Furnace Intake Grills

Topic: Furnace Intake Grills (Read 803 times) previous topic - next topic

Furnace Intake Grills

November 11, 2012, 12:44:55 pm

Just took a some pics of what I was talking about. The vent is obviously in line with the opening under toilet. I drilled a 4" hole thru then placed a plastic vent with small perforations (holes ) in it so no bugs can get in and siliconed it in place before gluing the cover on. I used a 3m epoxy (FOT suggested) and got the vent cover from them.
John H

Re: Furnace Intake Grills

Reply #1 – November 11, 2012, 01:18:40 pm

That's interesting John, that there is a vent that was just venting the area under the toilet but didn't serve any other purpose. On our coach, the vent in the toilet base is actually a heater outlet, the only one in the bathroom! However, our coach has what could possibly be termed as a useless vent in the shower base. I considered covering it, but since it is just large enough to reach my arm in and there is ducting and cables running underneath it, I figured I would leave it for access. However, I did manage to find a nice oak grill which I modified to replace the cheesy white metal one that was there. The grill's location tight to the floor made the molding and trim even more of a challenge, but I think it came out nicely.
Don

Quote from: John Haygarth – November 11, 2012, 12:44:55 pm

Just took a some pics of what I was talking about. The vent is obviously in line with the opening under toilet. I drilled a 4" hole thru then placed a plastic vent with small perforations (holes ) in it so no bugs can get in and siliconed it in place before gluing the cover on. I used a 3m epoxy (FOT suggested) and got the vent cover from them.
John H

Re: Furnace Intake Grills

Reply #2 – November 11, 2012, 04:03:35 pm

We have a vent with louvered metal cover in the bathroom near the base of the cabinets. The location would correspond with a vent in the base of the toilet for coaches that have no private water closet. It appears to be the air intake for the rear furnace. I see no other ports that would provide sufficient air flow into the furnace. The furnace is behind the aft wall of the shower and underneath a closet in the bedroom.

Check the "useless" vents for air flow when the furnace is operating. Those vents may be the intake ports for the furnace.

Re: Furnace Intake Grills

Reply #3 – November 11, 2012, 04:04:37 pm

By the way John, your bathroom floor looks very nice! Did you do it yourself? Also, is that vent cover made out of fiberglass, and do you remember how much it was?
Don

Quote from: John Haygarth – November 11, 2012, 12:44:55 pm

Just took a some pics of what I was talking about. The vent is obviously in line with the opening under toilet. I drilled a 4" hole thru then placed a plastic vent with small perforations (holes ) in it so no bugs can get in and siliconed it in place before gluing the cover on. I used a 3m epoxy (FOT suggested) and got the vent cover from them.
John H

Re: Furnace Intake Grills

Reply #4 – November 11, 2012, 04:08:29 pm

Ahh... that makes sense! I was actually thinking that the vent under the shower might just be to guard against dampness. The 295's with a similar floorplan have two furnaces, where as our 270 has just one that is under the fridge. I also replaced that metal grill with an oak one.
Don

Quote from: J. D. Stevens – November 11, 2012, 04:03:35 pm

We have a vent with louvered metal cover in the bathroom near the base of the cabinets. The location would correspond with a vent in the base of the toilet for coaches that have no private water closet. It appears to be the air intake for the rear furnace. I see no other ports that would provide sufficient air flow into the furnace. The furnace is behind the aft wall of the shower and underneath a closet in the bedroom.

Check the "useless" vents for air flow when the furnace is operating. Those vents may be the intake ports for the furnace.

Re: Furnace Intake Grills

Reply #5 – November 11, 2012, 04:13:04 pm

Don, your under toilet vent does look like a heater vent but our's was the same as the one under your shower. I tried to feel any heat from it before covering it up, but nothing, and I did get heat from the round adjustable ones in bathroom, so figured it must be a return. In the bedroom (under cabinet and vanity lights) is a similar metal rectangular vent cover and that too did not produce any heat, and those 2 are connected by way of the space under shower. This to me would seem to be a crazy way to have a heat source as the air flow would be seriously comprimised by all the plumbing/wiring and open area involved under both the toilet and shower. The area under my toilet is also very open in places to the cabinet in dining and the one in bathroom, another reason I figured it not to be a source of heat. I had previously taken the base of the cabinet behind toilet out to get at back vent to replace, so I checked what was in there etc.
John H

Re: Furnace Intake Grills

Reply #6 – November 11, 2012, 04:20:48 pm

JD,as our furnace is below the clothes closet, opposite side to shower we have a larger metal vent for the rear furnace in the bedroom below the stack of drawers which back onto this closet, so it cannot be for that. Even if it was there is enough air passing thru the doorway (open or closed) and I did not close off the bedroom one so air can come in my new vent (outside wall-post with pics) then go under shower base and out the bedroom one!
Don, yes I did the flooring the few days after getting the coach. I ripped out the kitchen hardwood (that was some job) and tiled from the bedroom door to a line between the ding/kitchen area and living room. I put down a 3/8th ply sub floor (glued 100%) then tiled on top. I have not had any tiles break or grout crack, and that is good considering the roads in Mexico etc we have been on. This is my next job taking the carpet out of there and doing cork or engineered wood-still not sure which.
Yes the vent is fibreglass and from FOT. I seem to remember something around $50+
John

Re: Furnace Intake Grills

Reply #7 – November 11, 2012, 07:28:11 pm

John,

Indeed the vent/intake arrangement for the rear furnace in our U295 is as you described. We have one intake in the bedroom and one at the base of the cabinets near the shower. They feed a common plenum to the rear furnace. I set a fan to blow into the bedroom intake and could feel air coming out the bathroom intake (furnace off). The plenum is under and/or behind the base of the shower and under the closet and drawers in the bedroom.

It's in those tight areas in the water closet, shower, Splendide platform, driver's controls, etc., that I need the expertise of Ernie or another experienced craftsman to do the flooring work. I am watching and reading with interest the progress of the project. I look forward to seeing a project that uses some kind of tile or vinyl tile.

Re: Furnace Intake Grills

Reply #8 – November 11, 2012, 08:53:03 pm

I'm going to take my flashlight and look under the platform that Willies Commode sits on. For the life of me, unless there is some weird plumbing issue, the commode has a drop straight down to black tank. he has no air to push solids to a remote tank. We had, in our Grand Villa, the same elevated platform, which Brenda hated as she is short and sitting on commode without feet touching the floor- you guessed it- we sold that coach.
AND- if there is no strange plumbing- I'd take out that platform and put in a nice porcelain toilet.

Re: Furnace Intake Grills

Reply #9 – November 11, 2012, 09:24:01 pm

If you are in freezing conditions that grill will let in warm air to keep your water lines under there from freezing. I guess that if in Mexico then you would have no issue with that, but if in the north the outside vent would let in freezing air. so do not think that a vent to the outside would be good.

Re: Furnace Intake Grills

Reply #10 – November 12, 2012, 12:12:18 am

Quote

"I'm going to take my flashlight and look under the platform that Willies Commode sits on. For the life of me, unless there is some weird plumbing issue, the commode has a drop straight down to black tank. he has no air to push solids to a remote tank. We had, in our Grand Villa, the same elevated platform, which Brenda hated as she is short and sitting on commode without feet touching the floor- you guessed it- we sold that coach.
AND- if there is no strange plumbing- I'd take out that platform and put in a nice porcelain toilet". Quote from Ernie.

If I remember it right, there is a drain line and back vent line coming under the toilet in that "box" along with a few electrical wires. Mine is same set up with the black tank right below, and a piece of 4" pipe as an extension from the floor level up to the top of box for flange of toilet. I think it could be dropped a couple of inches but that may be all.

Re: Furnace Intake Grills

Reply #11 – November 12, 2012, 12:18:05 am

Quote

Quote"If you are in freezing conditions that grill will let in warm air to keep your water lines under there from freezing. I guess that if in Mexico then you would have no issue with that, but if in the north the outside vent would let in freezing air. so do not think that a vent to the outside would be good."
from Red Tractor.

Well there is still the vent to that area coming from bedroom, and I did wrap the one cold pipe with foam tube-but-usually we do not have the coach here in the real cool part of the year-and- I have all lines blown out when coach is sitting, so that will not be a problem. If it is as you say I can easily put a piece of insulation under the vent cover to again address that very slight possibility.
John H

Re: Furnace Intake Grills

Reply #12 – November 12, 2012, 12:33:47 am

JD- so if it as you say then I have the direct air feed in from outside vent I put in, and, the one from bedroom so plenty of air for furnace,plus, some of my "make up air" is now coming from outside were it really should do for a furnace. Glad I did it that way. Understand what I am saying?
John h

Re: Furnace Intake Grills

Reply #13 – November 12, 2012, 12:59:09 pm

Quote

JD- so if it as you say then I have the direct air feed in from outside vent I put in, and, the one from bedroom so plenty of air for furnace,plus, some of my "make up air" is now coming from outside were it really should do for a furnace. Glad I did it that way. Understand what I am saying?
John h

John, it looks that way to me. I aimed a fan at the bedroom grill and I felt a bit of air coming out of the grill in the bathroom. I used some matches, along with the "fan test," and verified the air flow by the reaction of the flames and smoke to air moving through the grills. The grills both appear to be intake vents for the rear furnace. I expect they are set that way to keep air flowing well even if the bedroom/bathroom door is closed.

The system will require a bit of "make up" air for the rear furnace (or the only furnace on a U270) to compensate for the heated air forced into the bays. I would expect it to come mostly from the exterior port on your modified system, and from leakage or an open window or vent for the rest of us.

The intakes inside the coach are strictly for the heated air inside the coach. The intake air for combustion is drawn from outside the coach.

I like having a bit of outside makeup air on purpose. That is particularly good if the air is filtered. It can put a bit of positive pressure on the house and help keep dust from being sucked in through miscellaneous cracks. I don't have a system for positive pressure with filtered air in the coach, but I often crack open the small window near the passenger chair and the vent over the kitchen to allow a small flow of fresh air.

In your installation, the outside vent might be close enough to pull exhaust from the passenger side rear furnace. Be aware of the possibility of drawing carbon monoxide into the coach. The danger is probably very small, but worthy of consideration.

Re: Furnace Intake Grills

Reply #14 – November 12, 2012, 02:29:12 pm

JD, as I said before, the rear (and front) furnaces are both on the opposite side (of coach) to this vent so no chance of that.
John H

Re: Furnace Intake Grills

Reply #15 – November 12, 2012, 02:39:54 pm

Folks, There is no MAKEUP air on our FT furnaces. All air for combustion comes from the outside. If you look at the furnace outlet you will find it is a hollow ring, outside air enters and exhaust air leaves thru the same outlet. Same way with the water heater. Any heat device that used interior air for combustion is deadly in a MH. The vents in my coach simply allow air to pass from one area to another. Otherwise you would have a hot heated space and a cold unheated space. The bedroom is a good example, if all the heated air stayed there you would be too hot and hallway ( or other space ) would be too cold. Maybe a FT engineer can explain it better.
Gary B

Re: Furnace Intake Grills

Reply #16 – November 12, 2012, 03:14:48 pm

Gary,

Indeed, the OEM installation for propane furnaces is as you described. The rear furnace on our coach has air intake ports in the bathroom and bedroom. The front furnace has one intake port below the stove. Inside heated air stays inside and combustion air stays outside. The exception on our coach is that some heated air goes to the bays. I am not aware of any return air path for the heated air that flows into the bays via two 2" ducts from the rear furnace.

My understanding is that John modified the air intake system on the rear furnace on his U295 so that there is an external intake port for some of the "inside air" for the rear furnace.

John,

I was slow to comprehend that both of your furnaces are the same side of the coach. On our coach, the water heater and rear furnace are on the passenger side. The front furnace is on the driver side.

Re: Furnace Intake Grills

Reply #17 – November 12, 2012, 03:20:30 pm

Gary, I believe you and did not think that vent was meant to pass air to the burner, and it did not give hot air when furnace was running, hence me thinking it was ok to cover. In the 295 we have as anyone else a seperate thermostat for the bedroom / bathroom, and one for the living area so even if you have the door closed it would sense that heat and switch the rear furnace off. I have 1 vent in the bedroom and two in bathroom for the distribution of heated air( not including the ceiling vents for heat pump when on). These are the round ones that you can move to direct the flow.
Yes it would be interesting to hear from FOT on this "plumbing"so I will e-mail James to see what he say's
John H

Re: Furnace Intake Grills

Reply #18 – November 12, 2012, 03:43:22 pm

Gary,
In this case, I think what make up air means is extra air from the outside to be heated entering the furnace through the air return, which are what those intake grills inside to coach are for, at least when they're in a Plenum. Since the air that is use to warm the compartments can't make it back up into the coach, that would create a bit of negative pressure inside the coach without some extra fresh air making its way in, as it will through John's extra outside vent or through open windows etc.. In our case, since we only have the one heater, the extra grill under the shower would have been an extra return air for a rear furnace. the space inside our coach where we would have had a rear furnace in the bedroom streetside is just extra cabinet space now. I don't know for sure, but I figured that Foretravel just has all those parts made the same for the same types of floorplans, and in our case that just ended up with an extra grill under our shower. Probably not a bad idea to have some airflow under there anyway... speaking of grills, here's another picture of the one I modified to fit for our furnace's air return underneath the refrigerator. It is fitted for a filter of sorts, and since I have almost doubled size of the opening area of the original grill, I'm not too concerned about any slight restriction.
Don

Quote from: Gary Bouland – November 12, 2012, 02:39:54 pm

Folks, There is no MAKEUP air on our FT furnaces. All air for combustion comes from the outside. If you look at the furnace outlet you will find it is a hollow ring, outside air enters and exhaust air leaves thru the same outlet. Same way with the water heater. Any heat device that used interior air for combustion is deadly in a MH. The vents in my coach simply allow air to pass from one area to another. Otherwise you would have a hot heated space and a cold unheated space. The bedroom is a good example, if all the heated air stayed there you would be too hot and hallway ( or other space ) would be too cold. Maybe a FT engineer can explain it better.
Gary B

Re: Furnace Intake Grills

Reply #19 – November 12, 2012, 05:11:36 pm

Well folks, according to James Triana's e-mail to me a few moments ago the grille under toilet and back of shower wall in bedroom are only there for the actual installation of shower, so that plumbing could be joined up. No other reason. So nothing to do with furnace air. That makes me happy that I have covered it up, and unless I have an issue with a leak from that area I do not have to touch the front tile which covers that hole. My extra vent is doing what I hoped it would, keep the air under toilet fresh.
So, Ernie, you can change the box somewhat if you want.
End of issue

Re: Furnace Intake Grills

Reply #20 – November 12, 2012, 07:44:41 pm

John- Willie is the one that is going to give the "throne" a whole new look. Stay tuned for forthcoming photos.

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