooling your space, there could be a few potential causes. First, check if the thermostat settings are correct and that the system is set to cool mode. Ensure that all windows and doors are properly sealed to prevent warm air infiltration. Additionally, check the air filters for any clogs or dirt accumulation that may be restricting airflow. Insufficient refrigerant levels or a malfunctioning compressor could also be the culprit, in which case it's recommended to contact a professional HVAC technician to diagnose and resolve the issue. Regular maintenance and timely servicing can help prevent cooling problems with your Trane split system.