Is there Filtration for Heating System

[KEN9XL]

I own a 2017 F.R. Heritage Glen 272RL travel trailer.
Heat works but even on high seems as if on low.

My question - Does the heating system in these RV's have a filtration system and if so where is it?

Thanks in advance

[Mr. Dan]

Originally Posted by KEN9XL

I own a 2017 F.R. Heritage Glen 272RL travel trailer.
Heat works but even on high seems as if on low.

My question - Does the heating system in these RV's have a filtration system and if so where is it?

Thanks in advance

I’ve never had a filter on any furnace I’ve owned. I suspect you have crushed or disconnected air ducts.

[cavie]

No filter for the furnace and I don't know why other then the air is not going thru a condenser coil and clogging things up. It is heating the air not trying to clean it.

[KEN9XL]

OK! Solves one problem, no filter. Was thinking it was clogged.
It is in fact heating just not much air flow or force.

Heater is in bedroom, I can hear it kick on & fan activate with air flow, so things are working, plenty of hot air just seems to have very little force. Bathroom backs up to heater, other side of bedroom, has hot air but again very little force.

I can understand one duct if crushed or disconnected but two.

I opened up panels to heating system both in bedroom (under closet space) and in bathroom (under sink). Checked ducts, all connected and not crushed plus both have very short runs, one side of wall to other.

[KEN9XL]

Is it possible the fan is not functioning properly and if so, how would I check that?
Warranty has expired.

[5picker]

Originally Posted by KEN9XL

Is it possible the fan is not functioning properly and if so, how would I check that?
Warranty has expired.

No, if the fan didn't operate up to speed the furnace wouldn't ignite. There is a sail switch built into the system that senses fan speed. The fan blower is two part. One side blows the hot air that is heated. The other side separately draws air into the combustion chamber. Same motor. If the sail switch doesn't activate from enough airflow, the furnace wont light.

It isn't uncommon for several ducts to have issues. It also isn't uncommon for rodents to chew holes in the ductwork.

[jtesta1]

Flat surface's in your rv serve as filters. Every couple of days wipe the dust covered area's till clean. Repeat every few days.

[CincyGus]

If you have a vent that is getting more than it's share of volume, an adjustable floor vent might be the ticket to for more to the other two vents you are wanting more volume through. Maybe even using some aluminum duct tape to block half the vent from the inside on the strong one, much like closing a vent in your vehicle works, forcing more to the other vents.

[Larry-NC]

Originally Posted by CincyGus

If you have a vent that is getting more than it's share of volume, an adjustable floor vent might be the ticket to for more to the other two vents you are wanting more volume through. Maybe even using some aluminum duct tape to block half the vent from the inside on the strong one, much like closing a vent in your vehicle works, forcing more to the other vents.

Suburban does not recommend adjustable vents. The risk is that airflow around the firebox will be reduced, the high-limit switch will cycle the gas off and on, and heating will be REALLY uneven.

That said, I admit that I have been known to cover 1/3 of the bedroom vent (right next to the furnace) with a mat when others were sleeping in the cooler living room. It works best if you leave all the doors in the trailer open.

Larry

[jimmie2gunns]

I had a 2014 with the same floor plan and the same problem. I dropped the underbelly to investigate. They ran the duct for the rear of the living area too close to the track for the dining slideout. It ended up with a hole in it. We were losing most of the airflow into the underbelly and the living area never warmed up properly. It was our experience that we had better heat in the bedroom and bathroom because the heating unit was between those two rooms and didn’t have to travel far.

[Larry-NC]

Originally Posted by KEN9XL

OK! Solves one problem, no filter. Was thinking it was clogged.
It is in fact heating just not much air flow or force.

Heater is in bedroom, I can hear it kick on & fan activate with air flow, so things are working, plenty of hot air just seems to have very little force. Bathroom backs up to heater, other side of bedroom, has hot air but again very little force.

I can understand one duct if crushed or disconnected but two.

I opened up panels to heating system both in bedroom (under closet space) and in bathroom (under sink). Checked ducts, all connected and not crushed plus both have very short runs, one side of wall to other.

Well, you almost did enough, but could try one more step. The next step assumes a Suburban SF-series furnace.

Take the return air grille off the furnace cabinet again. You will see a big, silvery box called the "plenum." It surrounds the "firebox." The front panel is held on with just one or two sheet metal screws. Take the front panel off.

Now start the furnace. You should get a huge blast of warm air when you kneel in front of the furnace. This should confirm to you that the problem is not filtration. The problem is ducts between the plenum and vents.

People have reported various issues:

• Ducts that were crushed between frame members during build.
• Ducts that have become disconnected and are dangling beneath the floor.
• Ducts that have mice-caused holes.
• Ducts that are way too long, snaked around and kinked by lazy installers.
• Ducts clogged with lots of pet hair sucked completely through the plenum and deposited downstream. (We had this problem.)

Endoscopic inspection cameras for your phone or laptop are really cheap. Easy to snake it through ducts with this plenum cover off, and to remove the vent covers and snake forward and backward. This is the first example I found.

Let us know what you find.

Larry

[KEN9XL]

5picker - thank you for info on fan and multiple ducts as an issue.

CincyGus I like your idea on adjustable ducts to stem flow but in reading information from Larry-NC, I guess I might think twice or use idea occasionally with all doors open.

Larry-NC - plenum when opened & furnace started, definite blast of warm air

jimmie2gunns - I like the camera idea that Larry-NC mentioned to verify nothing is clogging duct work internally better than cutting open the underbelly and inspecting, repairing, rerouting, or replacing the duct work.

So I am afraid I may have to view the underbelly.
Duct tape will work wonders if holes are small on duct work.

Guess I must order myself the camera and wait for delivery.

How would you reseal underbelly once cut open.
Any special process, tape, tools?

[Larry-NC]

Originally Posted by KEN9XL

5picker - thank you for info on fan and multiple ducts as an issue.

CincyGus I like your idea on adjustable ducts to stem flow but in reading information from Larry-NC, I guess I might think twice or use idea occasionally with all doors open.

Larry-NC - plenum when opened & furnace started, definite blast of warm air

jimmie2gunns - I like the camera idea that Larry-NC mentioned to verify nothing is clogging duct work internally better than cutting open the underbelly and inspecting, repairing, rerouting, or replacing the duct work.

So I am afraid I may have to view the underbelly.
Duct tape will work wonders if holes are small on duct work.

Guess I must order myself the camera and wait for delivery.

How would you reseal underbelly once cut open.
Any special process, tape, tools?

Ken, it seems like the best course forward is to inspect the ducts non-destructively. Fortunately, as we enter the warm season you'll have time to wait for the camera.

I'll bet you got quite a blast of warm air when sitting in front of the open plenum, right?

I am guessing your underbelly is Coroplast. It's like corrugated cardboard, but made of plastic. You can cut windows in it with a utility knife. Best practice is to cut three sides of a rectangle, leaving the FORWARD side uncut. Bend down the flap to do the work, then bend it up and tape the three sides with Gorilla tape. Leaving the FORWARD side uncut eliminates the possibility that the wind while driving 60 mph will tear open your repair.

DO NOT use duct tape on the ducts or Coroplast. The duct tape you get these days dries up in 2-3 years and lets go. You don't want to do this job again. Get the kind of HVAC tape professionals use.

Often there's way too much duct stuffed in there because the installer didn't feel like cutting it off. You may be able to cut off a damaged end and have enough left to connect. Or you might want to replace an entire segment. You will have to see how connections are made at the ends. It could be a metal strap clamp around the duct and vent stub, or a couple of sheet metal screws through the flexible ducting. If there was nothing holding the flexible duct to the housing and it's come off, at least put a few self-drilling sheet metal screws in. These screws can be installed with your electric drill/screwdriver.

Remove all the vent covers and the plenum cover when you get the camera. Probe the vents. When you find a flaw, move the camera to the fault point. Put your thumb on the camera cable, right at the vent or plenum entrance. Then extract the cable and lay it on the floor with your thumb at the same entrance point. Look at where the camera end is with respect to a trailer window, door, or other outside feature. This gives you a front-back reference of where to cut the underbelly. Now look at how far the vent is from the outside wall. That gives you a side-to-side reference of where to cut. Repeat this process for each fault you find.

Larry

[quick83]

My vents do not put out “a lot” of air and I’m pretty sure having a 41 foot Rv with 4 vents, one 25 feet from furnace does not help. The same furnace with same fan goes into all size rvs. I block our bed room vent. We use Electric ceramic heaters a lot also. I think it’s just the way it is with large Rv and one size for all furnaces. Btw it does heat up our Rv fine and I also turn on Ac fans on low to help circulate heat while furnace is on and it draws air out of the heat vents faster. Also I clean inside vents every year, it gets pretty dirty in the vents. Just take off and vacuum.

[Larry-NC]

Originally Posted by quick83

My vents do not put out “a lot” of air and I’m pretty sure having a 41 foot Rv with 4 vents, one 25 feet from furnace does not help. The same furnace with same fan goes into all size rvs. I block our bed room vent. We use Electric ceramic heaters a lot also. I think it’s just the way it is with large Rv and one size for all furnaces. Btw it does heat up our Rv fine and I also turn on Ac fans on low to help circulate heat while furnace is on and it draws air out of the heat vents faster. Also I clean inside vents every year, it gets pretty dirty in the vents. Just take off and vacuum.

I have to call you on this one. The cases of the SF-series furnaces are all the same size, but the internals are different. This includes the burner and the blower. Here are a couple of images showing the differences in the SF-series fans.

That said, if you don't have the largest SF-series furnace, it would be simple to transfer the "guts" of a higher-capacity one into your existing plenum. Just make sure you have the required square inches of ducting and return air vent or it will cycle on high-limit and you will be really unhappy.

Larry

[grumpyoldman]

Has anyone added a filter to the furnace? I have a large wood panel with slots cut in it in front of the furnace. This is located in the kitchen area. Pulling this panel gives me access to the furnace but I can also see the front cargo area beyond the furnace. It would seem to me that the return air to the furnace is coming from the cargo area along with the living area. Is there a good location for a filter or should I not worry about it?

[quick83]

Interesting. So you are saying my Rv has a furnace with better output because it is so large, that an Rv like a FR 31 foot arctic wolf has a furnace with less output?

[quick83]

Hey grumpy. You may be on to something. I always thought my open vent under my steps was only for air circ for the inverter there for cooling. The furnace is under there also but about 6 feet away and gets its supply from under there and pulls air through the vent in the steps and a filter there may do something to help clean the air. I will try an experiment and turn on furnace fan and see how much air the vent is pulling when it’s on.

[Larry-NC]

Originally Posted by quick83

Interesting. So you are saying my Rv has a furnace with better output because it is so large, that an Rv like a FR 31 foot arctic wolf has a furnace with less output?

Yes. The only way to tell (for example) an SF-20 (20,000 BTU) from an SF-45 (45,000 BTU, over twice the capacity) is by reading the nameplate.

Not sure that an Arctic Wolf has a lower-capacity furnace, since I think it is a "four-season" trailer, but it could. For sure, our 22-foot Nash has a lower-capacity than our 38-foot Cherokee destination trailer.

Also possible that the furnace in your big RV is undersized. Why don't you look at your "build sheet" or furnace label and tell us what you have?

Larry

[Larry-NC]

Originally Posted by grumpyoldman

Has anyone added a filter to the furnace? I have a large wood panel with slots cut in it in front of the furnace. This is located in the kitchen area. Pulling this panel gives me access to the furnace but I can also see the front cargo area beyond the furnace. It would seem to me that the return air to the furnace is coming from the cargo area along with the living area. Is there a good location for a filter or should I not worry about it?

Suburban specifically instructs you to not put a filter in the return air stream. The problem is that restricting air flow could get the firebox too hot, causing high-limit cycling.

On the other hand, Suburban requires 55 square inches of return air vent. The installation in the Nash has about 150 square inches. The plenum and ducts were always clogged with dog hair (DW favors dog breeds that shed). I've installed filters on the return air, just haven't had a chance to try them yet. What I would really like to do is mount an LED across the high-limit switch, so I can tell if it's limiting. If not, everything should be fine.

Larry