# A question for you.



## ICE (Aug 27, 2011)

NMC enters the bottom of the furnace and then to the outlet box mounted on the top.  The snap switch is the disconnect for the furnace.

Would you allow this?


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## Msradell (Aug 27, 2011)

No, this unit is designed to operate mounted vertically.  The flame pattern from the burners will not properly impinge on the heat exchanger when it's mounted in this orientation.  Also the flow of fumes to the vent will not flow properly causing a potential for CO to enter the residence.


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## ICE (Aug 27, 2011)

Msradell said:
			
		

> No, this unit is designed to operate mounted vertically.  The flame pattern from the burners will not properly impinge on the heat exchanger when it's mounted in this orientation.  Also the flow of fumes to the vent will not flow properly causing a potential for CO to enter the residence.


Gosh I hope you are wrong about that.  I will be going back for corrections and I will check it out.  If you are right, I'll be back to thank you.

Tiger


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## peach (Aug 28, 2011)

usually the nameplate is the hint to the orientation.  A snap switch can usually be the disconnect.


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## Msradell (Aug 28, 2011)

I did some further research today in appears that Trane does make some units that can be operated both horizontally and vertically, I wasn't aware of that.  You will certainly need to consult the manuals for that unit to verify the installation meets the requirements specified by Trane.  As mentioned by peach, the snap switch for the disconnect an acceptable in most jurisdictions.


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## ICE (Aug 28, 2011)

Msradell said:
			
		

> I did some further research today in appears that Trane does make some units that can be operated both horizontally and vertically, I wasn't aware of that.  You will certainly need to consult the manuals for that unit to verify the installation meets the requirements specified by Trane.  As mentioned by peach, the snap switch for the disconnect an acceptable in most jurisdictions.


I will certainly be checking the orientation.

I don't question the use of a snap switch but it's location has me wondering.


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## steveray (Aug 29, 2011)

"location has me wondering."

Actual physical position? or the fact that they ran NM through the unit?


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## codeworks (Aug 29, 2011)

i don't get the pictures 'cause i'm on a municipal system that blocks them. as long as the motor is stationary, which i'm guessing it is and les than 2 hp, a snap switcvh is ok for a motor controller. NEC '08 section 430.83 © (1) and (2)


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## ICE (Aug 29, 2011)

steveray said:
			
		

> "location has me wondering."*Actual physical position? or the fact that they* *ran NM through the unit?*


For many years we wouldn't allow a cord and attachment plug as the disconnect because the units aren't listed with a cord and plug.  Now we allow it.

I am not so sure that utilizing the furnace as a raceway is appropriate and I am quite sure the unit wasn't listed with an outlet box mounted as shown.  To allow this leaves it open to place the outlet box anywhere on the unit.  It could be that I am being picky but since I'm not sure, I guess I'll be picky.


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## codeworks (Aug 29, 2011)

i'm guessing if nm is run through the unit, it's run "through the plenum", not permitted, it should be mc cable


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## chris kennedy (Aug 29, 2011)

440.14 allows the disco to be on the unit. As far as the wiring method passing through, think about RTU's, quite common.


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## ICE (Aug 29, 2011)

chris kennedy said:
			
		

> 440.14 allows the disco to be on the unit. As far as the wiring method passing through, think about RTU's, quite common


440.14 does indeed say the disconnect can be on or even within air conditioning equipment.  It goes so far as to say where it can't be located such as a removable panel or over the nameplate.  The implication is that it can be field installed.

Now what about the listing?  It seems problematic to allow any location other than a panel or nameplate.

What is a RTU?


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## pyrguy (Aug 29, 2011)

R oof

T op

U nit

Usually self contained (package) HVAC systems


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## ICE (Aug 30, 2011)

chris kennedy said:
			
		

> 440.14 allows the disco to be on the unit. As far as the wiring method passing through, think about RTU's, quite common.


Chris,

With a RTU the disconnect is mounted to the equipment or it is built into the equipment.  In either case, conduit brings power to the disconnect.  The conduit wouldn't hit the equipment on one side with the disconnect on the opposite side and the conductors passing through the housing to get to the disconnect.  At least I don't recall seeing such an arrangement.

Logically, I think there must be control of where a disconnect is mounted to the equipment rather than stating that since the code allows the disconnect mounted to the equipment, anywhere is OK.


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## Pcinspector1 (Sep 1, 2011)

codeworks sez: "i don't get the pictures 'cause i'm on a municipal system that blocks them."

It's a picture of a real hottie laying on her side, she's pretty hot, to bad you can't see the picture codeworks!

pc1


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## cda (Sep 1, 2011)

'''''''''''''''''''''◦Convertible to Horizontal'''''''''''''''''''

http://www.acservicenow.com/products/gas_furnaces/xl80.html

if this is the model in the picture

but what do you have to do to convert??????


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## peach (Sep 3, 2011)

the codes are a minimum.. if the code is silent and the manufacturer is silent, you need to accept... not what we "like" or "want to see"...


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## ICE (Sep 3, 2011)

peach said:
			
		

> the codes are a minimum.. if the code is silent and the manufacturer is silent, you need to accept... not what we "like" or "want to see"...


I understand the concept and debunk it.  On more than one occasion, I have come across something I didn't like that was not addressed by the code or the manufacturer and I ruled against it.  Subsequent discussions with the Chief {insert discipline here} Engineer and or the manufacturer have upheld my decisions.  I have written corrections after UL and third party listings and been upheld.

I get paid to question everything.  Clearly, my opinion counts, as is true with every inspector.  Inspectors are not automatons.  As great as the codes are, they are not perfect.  That which is not mentioned in code or mnf. instructions is not to be shunted off to an automatic acceptance.  Lawyers remark that the absence of evidence is not evidence of absence.  Just because it's not there, it doesn't magically become unimportant.

If nothing else, I learn from the questions.


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