Replacement for a Suburban NT30-K furnace?

[nickcrowhurst]

I contacted Suburban Customer Service today to ask which of their furnaces would be a suitable replacment for our NT30-K, which may be nearing the end of its economic life. I was told that the "three hole in the body" system of the NT30-K was obsolete, and that any replacement would require large amounts of work to the bodyshell, gas-lines and electrics, and might necessitate an external door in the bodyshell. I was told to look at the www.rvcomfort.com website, examine the range, and make my own decision. The modern NT30-SP looks to be a possibility. It is higher, but would just fit. It's not clear whether or not that would require an external door. Does anyone have any experience of the change I wish to consider? What is involved? Any other suitable furnaces?
Thanks in advance. Nick.

[Inland RV Center, In]

Nick.

Try what I suggested, before you buy another furnace.

But, if a new furnace is what you decide to do, a Suburban NT-30SP, is the proper replacement.

Andy

[Mike Leary]

Try what I suggested; vibration could be causing the noise, but I'd bet it's the motor.
Being full timers, we run the heck out of our Suburban and go through motors a lot.

[nickcrowhurst]

The 30-SP would be a very tight squeeze in my trailer, but I reckon I could probably just get it in for height. How about the 30-SF? It's much lower, has a front gas connection, and requires no exterior door. Would this work? Has any one installed one? Do the two tubes fit the spacing of the 30K?
Nick.

[Inland RV Center, In]

Originally Posted by nickcrowhurst

The 30-SP would be a very tight squeeze in my trailer, but I reckon I could probably just get it in for height. How about the 30-SF? It's much lower, has a front gas connection, and requires no exterior door. Would this work? Has any one installed one? Do the two tubes fit the spacing of the 30K?
Nick.

Nick.

No exterior door?

How does the exhaust exit the combustion chamber?

The NT 30 SP should be the same size as the NT-30 that you now have.

Andy

[nickcrowhurst]

Andy, our 30K is just over 9 inches high, but Suburban gives the height of the SP as 12 and a half inches:

Suburban > Products > Furnaces > NT Series Furnaces > Maximum heating power for large RVs > Dimension Chart

By exterior door, I presume Suburban means the large access door on the exterior through which some model furnaces can be serviced. This is not the same as the small orifices for the exhaust tube(s).
On the same website, the SF-30F looks interesting:

Suburban > Products > Furnaces > SF Series Furnaces

The furnace is very low at 7.5 inches, but the width increases to 17 inches. Our available space is 12.5 high by 20 inches wide. The width might be tight for fitting the duct collars. The front to back dimensions are not an issue.

Suburban > Products > Furnaces > SF Series Furnaces > Dimension Chart

The SF-30SF offers interior fitting and servicing, no exterior door required, and front propane and electrical connection, which are the characteristics of our current NT30-K. I need to get more detailed dimensions from Suburban to get the precise location of the exhaust and inlet tube orifices. I much appreciate your interest.
Nick.

[nickcrowhurst]

I've attached the installation manual for the SF-30SF, received today from Suburban. This low profile model has two vent tubes in the same vertical spacing ( 3 3/8") as those of my NT 30K, and they are both on the left side viewed from inside, whereas the 30SP has vent tubes on the right. The third vent can be fitted with an invisible blanking plate behind the existing facade, leaving the exterior appearance unchanged. I conclude that for my particular trailer, the SF-30SF is probably appropriate. Nick.

[Skatiero]

Nick, did you end up going with the SF-30?

[nickcrowhurst]

Originally Posted by Skatiero

Nick, did you end up going with the SF-30?

I did not replace the furnace as I finally cured my noise problem by dismantling the motor and oiling the felt bushes:

http://www.airforums.com/forums/f427...ace-60957.html

It's worked perfectly for three years since the oiling.
Nick.

[Skatiero]

That's great to know!

[pt1949]

Originally Posted by Mike Leary

Try what I suggested; vibration could be causing the noise, but I'd bet it's the motor.
Being full timers, we run the heck out of our Suburban and go through motors a lot.

Mike - where do you get replacement motors from - mine runs for about 15 minutes and then starts to slow down. They tell me you can't get the NK 30 motor?? Any help please

[Skatiero]

The Nt-30 motor is still available. Here is a link. It's available at other sites as well.

https://www.americanrvcompany.com/Su...per-Trailer-RV

Rob

[Skatiero]

Here is a link to a suburban service manual. Hope it helps.

http://bryantrv.com/docs2/docs/ntseries.pdf

Rob

[coloradopete]

I have recently replaced the furnace in my 1988 Excella 25'. It was the NT30-K by Suburban. It still functions, but is not reliable. Will complete the start-up cycle and the flame may or may not be there. The fan motor still runs well. The igniter works every time, and once in a while the flame is there. I have replaced the limit switch in March 2015.

I would like to sell this furnace to anyone who is interested, as long as you understand the unit is NOT reliable. I am adding photos of the unit.

[nickcrowhurst]

It would be helpful to some forum members, including me, if you would be kind enough to detail the replacement model furnace, and any tips you might have on the conversion. Thank you in anticipation.
Nick.

[coloradopete]

My trailer is the 1988 Airstream 25' Excella.
I have just completed the replacement of the NT30-K with the Suburban NT30-SP. The new model fit into the space of the old version very nicely. I did need to enlarge the opening in the inner wall for the furnace housing and cut two holes in the outer skin of the trailer for the intake/exhaust pipes. On the outside, I left the 2 holes (on the right) of the old unit covered with the old plate, for appearance, after plugging those holes. With the furnace in place, I then located the points for the 2 new holes and found that the location of the third hole of the old unit (on the left) was mis-aligned. I used a piece of 1/8" thick aluminum sheet, 6" x 8", to cover that hole, then cut the 2 holes for the new unit. Tools used: Small Dremel hand tool; hand drill; hand held jig saw with fine tooth blade. Used plumber's putty for the exhaust cover plates.

As the propane gas outlet is located on the opposite side of the new furnace, I used a piece of hose (made for propane) to make that connection. The hose is 22" long which assures it will not touch any part of the hot furnace housing. Be sure to test all new gas connections for leaks!

I also had to trim the wood cabinetry a little to permit the heat duct tubes to connect to the furnace duct outlets without undue stress. This is to the right of the furnace, inside that compartment.

I am favorably impressed with the performance of the new furnace: quiet, lots of heat, and starts quickly. I urge you to read the installation instructions very carefully and follow them to the letter!

[nickcrowhurst]

Very useful and complete information, thank you. I have the same year and model trailer, and expect any year soon to have to make this replacement.
Nick.