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Old 09-23-2020, 09:59 PM   #1
Join Date: Apr 2017
Location: Lacey
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2017 Raptor 412TS - furnace return question

I'm curious if anyone has blocked off the space under the stairs from the underbelly compartment.

When I pull the bottom grate off, I can see the furnace and what looks like an intake to the right side.

We're dealing with some mice getting into this area under the stairs. I was thinking about cutting a board to fit that opening and tacking it in to keep the mice on the other side of this opening. I'm referring to mounting the board to the steel studs up next to the furnace, not up where I removed the grate.
Per that vent/fan on the right side of the furnace, I would cut a hole so as not to impede air flow there.

We've successfully eliminated mice before, but this is the first time they came in this area.

I've come to learn from reading this website and others that an RV furnace does not operate like a traditional home furnace, so there is no true 'air return'. Still, air flow is necessary for the furnace to function as best it can.
In addition to keeping the mice out of this area, blocking off that opening would help stop the cold draft that blows in from this spot. Some nights we have the furnace running, which does a great job warming the coach, but then you can feel the cold air blowing in on your feet anyway.

I have always appreciated the help and kind words from y'all since we bought our Raptor in 2017. More than a few times, the advice I have received here either directly or indirectly has gotten is out of a tight spot, so thank you.


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Old 09-30-2020, 10:07 PM   #2
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Old 10-01-2020, 02:28 AM   #3
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Just now seeing this. If you block/cover that return area, Im thinking it might cause enough restriction to cause the furnace to overheat and shut down.

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Old 10-01-2020, 05:29 AM   #4
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I had not seen it either. I'm thinking Chuck is right. I don't know exactly how much of those vents would be needed but I figure they built it with some thought of the volume required. I do know that I put a mesh bug screen over the exhaust of my last trailer and had to remove it because that tiny bit of extra restriction caused the limit switch to kick off the furnace so they're pretty finicky. You might try blocking one of them to see but if they're using one grate they can/will use both.

Have you tried sealing all possible points of entry from the outside? Do you leave the doors open? I know I went out to the little barn the other afternoon about dusky dark leaving the gate open. Came back in about 5 minutes later and closed it. When the outside lights came on just at dark saw a skunk wander by. He had come into the yard in that brief time I left the gate open. After scolding it good and proper and opening the gate it left but critters take advantage of any opportunity.
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Old 10-01-2020, 05:49 AM   #5
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My 2014 Alpine has furnace return vent on stairs as well... I block off with a piece of card board to keep out heat during summer... during winter use I remove to allow the furnace to breath better...

However... on our last trip just a week ago we used furnace in the early mornings for two weeks and I forgot to remove cardboard... temps were down to 17 degrees a few evenings.

Suburban furnace ran fine and had no issues ... there is a plethora of open space under the flooring with... in my RVs case small open holes that the furnace can draw outside air as well as the air in that huge basement and underflooring area

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Old 11-12-2020, 08:33 AM   #6
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I was always told those vents were for heating the under neath in cold weather, it let the furnace heat circulate and help prevent water freezing up in cold temperatures.

I have a 2015 412TS
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Old 11-17-2020, 06:30 PM   #7
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If it is the intake, blocking it off will cause your furnace to overheat and shut down. If you are wanting to block it off when not using the RV furnace, temporarily place a piece of plywood cut to size in front of it to block the mice trail, tape it in place, then remove when spring comes and the rodents go back outside. Mouse traps baited with peanut butter is an easy kill method if you need to be on the offensive.
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Old 11-17-2020, 07:23 PM   #8
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I installed hardware cloth behind all my vents, air flow and mouse tight.
24" x 1/2" x 50' 19ga Galvanized Hardware Cloth.
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Old 11-18-2020, 02:19 AM   #9
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"hardware cloth behind all my vents, mouse tight.
24" x 1/2" x 50'"

Sorry Brent, 1/2 x 1/2 isn't even close to mouse tight. From beesource.com:
"!/4" mesh is the size to use. Bees go through it fine but mice can't quite squeeze down that small, so it works great."
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Old 11-18-2020, 07:01 PM   #10
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I should be more carefull what link I grab, couldn't remember what the mesh was called, so thats what I googled up. The stuff I actually installed is very fine, not screen door size, but pretty tight.
Good point, Appreciate the reply.
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Old 11-19-2020, 07:15 AM   #11
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Thinking about the efforts to keep mice from going through the holes/vents in the stairs ???? If they're already in either the main cabin or in the front storage/passthrough/basement area of a fifth wheel, blocking those stair vents is only ONE of the many avenues for mice to travel "freely" throughout the trailer. The entire "covered basement", the holding tank area, the furnace ducting runs, the area under the shower are just a few of the "wide open spaces" for mice or other rodents to travel thoughout the trailer....

If you've got mice migrating through the stair vent spaces, you really need to "back up a couple of steps" (pun intended) and stop their entry into the trailer long before they get to the stairs....

It's sort of like putting screens on the windows and then leaving the front door wide open... You're still going to have problems, no matter how many windows you screen.

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Old 11-19-2020, 08:16 AM   #12
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Out of sight out of mind? Until they chew thru the wires, the water lines, etc. Like John said, treat the problem not the symptom.

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furnace, raptor

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