High End heat Pump - Trane XL20i Versus Amana ASZC18

[motoguy128]

The Maytag guy wil most likely try and sell you their top of the line IQ Drive unit. I've heard mixed reviews but overall inverter drive machine that can go from 30-100% capacity are the way the industry is headed.

[Florida Joy]

This guy also told me something about my return air filter grille that kind of contradicts what I've heard out here in this forum. He told me he'd take out my 20x20 grille and install a 20x24. I asked him how that could be adequate when the "standard" was 200 square inches per ton. He said that's not correct. The return needs to be at least the same size as the air handler intake, i.e., the size of the hole in the bottom of the a/h. Since the Lennox a/h intake is 20x24, that's the proper size of the filter grill.

Is that correct or not, given that the "duct space" under the a/h stand is fed directly from the filter grille on the other side of the wall, and that "duct space" measures 26"D x 30"H x 36"W?

[RyanHughes]

Joy, there is no single answer to your question. There are many different return grille options -- some can accept higher volumes of air at lower noise levels. There are 0 deg. deflection grilles in which a 24x20 size would be sufficient for a 4 ton at reasonable noise criteria ("NC") levels. However, for most residential style return grilles, 24x20 would not be enough due to the lack of open area in them. If possible, I would definitely prefer adding a return as opposed to using a single return with a more expensive commercial style return air grill. I have the 4 ton XL20i heat pump and TAM8 air handler in my house, and I'm very happy with it's performance. To give you my opinion I would give it a strong look (I think you are already). it works very well if installed and setup properly. The TAM8 gives you lots of control and monitoring capabilities of its performance that other 2-stage systems do not.

[Florida Joy]

Joy, there is no single answer to your question. There are many different return grille options -- some can accept higher volumes of air at lower noise levels. There are 0 deg. deflection grilles in which a 24x20 size would be sufficient for a 4 ton at reasonable noise criteria ("NC") levels. However, for most residential style return grilles, 24x20 would not be enough due to the lack of open area in them. If possible, I would definitely prefer adding a return as opposed to using a single return with a more expensive commercial style return air grill. I have the 4 ton XL20i heat pump and TAM8 air handler in my house, and I'm very happy with it's performance. To give you my opinion I would give it a strong look (I think you are already). it works very well if installed and setup properly. The TAM8 gives you lots of control and monitoring capabilities of its performance that other 2-stage systems do not.

Thank you so much for your input! What you say makes TOTAL sense to me, in that the correct answer is, "It depends".

I hear you and have to agree with you about adding a return to accomodate the increased size of the 4-ton a/h over my existing 3.5 ton Rheem. Also am seriously considering the XL20i with the TAM8 as my "solution".

Some of the other "pro's" in this forum had me scratching my head as to whether the 20x20 filter grille I currently have was "proof positive" that the ductwork in my house wasn't designed to handle the 3.5 ton installed by the builder (or the 3.5 ton replacement that's currently running on borrowed time). Their assumption was 200 square inches per ton would have been a "minimum" requirement for the builder if he installed a 3.5 ton system. For some reason, that didn't make sense to me and now I know why. My filter grille IS a heavy duty aluminum 0 deg. deflection, commercial style filter grille AND I looked up the Rheem specs on my a/h. Guess what, the return size on my equipment is 20W x 19-7/8D. Okey, dokey, I guess that's why the Trane dealer who's #1 on my list said my 20x20 grille what the right size, but he'd add another to accomodate the 4 ton XL20i.

Whew.... guess I'm not as crazy as I was beginning to think!

Another question for you, while I've got your attention.... with a 4-ton condenser matched with the 4-ton TAM8, can the TAM8 be adjusted to 1400 cfm airflow to assist with dehumidification, given that Manual J load calc calls for 3.5 ton in my home? The Lennox dealer said that's what he'd do for me with his equipment, but I'm sold on Trane at the moment.

[RyanHughes]

The factory setting for the TAM8-048 is 1400 cfm. I would start at 1600 cfm (400 cfm/ton) for both cooling and heating for a couple of reasons: You will already have Comfort-R set up to provide a slow ramp up in the beginning of the cycle for better dehumidification as it gets the coil cold quickly and removes a good amount of moisture in the process. Secondly, I would set the dehumidification airflow setting (installer option) to 80%, meaning the system will attempt to control the humidity better by running at 80% airflow on either stage. While dehumidifying, my system runs at 640 cfm on low (virtually silent) and 1280 cfm on high. This is about 320 cfm/ton, which is great for dehumidification. During normal operation the airflow would be 800 cfm on low and 1600 on high. If sized properly, I think you'll find that the system does not spend much time at 1600 cfm. The TAM8 has an LCD monitoring menu on the door of the air handler itself where you can see the system's external static pressure, airflow demand, calculated airflow, etc. among other things. Your installer can adjust the airflow specifically for your application depending on what your duct system is capable of.

[Florida Joy]

The factory setting for the TAM8-048 is 1400 cfm. I would start at 1600 cfm (400 cfm/ton) for both cooling and heating for a couple of reasons: You will already have Comfort-R set up to provide a slow ramp up in the beginning of the cycle for better dehumidification as it gets the coil cold quickly and removes a good amount of moisture in the process. Secondly, I would set the dehumidification airflow setting (installer option) to 80%, meaning the system will attempt to control the humidity better by running at 80% airflow on either stage. While dehumidifying, my system runs at 640 cfm on low (virtually silent) and 1280 cfm on high. This is about 320 cfm/ton, which is great for dehumidification. During normal operation the airflow would be 800 cfm on low and 1600 on high. If sized properly, I think you'll find that the system does not spend much time at 1600 cfm. The TAM8 has an LCD monitoring menu on the door of the air handler itself where you can see the system's external static pressure, airflow demand, calculated airflow, etc. among other things. Your installer can adjust the airflow specifically for your application depending on what your duct system is capable of.

Hip, hip, hurray! You have greatly eased my mind! Adjusting the airflow based on what my duct system is capable of.... makes total sense to me! No wonder the Trane trained Comfort Specialists looked at my ductwork and said I'd have no problem with the 4 ton XL20i.... they never heard of "blowing out the ductwork" when replacing a 3.5 ton single stage with a 4 ton dual stage/two compressor unit.

I'd guess the installer could also tweak performance to allow for slight oversizing, to avoid short cycling in stage 2?

[RyanHughes]

Obviously oversizing is a bad thing, as you already know. In terms of ways to "tweak" performance for oversizing, there are ways. There is a cycles per hour (CPH) setting for both high and low compressor stages. These are generally set to 3, meaning that during normal operation (more moderate days with respect to design temp) when the system is attempting to maintain temperature, the compressor will cycle 3 times per hour. This is not a hard number -- on hot days when it needs to run longer cycles, it will. If it's running short cycles on high stage, you could theoretically lower this number to attempt to get longer cycles as it attempts to achieve the CPH. There is also a minimum compressor on-time setting. Lowering the airflow is another common way to combat oversizing. If the system is sized per Manual J, I don't think you should worry about this. A full load calculation will tell you the capacity and total airflow you need.

[Florida Joy]

If the system is sized per Manual J, I don't think you should worry about this. A full load calculation will tell you the capacity and total airflow you need.

The question regarding sizing is this.... suppose Manual J calls for 3.5 ton (42,000 BTU) of cooling, dead on, no more, no less... as I'm pretty sure it will... do you install a 3 ton that may not provide the >20 degree temp differential I need to maintain a 75 degree setting on those days when it's 98 degrees outside... or do you upsize to 4 ton and make adjustments to prevent short cycling when stage 2 is called into action?

It's the 1/2 ton differential from Manual J that causes me concern, even though the Trane contractors in my area have no concern and will upsize unless I demand otherwise.

[hvacvegas]

You're in Ohio? Florida code requires copper wire to AC components, installed by a licensed EC. Of course, they don't go around to your house and check to see if what you have already is up to code, BUT.... you won't pass a permit inspection on a new install if it's not copper. I suppose HVAC contractors get away with leaving it, or changing it without an EC license, all the time, but it's my house and if it burns because of the aluminum or unlicensed installation (after I spent several thousand to upgrade my panel, the main, and the meter box) it would be MY problem because I allowed it!

The alluminum requirement isn't a code. It's a manufacturers requirement. Copper must be used in the equitment, but not in the disconnect going to the equitment. In ohio.
We're licensed electrictians. I work under my bosses license.

By the way, check your feeder that comes from you weatherhead. Then out of the meter into the main lugs on the panel. It's alluminum.

[Florida Joy]

The alluminum requirement isn't a code. It's a manufacturers requirement. Copper must be used in the equitment, but not in the disconnect going to the equitment. In ohio.

Haven't personally checked the code requirements. But... I am 100% positive it's a property insurance underwriting requirement in the state of Florida! If I had a fire and they found aluminum wiring in my home, they'd deny the claim! There was a big hullaballoo a few years back about Florida homeowners getting screwed by insurance companies over aluminum wiring.

We're licensed electrictians. I work under my bosses license.

Good for you! Not a common situation in my Florida county. Of all the HVAC contractors in my area (dozens), only ONE has an EC license and in-house electricians. The Florida BPR website makes it easy to verify licensing.

By the way, check your feeder that comes from you weatherhead. Then out of the meter into the main lugs on the panel. It's alluminum.

Weatherhead? All our utilities are underground. I personally observed the replacement of my FPE breaker panel, the FPE main breaker, and the meter can.... the wires are copper. Replacing the Federal Pacific Electric (fire hazard) panels and breakers had to be done to comply with insurance requirements.

[Florida Joy]

Obviously oversizing is a bad thing... If the system is sized per Manual J, I don't think you should worry about this. A full load calculation will tell you the capacity and total airflow you need.

The question regarding sizing is this.... suppose Manual J calls for 3.5 ton (42,000 BTU) of cooling, dead on, no more, no less... as I'm pretty sure it will... do you install a 3 ton that may not provide the >20 degree temp differential I need to maintain a 75 degree setting on those days when it's 98 degrees outside... or do you upsize to 4 ton and make adjustments to prevent short cycling when stage 2 is called into action?

It's the 1/2 ton differential from Manual J that causes me concern, even though the Trane contractors in my area have no concern and will upsize unless I demand otherwise.

Humidity is such an issue here, I'm concerned I might have to lower the t-stat setting to 70 or 72 degrees on a newer, more energy efficient system to counteract the reduced efficiency in controlling humidity. I've been comfortable at 77 degrees and 40% humidity with my old 3.5 ton, but today is the calm before the storm (Isaac) in Florida. It's cooled off a bit and the A/C didn't run much last night, so the humidity went up.

Right now it's 76 degrees in here with the humidity at 51% and the sweat is beginning to run down the back of my neck, so I have to sit under the ceiling fan to make it stop! If i have to turn the t-stat down to 70 or 72 on a new 3-ton system to be comfortable, I'm afraid it won't keep up a 28 degree differential when it's 98 degrees outside.

[Florida Joy]

If you do go with the Amana ASZC18, tell them exactly these words:

"Take the nuts that hold the fan to the shroud off, and replace them with REAL 3/8 stainless steel nuts."

We've had to many fans fall off the shroud, due to the type of nut that is used, and replace the nuts on every 18 seer unit before they get sent out on an install.

Does the 16 SEER unit have the same issue? Seriously considering Amana over Trane at this point, based on recommendations from my son and daughter-in-law over the Labor Day weekend. Both are employed in the HVAC industry and have heard nothing but bad news regarding Trane/American Standard evaporator coils.

[jtrammel]

I don't remember if we've discussed York equipment yet but their LX line of equipment is reasonably priced and very good quality.