Reply
 
Thread Tools Search this Thread Display Modes
 
Old 12-20-2010, 01:59 PM   #99
Wise Elder
 
Jammer's Avatar
 
2010 30' Classic
Vintage Kin Owner
South of the river , Minnesota
Join Date: Dec 2009
Posts: 4,119
Robert,

It has been suggested. The Atwood installation guide for this furnace says that a minimum of four, 4" diameter ducts leading to nonadjustable (that is, always fully open) registers are required. Blocking off one of the front outlets, completely, would leave only three 4" diameter ducts plus the three 2" outlets, somewhat less than the total area Atwood says is required. In measuring the outlet temperature, it's 170 degrees once the trailer is warm. The high limit trip point for the furnace is 190 so there's not much blocking off of the outlets that I can do without getting close to the trip point.

The furnace is more or less in the center of the trailer and so the idea of having two forward vents and two aft vents makes sense except for the fact, as you point out, that the two forward vents emit far more heat due to their proximity to the furnace.
__________________

__________________
Jammer is offline   Reply With Quote
Old 12-20-2010, 02:11 PM   #100
Rivet Master
 
ROBERTSUNRUS's Avatar

 
2005 25' Safari
Salem , Oregon
Join Date: Mar 2006
Posts: 7,269
Images: 18
Blog Entries: 51
Hi, then what if we block off one of the front vents and run a new one to the bedroom instead? [two in the bedroom and one in the living room]
__________________

__________________
Bob

2005 Safari 25-B
"Le Petit Chateau Argent"
[ Small Silver Castle ]
2000 Navigator / 2014 F-150 Eco-Boost / Equal-i-zer / P-3
YAMAHA 2400 / AIR #12144
ROBERTSUNRUS is offline   Reply With Quote
Old 12-20-2010, 02:18 PM   #101
Rivet Master
 
dznf0g's Avatar

 
2007 30' Classic
Oswego , Illinois
Join Date: Jul 2010
Posts: 9,407
Images: 5
I don't know why that wouldn't be OK.
__________________
dznf0g is offline   Reply With Quote
Old 12-20-2010, 03:02 PM   #102
Rivet Master
 
Gene's Avatar
 
2008 25' Safari FB SE
Grand Junction , Colorado
Join Date: Sep 2007
Posts: 10,840
Quote:
Originally Posted by Jammer View Post
The Atwood installation guide for this furnace says that a minimum of four, 4" diameter ducts leading to nonadjustable (that is, always fully open) registers are required.
Don't the 2" registers count? I would think 3 2" registers should count as 1 4" register allowing the closing or partial closing of one 4" duct.

Gene
__________________
Gene is offline   Reply With Quote
Old 12-20-2010, 03:07 PM   #103
Rivet Master
 
dznf0g's Avatar

 
2007 30' Classic
Oswego , Illinois
Join Date: Jul 2010
Posts: 9,407
Images: 5
Gene, I think that any combination of ducts adding up to the total area of about 50 sq. in. (for the larger 4 duct furnaces) would be fine. Jammer added to the original four openings. The point is not to reduce the total area of opening or introduce additional restrictions.

As I am sure you are aware the original 2" ducts branch off the 4" ducts.
__________________
dznf0g is offline   Reply With Quote
Old 12-20-2010, 03:09 PM   #104
Rivet Master
 
dznf0g's Avatar

 
2007 30' Classic
Oswego , Illinois
Join Date: Jul 2010
Posts: 9,407
Images: 5
It would take four 2" to make up for 1 4" duct. Maybe even a little more as you will have more restriction due to more duct wall surface area. That MAY not be a big deal though.
__________________
dznf0g is offline   Reply With Quote
Old 12-20-2010, 03:56 PM   #105
Wise Elder
 
Jammer's Avatar
 
2010 30' Classic
Vintage Kin Owner
South of the river , Minnesota
Join Date: Dec 2009
Posts: 4,119
Quote:
Originally Posted by ROBERTSUNRUS View Post
Hi, then what if we block off one of the front vents and run a new one to the bedroom instead? [two in the bedroom and one in the living room]
As noted upthread, there isn't room for another 4" duct under the coat closet or behind the shower.
__________________
Jammer is offline   Reply With Quote
Old 12-20-2010, 05:31 PM   #106
Rivet Master
 
Dave Park's Avatar
 
2005 22' Safari
Hyde Park Place , Ohio
Join Date: Jul 2010
Posts: 972
A lesson/trick I learned from a guided tour of Palm Harbor Homes (prefab housing):

PHH uses roof gutter as the underfloor air distribution channels. They fix it all together then attach it, and cover it with foam in place. If doing a floor replacement, this is an excellent opportunity to do something like this. I was thinking narrow aluminum downpipe inside wide aluminum downpipe, with the gap filled with expanding foam.
__________________
TX-16
Dave Park is offline   Reply With Quote
Old 12-20-2010, 05:47 PM   #107
Rivet Master
 
Gene's Avatar
 
2008 25' Safari FB SE
Grand Junction , Colorado
Join Date: Sep 2007
Posts: 10,840
Quote:
Originally Posted by Dave Park View Post

PHH uses roof gutter as the underfloor air distribution channels. They fix it all together then attach it, and cover it with foam in place. If doing a floor replacement, this is an excellent opportunity to do something like this. I was thinking narrow aluminum downpipe inside wide aluminum downpipe, with the gap filled with expanding foam.
You could use anything that can stand the heat. Certainly any smooth surfaced pipe could work. A pipe less than 4" may allow more air than larger flexible heating ducts. Perhaps CPVC would work well—it's the version of PVC for hot water (light tan in color). There are lots of connections available for T's, turns, etc. It's easy to glue together and a variety of types of insulation could be attached to it.

Gene
__________________
Gene is offline   Reply With Quote
Old 12-20-2010, 06:00 PM   #108
Rivet Master
 
Dave Park's Avatar
 
2005 22' Safari
Hyde Park Place , Ohio
Join Date: Jul 2010
Posts: 972
I should add that I am designing my "forever airstream" with the furnace just fore of the wheel arch, and with a 6"x6" channel down the back of all cabinetry to allow plenty of duct, wiring and plumbing access front to back. I plan to use household solid ducting - it fits well within my weight budget.
__________________
TX-16
Dave Park is offline   Reply With Quote
Old 12-20-2010, 09:08 PM   #109
Rivet Master
 
Gene's Avatar
 
2008 25' Safari FB SE
Grand Junction , Colorado
Join Date: Sep 2007
Posts: 10,840
Quote:
Originally Posted by CrawfordGene View Post
Perhaps CPVC would work well.

Gene
Upon reflection, I doubt CVPC comes in 4" and maybe not 3". It for hot water in a house or business and there's not much call for anything over 1" but I think I've seen 2".

You could use smaller pipe for the water tanks with vanes on them—like a hot water heat baseboard—to radiate heat. That might mean you could use smaller pipe, but I don't know whether hot air would radiate outward through the pipe wall that much. European Airstreams have hot water heat—obviously there's a freezing problem during winter storage. Perhaps filling the pipes with mineral oil would solve that. You could run a pipe through each tank to heat them from the inside—that would be more efficient. Then spray the tanks with insulating foam.

Gene
__________________
Gene is offline   Reply With Quote
Old 12-20-2010, 09:35 PM   #110
2 Rivet Member
 
bugnot1's Avatar
 
1990 34' Excella
Springfield , Missouri
Join Date: Dec 2010
Posts: 84
Images: 4
Blog Entries: 3
I have experienced the same temperature difference in our 34' - but decided to approach the problem by insulating the bedroom better. Our coach has rear twins. I took off the mattresses, then the platform, and insulated under the beds and the back wall (took the drawers out of the nightstand and insulated the back wall). The outside compartments aren't going to be used this winter - so I just insulated over them. I also took the splines out of the window screens and insulated the windows.......end result? Much warmer bedroom and the warmth is adequate. I may end up using an electric heater in the bedroom additionally in the single digits -

bugnot1
__________________
bugnot1 is offline   Reply With Quote
Old 12-21-2010, 01:05 PM   #111
Wise Elder
 
Jammer's Avatar
 
2010 30' Classic
Vintage Kin Owner
South of the river , Minnesota
Join Date: Dec 2009
Posts: 4,119
OK well I'm too old not to believe my own test results so it's time for another run at this. I'm going to try a combination of additional measures.

Step 1. I'm going to replace an 8' section of the duct to the bedroom with a piece of galvanized steel duct. I believe that I can work the solid duct under the drawers before locking the seam together. Solid duct has, as others have noted upthread, somewhat less resistance to airflow. Also, there are some thin, self-adhesive foam insulating materials that will work with solid duct but which don't really fit flex ducts. I'm going to apply the self-adhesive duct insulation as space permits on the straight section.

Step 2. I have a piece of 1/2" polyisocyanate foil-faced insulating board which I'm going to use to insulate a couple of key areas. I have not worked out details, but the main candidates are the coat closet false floor, and the space between the beds and the outside compartments below them.

Step 3. I'm tentatively considering running the 2" line intended for the bedroom out next to the existing register in the head. This would involve cutting a 4.25" hole and installing a 4" register to match the existing one, and attaching the 2" line with a reducer. 2" registers are available but for a visual match I'll use the 4."

Step 4. If all that doesn't do the trick I'm going to get a 4" duct fan and install that as an experiment. If it helps, I'm going to figure out a way to build a 12 volt duct fan out of low noise computer fan components that will provide the necessary CFM with minimal power draw and noise.
__________________
Jammer is offline   Reply With Quote
Old 12-21-2010, 01:11 PM   #112
Rivet Master
 
dznf0g's Avatar

 
2007 30' Classic
Oswego , Illinois
Join Date: Jul 2010
Posts: 9,407
Images: 5
Awesome Jammer, keep us informed.
__________________

__________________
dznf0g is offline   Reply With Quote
Reply

Tags
furnace tuning


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
Using the heat pump/heat strip instead of furnace. crazylev On The Road... 38 10-28-2016 08:58 PM
New AC, Heat Pump or Heat strip? firedog 1990 - 1993 Excella 3 01-22-2010 05:23 PM
The Heat is ON!! GlenCoombe Mechanics Corner - Engines, Transmission & More... 5 10-09-2005 04:48 PM
Odd back-to-back eBay auctions .... summerkid Trailer Values 5 09-12-2005 01:34 PM
need heat whistler Furnaces, Heaters, Fireplaces & Air Conditioning 3 06-07-2004 02:32 PM


Virginia Campgrounds

Reviews provided by




Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -6. The time now is 11:13 PM.


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.