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#179944 - 08/06/08 08:50 PM Furnace disconnects  
M_Grabill  Offline
Member
Joined: Apr 2008
Posts: 11
Indiana
am in the process of having 30 furnaces changed out in some rental units and am in a bit of a disagreement with the HVAC guys about the disconnects. While we both agree that one is required, they want to remove the existing SSU's and just install a switch. I would like to leave the SSU's intact, but see the point that an accessible switch serves the purpose. So, I figured I would pose this question to you guys and see what your opinions and/or facts are.

Thanks in advance


"We can do it, you can't help" said my son to the HD guy

Building Codes & Related References

#179952 - 08/06/08 10:39 PM Re: Furnace disconnects [Re: M_Grabill]  
EV607797  Offline
Member
Joined: Oct 2006
Posts: 745
Fredericksburg, VA, USA
Please forgive me, but what do you mean by the acronym "SSU"?


---Ed---

"But the guy at Home Depot said it would work."

#179953 - 08/07/08 01:10 AM Re: Furnace disconnects [Re: EV607797]  
mbhydro  Offline
Member
Joined: Feb 2003
Posts: 347
Winnipeg MB Canada
Service/safety/switched shut-off unit?

I wonder if that is another name for disconnect?


#179973 - 08/07/08 06:53 PM Re: Furnace disconnects [Re: mbhydro]  
M_Grabill  Offline
Member
Joined: Apr 2008
Posts: 11
Indiana
SSU/SSY....the terminology escapes me at the moment, but it is the switch used as a disconnect that also incorporates a fuse block.


"We can do it, you can't help" said my son to the HD guy

#179975 - 08/07/08 07:25 PM Re: Furnace disconnects [Re: M_Grabill]  
EV607797  Offline
Member
Joined: Oct 2006
Posts: 745
Fredericksburg, VA, USA
Are these gas/oil units or electric? If gas/oil, then a standard switch will suffice. The existing disconnects can be reused, but I'd spend the extra couple of bucks and replace it with a new one. If it it an electric/heat pump unit, then that depends upon the manufacturer's name plate ratings as to whether a fused disconnect is required or not.


---Ed---

"But the guy at Home Depot said it would work."

#180307 - 08/21/08 10:57 AM Re: Furnace disconnects [Re: EV607797]  
Alan Nadon  Offline
Member
Joined: Mar 2005
Posts: 399
Elkhart, IN. USA
SSU is a switch and Edison base fuse holder on a handy box cover, manufactured by Bussman.
A switch only would work for the furnace.
The advantage of the SSU is that a T rated, time delay fuse with a setting close to the rating of the motor can be used to aford better protection than the branch circuit over current device.
I used one on my water well, going from a 20 amp circuit breaker to a time delay 8 amp fuse at the pump. It has been in service this way for over 25 years. The fuses cost about $ 3.oo each now but that is still a lot cheaper than a new pump motor.


Alan--
If it was easy, anyone could do it.

#180323 - 08/21/08 08:16 PM Re: Furnace disconnects [Re: Alan Nadon]  
HotLine1  Offline


Member
Joined: Apr 2002
Posts: 6,833
Brick, NJ USA
OK, now that Alan explained that one; I have not seen one of those in 20 years. Didn't know that Bussmann still made them!

Alan: Is it a true Edison base fuse, or a Fusestat?



John


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