TrailManor Owner's Forum - View Single Post

04-09-2010, 06:40 PM

Well, Cochise, I have similar problems, but I'm not sure if it's a return airflow problem in my case.

First, I've had a closer look at our Elkmont's furnace and its manuals and am a bit confused. According to these manuals, our furnace is a NT-20SE. The serial # on the manual and on the furnace match. I could not find any model # on the furnace.

The problem is that the Suburban NT-20SE is supposed to have a large rectangular (~10"x10") louvered grill covering the end opposite the end with the combustion intake & exhaust pipes through which most of the heat exhausts. It also has a single, round 4" opening on the side that can be used in addition to the main grill. But ours has a blank cover instead of the grill, and the single 4" side opening is all that feeds heat to both the bathroom and living area.

By contrast, the NT-20S is not supposed to have a rectangular end grill but, I believe, *two* side 4" openings. The bryantrv.com web site has a couple of Suburban furnace manuals, one of which has a table (the upside down one on p.12) listing the NT-20S and NT-20SE clearances and duct requirements. The 20SE model has "special clearances for discharge grills", the 20S requires two 4" round ducts with a total of 25 sq in discharge area and 55 sq in of return area. There is no return area specified for the 20SE but I imagine it is the same as the 20S.

I don't see any cutouts for another 4" duct on ours, so I really do think it must be a 20SE with what is supposed to be the louvered end closed off.

Also, according to the manuals we received, the return intake for the NT20SE is through louvers in the two sides and top near the end with the combustion intake & exhaust pipes, and through the end itself when that is separated from the trailer wall. Our installation has one side covered but good access to the other side, top and end. So as long as return air can get under the setee, it can get into the furnace ok. And there do seem to be enough gaps and vents for air to get under the setee in our installation, although we would prefer that more of the return air came from the bedroom area than the dining area. This would improve circulation and reduce re-heating of already heated air.

So our heating problem seems to be inadequate discharge vent area and inefficient recirculation. It seems to me that the discharge vent area should be at least what the NT-20S requires, two 4" vents or 25 sq in. And the ~10"x10' louvered grill of the NT-20SE probably has more ... closer to 50 sq in.

I'll be contacting Trailmanor about this next week. We'll see what they say.

Oh, and the furnace was not screwed to the floor after all. But they had boxed it in sufficiently to make it tight. Still ...

04-09-2010, 06:40 PM	#30
brulaz Guest Posts: n/a	Well, Cochise, I have similar problems, but I'm not sure if it's a return airflow problem in my case. First, I've had a closer look at our Elkmont's furnace and its manuals and am a bit confused. According to these manuals, our furnace is a NT-20SE. The serial # on the manual and on the furnace match. I could not find any model # on the furnace. The problem is that the Suburban NT-20SE is supposed to have a large rectangular (~10"x10") louvered grill covering the end opposite the end with the combustion intake & exhaust pipes through which most of the heat exhausts. It also has a single, round 4" opening on the side that can be used in addition to the main grill. But ours has a blank cover instead of the grill, and the single 4" side opening is all that feeds heat to both the bathroom and living area. By contrast, the NT-20S is not supposed to have a rectangular end grill but, I believe, two side 4" openings. The bryantrv.com web site has a couple of Suburban furnace manuals, one of which has a table (the upside down one on p.12) listing the NT-20S and NT-20SE clearances and duct requirements. The 20SE model has "special clearances for discharge grills", the 20S requires two 4" round ducts with a total of 25 sq in discharge area and 55 sq in of return area. There is no return area specified for the 20SE but I imagine it is the same as the 20S. I don't see any cutouts for another 4" duct on ours, so I really do think it must be a 20SE with what is supposed to be the louvered end closed off. Also, according to the manuals we received, the return intake for the NT20SE is through louvers in the two sides and top near the end with the combustion intake & exhaust pipes, and through the end itself when that is separated from the trailer wall. Our installation has one side covered but good access to the other side, top and end. So as long as return air can get under the setee, it can get into the furnace ok. And there do seem to be enough gaps and vents for air to get under the setee in our installation, although we would prefer that more of the return air came from the bedroom area than the dining area. This would improve circulation and reduce re-heating of already heated air. So our heating problem seems to be inadequate discharge vent area and inefficient recirculation. It seems to me that the discharge vent area should be at least what the NT-20S requires, two 4" vents or 25 sq in. And the ~10"x10' louvered grill of the NT-20SE probably has more ... closer to 50 sq in. I'll be contacting Trailmanor about this next week. We'll see what they say. Oh, and the furnace was not screwed to the floor after all. But they had boxed it in sufficiently to make it tight. Still ...