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Crusin Motown~Top Down
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Discussion Starter · #1 ·
First off HAPPY NEY YEAR EVERYONE :party:

I have a Carrier 48GS packaged unit on a ground slab heating my home. The unit has been in service for almost 5 years now and just recently started having a problem with the flame rolling out and burning the insulation of few wires . Rollout (sw)wire and spark ignitor lead.

The unit was looked at by a service tech who said the heat exchanger along with everything else checked out ok and suggested I extend the flue hood with a 2 turn elbowto control the wind which he thinks is causing the flame roll out. We have had some strong winds from the exposed side (south) that we normally don't encounter during the heating season. The unit is sheltered on 3 sides.

So I guess my question is, can I install a flue extension as he suggested without causing other issues ?
 

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If the wind was the problem, wouldn't the pressure switch open? There is a safety switch to insure that the furnace exhausts correctly so that the flame does not roll out. If the problem was that the system locks out on that switch in particular, then yes, I would think the wind is the issue.

There is a special vent cap that will rotate so as to insure that the wind will not effect the exhaust. But, the fact that the flame is rolling out in such a manner that the insulation is burning, that isn't good. Granted, this is armchair teching, and if he says the heat exchanger is good sobeit.
 

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Crusin Motown~Top Down
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Discussion Starter · #3 ·
I asked the same question of the tech, he said this is controlled by the rollout sensor, that the wiring diagram shows no pressure switch on this unit. There also was no LED error codes showing
 

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You should be ok. In this case, the cs (centrifugal switch) is substituted as the pressure switch. It assures that the draft motor is operating. To make a long sentence short, You can do as the guy says. But, if the roll out switch does go out again, I would do a thorough check of the heat exchanger.

I certainly do not claim to be the end all of knowledge, but I would think that if the winds were so bad that the flame were rolling back, then, the cs would have tripped.

Good luck. Hopefully, someone else can chime in with something more useful.
 

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Sounds like a heat exchanger leak. Did the technician take panels off and physically inspect the heat exchanger?

Better get them out and tell them they didn't fix it and shouldn't be charged for further diagnosis. If they don't agree to this call someone else.
 

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Crusin Motown~Top Down
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Discussion Starter · #6 ·
Sounds like a heat exchanger leak. Did the technician take panels off and physically inspect the heat exchanger?

Better get them out and tell them they didn't fix it and shouldn't be charged for further diagnosis. If they don't agree to this call someone else.
A limited visual inspection and a sniffer were used. No rust residue was seen. He also said the flame held steady as the blower started, he said that was also an indicator that there is no crack.
 

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It is actually easier to remove the panel on the side that has the discharge chute for the inducer.

The other possibility is a slight obstruction in the inducer or the inducer wheel combustion blades are rusting and reducing in surface area. Remember Carrier uses a hall effect sensor to determine that the inducer motor is operating not a draft pressure switch. Found a wasp nest once on a Lennox RTU that would open the fusible link roll out switch after several minutes of operation.
 

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If the wind was the problem, wouldn't the pressure switch open? There is a safety switch to insure that the furnace exhausts correctly so that the flame does not roll out. If the problem was that the system locks out on that switch in particular, then yes, I would think the wind is the issue.

There is a special vent cap that will rotate so as to insure that the wind will not effect the exhaust. But, the fact that the flame is rolling out in such a manner that the insulation is burning, that isn't good. Granted, this is armchair teching, and if he says the heat exchanger is good sobeit.
The 48GS uses a hall effect sensor mounted on the end of the inducer to prove to the control board that it is running.
http://www.xpedio.carrier.com/idc/groups/public/documents/techlit/48gs,gx-7si.pdf#xml=http://www.xpedio.carrier.com/idc/idcplg?IdcService=GET_XML_HIGHLIGHT_INFO&QueryText=dDocTitle+%3Csubstring%3E+%6048GS+%60+%3COR%3E+dDocName+%3Csubstring%3E+%6048GS+%60+%3COR%3E+%2848GS+%29&SortField=dInDate&SortOrder=Desc&dDocName=48GS,GX-7SI&HighlightType=PdfHighlight
 

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ya i would be doing a co test on that exchanger from 6ft away from ur second vent, sounds like u got a bad chamber,roll outs just dont go....theres a reason carrier have always had problems with there exchangers since the early 90's and were installed in just about every type of unit. if u have a manometer i would also insure that proper gas pressures are there.
 

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The 48GS uses a hall effect sensor mounted on the end of the inducer to prove to the control board that it is running.
http://www.xpedio.carrier.com/idc/g...ocName=48GS,GX-7SI&HighlightType=PdfHighlight
I do recall the sensor you are describing. But, if the wind were strong enough to cause the flame to roll back, wouldn't it also effect the action on the inducer motor as well?

I am not claiming to be Mr. Knoitall, but, the wind currents would have to be stronger than the current created by the motor for the flame to roll back. So, this I would think would cuase the sensor/switch to trip.

It would be interesting to find out what the final outcome was
 

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na i have never had a flame roll out switch trip on high winds. if it was installed on a north wall sure...i could see it..but i deal alot with commical roof top package units 7 story's up still dont get this...when ever i have this problem ur having faults with the heat exchanger/gas pressures. could be pulling off the burner or lift off burners. seriously...if its tripping the flame rollout.... i would be very concerned.

if u have access to a manometer then u should be sitting at 3.5inch water column. this type of switch does not usually fail....there has to be a reason do u see scorch marks rusting...on the front of the chamber...would be an easy look and may save alot of time.
 

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and most package units use a centrifuge switch not a pressure switch...when it gets up to full speed it clicks in usually send 24 volts threw ur safety controls. then turning on the sparker then gas valve.. but what do i no...i work on alot of carriers....and carriers are known for bad chambers i had one today i shut down had 17ppm of co detected 10 ft away at the first register after removing the top of the unit and using my mini cam i found a 3inch long crack on my 3rd burner tube and it was only 8 years old...reason gas pressure set almost 5inch....installer never set. any idiot can install a unit a technician takes the 20 mins and sets it up.
 

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and most package units use a centrifuge switch not a pressure switch...when it gets up to full speed it clicks in usually send 24 volts threw ur safety controls. then turning on the sparker then gas valve.. but what do i no...i work on alot of carriers....and carriers are known for bad chambers i had one today i shut down had 17ppm of co detected 10 ft away at the first register after removing the top of the unit and using my mini cam i found a 3inch long crack on my 3rd burner tube and it was only 8 years old...reason gas pressure set almost 5inch....installer never set. any idiot can install a unit a technician takes the 20 mins and sets it up.
I have a question for you,can you explain this? Do you mean at 10 ft away from the first supply register in the building? If so, why not just probe it at the trunk next to the unit?
 

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indeed a probe would be the best thing to have...but i own alot of my own equipment and we use gastec for fuel combustion analyzer. and i carry personal now im in a high place commical refrigeration shop i deal with 8 to 10 cust a day on avg . sure we all like to make things quick and easy...but with 18 service tech we all dont have them. so you u learn the best ways to deal with it and im young so i love using my drill and investigation a unit hell we all charge by the hour...but i like to learn and eventually id like to work for some of these companys and tell them were they went wrong. and least u get what you pay for, i was brought up in this trade and i see **** installed everyday were alittle pride in there workmanship would have saved this piece of equipment.
 

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o and i do 10 ft away so heat isnt my factor, keep my co dector cailbrate and sent it. i also take one at the r/a aswell. and i also take one every jobsite i enter..from wendys....to some little old ladies. cause my ass at the end of the night is on the line.
 

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I see. I use a bacharach. I am unfamiliar with the particular tester you speak of. Just so I understand, The meter you use, you stand back ten feet from the registers, hold it up to the air stream, or close, and take the readings?This is similar to walking in with a combustable detector and doing a walk through?
 

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and most of the times roof tops..have no trunks :) some but not many...and then drilling holes in sealed panels, silcon needed sure. could but who's going to do that every unit they work on? nor is every cust going to be happy if damage is done. you get picky people..:) hey man im just here to help,
 

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indeed a probe would be the best thing to have...but i own alot of my own equipment and we use gastec for fuel combustion analyzer. and i carry personal now im in a high place commical refrigeration shop i deal with 8 to 10 cust a day on avg . sure we all like to make things quick and easy...but with 18 service tech we all dont have them. so you u learn the best ways to deal with it and im young so i love using my drill and investigation a unit hell we all charge by the hour...but i like to learn and eventually id like to work for some of these companys and tell them were they went wrong. and least u get what you pay for, i was brought up in this trade and i see **** installed everyday were alittle pride in there workmanship would have saved this piece of equipment.
I agree 1000%.. That drives me mad.
 
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