Suck-starting my Carrier furnace . . .
Older Carrier condensing gas furnace (Model 58EJA125-LC). Chimney fan won’t generate enough vacuum to consistantly actuate the vacuum-diaphram on the “safe” switch that allows the burner to light. Been that way for years.
I can detach and suck on the tube, and the ignitor and burner start right up; I can even carefully re-attach the tube to the fan housing while everything is running, and if I pinch the tube until it’s connected to the housing nipple, the furnace will continue to run until the thermostat setpoint is reached.
So, there is enough vacuum to maintain the switch diaphram, just not to engage it. If I pull off the hose, the burner immediately shuts off, as it believes there is a problem with the chimney draft – a nice safety.
Can’t just jump out the switch; control board needs to see NO vacuum before anything will start.
Next cycle, I’ve got to suck on it again, or wait a while, and it MIGHT start. Many, many techs have looked at this; I’ve replaced the draft fan assembly and the vacuum diaphram switch, and it might work for a while, but not for long.
Carrier will not talk to me; I’ve had this damm tube sticking through the kitchen floor, to suck-start my furnace, for years.
I can think of two ways to bypass this – use a relay on the 120V draft fan power to trip the (formerly) vacuum switch, or restrict the inlet air to the draft fan to pull more vacuum.
I don’t really like either idea. Anyone know a solution?
Forrest – lips are tired
Replies
Carrier will not talk to me; I've had this damm tube sticking through the kitchen floor, to suck-start my furnace, for years.
I don't know but that statement made be guffaw out load.
Why not have a little fishtank type vacuum by the furnace running of an easily accessible upstairs wall switch?
be jury rigged to practicality
'Cuz the vacuum has to cycle on and off with the draft fan, or the control board sees it as a fault.
I kind of hate to just cheat use just the fan power signal to trip the switch rather than the fan effect; then there could be a draft problem (bird or chipmunk in the pipes) that would pass undetected.
Restricting the intake air to create more vacuum also seems like a recipe for poor combustion.
Forrest
"I kind of hate to just cheat use just the fan power signal to trip the switch rather than the fan effect; then there could be a draft problem (bird or chipmunk in the pipes) that would pass undetected."And we all know just how constantly people without this little switch have problems with birds and chipmunks...;o)Bypass the dang switch. You'll know if a bird or chipmunk gets into the pipe, the same way everyone else does.
Get your head out of the box.
Okay - pulled off both the intake and exhaust. Furnace fired right up the first time, raising all kinds of excitement, but cut itself off even before the air-handler blower came on (30-40 seconds). Never got it to do even that, again.
Ran a snake through both PVC pipes; clean.
Suck-started it, fired off instantly; it's running now. Once it reaches thermostat temp, though, it won't restart with that switch tripped. (gotta' blow, then suck to restart!)
Tried putting little bits off paper over the draft fan vacuum tap (it comes out horizonally); it would hold a 2x2" bit of manilla envelope paper against itself, but not one bit bigger.
Another thing - this is a differential pressure switch; the Tygon tube from the other side of the switch disappears into the furnace. If I disconnect it, I can suck and blow through it, seemingly without restriction.
Forrest - confused
Wait is that Ice cream or did you blow a seal?
Sorry, yer killing me here all this seal sucking and such.Spheramid Enterprises Architectural Woodworks
"If you want something you've never had, do something you've never done"
Just got back in so can spend more time.
My thought is along what I first said. If you have a contact that is corroding then perhaps this intermittent/ more pressure effect. Less vacuum not enough pressure to make the contact, more vacuum/pressure contact made till next time cause the elect stops flowing contact broken start over suck on the tube.
The sequence of your original fix suggests that. You said you replaced ? and the? and then it worked for a while then started doing the same thing.
I'm gonna look at the model # you gave and see if I can see some parts or the schematic.
Cool - thanks a million
Forrest - shivering in the kitchen
Edit - serial # is 2292V00526
Edited 11/8/2007 6:36 pm by McDesign
Forrest,My furnace has a similar vacuum switch on said switch is an allen screw that adjusts the amount of vacuum it takes to activate.my furnace guy said thaat yer not sposed ta fiddle with it but....
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I have Transcended the need for Pants....oooohhhhmmmmmm......
any old ugly cheap hookers in the neighborhood? you could just hire them to sit with the hose in the kitchen and watch the thermastat. just a thought .larry
if a man speaks in the forest,and there's not a woman to hear him,is he still wrong?
Edited 11/8/2007 9:51 pm by alwaysoverbudget
any old ugly cheap hookers in the neighborhood? you could just hire them to sit with the hose in the kitchen and watch the thermastat.
It would be cheaper to replace the furnace than to keep an old hooker in teeth...
In today's The Washington Post, there was a recall notice on Carrier products. I don't have this brand, so I didn't keep the article. You may want to check out the recall on the internet.
MissD
Almost sounds like you might have a vacuum leak if it won't generate enough vacuum to pull the diaphram switch. Any chance it's a diaphram leak on the switch or a sticky switch? You are probably sucking harder than the furnace ever would and are able to bypass a leaky diaphram or sticky switch. If switch is good then maybe furnace doesn't generate enough suck as you are assuming. Have you put a vacuum gauge on the hose to check how much vacuum it generates vs. the specs? I might be able to get you some Carrier information if you need it. Carrier/Bryant is local and I am buddies with our HVAC guy.
John
J.R. Lazaro Builders, Inc.
Indianapolis, In.
Thanks for the reply. I have replaced the switch / diaphram assembly before, but it could be a sticky switch. I'm pretty sure there's no leak on the tube/switch side; I can suck a vacuum, and pinch the tube, and it will hold for 8-10 minutes - 'til the temp setpoint is reached. Draft fan blows hard; just pulled the housing apart and lubed and re-sealed it.
Vacuum tap is in an odd place; kind of under the squirrel-cage disc - you can see it near the bottom of the first pic on this thread - http://forums.taunton.com/tp-breaktime/messages?msg=96775.1.
I'll need a pretty sensitive manometer to measure the vacuum (inches of water) - it's tiny. Might be able to make up something with an inclined water column. I'm sure Carrier won't give me specs, though!
Forrest
Hey - looking at that pic, just had a thought. What if I'm getting a vacuum leak through the bearing and seal at the base of the fan, where the shaft comes out from the motor?
Hmmmmm.
Forrest
I just went and checked. I have an automotive vacuum/fuel pressure gauge that measures inHg (I can only suck up to 7.....it says I've got an intake leak). A light suck is 3 in. Probably won't be precise enough for what you need. It could be possible that you are leaking around the shaft as you stated.....but you said when you replaced cages that you replaced the motor. Has your problem only been with this motor?John
J.R. Lazaro Builders, Inc.
Indianapolis, In.
I just repaired the cage; also kept the same motor - I've had this motor 7-8 years, at least. I do recall seeing a little yellow resilient "disc" where the motor shaft comes into the housing - maybe it's the seal?
Forrest
I have a long story but I'll give you the short one, and I do see you said you replaced the switch? sensor?
Any way I spent 3 hours on a carrier troubleshooting and got to one? (It's been about 4 years ago) sensor can't remember which one but I went to carrier hvac supply and they had a bag with a couple of hundred replacements cause of a defect. Made me feel a little better. Plus a carrier guy had spent 2 hours trying and couldn't find it. It was intermittent.
Also If you jump the switch it will tell you if thats it? you said you couldn't do that why?
And the moisture/rust on the housing looks pretty wet. so electric? seems pretty likely.
once you have it running, can you use a piece of tube to "listen" for a leak as you move around the area with the vacuum switch?
All this time I thought when people said that Carrier products didn't suck, it was a compliment :-)
"Can't just jump out the switch; control board needs to see NO vacuum before anything will start."
got it on the above start sequence no contact at call to start.then pressure switch is activated/ok gas to flow. Part # on the switch? I've got a johnstone catolog in my hand.Didn't you say you replaced it once and it worked for a while? I got reminded of the headace I got with trying to find carrier stuff, easy to find the class action suites and stuff.
Carrier site didn't show me any listing under the model#s
(gotta' blow, then suck to restart!) Sticking -blow releases contact
I followed some of your picture threads so I know your mecanical talents, this has got to be driving you nuts. This switch is where the surgery is required. Slice and dice ,it's already broke.
"I've replaced the draft fan assembly and the vacuum diaphram switch, and it might work for a while, but not for long." What would cause it to fail in not to long? Moisture.
SPDT=
Edited 11/9/2007 7:57 am by ClaysWorld
Yeah! Isn't that an amazing link? I could have written that - it was our experience EXACTLY!
Gonna' pull the switches off this AM.
Thanks for the input -
Forrest
Been kinda' fun in the mornings this week, in the 40º kitchen, having to make a fire . . .
View Image
Probably miss having to do it once the furnace is fixed or replaced; not normally motivated enough in the early AM.
Best smells in the world - hardwood smoke, bacon, and coffee.
Forrest
Edited 11/11/2007 9:37 am by McDesign
View ImageIs this the part?HK06WC012 Carrier Pressure/VAC Switch SPDT HKhttp://estore.websitepros.com/1764801/Detail.bok?no=12706WC012 Carrier Pressure/VAC Switch SPDT
Or is it this one?View Image
One looks like the top pic - the one I have problems with is like it, but with two diaphrams.
Forrest
??????? any updates on the sucker furnace??
New pressure switch?
Carrier rep and my HVAC guy promise to be there 8:30 Wed morning. We're 700 miles away, so we'll see what happens!Forrest - hopeful
Just got in tonight; note from my HVAC guy that he and the Carrier rep fixed it. Seems to have run since Wednesday (it's Monday night now). I'll call tomorrow and get the full report.
Forrest
OKAY - Y'ALL AREN"T GONNA BELIEVE THIS!!!!!!
I'm sorry, was I shouting?
Finally, after 15 years and who knows how many service visits and cold mornings and teeth-gnashing, a Carrier rep or two came out Wednesday. Along with my HVAC guy, they completely disassembled the heat exchanger. First time it had ever been apart.
My guy tells me today, "one of the reps looks at the two clear pressure tap tubes connected to different places on the HE that feed the draft safety switches - "Hey, this isn't right!""
THE PRESSURE TAPS HAD BEEN CONNECTED WRONG (reversed), INSIDE THE HEAT EXCHANGER, AT THE FACTORY, FIFTEEN FREAKIN" YEARS AGO!!!!!!!!!!
Okay, I sat down. 1 2 3 4 5 6 7 8 9 10.
They simply swapped the tube positions. Been fine ever since.
God, I hate counting on other people.
Forrest
Yep, below freezing this AM; furnace worked fine all night.
Unbelieveable. Hasn't done that in years
Forrest - still bitter
Congratulations!
the bitternes will end...
'til the gas bill arrives
Liberty = Freedom from unjust or undue governmental control.
American Heritage Dictionary
Well for this we are seeing an improving customer service commitment.
Below from 05
George DavidTotal Compensation: $88.7 mil (#5) 5-Year Compensation Total: $210,793 thou
George David has been CEO of United Technologies (UTX) for 11 years. Mr. David has been with the company for 30 years . The 63 year old executive ranks 1 within Conglomerates
I'm happy to hear that the poor man is struggling through!
Forrest
Ah, Confucius say, better to be bitter than bitterly cold.Does this mean you'll be adding HVAC Repairfellow to your repertoire?
Ba-dump-bump!
Hey - I enjoyed dinner last Monday - hope DW enjoyed her take-out. Now I gotta look at all my imaginary friends as if they might be real!
I'm crawling under a big ol' house today (the client who called me at dinner) with my same HVAC guy - after long deliberation, we have decided NOT to go with Carrier equipment
Forrest
Hey Forrest,I enjoyed it as well; have to do it again next time you're up this way. DW loved the Pho, so I got extra points.How did you make out at your SIL's? Aside from the minor explosion. LOLBest,
Steve
Made out well. Finished the last thing on my list (sidewall shingling) at 10 PM Sunday night, then drove down to Solomons; drove home Monday.
Just got an e-mail; she's attempting to bribe us to do the same thing for Christmas vacation!
Forrest
Very good. If you wind up here for Christmas vacation be sure to let me know, and if you need a hand, I'd be happy to pitch in.
Bet the yahoo's at the factory were standing around saying..."those field guys think they are so smart, watch this!"
Not bad service after 15 years huh?
I'm pretty impressed that Carrier stuck with this problem a decade and a half after they sold the unit.
Jon Blakemore RappahannockINC.com Fredericksburg, VA
I'm not a tech but I did diagnose and repair a similar problem . If there is a draft problem the furnace will stop or short cycle. At this customers house someone had installed an ell on the pvc furnace vent and whenever the wind blew in a certain way it would cause insufficient draft and the furnace would shut off. Removed the ell and problem went away.