XL16C - so far not happy any ideas?

[gvanegas]

Hi, I purchased and had installed from a trane comfort specialist(authorized dealer) a trane xl16c packaged unit.
4 ton r410a 16 seer.
It replaced an old 3.5 ton day and night packaged unit, probably at least 20-25 years old.
The reason I replaced the old unit, was the electricity costs were through the roof!

Anyways, the trane is installed and I am disappointed that I cannot get my temperature down below 80 degrees. I recall the old unit being able to go down and then "shut off" until the temperature needed to be cooled again.

I can only get this unit down to about 76 degrees at night (say 10:30 pm and after a long time running.

Even around 05:30 - 06:30 pm when its cooling down considerably, I cant get the thermostat to show below 80 degrees.

Basically, this unit runs constantly, dont the units have to "cycle a couple times an hour?"

My questions are this
1) I have a 16 by 25 return air filter and its a 16 inch round ducting to the return.
I have been reading that its mininum 18 inch round ducting for a 4 ton, is it possible to add another return box but keep the existing 16 inch round ducting? (its already installed in the attic and I have hardly any space in the attic)
If so, would the additional return box give it more air intake? Or would it be constrained by the 16 inch duct diameter regardless?

Would having too little return airflow give such a sympton as I'm describing?

2) According to the contractor, this 4 ton unit would work "good" for my house, he wanted to sell me a 5-ton split system, but he wouldnt install a 5 ton without upgrading my entire duct system at considerably more expense.

Since, he said the 4 ton unit would work "good", I decided on going with the high efficiency xl16c package, rather than the migration to a split system.

3) The digital thermometer they gave me is the TRANE tcont802 digital unit.
From reading the installer documentation, there is supposed to be a jumper "The installer must jumper at the LVTB "R" to "O" which I take to mean that on the control unit itself on the packaged unit, there should be a jumper setup on "R" to "O", what are the ramifications of not having that? It has to do with two stage cooling on the scroll compressor, and I dont know if they set that jumper, I rather doubt it, because its only documented at the thermostat documentation and not the package unit documentation.


Please, can anybody help here?
I also want to know If its realistic to expect a central air conditioner to be able to cool to about 78 degrees (or even less).

If so, how long should it normally take to cool a house down from say 85 degrees (at starting up of the unit) to 78 degrees?

I have been running the thing all day, and it never goes below 80 degrees, I am worried now, because I thought I was buying the trane quality and also went the right way in going with a trane dealer comfort specialist?

P.S.
They tested the ducts and although my ducts are the old metal kind, they said the ducts were up to specs in terms of leakage (this test was administered by the company)

Thanks...

[ar_hvac_man]

Originally Posted by gvanegas

Hi, I purchased and had installed from a trane comfort specialist(authorized dealer) a trane xl16c packaged unit.
4 ton r410a 16 seer.
It replaced an old 3.5 ton day and night packaged unit, probably at least 20-25 years old.
The reason I replaced the old unit, was the electricity costs were through the roof!

Anyways, the trane is installed and I am disappointed that I cannot get my temperature down below 80 degrees. I recall the old unit being able to go down and then "shut off" until the temperature needed to be cooled again.

I can only get this unit down to about 76 degrees at night (say 10:30 pm and after a long time running.

Even around 05:30 - 06:30 pm when its cooling down considerably, I cant get the thermostat to show below 80 degrees.

Basically, this unit runs constantly, dont the units have to "cycle a couple times an hour?"

My questions are this
1) I have a 16 by 25 return air filter and its a 16 inch round ducting to the return.
I have been reading that its mininum 18 inch round ducting for a 4 ton, is it possible to add another return box but keep the existing 16 inch round ducting? (its already installed in the attic and I have hardly any space in the attic)
If so, would the additional return box give it more air intake? Or would it be constrained by the 16 inch duct diameter regardless?

Would having too little return airflow give such a sympton as I'm describing?

2) According to the contractor, this 4 ton unit would work "good" for my house, he wanted to sell me a 5-ton split system, but he wouldnt install a 5 ton without upgrading my entire duct system at considerably more expense.

Since, he said the 4 ton unit would work "good", I decided on going with the high efficiency xl16c package, rather than the migration to a split system.

3) The digital thermometer they gave me is the TRANE tcont802 digital unit.
From reading the installer documentation, there is supposed to be a jumper "The installer must jumper at the LVTB "R" to "O" which I take to mean that on the control unit itself on the packaged unit, there should be a jumper setup on "R" to "O", what are the ramifications of not having that? It has to do with two stage cooling on the scroll compressor, and I dont know if they set that jumper, I rather doubt it, because its only documented at the thermostat documentation and not the package unit documentation.


Please, can anybody help here?
I also want to know If its realistic to expect a central air conditioner to be able to cool to about 78 degrees (or even less).

If so, how long should it normally take to cool a house down from say 85 degrees (at starting up of the unit) to 78 degrees?

I have been running the thing all day, and it never goes below 80 degrees, I am worried now, because I thought I was buying the trane quality and also went the right way in going with a trane dealer comfort specialist?

P.S.
They tested the ducts and although my ducts are the old metal kind, they said the ducts were up to specs in terms of leakage (this test was administered by the company)

Thanks...

If the 3.5 cooled your house the 4 ton should as well.
Central a/c has the ability to go much lower than 78 deg. (I have one customer that keeps hers at 66 deg. and it cycles.)
Yes it should cycle on and off.
Being a dealer doesnt necessarily make you a specialist.
Not sure about the jumpers or if its a 2 stage compressor. Theyll be some here that do, keep checking in.
If it is a 2 stage then it sounds like to me the second stage is never being engaged.
Call them back to make it right.
Why did he want to go from 3.5 - 5 tons????

[beenthere]

Sounds like it may be mis wired.
Call them back to check it.
In first stage that 16c is only at about 3.2 tons capacity.

[Airmechanical]

yes it does sound like something is wired incorrectly!

on the package units, you should not need to mess with any of those jumpers!

your return duct is undersized, but the affects of that can vary from system to system!

a static pressure test would determine if the airflow is correct.



.

[mark beiser]

Did the installer set the thermostat for 2 stage cooling operation in the installer setup menu?

[bmathews]

Originally Posted by mark beiser

Did the installer set the thermostat for 2 stage cooling operation in the installer setup menu?

I'll bet you a cup of coffee the thermostat isn't set right. Very common mistake. The return is a tad bit small. My other question is do you turn it off while you're gone or just raise it a few degrees from where you keep it while you're home.

[sammy37]

I wonder where the OP is located. I see that same mentality here alot also, contractors always want to bump up to the next larger size even if the old unit cooled fine.

Three of my neighbors have all jumped from 4 to 5 ton units even though their previous units cooled just fine.

I think the contractor should have at least upsized the return during the install, a 16x25 return can is pretty dang small for 4 tons, I like to see 18 or 20 inch duct and a 20x40 return grill for that size of unit.

[sammy37]

Originally Posted by beenthere

Sounds like it may be mis wired.
Call them back to check it.
In first stage that 16c is only at about 3.2 tons capacity.

Even at 3.2 tons, I would think it might cool a little better than what it is doing.

Too many times with a package unit, installers just dump and run. May even be an issue with the unit, low charge etc.

Hope the OP gets back with us on this, curious to see what the problem is.

[gvanegas]

First of all, thanks for all your replies, deeply appreciated.

I was reading about the second stage from a couple of your replies and I know its hard to tell if second stage is working or not from my tcont802 thermostat.

By "miswired" though, since this is a package unit, the only wiring really would be from the package unit down to the thermostat right? What I mean to say, is, isnt that pretty much the only wiring that could be miswired, since the package unit came already assembled?

To Mark Beiser, yes I was able to verify the installer setup menu on the thermostat is set to 8 (2 heat / 2 cool) I did not change any installer settings, just was able to get the installers manual for the tcont802 digital thermostat and look at the settings. There is a graphic in the t802 thermostat installation manual that says the "installer must jumper the lvtb "r" to "o", which I take to mean something on the packaged unit circuit board correct? I have attached that graphic to this post, I would be very happy if somebody can take a look at it. This graphic taken from the manual is titled "fig 8. Typical hookup of two-stage indoor and two-step scroll cooling unit in a single transformer". If this was not to be jumpered on the lvtb as documented, does anybody know if this causes my 2 stage compressor not to work right?

And to Sammy37, I am located in southern california, by upsizing the return is it possible to "branch" another return into the existing one, thereby increasing the return air flow? Or does the old return have to be completely removed and the 16 inch round ducting removed? The reason I ask, is because I have literally no attic space to work with. I wish I had a decent sized attic but I do not.

Also, to Sammy37, the installer ran some tests and say that my freon charge is good, within the prescribed limits.

It appears many of you are suggesting the second stage is not kicking in, I sure do with that thermostat would simply tell us laymen whether or not its running on stage 1 or stage 2.


Thanks again to all, this is a great forum and I appreciate all your time to respond to my posts.
I am a little worried here, because I spend a good amount of money, money that would be happily spent as long as I was happy with the results.

So far, I dont think its acceptable to have the unit run for hours and hours and not go below 80 and from your responses it sounds like it should maybe run an hour or so to get to around 78 and then cycle off. Once the temperature rises again, it should cycle on.

Also, to ar_hvac_man, the installer wanted to go 3.5 to 5 ton only if I changed out to a split system and got new ducts which were sized right for 5 ton, he said it was not a good idea to put a 5 ton with my existing duct work because of size issues (something about wanting a 20 inch return at minimum (duct size), he didnt mention anything about the return grill size.

I could have gone with a 13 seer split system for about 20 percent more.
My house is about 1800 square feet interior space, with low attic space but one side of the house (the dining area, has vaulted ceilings, with no attic insulation). Still, the installer said 4 tons would be good, even the ferguson rep was out there, and he said 4 tons should be good.

So, thats why I went with the packaged unit install, the 16 seer trane/4ton.

[gvanegas]

Hi, its me again the OP of this thread.
I noticed the graphic I attached did not come out too good
The PDF file of the tcont802 installers manual is attached to this post now


(see figure 8 on page 3 please)

In which it says
3 - The installer must jumper at the lvtb "R" to "O".

I was wondering about what the ramifications of the installer "not doing that jumper at the lvtb "R" to "O" would be.

Would my 2 stage cooling/heating therefore not work?

Thanks..

[DanW13]

What type of filter is on your return side of the furnace ? What's the merv rating ? Or do you hace a EAC in place of a media filter ? Where there dampers put on your duct runs ? If there was new flex duct installed is the flex duct nice and straight and hung from the rafters ? Are all your ducr runs and trunk runs sealed with matic and metal tape ? How much attic insulation is there ? Do you by chance have any heat strips in your air handler, that maybe be on when the AC is on I have read many post where the OP has found this to be the problem. Did the installers do a heat calc (Manual J&D) to size your equipment properly if he said he did tell him you would like a copy of both, It should show that your home requires 4 tons of cooling for your house, since you do not state the sq footage of yoru home but chances are your AC is oversized, for a home to need 4 tons of cooling your house should be in the neighborhood of 3,000 sq ft. or you have alot of windows and bog ones at that. the majority of homes only need around 2-3-1/2 tons of cooling load so I would suspect your's is currently oversized. Ask your installer about the Heat load calc's and manual D for sizing of your duct work and then post back.

[gvanegas]

Hi Dan, Thanks for your input.
I have a 16 by 25 electrostatic silver (electra silver)filter they just gave me.
Its says for mev rating 6-8

As for my ducts, my existing ductwork was used, as its almost impossible to get to my attic. I have 10 ducts with adjustable air flow (are those the dampers you are asking about?)


The packaged unit, I dont know if it has heat strips in the air handler.
He did not do a manual j and D heat calc
My square footage is 1800 square feet interior and I would say I have poor attic insulation as the house was built in 1962.

I was quoted from at least 7 contractors that I needed either a 4 ton or a 5 ton, now from your recommendation, you are saying my house should be about 3,000 square foot before I would need a 4 ton. Wow!!

But..
If it was oversized, wouldnt the problem be more that its cooling too quickly and short cycling?
My problem is I cant get the blasted thing below 79 degrees during the day, it runs constantly.

by going to weather.com for my zipcode 92404, it currently says its 92 degrees out...

[beenthere]

Its probably not going to second stage.