The key item in Keystone's basement heating and Arctic/Polar/etc. tank package is the heating ducts that come off the furnace and their vents to the tank valves and fresh water tank area. While I am not sure of other models, in my Alpine 3640RL, the "return air plenum" for the furnace amounts to louvered vents in the vertical portion of the stairs to the bath and bedroom ("Vent Panel.JPG"). However, to draw air into these louvers and thus into the basement, the furnace must be running. I agree with mikell that the heat pump on the Alpines is a wonderful addition. Our dogs like the fireplace heater. I also know of many who use electrical heat sources inside the fifth wheel living area. I'm guilty of this myself! But the only heat source that can add heat to the basement is the furnace. Now, I do understand that some owners have removed the basement panels in the storage basement and used small electric heaters. Others have skirted their RVs and used a small electric heater under the RV. Sorry, but I'm a little nervous about either of these latter ideas of unattended space heaters.
About a year ago, I posted on the Modifications topic that I had added a warm air circulator for the basement. Now that the year has passed and met with success, I am ready to modify this idea to the next level – more power! Last year I mounted a 200mm "Cooler Master" Computer Case Fan beneath the stairs to pull warmed air from the living area of the Alpine into the basement. This particular fan is extremely quiet and can move 110 cubic feet of air per minute. I wired this fan in parallel with a Inboard/Outboard Bilge Fan and placed the switch for this contraption inside the WaterWorks area. Not one of my best moves – had to go outside in the cold to turn on the warm for the basement!
This year, I am adding a second 200mm fan under the steps. These two fans combined will move approximately the same amount of air per minute that is represented by the primary utility basement volume beneath the bath and between the storage basement and kitchen. Warm air is drawn into the basement area by the fans, and returned either through the louvered grill of the steps or by the furnace. So if the heat pump is operating, or the fireplace, or an oil filled electric radiator – no matter what is heating the living space of the Alpine, some of that heat will be pushed into the utility basement area.
I removed the top louvered vent panel from the stairs by removing the four attached screws ("Vent Panel.JPG"). Basically, this gives one "reaching space". I positioned the 200mm case fan in place behind the lower step. Using a punch awl, I carefully placed the point inside the two upper mounting tabs of the fan and tapped it with a hammer, thus punching a small hole into the aluminum frame. I then inserted 1 ½" sheet metal screws and firmly secured the fan to the frame. I used some thin plywood to block the open side of the lower step area to the fan would primarily pull air from the living area of the Alpine.
However, the wiring and switch needs to be moved – to the inside! To the Control Panel! I purchased a simple 12VDC rocker switch from an auto parts store that also has a mounted LED to signal the switch is active. The mounting of the switch is quite simple – drill a ¾" hole into the Control Panel area. I added a jumper from the +12VDC source for tank heater to the Source blade of the rocker switch. (This power source lead connects to the 12VDC fused portion of the Power Panel – see Tank Heaters, Part 2 – Control Panel.) The rest is fairly simple – the lead from the rocker switch drops into the basement via the wiring duct and over to the fans. I left the pin connectors on the fans and just crimped the female side of the connector to the 18 gauge stranded source wire. In this way, I can replace the fans easily when needed. The 18 gauge neutral wire returns to the Control Panel to be joined with other 12VDC neutrals.
Now, when the weather turns cold and the temperature approaches freezing, I just open the Control Panel door, flip the rocker switch on, and warmed air is pushed into the basement area. There are actually several pluses to this arrangement. Obviously, the basement area containing most of the Pex plumbing is supplied with warmed air. But another plus is that by pushing warmed air forcibly into the basement area and keeping that area warmer, the return air to the furnace is kept warmer! And so, if I use the furnace (while camped or towing) its efficiency is increased by having the return air warmer. (The output air from the furnace is hotter because the input air is warmer.) The last item is two fold. Yes, Keystone has mounted small "step lights" to the stairs. However, this particular fan has two mounted LEDs that can be purchased in two different colors – red or blue. I chose blue – didn't want the inside of the Alpine to appear like a WWII night-running diesel submarine interior bathed in red lamps! When the fans are on, I know because of the soft blue light from beneath the stairs, and it also lights the stairs at night!
The second part to the original basement air circulator was the Inboard/Outboard Bilge Fan. This 12VDC fan is somewhat loud, even when encased in foam and isolated from the basement floor by vibration pads! As I am modifying this arrangement in conjunction with tank heaters, the need for the 12VDC circulator fan was lessened by the tank heaters. Most all the Pex plumbing is located in the upper basement area. The only Pex plumbing in the lower basement area is the connection to the 12VDC water pump and a flexible 1" tube for filling the fresh water tank. If underway during a cold spell, the furnace will be running and supplying warmed are to the upper and lower basement areas. Only when encamped will there be a chance that the furnace might not supply all the warmed are to the Alpine if I use other heating sources. I decided to use a different type fan that utilized 120VAC for use when encamped. I found that a Radon Abatement Fan would provide the solution. Besides, the radon abatement fan is very quiet and has a 7 to 10 year continuous use life expectancy. Just as precaution, I implemented some sound dampening on the radon abatement fan. I attached a thick piece of foam to the fan "bottom" with plenum tape, attached a short lead-in plastic duct, and attached plastic pipe strap as mounting material (Fan Prep.JPG).
Notice I am adapting a fan normally used to rid basements and low areas of radon gas to, in this case, distribute warmed are into far reaches of the Alpine basement. These far reaches do not have "easy air circulation" under non-furnace use, and probably limited air circulation with the furnace. While not enough warmed air to assure the Fresh Water tank and Gray1 tank from not freezing, it will provide a flow of warmed air to keep the Pex plumbing from the fresh water tank from freezing. Though the radon abatement fan moves less air per minute than the bilge fan, it is VERY quiet! A huge plus when dealing with noise below the bedroom!
Within the Control Panel area of the Alpine, I cut out space for a light dimmer switch. The power source wire is the same power feed for the 120VAC tank heaters. From the dimmer switch, I ran 14 gauge solid wire down the wiring drop to the basement, over the furnace via hangers, and left enough wire to be able to connect the fan while sitting in the storage basement. Once the wiring was connected to the radon abatement fan, I lifted it into position and coiled the extra wiring beside it. I stabilized and attached the fan via the plastic pipe straps. Again, I used the 4" plastic duct (from a woodworker's dust gathering system) to connect the radon abatement fan to the distribution duct for the basement. However, the only distribution duct I left connected was the one that ran back into the fresh water tank area. I no longer needed the smaller ducts that ran to the gray water areas ("Fan.JPG").
The light dimmer switch for the radon abatement fan in the Control Panel area allows me to adjust the speed of the fan to my wishes or need. The fan is rated for such a switch. A small tab at the right of the switch glides up and down to increase or decrease the fan speed and air volume delivered ("Close-up Control Panel.JPG").
This whole process is fairly easy and quick. Since I did this task while doing the tank heaters, I cannot give a definite time to complete only this modification. I would guess maybe two hours or so if only this task was performed.
As far as expense, this is an inexpensive modification that will probably pay for itself in propane savings quickly! (Not to mention split, frozen Pex plumbing!) Two rolls, different colors of 18 gauge wire from HD – around $10. The rocker switch was $3.50 at Pep Boys (got the one with the blue LED also!). The fans were the most expensive parts. They were around $17 each from Amazon. They were approximately the same price at Fry's Computers, but I didn't have to drive 25 miles one way to get them! These are lower speed, large (200mm or 7.8") fans that are basically silent running. One cannot hear these fans running even when seated on the stairs. The Radon Abatement Fan was fairly pricey. It was $140 from Amazon as Radon Abatement is not an issue in north Texas (could not find one locally). The dimmer switch was $16 from Home Depot. The 4" plastic duct was "left overs" and the 14 gauge solid wire was used from the tank heaters. Admittedly, some of the work had been performed and parts purchased earlier when I did the Bilge Fan circulator, see:
http://www.keystonerv.org/forums/showthread.php?t=2001.
Ron
Warmed air circulation system for plumbing basement.
But also, one wouldn't be running it as much on the warmer weather trends (at least above freezing), so it would not be so much of an impact in the pocketbook. That's another reason I wanted to move the controls inside to the Control Panel rather than my first goof of putting them outside on the opposite side as the door! Like I said, not by best idea! 
Linear Mode
