Furnace heat exchanger problems - previously (mistakenly) posted to alt.HVAC

[louie]

I recently bought a house with an older gas furnace (probably 15 years old, nameplates have been mostly painted over). Recently discovered that the blower will no longer start up on its own, and have had the capacitor tested - it tested ok. So... I happen to have a home warranty left over from the purchase and I called to have the furnace repaired (it is covered under the warranty). Unfortunately, I have no say in the technician/company who services my furnace - it is chosen by

the warranty company for me. The guy comes out, my wife is there to let him in, I showed up from work about 10 minutes later. When I got there, he was in the process of trying a new capacitor (didn't work) and then decided that the blower motor needs replacement. I took the opportunity to mention that I had seen a lot of LARGE rust flakes piled

on top of the burners (almost to the point of completely covering several of the burners). I asked did he check the heat exchanger for holes? He replied that he hadn't seen any holes in it but that he would check for CO coming from the upstairs registers once the new blower motor was installed. He also mentioned that the burner chamber needed to be cleaned out and that wasn't covered by the warranty, nor was it included in his or his company's job duties. I later asked my wife how he inspected the heat exchanger (ie. did he use a camera, mirror, what?). She replied that he didn't do anything more than what I had seen him do when I got there (nothing). We will be called once the motor is ordered and received to schedule the next appointment. This is not an emergency for us, since we're currently living elsewhere while we do some rennovating.

So, I'm thinking, though I don't have any inspection mirrors or cameras, those large (when I say large, I'm thinking they look to be a few inches across and about 1/8" or thicker) flakes of rust coupled with the fact that someone has done a less-than-classy installation of an A/C coil in the plenum above the furnace means I have problems. Anyone have any ideas here? I don't want this thing to "pass" some half-a$$ed test by bubba the technician only to fail later on after my warranty has expired.

also - appologies to any ruffled feathers/offended HVAC folks who might not have appreciated my posting to "their" special group. I didn't realize it was a "He-Man-Homeowner-Haters" club for professionals only.

[HeatMan]

Big Snip

Funny thing, the people that complain and moan over there don't seem to realize that usenet is open to the public. It's an unmoderated group. They need to grow up.

>

[CJT]

I doubt they'll ever grow up. They've pretty much killed the group's usefulness.

[Edwin Pawlowski]

That is not necessarily a good thing.

You can buy a mirror on a stick for about $5. A good light and some poking around will tell you a lot.

Yeah, a couple of ignoramuses there think they control USENET. Probably afraid to teach others as they may lose a service call.

[T.G. Lambach]

Perhaps your local gas utility could do a safety inspection (CO) of the gas furnace and express an opinion.

[buffalobill]

a google search found a nice checklist of things to do at:

"Service requirements for older furnaces If your warm air furnace is old (say, 20 years or older), I suggest you have a professional heating contractor servi ce it every year. This is your best protection against carbon monoxide dangers and heating problems. Routine service will also ensure peak efficiency to save you operating costs. A good service and inspection costs about $80 and should include a complete cleaning, safety check, and tuning. The service contractor should:

clean the burner and heat exchanger, and inspect for cracks. remove the burners, clean them, and tune for proper combustion. perform a carbon monoxide test in the heat exchanger. check the vent pipe and draft diverter. inspect the chimney for obstructions and draft. check vent pipes for proper clearance and materials. test fan controls and safety controls. check the thermostat. run the furnace through a complete cycle. check flame roll-out. check gas pressure (if appropriate for your furnace). clean and adjust the pilot light assembly. inspect gas fittings and repair any leaks. lubricate the fan and motor. check belt condition and tension. service the filter. clean the fan and housing if excessive dirt has accumulated. Replacing parts or cle aning extensively will cost extra. You should have a basic understanding of how the system works, so ask the service contractor to explain the basics. You should routinely service the filter and lubricate the fan and motor a second time during the heating season. You should also inspect the flue connection to the chimney. "

[buffalobill]

it is important to see that there is actually a poster named bubba in the hvac group who is quite full of knowledge and humor.

[Dr. Hardcrab]

"buffalobill" wrote

"Bubba??!! That guy's a FAG!!!!!!"

;-]

[Bubba]

I am Not! :-) Bubba

[louie]

LOL, no offense meant to guys with that name, or to HVAC technicians in general. I just have not been impressed with the particular fellow who showed up at my house the other day.

Update:

I shut off the gas supply to the furnace and removed the burner assembly. It consists of five burners, the middle one is so badly corroded that the "tab" on the end of the burner that fits into a slot on the inside of the chamber stayed in the slot while the burner came out. About 2 or 3 inches of that particular burner has deteriorated and flaked off, leaving the end of the burner open. I shop-vac'ed out the rust flakes from the burner chamber and inspected with a flashlight (will have to get a mirror tonight). I also started up the circulation blower (still does not start without a little push) and felt inside the burner chamber. I CAN feel air moving in there in a couple of spots (mainly near the opening of the burner chamber - just above the opening at what feels like a seam in a couple of places), and I can also feel air moving where the vent pipe connects at the top. It's not a lot of air, but it's definitely noticeable. Maybe it's nothing to be concerned about, but if everything I've read is correct, you really don't want combustion gases and circulation air mixing together. Also, in all my years as mechanical engineer, I have yet to hear about a crack or corrosion hole spontaneously shrinking. Thanks for the info so far. I like the idea of contacting the gas utility. I think I may give my favorite service guy a chance to fix it right first, then have a safety inspection done afterwards just to double-check.

[m Ransley]

Get a digital read out Co meter apx 40$ , check peak level often.

[HeatMan]

Where are you going to find a decent CO tester for $40? Not at HD...

[louie]

well, HD does sell a digital readout CO tester for approximately $40. I can't say if it's decent or not...

[Goedjn]

Pet store.

[m Ransley]

Several decent makes go for apx 40$ Nighthawk. Kidd. First aler.t

[CBHVAC]

Man..thats a POS. Period.

A barely decent (UEI, Fluke) CO detector runs min $199. A good one...Bacharach...closer to $500.

You dont get jack for $40 but a false sense of security...thats a CO ALARM you are looking at...not a DETECTOR. While an alarm detects, it is NOT the same...not even in the same ballpark.

[HeatMan]

Right. And those do meet UL2039 Standard. IIRC, that's 50PPM of CO for 30 minutes? Brain damage territory....

[m Ransley]

Read my first post it says " check Peak level often"

[CBHVAC]

Its still a stupid idea to trust an ALARM for a dectector.

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[louie]

Further update: The service guy returned with a new blower motor, went down to the basement, took one look at the burners that I had removed for cleaning and said: "Ok, I'm condemning the whole unit, I should have taken the burners out last time I was here and looked at them and the heat exchanger." It looks like the warranty company will honor the contract we have and will probably do so by paying us a cash amount to replace the furnace. We'll likely have to add some of our own money to upgrade that, since I suspect this furnace is less than 80% efficient (again, most of the tags and model information has been painted over and isn't readable).

Anyhow, thanks for the helpful replies and discussion on this. Just thought I'd leave a feedback post, since it's been mentioned before that most OP's don't bother to do that. Thanks again!