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Posted: 10/1/2011 4:23:36 PM EST
[Last Edit: 10/3/2011 1:23:22 PM EST by snakeshooter1]
Tappan gas pack about 10 years old or so. The roll out switch is tripping out, burner tube look good. Flam is pretty and blue, not hitting outside of heat exchanger. I'm at a lose not sure why it is getting so hot. exhaust vent air is very hot. What am I missing? ETA it is propane.
Link Posted: 10/1/2011 4:36:10 PM EST
Check the gas pressure?
Link Posted: 10/1/2011 4:38:07 PM EST
why would it just start to be a problem now? not being a smart ass, really serious as to why it would just show up now? it is a two stage system with it's own regulator.
Link Posted: 10/1/2011 4:43:24 PM EST
Originally Posted By snakeshooter1:
Tappan gas pack about 10 years old or so. The roll out switch is tripping out, burner tube look good. Flam is pretty and blue, not hitting outside of heat exchanger. I'm at a lose not sure why it is getting so hot. exhaust vent air is very hot. What am I missing? ETA it is propane.


Maybe I was suppose to point out the mistake for the first reply...
Link Posted: 10/1/2011 4:45:34 PM EST
[Last Edit: 10/1/2011 4:49:10 PM EST by Ricoch3T]
Sometimes pressure regulators can go bad... I would check incoming regulator pressure, then out going first. Then check before and after the gas valve.. I've had it happen before on some service calls



Course you can have a stopped up vent or partially blocked. I didn't mention it first since it sounds like you checked it. May need to take it apart to make sure it's good and clean. I've seen cooked birds in there
Link Posted: 10/1/2011 4:46:17 PM EST
[Last Edit: 10/1/2011 4:46:58 PM EST by snakeshooter1]
Originally Posted By Ricoch3T:
Originally Posted By snakeshooter1:
Tappan gas pack about 10 years old or so. The roll out switch is tripping out, burner tube look good. Flam is pretty and blue, not hitting outside of heat exchanger. I'm at a lose not sure why it is getting so hot. exhaust vent air is very hot. What am I missing? ETA it is propane.


Maybe I was suppose to point out the mistake for the first reply...


well parden my spelling then thanks alot next will it be grammar or sentence structure?

ETA I will check that first thing in the AM
Link Posted: 10/1/2011 4:47:50 PM EST
Seriously though I'll check the gas pressure at the valve and manifold. Do you think it could be a cracked combustion chamber?
Link Posted: 10/1/2011 4:53:27 PM EST
Originally Posted By snakeshooter1:
Originally Posted By Ricoch3T:
Originally Posted By snakeshooter1:
Tappan gas pack about 10 years old or so. The roll out switch is tripping out, burner tube look good. Flam is pretty and blue, not hitting outside of heat exchanger. I'm at a lose not sure why it is getting so hot. exhaust vent air is very hot. What am I missing? ETA it is propane.


Maybe I was suppose to point out the mistake for the first reply...


well parden my spelling then thanks alot next will it be grammar or sentence structure?

ETA I will check that first thing in the AM


Lol.. Isn't it a general discussion rule to point it out first?

Anyhow.. Heat exchanger is a possibility BUT from what you say you'd see some yellowing in the flames or a change in how the flame looks when the fan comes on.
I'm not suggesting that you or a professional shouldn't inspect it, just from what you are saying it sounds more like something else.
Link Posted: 10/1/2011 4:54:30 PM EST
I would check manifold pressure ,make sure you don't have a blocked flue or down draft also
look at the burner flame if its wavering after the blower comes on you could have a cracked heat exchanger
Link Posted: 10/1/2011 4:57:36 PM EST
I guess I should add that I assume some common sense in dealing with gas. Most professionals will look at a 10 yr old furnace and assume a crack from the age which is why I suggested a few other things to check first.

So take that as a disclaimer
Link Posted: 10/1/2011 5:03:37 PM EST
well I was in the business for 17 years as propane service tech. That was ten years ago though. I didn't notice any change when the fan came on and I blew air through each of the tubes froma compresor and got air and rust out of the exhaust vent.
Link Posted: 10/1/2011 5:13:44 PM EST
Also could it be the turbulators. I think that is the term for the sheetmetal air inducers on a Tappan. Most of the stuff I dealt with was ribbon style burners.
Link Posted: 10/1/2011 5:16:37 PM EST
is this happening on ignition or after its running for a while
Link Posted: 10/1/2011 5:26:31 PM EST
1. check the end of the vent run, if there is ANY carbon [even a trace] then your heat exchanger is plugged or cracked.
2. check pressure on both sides of he gas valve. should be 10-11 IWC.
3. check for obstructions on intake and exhaust side.
4. it is possible you have a plugged secondary heat exchanger or a cracked primary.
5. what does the inducer [ventor] sound like?
6. check the burner tubes themselves, they like to rust and partially plug, that will create problems.
7. Pull the burner box cover and see if it runs properly, if it does, check for intake obstructions, especially if it's a 2 into 1 intake/exhaust set up. check WELL.
Link Posted: 10/1/2011 5:32:19 PM EST
Originally Posted By fxntime:
1. check the end of the vent run, if there is ANY carbon [even a trace] then your heat exchanger is plugged or cracked.
2. check pressure on both sides of he gas valve. should be 10-11 IWC.
3. check for obstructions on intake and exhaust side.
4. it is possible you have a plugged secondary heat exchanger or a cracked primary.
5. what does the inducer [ventor] sound like?
6. check the burner tubes themselves, they like to rust and partially plug, that will create problems.
7. Pull the burner box cover and see if it runs properly, if it does, check for intake obstructions, especially if it's a 2 into 1 intake/exhaust set up. check WELL.


1 power vent, air is extremely hot coming out of it
2 will check pressure tommorow
3 didn't see any, air is coming out of vent seems pretty good flow
4 blew through all tubes with air compressor and got air out of exhaust vent
5 all of them sound good with the drone of turbine engine sound
6 ran a 1/4 copper tube up into them can't see past the turn of them
7 lost me with that one not sure what you mean
Link Posted: 10/1/2011 5:33:05 PM EST
Originally Posted By ajk:
is this happening on ignition or after its running for a while


after been on for while and after indoor blower comes on
Link Posted: 10/1/2011 7:18:03 PM EST
Either a cracked heat exchanger or a severely corroded combustion blower blade. i would start the unit up and watch the flame for movement when the indoor fan kicks on, If you get flame movement then you have a cracked h/e.
Link Posted: 10/2/2011 4:12:43 AM EST
[Last Edit: 10/2/2011 4:17:49 AM EST by fxntime]
Originally Posted By snakeshooter1:
Originally Posted By ajk:
is this happening on ignition or after its running for a while


after been on for while and after indoor blower comes on


80% [metal vent, open burners, non condensing] or 90% furnace [plastic venting, condensing, closed burners]? If it's plastic, then it should only be about 90-100F temps on the exhaust vent. If it's popping the roll out switch on a 90% and all else is OK then you have a heat exchanger issue, a bad ventor motor MAY cause issues if it's not running up to speed but there are usually issues with the pressure switch closing.

You can always replace the roll out with a new one, if it still does the same thing then [especially with propane] the problem is internal.

Link Posted: 10/2/2011 4:41:31 AM EST
how much wind have you had? I had a package unit that was giving me fits similar to yours that was taking wind gust 10-15 mph. wind baffles resolved it.

you should be able to raise the top and look at the heat exchanger tubes if you are concerned they comprised.
Link Posted: 10/2/2011 5:03:16 AM EST
[Last Edit: 10/2/2011 5:05:18 AM EST by fxntime]
Originally Posted By 2tom2:
how much wind have you had? I had a package unit that was giving me fits similar to yours that was taking wind gust 10-15 mph. wind baffles resolved it.

you should be able to raise the top and look at the heat exchanger tubes if you are concerned they comprised.


If there is a crack or the rivets are popped, it won't be noticable just looking down the tubes as it's usually 1/2 way thru the primary. You can pull the blower motor and see if any rivets are lying in the housing or pull the hi limit and use a flashlight or wand camera, check out the rivets and any cracks around them. If one is popped or there is a crack evident, there will be more.

There were a lot of issues with heat exchangers in that era and many manufacturers were involved. Bryant/Carrier were pretty bad, I can almost guarantee if the roll out is popping on those, the heat exchangers are bad. They were sued on the 58SX series, settled without admitting anything but will give around a grand to the customer with one to replace it or replace the heat exchanger in it for a minimal charge.

Most furnace companies offered a 10 year heat exchanger warranty so check the INSTALL date [when the warranty goes into effect] and call the manufacturer if you suspect a heat exchanger issue.
Link Posted: 10/2/2011 5:23:44 AM EST
Originally Posted By fxntime:
Originally Posted By 2tom2:
how much wind have you had? I had a package unit that was giving me fits similar to yours that was taking wind gust 10-15 mph. wind baffles resolved it.

you should be able to raise the top and look at the heat exchanger tubes if you are concerned they comprised.


If there is a crack or the rivets are popped, it won't be noticable just looking down the tubes as it's usually 1/2 way thru the primary. You can pull the blower motor and see if any rivets are lying in the housing or pull the hi limit and use a flashlight or wand camera, check out the rivets and any cracks around them. If one is popped or there is a crack evident, there will be more.

There were a lot of issues with heat exchangers in that era and many manufacturers were involved. Bryant/Carrier were pretty bad, I can almost guarantee if the roll out is popping on those, the heat exchangers are bad. They were sued on the 58SX series, settled without admitting anything but will give around a grand to the customer with one to replace it or replace the heat exchanger in it for a minimal charge.

Most furnace companies offered a 10 year heat exchanger warranty so check the INSTALL date [when the warranty goes into effect] and call the manufacturer if you suspect a heat exchanger issue.



Package unit HX like Tappan is clam shell if I recall correct. If it is fractured it enough to cause roll out it should be easily seen through the blower. Tube type heat exchangers similar to RUUD which rot along the welded seam can seen pretty easily from looking down into. I use a bore camera to get to the nick & crannies though
Link Posted: 10/2/2011 7:03:12 AM EST
thanks going to check the pressures today and see if it is over fired, also will check as to what I can see on the exchanger. There was some rust in the bottom of the exchanger holes. BTW it is an 80% unit.
Link Posted: 10/2/2011 7:56:03 AM EST
I'm betting it'll have popped rivets and cracks around them. it heats up, the cracks open and it goes off due to air forced by the blower into the combustion side of the exchanger. You will NOT get any CO reads off it but going off on either the hi limit or roll out limit is pretty common.
Link Posted: 10/3/2011 1:27:37 PM EST
this Tappan has stainless steel tubes almost like auto exhaust pipes, makes 3 u style turns. I popped the top today and I could see holes in the top of the first u turn . The tube closest to the roll out switch is the one with holes in it. I checked and it wasn't overfired either . Sh_t happens I guess. $540 for the heat exchanger.
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