Friday, November 23, 2012
Amana 90% Down Flow Furnace Fix
This post deals with furnace repair. This is best left to a competent service technician and in fact this is a technician tip. If you're inclined, remember that improper repairs can cause injury, death, or property damage. Doing this repair can expose you to some nasty cuts from the burrs on the heat exchanger or the drill bit, electrical shock, burns, asphyxiation from improperly tightening the screws or breaking a vent pipe. Breathing in the acetic acid from the silicone isn't exactly healthy either. You can break parts on these in a New York minute, and I have no control over the quality of your work. Do these and any other fixes at your own risk.
A few days ago, the office sent me to a maintenance call on a second story Amana 90% down flow furnace. The inducer motor was noisy as a cat trapped in a rain barrel and the collector box resembled Niagara Falls. The first picture is the burner box. Good thing the control board was above this mess. The furnace was made in 2005 and has the green cabinet.
The picture is off my camera phone, so it will never do the situation justice. Note the hole with the gasket in the center of the black plastic collector box. Someone replaced the inducer prior to my visit and reused the old gasket, hence the water tracks. A better idea would have been to scrape this mess out and use a high temp silicone, but I digress. Do you see the screws all around the outside of this mess, and the PVC elbow in the upper left hand corner? This is going to make getting that screw out a pain in the butt. The elbow was glued in at the factory. Because of the wiring next to same, a jigsaw was out of the question.
Here's a little better shot of the elbow and the wiring. I could have lopped this off with a PVC cutter in retrospect. However, the wiring was in the way and mine wasn't quite big enough to get around that pipe. My socket wrench was also a bit awkward and my hands aren't what they used to be. Since I was out in the middle of nowhere, my options were limited. I do have a drill, and more than a couple bits, so here's what I did.
Instead of getting frustrated, I took my drill and made two holes in the elbow. This allows me to get my nut runner in there to get the screw out. The one that was in there has a 5/16 inch head. To make life easier, I switched to one with a 1/4 inch head from the collector box. Rather than trying to use a gasket on these furnaces and risk cracking the plastic collector, use a good high temperature, room temperature vulcanization (RTV for short) silicone gasket. Clear or aluminum silicone will work in a pinch, but never use black as this will inevitably fail. Get a 1/4 bead around the sealing surface and the screw holes on that box or plate. Peel off all the old foam gasket off the heat exchanger with your fingernail, or use a plastic scraper. Put the works back together, run it, check for leaks and you're done. Maranatha!