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Old 06-24-2021, 12:24 PM   #1
Join Date: Aug 2012
Posts: 60
Suburban Furnace replacement

Hi All,
Looks like we're about to replace our furnace.....thirty years old and "obsolete" NT-45s. Seems to have been the only one ever built with two burners, and two exhausts; so three holes through outside wall (2 exhaust 1 fresh air to combustion). Found one other fellow with one on an older Executive.....mine is Crown Royale...who was having issues with motor. Wish I could get him mine for parts....motor was replaced in early 2000s when still available and is good.
Anyway we've decided to give up on antique, discontinued unit and get a new one, and I'm wondering if anyone has experience with the park models...specifically the Suburban 2456A also known as P-40. We only use the thing when plugged in, and I suspect 120 volt motor would make fan stronger...always an issue with old one. The unit is apparently identical to the 12 volt NT-40 so I would love to hear from anyone with experience with those as well. All comments, reviews, or general scuttlebutt greatly appreciated!
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Old 06-24-2021, 02:14 PM   #2
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Location: Capistrano Beach, California
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Originally Posted by ROADOG View Post
Hello to All,
Any suggestions on a replacement for discontinued Suburban NT-45s? Only one I've seen that was a "three holer" so I know I'll have to modify outside wall panel...GROAN!!! Oh well I live to tinker. So far looking at Suburban NT-40 or maybe the "park model" version of same hoping for a stronger fan. All thoughts appreciated.
Have you diagnosed the cause of failure? Maybe it would be easier to replace the failed parts rather than buy a complete new furnace if a 45K BTU is desired.
Larry, Eileen, and Finley
2004 Alpine 36FDDS
Third motor home, first Alpine, no need for another.
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Old 06-24-2021, 10:13 PM   #3
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NT-40 And P-40.....same furnace except NT-40 is all DC and the P-40 uses 120VAC for Motor and24VAC transformer for controls/functions

Same 40K btu and Air flow is SAME 441 CFM

Service Manual

Suburban NT-40 may still be available

Higher cost (roughly $200 more)
Need 120VAC Circuit ...CB, Wiring

Some parts still available but most related to burner assembly are No Longer Available
Very little info about the NT-45s exists any more
Is it time for YOUR Medication or Mine?
Dodge 3500 w/Tractor Motor & NUWA 5vr
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Old 06-25-2021, 07:00 AM   #4
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I think you may have an issue with the 120v model if you use a common thermostat for both the 120v unit uses a thermostat that is powered by 24v and your thermostats currently are powered by 12v
New to us 2000 Monaco executive 40 500hp tag
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Old 06-27-2021, 01:26 PM   #5
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Thanks to those who have responded. We are probably giving up on the park model. Is there anyone out there who has an NT-40 who whishes to say what they think of it? We've seen reviews that comment on noise and build quality...and not in a good way! Any suggestions on other units to consider as a suitable replacement for the old 45,000 BTU unit? Does anyone other than Suburban make an RV unit this size?
Thanks Again,
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Old 06-27-2021, 04:45 PM   #6
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You might want to make a call to Visone.RV salvage yard.. 606 843 9889 they might have a suggestion..
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Old 06-27-2021, 06:51 PM   #7
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I replaced mine with a diesel heater look on YouTube about them some like them some donít.
New to us 2000 Monaco executive 40 500hp tag
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Old 06-29-2021, 04:17 PM   #8
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Diesel fired heater

Thanks for the suggestion. We're getting VERY interested in this idea, partly because we continue to get more disgusted with Suburban. They seem to be almost the only game in town, particularly in larger sizes, and they act like it. You can buy a new free standing gas range with four burners and an oven for less than half what they want for the oven! OK it has a 12 volt fan blowing air past it, woooo.... We got into this because our old unit was discontinued so long ago that replacement parts completely unobtainable, and now we have learned, from their customer service, that the NP-40 has, as of last week, been discontinued as well! Though they assure us that parts will be available for 10 years. Whatever.

ONWARD TO DIESEL We have a diesel coach with a large tank, so that's pretty easy. Still working on how many and where we could put them, whether or not we could tie them/it into existing ducts etc. The first thing of course is the big the "real thing" Webasto etc. or the Chinese knock off question. As we are not made of money, we are leaning pretty hard toward the Chinese version. Anyone know of anything in between the $150 and the $1500 extremes? I've been watching you tube all day, and while everyone has great respect for the German versions, there are several folks who make strong arguments for the cheapies and point out that a great many of the problems that have cropped up are the result of really sloppy installs.

I would love to hear from anyone who has made the conversion, and or has long experience with the diesel heaters in general, and the Chinese models in particular.
Thanks to all,
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Old 06-30-2021, 12:11 AM   #9
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I installed a Chinese unit, kind of an odd install on its side with the glow plug up. Others have said this is ok.

I originally installed connected to the original duct work but have issues with the ducts so for now the output is one tube out and I point it toward the back or front of the coach depending on where we are at.

It came with a remote and we have electric mattress pad so if itís not to cold we will turn it on the morning and warm up the rear of the coach (about 15-20 min then switch it to the front of the coach.

The one unit has kept the coach comfortable down into the 20ís at night left on any colder and the big round things on the bottom of the coach will start turning. I have a thread about my install on the site so look for it. We where at quartzsite this last year and there was a cold rainy day it worked just fine to keep the entire coach warm.

I think the power draw is about the same as keeping the old furnace on but the fan runs constantly at a lower speed. So I think itís quieter than that big fan on the old furnace that would turn off and on we find it to be a good white noise. I recommend putting the fuel pump in a basement compartment to reduce the ticking noise that is also on my list but you get used to it.

We also use a fan to move the hot air around the temperature coming out the duct is hot really hot and the fan helps move the heat around this has helped keeping the front of coach warm on cold days. If connected to the ducts I think it would not be needed.

Regarding Chinese vs not, I figure I can replace my unit at least 4 times and still pay less than the others.

My next move is to fix the ducting and install a diverter for back and front if only to boost the temp rise after a cold night.

All in all I am happy with it my install was due to the removal of my furnace for a residential refrigerator install.

Vito has a video on YouTube about his install of course he did the name brand but got it for free I think.

I have a 40í coach I think one unit would work fine for you unless your in the low low temperatures for all day. But best to try one you can always add another and your cost to buy and install is low (from Amazon) if it does not work out return it.
New to us 2000 Monaco executive 40 500hp tag
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ace, furnace, replace, replacement, suburban

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