36FL return air duct question

[Char & Steve]

Any of you with the FL models....question is how many and how big are your return air registers? Location?
I have been having issues with our heater blowing the cage fan apart and been talking with my tech and Suburban. They call for 142 sq.in. of return unless you have 5 ducts which we do so it can be reduced to 88 sq.in. Our return is about 24 sq.in. located on the bottom stair riser. Have 5 ducts out of the furnace and whoever installed at the factory removed all the blanks so there are two extra 4" blanks missing allowing the hot air just to circulate in the basement area.
We narrowed the problems down to this and will be calling RW and Suburban in the morning.

Steve

[r time soon]

Steve, Not to familiar with the FL models, but on our RL there is the Return register below the hall steps, and a 2" by 3' or so screen section below the cabinet by the entry door. All this air returns freely, not by direct ducting like cold air returns in residential home HVAC systems. Those missing blank covers are probably allowing heated air to just do a quick loop back into the intake, causing the air to become super heated. They need to be blocked off for sure. Those blank covers don't fit very snug, and just twist or spin in the opening. I would suggest to aluminum foil tape in place so they can't fall out. Good Luck and keep everyone informed.

Chris

[ted 95]

When I was at a RV show recently the rep from Redwood told me the basement is supposed to be heated to a degree so water will not freeze in the tanks. Is it possible the open ducts are that way on purpose?

[r time soon]

Pretty sure they are not left off for heating the underbelly and tank area. The hoses restrict and direct the movement of air. You wouldn't the hot air blowing on the water lines and foam insulation for your water heater for example. They use a 4" to 2" reducing collar and attach 2" duct hose in order to 'heat' the underbelly and tanks. Normally the holes in the plenum are punched by Suburban, and typically the employee either knocks the area out, or grinds the piece off to install the heat duct and collar. If they knock out too many blank holes, then they can fill it with a cover. The blank cover is called a cover. The 4" flange that the heat duct flex hose attaches to is a collar. And then there is the 2" reduced collar.

Chris

[Char & Steve]

Originally Posted by ted 95

When I was at a RV show recently the rep from Redwood told me the basement is supposed to be heated to a degree so water will not freeze in the tanks. Is it possible the open ducts are that way on purpose?

My underbelly has it's own 4" duct and a 4" hole for return. Knock outs should be there since you don't want a continuous circle of air that close. I believe there is enough heat generated by the return and unit itself to heat the filter area. Again this is the FL layout witch has a very,very small basement area.

Steve

[rob_fla]

As I remember the last time I was in the service area in our FL, there was a foil duct line that ran back up to the underbelly area, then three foil ducts connected to the main truck line that feeds the kitchen, bathroom and rear bedroom area, then a foil duct line to the front living room register.
I do not remember seeing any open knockouts on the heater box with no foil duct line on them.
I would have to look again to confirm, the last time I was under there I was just making sure all the foil duct lines were fully taped with foil duct tape and none were loose or falling off.

[Char & Steve]

Originally Posted by rob_fla

As I remember the last time I was in the service area in our FL, there was a foil duct line that ran back up to the underbelly area, then three foil ducts connected to the main truck line that feeds the kitchen, bathroom and rear bedroom area, then a foil duct line to the front living room register.
I do not remember seeing any open knockouts on the heater box with no foil duct line on them.
I would have to look again to confirm, the last time I was under there I was just making sure all the foil duct lines were fully taped with foil duct tape and none were loose or falling off.

You have the info 100% correct on the duct runs. The two knockouts that are missing are on the right side of the furnace if you were on the outside looking at it which is also towards the rear of the RW. You could only see the two missing knockouts either with a mirror from the inside or pull your outside furnace cover off. In my case I have the furnace out and noticed it.

Steve

[spindrift]

Steve -
I have the same set-up as you. No knock outs on my furnace, however.

[mhs4771]

Almost sounds like the furnace was prep'd for a different floor plan that may have used those outlets, but sure doen't sound right to be open with nothing connected.

[rob_fla]

Originally Posted by Char & Steve

You have the info 100% correct on the duct runs. The two knockouts that are missing are on the right side of the furnace if you were on the outside looking at it which is also towards the rear of the RW. You could only see the two missing knockouts either with a mirror from the inside or pull your outside furnace cover off. In my case I have the furnace out and noticed it.

Steve

The next time I have the access panels off I will have to take a look

[atom ant]

Doesn't sound right at all. Is it possible it had a flex duct connected to the openings and they have come off and are laying in there? Several have had to do some major reconnecting and securing after the factory install came apart.

[Char & Steve]

NO... all 5 are attached just fine on other outlets. These have no use on this model but are open.


Steve

[Char & Steve]

Update..
Talked with Suburban who makes the furnace and my tech had sent them pictures. They said absolutely must add another return vent for the inside air and also must replace the furnace housing since knockouts are missing. I believe a new housing came with the new furnace.
My tech has also been in touch with RW to let them know it is an RW screw up and not Suburban.
Wonder if Suburban will get their money back from RW???

Sooooo..... now we must all check your return vents to see if you meet the minimum requirements for your furnace. I'm hoping they just forgot a return on ours and if not there will be more problems out there.

Steve

[atom ant]

I'll be curious to see how they add a return.

[Shane Wood]

In my RL I have returns under the closet at the front door one on the stairs and another in the bathroom for 195 Sq in and 5 heat ducts. Steve maybe you have to go to Chicago to get your squirrel cage they have them that hold them big greys

[Char & Steve]

Update,
New heater and housing installed along with a return added. Have run the new set up for about 8 hours and flawless. Both the previous ones blew apart or made noise within 1 hour so I'm hoping this problem is now in the past.
We believe most of the problem was due to the missing knockouts more then the missing return. The hot air was just circling around in the basement area and overheating the unit.

I still am laughing at what customer service told me when I called the last time. "It must be operator error on the way I am shutting it down" There is only one little button to slide and I let them know that I was pretty capable of doing that


Steve

[Shane Wood]

Originally Posted by Char & Steve

Update,
New heater and housing installed along with a return added. Have run the new set up for about 8 hours and flawless. Both the previous ones blew apart or made noise within 1 hour so I'm hoping this problem is now in the past.
We believe most of the problem was due to the missing knockouts more then the missing return. The hot air was just circling around in the basement area and overheating the unit.

I still am laughing at what customer service told me when I called the last time. "It must be operator error on the way I am shutting it down" There is only one little button to slide and I let them know that I was pretty capable of doing that


Steve

Now you can go out and sit in it without the parka and watch it snow