Do I need access to AC coil and fittings?

[krxman]

Doing an attic renovation and my contractor installed a new Ameristar furnace and AC up against a hip roof, encased by a kneewall w/pocket door for access to furnace. He installed the AC coil on the back side of the plenum, up against the roof, w/the coil access panel and fittings completely inaccessible. He's saying we'll never need access to the coil or the fittings which I think defies common sense. It seems there are lots of reasons we might need to get to the coil or these fittings - maybe not in the immediate future but some day. He also says he did it this way because to put the coil on the front of the plenum (where it could be easily accessed) would significantly decrease velocity. Does this make any sense?

[mark beiser]

I would absolutely demand it be changed so there is easy access to the coil for cleaning and maintenance on the drains.

There is absolutely no excuse for an installation as you describe it. That type of installation makes it nearly impossible to clean out the drains during regular maintenance, or if they become clogged, wich is inevitable.
If the coil ever develops a leak, an installation like that greatly increases the dificulty, thus the expense, of diagnosis and repairs.

[rookie 19]

Basically your contractors B.S ing you have him fix it. Tell him you have a big mouth and the whole town will know hes a horrible contractor if its ot fixed.

I bet he was thinking you were stupid but he you confronted him he said its ot nessicasary

[krxman]

Yeah, that's what I was thinking. Just seems like common sense. But can he just reinstall the coil now on the front of the plenum, where it's accessible, w/out causing other problems? Is this loss of velocity issue something I need to be concerned about? Cause otherwise he's done top -notch work and I can't imagine he would do something so obviously wrong without some reason.

[Edited by krxman on 10-29-2005 at 11:59 PM]

[amickracing]

In a perfect world you wouldn't need any access to anything, it'd just run for ever with out any problems. Good thing that's not true or we'd be out of a job.

There shouldn't be any problems spinning the coil around. The only problem would be for the contractor who should have done it right the 1st time.

[mark beiser]

What brand is the coil? and is the airflow left to right, or right to left through the system?

Some brands/modles of cased coils require the airflow in a particular direction.

[Edited by mark beiser on 10-30-2005 at 12:32 AM]

[krxman]

It's an American Standard cased coil, model number TXC042C4. The furnace (AS - CDX080) is in a horizontal installation w/airflow running left to right (assuming I know what you mean by this: standing in the attic facing the furnace the air flow moves from left to right thru furnace).

But here's some info I just found in the Installer's Guide that may explain why he did it this way:

"IMPORTANT: The TXC-C cased coil must be placed downstream of the furnace, with the apex of the coil always pointing in the direction of the airflow for horizontal installation. The TXC-C cased coil may be installed with upflow or downflow furnace models that provide horizontal right airflow applications. However, the coil must be rotated 180 degrees placing the coil service access opposite the furnace service access."

I'm not sure my coil is a TXC-C, but I'm guessing it is. If so, can a different coil be installed w/the same service access as the furnace?

[johnl45]

Was a permit pulled for this job?

[krxman]

That's another confusing thing. I was told by the GC that the HVAC sub would pull a "one day permit" for the job. Now the sub says GC never mentioned this to him, but says he doesn't need one because he has a permit to work in our village which supercedes the need for a permit for this particular job. Just got this from him yesterday so I'm going to call the village tomorrow and check it out. Also, the inspectors in this town have approved some really crap work in the past so I wouldn't want to leave it up to them. My next door neighbor has 50 years in the HVAC industry as contractor and now consultant and he's the one who pointed out that the coil installation was really screwy (though he said otherwise the guy does great work and he'd hire him himself). But he said he'd make him change the coil.

[tyreman]

Best to make a coil slide
This can be done with s cleats and then a slide door if you will with a double 1/4" fold 90 degrees for a grip to slide the access panel.It slides on the cleats
This can be used to observe the evapourator under load no load observe the circuits and see what is going on.
Additinally if done allows the coil T pee to be removed for evapourative coil cleaning.
As well as drain line cleaning from within.

[mark beiser]

Well, technically a different coil would have to be installed.

AS/Trane makes reversable cased coils, but the biggest one is the TXC036D4HPC.

What outdoor unit do you have?
I was just looking at some random matchups with 3 ton and 3.5 ton outdoor units with this coil. It looks like the performance and SEER may be nearly identical between the reversable TXC036D4HPC coil and the non reversable TXC042C4 coil you have.

There are a couple of modifications that can be made to your existing coil that are not "officially" supported by AS/Trane, but gets a wink and a nod from our field tech rep, that will allow the coil to have front service access in s horizontal right installation.
We have installed many of them turned around the "wrong" way with no problems. It requires some modifications to the apex baffle, and for some coils, a sheet metal fitting between the furnace and coil to move the coil about 6" away from the furnace. Your installer my not be comforterable with, or know the modifications required, wich is understandable.


Another thing the installer could do is use a slab coil, wich is the best option for a horizontal installation anyway, regardless of airflow direction. We use slab coils every time space allows because they are flat out more reliable, and have lower pressure drops than cased A coils.

[krxman]

Well it so happens that the installer called me this morning to say he talked to his supplier and the supplier told him how to install the coil the "wrong" way, as you mention. Yesterday he told me this would cause serious pressure loss and other problems (having to do with brackets and such). Today he says everything will be fine. I'm not sure what to think.

The outdoor unit is an Ameristar 2A7B0042A1000AA. I would be great to know if there is a reversible or other coil that would work. Cause doesn't it make better sense to use a coil that's made for a right horizontal installation instead of one that has to be rigged?

How much more space would a slab coil require? The furnace is up against a hip roof, w/a kneewall enclosure, so the depth is tight.

[krxman]

I guess what I need to do is call a local American Standard dealer in the morning and see which coil they recommend in this situation, and see what they say about moving the current coil to the front of the unit, which is what my installer now wants to do. It sounds like if done right it might be okay, but I'd rather have the "right" coil in there, if there is a "right" one.

[mark beiser]

The "right" coil would be one that is ARI rated with your outdoor unit so you know what the actual capacity of your system is. for that to be meaningfull a load calculation would have had to be performed so the equipment can be selected properly.

Without knowing the specifics of the situation, nobody here can do much but call BS on the say he installed it.

Considdering it isn't a true matched system, I kinda wonder why he picked that coil instead of one of a number of more generic coils that was designed for that airflow direction.

[docholiday]

I dont guess you have a digital camera.

[krxman]

Yes, I do. I'll take some pics and see if I can post them.

In the meantime, my installer called me this a.m. to say his supplier now says he can't reverse the coil. I've talked to 2 AS distributors and both say he's right and that there is no other coil option for this furnace except a much larger horizontal unit (TXH041A4HPA) that wouldn't fit in the space available (from what I can tell). So if anybody has any other suggestions, or knows somebody in the Chicago area who could help me w/this, I'd be eager to hear about it. Thanks!

[coolcray3]

aspen makes a coil that they can match up to that unit that has multi position install.

[krxman]

Do you happen to know the model no.? Is it a cased A or slab? Thanks.

[coolcray3]

i dont now the model # but we use then sometimes on york furnaces.and you can get them through york.

[coolcray3]

what is the coil going on air handler or furnace.