ReplyOn a number of furnaces, the ignition takes place at one burner and the flame sensor proves flame at the last burner. If you plug one of the orifices, your flame isn't going to carry across and furnace will not remain lit.
Regular Guest
On a service call to check out a newer 125,000 BTU 90+ furnace. It is running a supply temperature of 146 degrees and the blower is on medium high speed. The homeowner is complaining that the fan noise is bothering them. The furnace seems somewhat oversized and is short cycling when on. Is there any reason why we shouldn't plug one or more of the burners, reducing capacity to 100K or less, and then reduce fan speed to get nameplate temperature rise?
Professional Member
On a number of furnaces, the ignition takes place at one burner and the flame sensor proves flame at the last burner. If you plug one of the orifices, your flame isn't going to carry across and furnace will not remain lit.
Regular Guest
How about either blocking a center burner or if the furnace has provision for two positions for the flame sensor (like some Lennox's do), block and reposition flame sensor.
Professional Member*
I would not do this at all. Your right about the ignitor lighting the first burner & the sensor is on the last so if you blocked a middle one its gonna have a buildup of gas til it connects with the first 2 burners. It would likely blow out into the cabinet when it lit.
As far as moving the flame sensor, I would never do that. That gas valve is sending enough pressure to blow the fire through those 6 burners. If you plug one, its gonna blow a stronger flow through the other ones. the chambers might not be able to handle that much extra fire. If I was the contractor, i'd rather walk away than try something like this.
At the very least, ask the manufacturer. Even then I'd get em to give it to me in writing that its ok. I can guarantee you they wont do it though.
[Edited by hvac hero on 10-17-2005 at 09:04 PM]
Life is like a jar of jalapenos. What you do today might burn your ass tomorrow.
Professional Member
never block a burner. Most furnaces have derating kits you can buy to SAFELY derate them about 10%. Don't go anymore than that.
How much is it an hour?
Professional Member
Make sure the heat anticipator is set for longer cycles. If you plug a burner you are exposing yourself to a lot of liability. Dont do it.
Professional Member*
chances are the burner tubes not being use could start to condensate and cause prmature failure of the heat exchange
also to change the design and operation takes all the responsablitity on you and completly off the manufactor if something happens.
if the furnace is to big bring you thoughts to your bass and let him deside how to rectifie the problem
God Speed, Jim. We'll miss you - 2-26-23
See what size they REALLY need, and sell them a correct size furnace. And duct changes that may be needed.
Professional Member
How do you figure? (If you plug one, its gonna blow a stronger flow through the other ones.)
Just wondering/
Professional Member
" One idea I might try is partially closing the shutoff valve going into the furnace. Again I would want to ask the manufacturer, but this seems a lot less dangerous. All you would be doing is lowering the gas pressure going into the system."
Your not serious that this would lower pressure, are you?
Professional Member*
How about bringing the gas press down to 3hg?
Quality and Value Service and Repair
Professional Member*
sorry, didnt mean to respond to a question like this in the residential section
[Edited by hvac hero on 10-17-2005 at 09:06 PM]
Life is like a jar of jalapenos. What you do today might burn your ass tomorrow.
Professional Member*
....
[Edited by mo-flo on 10-17-2005 at 09:37 PM]
Professional Member*
...as far as noise,you may have to do something different with return location?I was told that if you plug burner then you have re-engineered furnace design and ul rating is void......
[Edited by mo-flo on 10-17-2005 at 09:38 PM]
Professional Member*
have to tell ya' though i'm probably not the best guy to listen to......
Professional Member*
How's about CALLIN' A FRIGGIN PROFESSIONAL, before you blow yourself up along with the houses on either side of you! Geeeesh!!
Everyone has a purpose in life..........even if it's to be a bad example.
Seek first to understand, before seeking to be understood.
Professional Member*
LMAO AMEN!!!!!!!! Sorry that I responded to the question when it was in the residential section John. Like I posted on your other thread, I assumed he is a technician/professional.Originally posted by John Lloyd
How's about CALLIN' A FRIGGIN PROFESSIONAL, before you blow yourself up along with the houses on either side of you! Geeeesh!!
Life is like a jar of jalapenos. What you do today might burn your ass tomorrow.
Grumpy Old Man
Even if it was, what do you think regulates the gas pressure? It's not the orifices!Originally posted by hvac hero
I assumed he is a technician/professional.
And the gas cock is just plain... well I think you get my point.
Most of the replies on this post are:
EXTREMELY DANGEROUS!!!!!!!!!!!!!!!!!!!!!!
Former Site Administrator- Now Retired
To everyone concerned
Review your posts... are we being careful?
Are we giving too much here that may cause harm?
This thread is way off base IMHO
Professional Member*
hvac: I have certainly been guilty in the past, but I force myself to be more careful, for a number of reasons.
Everyone has a purpose in life..........even if it's to be a bad example.
Seek first to understand, before seeking to be understood.
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