Reply
 
Thread Tools Display Modes
Old 02-09-2019, 07:31 PM   #1
Site Team
 
Mr. Dan's Avatar
 
Join Date: Mar 2014
Location: Grayson County, Texas
Posts: 11,112
Gaping opening in Furnace

Quote:
Originally Posted by Larry-NC View Post
I had this exact situation. It would even light if I left the plenum cover (sheet metal that covers the heat exchanger) open. If I installed that cover, it would not light. It turned out to be a failed propane regulator at the tanks.

More detail:
The first thing the Suburban manual tells you to check is the propane pressure at the furnace. I ignored that because:
  1. The range worked okay/
  2. The water heater worked okay.
  3. I didn't have a gauge to measure 11" water column (0.4 psi)
After wasting hours of time trying other things, I finally spent 60 minutes building a gauge (picture on request) and discovered the regulator was out of wack. Attempting to adjust it caused a strong smell of propane, telling me three things:
  1. The regulator diaphragm had developed a hole.
  2. The life of a regulator really is ten years, just as everyone tells you.
  3. DW probably should have put a new shroud on the regulator and tanks when the old one fell apart.
Everything worked fine with a new regulator.

Larry
Moved from another thread to cure my high-jack!
Larry, in the pic I'm attaching, is the hole in my furnace where you're saying my plenum cover goes? Last fall, we were running our furnace (which we rarely do) and DW told me warm air was coming OUT of big air return grate. I found this hole open - no cover ever on it since we've owned it. I guess I should just get a piece of sheet metal and attach it to cover that hole. Right?
Attached Thumbnails
Click image for larger version

Name:	IMG_1114.jpg
Views:	257
Size:	262.7 KB
ID:	196449  
__________________

__________________
SEARCH is your friend!
FR Wildcat 295RSX / GMC Sierra

Nights Camped: '13 = 49/'14 = 74/'15 = 74/'16 = 85/'17 = 110/'18 =111/'19 = 40; booked = 14
Mr. Dan is online now   Reply With Quote
Old 02-09-2019, 08:03 PM   #2
Senior Member
 
Join Date: Jan 2018
Location: Raleigh, NC
Posts: 1,470
Plenum cover

Quote:
Originally Posted by Mr. Dan View Post
Moved from another thread to cure my high-jack!
Larry, in the pic I'm attaching, is the hole in my furnace where you're saying my plenum cover goes? Last fall, we were running our furnace (which we rarely do) and DW told me warm air was coming OUT of big air return grate. I found this hole open - no cover ever on it since we've owned it. I guess I should just get a piece of sheet metal and attach it to cover that hole. Right?
Mr. Dan,

The plenum is the big box that surrounds the firebox (flame is inside the firebox). The plenum cover is that rectangular piece of sheet metal (maybe 8" x 24") on the front of the furnace. There's a baffle (partition) near the back which separates the return area and blowers from the plenum/heat exchanger. You have to take the plenum cover off to slide out the firebox/blowers/controller assembly.

The plenum itself is like an electrical junction box in that it has knockouts on the front and sides and bottom where ducts could be attached. Holes in the back are where air going through the return air grate enters the blower, to be blown into the plenum.

I couldn't make sense of your photo, but your description sounds like the installer punched out a knockout he never used. If that's the case, you would close it off. Duct tape for a temporary fix.

For something more permanent, if you have space you could pop-rivet a piece of sheet metal across the hole, working from the outside. If you don't have working room on the outside, you could take the firebox/blowers/controller assembly out and pop-rivet a piece of sheet metal to cover the hole from the inside. It's not as big a job as it sounds.

EDIT
Looking at the photo again, I realized you were talking about the perforated area at the back part of the case. (Actually that back part is the intake area. The plenum is the unpierced part forward of the grating.) That's where return air goes in. Don't restrict it. In fact the Suburban Installation manual dictates how many square inches must be open. If you run the furnace and hold a dollar bill over that grating, you will find that it's sucked to the grating, not blown away. But while you are in there, you might be able to see where the warm air is coming from.


Larry
__________________

Larry-NC is online now   Reply With Quote
Old 02-09-2019, 08:16 PM   #3
Site Team
 
Mr. Dan's Avatar
 
Join Date: Mar 2014
Location: Grayson County, Texas
Posts: 11,112
Quote:
Originally Posted by Larry-NC View Post
Mr. Dan,



The plenum is the big box that surrounds the firebox (flame is inside the firebox). The plenum cover is that rectangular piece of sheet metal (maybe 8" x 24") on the front of the furnace. There's a baffle (partition) near the back which separates the return area and blowers from the plenum/heat exchanger. You have to take the plenum cover off to slide out the firebox/blowers/controller assembly.



The plenum itself is like an electrical junction box in that it has knockouts on the front and sides and bottom where ducts could be attached. Holes in the back are where air going through the return air grate enters the blower, to be blown into the plenum.



I couldn't make sense of your photo, but your description sounds like the installer punched out a knockout he never used. If that's the case, you would close it off. Duct tape for a temporary fix.



For something more permanent, if you have space you could pop-rivet a piece of sheet metal across the hole, working from the outside. If you don't have working room on the outside, you could take the firebox/blowers/controller assembly out and pop-rivet a piece of sheet metal to cover the hole from the inside. It's not as big a job as it sounds.



Larry
Thanks. I may make a better pic later. In this pic I can see unused round duct punch outs on the left side. It’s the rectangular opening in the top/horizontal panel of the case and just past the front/vertical edge of the furnace case that surprised me. I assume what I see in that rectangular opening is the heat exchanger. I was surprised to see such a large un-ducted opening in the case.
__________________
SEARCH is your friend!
FR Wildcat 295RSX / GMC Sierra

Nights Camped: '13 = 49/'14 = 74/'15 = 74/'16 = 85/'17 = 110/'18 =111/'19 = 40; booked = 14
Mr. Dan is online now   Reply With Quote
Old 02-09-2019, 08:19 PM   #4
Site Team
 
Mr. Dan's Avatar
 
Join Date: Mar 2014
Location: Grayson County, Texas
Posts: 11,112
No, I wasn’t talking about the “perforated” grate. I knew that was the intake. On my side of the input grate is a printed diagram, etc., and the opening I’m talking about is closer to the camera that the printed label.
__________________
SEARCH is your friend!
FR Wildcat 295RSX / GMC Sierra

Nights Camped: '13 = 49/'14 = 74/'15 = 74/'16 = 85/'17 = 110/'18 =111/'19 = 40; booked = 14
Mr. Dan is online now   Reply With Quote
Old 02-09-2019, 08:40 PM   #5
Senior Member
 
Join Date: Jan 2018
Location: Raleigh, NC
Posts: 1,470
Oh, that one!

Quote:
Originally Posted by Mr. Dan View Post
No, I wasn’t talking about the “perforated” grate. I knew that was the intake. On my side of the input grate is a printed diagram, etc., and the opening I’m talking about is closer to the camera that the printed label.
Oh, still don't see it, but if it's forward, it should be plugged. Otherwise, some heat could be sucked right back in and re-heated. And if it's plugged you will get more air volume at the vents.

Larry
Larry-NC is online now   Reply With Quote
Old 02-09-2019, 08:42 PM   #6
Site Team
 
Mr. Dan's Avatar
 
Join Date: Mar 2014
Location: Grayson County, Texas
Posts: 11,112
Quote:
Originally Posted by Larry-NC View Post
Oh, still don't see it, but if it's forward, it should be plugged. Otherwise, some heat could be sucked right back in and re-heated. And if it's plugged you will get more air volume at the vents.



Larry
Did you click on the pic so you can see all of it?
__________________
SEARCH is your friend!
FR Wildcat 295RSX / GMC Sierra

Nights Camped: '13 = 49/'14 = 74/'15 = 74/'16 = 85/'17 = 110/'18 =111/'19 = 40; booked = 14
Mr. Dan is online now   Reply With Quote
Old 02-10-2019, 06:01 PM   #7
Senior Member
 
onetonford's Avatar
 
Join Date: Oct 2010
Location: TEMP for now
Posts: 973
what is off to the right it looks like it may go on top is that the duct work or something else.
__________________

2001 Ford F-350 DRW 7.3
2011 25 RL Wildcat
former fiver 1976 Fourwinds had for 35 years
onetonford is offline   Reply With Quote
Old 02-10-2019, 06:15 PM   #8
Site Team
 
Mr. Dan's Avatar
 
Join Date: Mar 2014
Location: Grayson County, Texas
Posts: 11,112
Quote:
Originally Posted by onetonford View Post
what is off to the right it looks like it may go on top is that the duct work or something else.
No... good question, however. What you see is foil-wrapped packaging I used for insulation to keep heat from the furnace away from my PI EMS box further off to the right.


Larry-NC and I had a PM exchange later and Larry thinks the hole SHOULD BE covered with an inspection panel which we could see drawn in stick-figure furnace manuals. That said, I don't remember seeing the gaping hole when I installed the EMS so I will go out soon and look in the area to see if I can find a stray metal panel. I will fix it before my next trip because the opening causes two problems: 1. reduced flow to downstream vents and 2. heated air being drawn into the intake grate further back and reheated instead of being sent downstream.
I'll report back.
__________________
SEARCH is your friend!
FR Wildcat 295RSX / GMC Sierra

Nights Camped: '13 = 49/'14 = 74/'15 = 74/'16 = 85/'17 = 110/'18 =111/'19 = 40; booked = 14
Mr. Dan is online now   Reply With Quote
Old 02-11-2019, 04:36 PM   #9
Site Team
 
Mr. Dan's Avatar
 
Join Date: Mar 2014
Location: Grayson County, Texas
Posts: 11,112
Three more pics. I fished around in this cavern feeling for this cover in case it just jiggled off but no luck.
Click image for larger version

Name:	IMG_1456.jpg
Views:	44
Size:	220.3 KB
ID:	196595Click image for larger version

Name:	IMG_1457.jpg
Views:	42
Size:	270.8 KB
ID:	196596Click image for larger version

Name:	IMG_1458.jpg
Views:	41
Size:	231.9 KB
ID:	196597
__________________
SEARCH is your friend!
FR Wildcat 295RSX / GMC Sierra

Nights Camped: '13 = 49/'14 = 74/'15 = 74/'16 = 85/'17 = 110/'18 =111/'19 = 40; booked = 14
Mr. Dan is online now   Reply With Quote
Old 02-11-2019, 04:48 PM   #10
Senior Member
 
Join Date: Jun 2012
Posts: 9,607
Dan, that serpentine shaped thing inside is your heat exchanger. Seems there should be a plate/cover over the big square hole. Do you have a manual for this furnace?
__________________

__________________
1988 Coleman Sequoia - popup (1987-2009) - outlasted 3 Dodge Grand Caravans!
2012 Roo19 - hybrid (2012-2015)

2016 Mini Lite 2503S - tt (2015 - ???)
2011 Traverse LT, 3.6L, FWD
2009 Silverado 1500 Ext Cab, 5.3L, 4x4, 3.73
2016 Silverado 2500HD Dbl Cab, 6.0L 4x4, 4.10
rockfordroo is offline   Reply With Quote
Reply

Thread Tools
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



» Featured Campgrounds

Reviews provided by


Disclaimer:

This website is not affiliated with or endorsed by Forest River, Inc. or any of its affiliates. This is an independent, unofficial site.




Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -5. The time now is 09:59 PM.