Coils Rusting on Air Handler - Replace vs Repair

comkowOctober 4, 2009


We are looking to replace the fiberglass duct board in our downstairs zone due to health reasons. While the HVAC tech was here, we told him that we were told a few years ago that the coils on the upstairs air handler were rusted, so we had him look at it for us. Downstairs unit is also a little rusted, but not as bad.

He was trying to sell us the entire BS story about how R22 will not be available after January (which is true to a point) and we need to switch both air handlers and get new A/C units now. I wasn't falling for it until we checked it out here on the handy-dandy HVAC forum which I found a post which says this is not so.

However, these are our questions.....

1) the coils are definitely rusted on the upstairs unit. The unit is roughly 15 years old.

Do we try to have the coils replaced or do we install a new air handler? I did read on another post that in the HVAC world, you can add an adapter to a 410 air handler to go with a R22 A/C unit (??).

Current air handler is an Inter-City Products air handler. Yes, we have a mish-mosh of equipment. I guess it was whatever the cheesy builder could get his hands on for the "cheapest" price.

Is the cost of replacing the coils vs replacing the entire air handler significant? If we are dismantling the duct board in the basement maybe we should get a new air handler anyway. We will also have a new 4" HE filter unit installed. However, what about the unit in the upstairs zone which we were not planning on doing anything with?

He ALSO told us that we would need ALL new duct work upstairs to adapt to the new 410 air handler. We currently have flex duct throughout the house.

2) he also looked at one of the A/C units.. (AG high efficiency - model AG036G1) and said the motor inside looked like it was running hot b/c of how brown/rusted it looked. Our second unit is a Lennox (prior owners had replaced that one which I would guess would have been an AG HE as well). He told us the AG unit will probably need to be replaced too. Both units are clean inside, no debris, but no we have not had them serviced.

Thus why he told us we would need two new air handlers and two new A/C units for $15k-$20k, but the gov't is offering some great energy star rebates....LOL!!

One last question, we are wondering if the anti-freeze that is in the pipe lines could have possibly contributed to the corrosive nature of the coils or does this generally occur of so many years regardless. We hired a new HVAC tech last year and he told us the anti-freeze begins to attack metal after so many years and you need to have it drained and replaced. We are actually going to have it drained and leave it at that.

If you have any questions to help you understand this please let me know.

As always, thank you for your help.

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Are the coils leaking? I would not put a bandaid your (upstairs) system up at this point with just a new indoor coil (or air handler). If you replace anything, the indoor and outdoor units should be replaced. It's not a smart move to install a R-410A air handler and the outdoor unit later, because it is difficult to remove the incompatible R-22 mineral which cannot be mixed with the POE oil of R-410A.

True that there is a federal energy tax credit of up to $1500 (30% of total installed cost) for qualifying systems AND buyers.

Usually new systems don't "require" new ductwork, but depending on the design and size of your current ductwork (most are undersized), a new system won't perform to its fullest efficiency nor deliever its fullest capacity.

I have no idea what you or the tech is referring to with regards to anti-freeze. The pipes you see (insulated suction line and smaller copper liquid line) carry refrigerant, and the refrigerant doesn't need to be "drained" as the tech suggests.

Doesn't sound like everything he said was bs, even though you may not have liked everything he had to say about your systems, which may very well be in poor shape since as you mentioned, it is true that builders go all cheap (which may be partly why he said what he did about the ductwork).

Let me know if you have any more questions and I'm happy to give my advice. I'm not an HVAC professional, so my opinion isn't biased to sell you anything. I've done enough reading, discussing and watching over the years to have a general knowledge of HVAC, however.

    Bookmark   October 4, 2009 at 9:41PM
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Coils are not made of iron and therefore don't rust. For brown, do you smoke either tobacco or other substances?
There are many "coil cleaners" on the market. Just follow instructions.

    Bookmark   October 6, 2009 at 7:17PM
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I think you are reffering to the tube sheet portion of the coil. I would be supprsed to see ANY 15 y/o air handler that did not have rust on them. I am an HVAC professional and I say get another opinon because I just read some bs lines this guy gave you. A 15 year old resadential system is near the end of it engieered life so either replace all or wait and do it all later with a matched system. As for finding a reputable dealer start with ACCA. Then call AC ditributers they will not recomend someone who does not know what they are doing.

    Bookmark   October 6, 2009 at 7:41PM
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The first guy you had out isn't giving bs. I am not aware of any system that will allow mixing refrigerant and I wouldn't recommend using this system if it did exist. As noted, mixing two kinds of oils isn't possible and will result in more costly repairs. Do you realize a 15 yr old system is costing you most likely 50% more each month on utility bills. Basically your making monthly payments on a unit on borrowed time with no warranties. Definitely get several quotes. Don't worry there are professionals that can help and recommend what's best for your needs. Just know it's not going to be cheap. But will be a great investment in the short run. And call companies that have references and offer 100% customer satisfaction in writing. You won't go wrong. And yes ACCA is a good place to get references.

    Bookmark   February 25, 2011 at 11:55AM
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