Reply
 
Thread Tools Search this Thread Display Modes
 
Old 10-15-2011, 04:56 PM   #1
2 Rivet Member
 
Bethany533's Avatar
 
1983 30' Airstream 300
Covington , Louisiana
Join Date: Aug 2011
Posts: 54
Furnace Replacement

I have a Suburban NT-30 S furnace that needs to be replaced. I've read through many of the old posts to get some background info. From what I understand the Suburban NT30SP or NT34SP would be the correct replacement. I recenlty acquired my 1984 300. I've never used the furnace so not sure if would be best to upgrade to the 34,000 BTU or just stick with the 30,000 BTU. Any thoughts?
__________________

__________________
Bethany533 is offline   Reply With Quote
Old 10-15-2011, 06:06 PM   #2
Site Team
 
Aage's Avatar
 
1974 31' Sovereign
Ottawa , ON
Join Date: May 2008
Posts: 11,204
Images: 25
Interesting thing about the three Suburban furnaces: from the spec sheet, the only difference apart from the BTU input (heating power) is the current draw of the fan motor. They all weigh the same, have the same dimensions, look the same.

So, there's the 30k and the 34k models. My '74 Sov has a 32k, so I felt that there couldn't be a huge difference in what a 30k OR a 34k could do heat-wise. I live in a colder climate, but I don't live through the winter in it. Spring and fall, I just wanted to extend the time I could spend in the trailer.

So, the current draw on the 30k model is 4.5 amps, and the 34k is 7 amps. I wanted the quietest one I could have, so I took the 30k.

I hope I chose right!
__________________

__________________
“Courage is being scared to death, but saddling up anyway.”
...John Wayne...........................
Aage is offline   Reply With Quote
Old 10-15-2011, 06:42 PM   #3
Full Timers/Diesel power.
 
Mike Leary's Avatar
 
1983 31' Airstream310
Cactus Hug , Arizona
Join Date: Mar 2007
Posts: 2,540
Images: 11
The lag with Suburbans and our need for heat is to order too large of a unit which does not provide proper cooling of the housing. In other words, if the furnace has four knockouts for distribution, you better use them. If you use only two or three, get set for big fun with the high limit switch and everything else. Oh, by the way, I know the hard way and the tech that installed it has heard nothing but guff from me.
__________________
"A settled wisdom, plus the itch to be elsewhere"
Mike Leary is offline   Reply With Quote
Old 11-21-2011, 08:03 PM   #4
2 Rivet Member
 
1972 31' Sovereign
1979 29' Ambassador
west monroe , Louisiana
Join Date: Oct 2011
Posts: 81
Existing Housing

I'm sorry, but I thought this might be an appropriate jumping on place. I am a new member who recently acquired a 1972 Int'l Sovereign. I probably paid too much for it ($6,500) as I have found a few items that need repair or replacement. I removed the Suburban NT-30 S furnace after finding that the burner tube was rusted out. A factory Airstream tech emailed that a NT30SP was the correct up-grade for it. Because of the very tight space next to the original water pump, I decided not to remove the furnace housing. Instead, I want to purchase another furnace and insert the new 'guts' into the existing housing. Can anyone tell me for sure that the 'guts' of the new NT30SP will slide into the existing housing AND match up to the exterior inlet/exhaust holes? Thanks for any helpful responses you can offer.
__________________
litlgeezer is offline   Reply With Quote
Old 11-21-2011, 08:25 PM   #5
Rivet Master
 
1974 Argosy 20
2014 20' Flying Cloud
Kooskia , Idaho
Join Date: Jul 2009
Posts: 4,591
Quote:
Originally Posted by litlgeezer View Post
I'm sorry, but I thought this might be an appropriate jumping on place. I am a new member who recently acquired a 1972 Int'l Sovereign. I probably paid too much for it ($6,500) as I have found a few items that need repair or replacement. I removed the Suburban NT-30 S furnace after finding that the burner tube was rusted out. A factory Airstream tech emailed that a NT30SP was the correct up-grade for it. Because of the very tight space next to the original water pump, I decided not to remove the furnace housing. Instead, I want to purchase another furnace and insert the new 'guts' into the existing housing. Can anyone tell me for sure that the 'guts' of the new NT30SP will slide into the existing housing AND match up to the exterior inlet/exhaust holes? Thanks for any helpful responses you can offer.
Probably not. Although the box size may be the same, the new ones have a different electrical connection system, different cooling vent holes for the electronic ignition, and usually a different gas inlet location from the one you have in a '72. The outside inlet and exhaust tubes probably are in the correct location.

I would recommend you consider changing both the guts and the box both. It is not difficult to remove the box, it is generally held in with only two screws in the bottom, near the front. It will slip right out, assuming that you are not one of the unlucky ones with a furnace with a shelf on top of it, and a bar in front of it.

Let us know how you make out.
__________________
idroba is offline   Reply With Quote
Old 11-21-2011, 08:30 PM   #6
3 Rivet Member
 
1969 27' Overlander
Albuquerque , New Mexico
Join Date: Sep 2011
Posts: 168
I just went through these same issues with my new Suburban furnace I put in my '69 Overlander, so here's my 2 cents:
First: The original Suburban furnace and the new replacement units are NOT one-for-one. You won't be able to re-use the old housing, the furnace duct doesn't line up, and the inlet/exhaust is at a different elevation. You'll have to frame up a pedestal to mount the new unit, and fabricate some duct. No big deal, you can do it. It will take at least a day or two, if you're handy with tools. Be prepared for a real hassle connecting the propane fitting. It's right at the bottom corner (?!?).
Second: the actual furnace (enclosure, fan, heat exchanger, etc) is pretty good quality, but the electronics are NOT. Plan on replacing the original control board with a new "Dinosaur" board pretty quickly. The OEM board material and components are cheap, which is surprising, because the board is manufactured by Fenwall. (Fenwall used be be outstanding in the controls industry.) I had nothing but problems with the old board, which was traced back to a $0.50 connector and a bowed circuit board. So I spent another $150.00 on a replacement control board.
Third: Suburban's "customer support" is the WORST. Their response to my problem was "We can't help you trouble-shoot any gas appliance, and you can't send anything back to us. You have to take it to one of our "authorized" repair centers for warranty service, which we only pay a flat rate and you're responsible for the rest. Sorry." Good thing I was an electronic tech in a past life, or I would have tossed the whole furnace in the street and bought an Atwood.
Fourth: Use the same BTU rating as the old unit. Don't go bigger or you'll have the unit shutting down. It must have the proper airflow to keep itself cool. Remember, when it's heating, IT'S ON FIRE !!!!
Fifth: I promised the nice lady at Suburban that I would tell everyone I could about their poor customer service. She seemed amused.
So, there you have it.
__________________
edglenn is offline   Reply With Quote
Old 11-21-2011, 09:02 PM   #7
2 Rivet Member
 
1972 31' Sovereign
1979 29' Ambassador
west monroe , Louisiana
Join Date: Oct 2011
Posts: 81
Idroba, I certainly will entertain your suggestion. The one screw on one corner of the housing, next to the outer water, seems to be impossible to get to, without removing the water pump assembly - and, even the pump assembly is going to be a real chore to remove and replace. Thanks.
__________________
litlgeezer is offline   Reply With Quote
Old 11-21-2011, 09:08 PM   #8
1 Rivet Member
 
1972 27' Overlander
Marietta , Georgia
Join Date: Aug 2011
Posts: 5
Check this out
__________________
Island Time is offline   Reply With Quote
Old 11-21-2011, 09:09 PM   #9
1 Rivet Member
 
1972 27' Overlander
Marietta , Georgia
Join Date: Aug 2011
Posts: 5
I just did this. I hope the pictures help!
__________________
Island Time is offline   Reply With Quote
Old 11-21-2011, 09:09 PM   #10
2 Rivet Member
 
1972 31' Sovereign
1979 29' Ambassador
west monroe , Louisiana
Join Date: Oct 2011
Posts: 81
Thank you Edglenn for your informative reply. To save the $$ and the aggravation, I may just settle on replacing the existing catalytic heater. It too, is not working properly. It lights and seems to start working fine. Then, I hear an 'internal' bump sound and the fire immediately begins to die out. Evidently, the gas valve has shut itself off for some unknown reason. Thanks.
__________________
litlgeezer is offline   Reply With Quote
Old 11-21-2011, 09:14 PM   #11
1 Rivet Member
 
1972 27' Overlander
Marietta , Georgia
Join Date: Aug 2011
Posts: 5
I did use the old box as the plennum. I cut part of the original cover to make the duct transition. I bought my new system from California. Less than 600$ I spent about 8 hours doing the new install. The tools were a great exspense. However, they are tools to be used on other projects.
__________________
Island Time is offline   Reply With Quote
Old 11-21-2011, 10:37 PM   #12
3 Rivet Member
 
1969 27' Overlander
Albuquerque , New Mexico
Join Date: Sep 2011
Posts: 168
Litlgeezer,
I wouldn't want to discourage you from replacing the furnace. They're the best for primary heat. The catalytic unit is fine for backup, but the furnace is the only way to go. I can't say Atwood is any better, I haven't used one.
The "bump" you hear on the catalytic is probably the safety. The heat sensor tube, or thermistor, thinks the flame has gone out and shuts the valve off, depending on what model you have. Pretty simple replacement.
__________________
edglenn is offline   Reply With Quote
Old 11-21-2011, 11:07 PM   #13
RGates
 
Randy Gates's Avatar
 
1968 20' Globetrotter
Thousand Oaks , California
Join Date: Apr 2010
Posts: 124
Would you consider a different Heater?

I went through just what you are going through. I have a 1968 Globetrotter and researched the same equipment. I ended up going with a catalytic heater and mounted it higher up where it heats more efficiently. Mine is a 20 foot. These are very safe units, no worry about CO2 with these. Take a look before you invest in the Suburban. Just a thought.
Randy
__________________
Randy Gates is offline   Reply With Quote
Old 11-22-2011, 10:48 AM   #14
3 Rivet Member
 
1969 27' Overlander
Albuquerque , New Mexico
Join Date: Sep 2011
Posts: 168
CAT vs. Suburban furnace?

Yeah, mine's a '69 Overlander. Love the CAT heater. They work great. Have one in my Mohawk, too.
You DO have to have a small amount of combustion air, however. The CAT does create CO. There's a calculation for the vent area on the Wave site, somewhere. I guess the AS isn't airtight enough to be a problem, but you're supposed to crack a vent!
I think a 2-3" round bird-screen should work, adjacent to the door.
Here's one at my battery compartment (ignore the lack of polish, still in progress!):
Click image for larger version

Name:	Vent_2inch.JPG
Views:	99
Size:	133.1 KB
ID:	145791

I still prefer the furnace. Can set the T-stat, and leave it overnight.
__________________

__________________
edglenn is offline   Reply With Quote
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Furnace Replacement Bethany533 Classic Motorhomes 17 03-08-2013 06:42 PM
Duo-therm and furnace question... NoMoSOBs Furnaces, Heaters, Fireplaces & Air Conditioning 13 10-21-2011 10:17 AM
Suburban furnace trying to kill me? icebox500 Furnaces, Heaters, Fireplaces & Air Conditioning 4 07-31-2011 11:21 PM
Need advice on furnace. SilverRanger Furnaces, Heaters, Fireplaces & Air Conditioning 5 05-28-2011 04:47 PM
Suburban furnace replacement for '66 Trade Wind Ben in MT Furnaces, Heaters, Fireplaces & Air Conditioning 0 05-17-2011 09:12 PM


Virginia Campgrounds

Reviews provided by




Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -6. The time now is 11:05 AM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.

Airstream is a registered trademark of Airstream Inc. All rights reserved. Airstream trademark used under license to Social Knowledge LLC.