Main Page Navigation:

 

WINTER INSIDE SLIDE SHOW HERE

 Surviving Winter P2 - Dealing with freezing weather, snow, ice and wind

Introduction

     In Part I of this series I dealt with the outside considerations for those finding themselves staying the winter in a bus. Part II covers modifications on the inside you can perform to improve comfort and save energy in the process. Herein you'll find tips and tricks we've learned from 4 winter season stays. Our bus is a 2006 40' Country Coach Allure 430 series. This bus is well documented elsewhere on our site in the Bus-Stead Tour section. There are many ways to deal with winter cold and I offer our solutions/modifications as just one approach. What's presented herein may or may not be appropriate for your specific vehicle, climate and situation. That said, I hope what is presented is useful, interesting and thought provoking. Maybe some of our approaches will help you taylor your own solutions and avoid some of the pitfalls we've encountered. Chances are your stock bus won't go through a full blown winter without problems, damage and loss of comfort. Certain features will require attention, improvements and upgrades. Finding this out in warm weather, when it's easy to work inside/outside, is much better (and safer) than discovering short falls in the freezing cold.

Design Limits

     Busses, in general, don't handle extremes in temperatures very well. Some units can't be used in freezing weather owing to uninsulated plumbing and holding tanks which would readily freeze. If your bus isn't winter rated it's best to head for the warm climates. Our bus does have a heated and insulated plumbing bay. Yes, it's rated for cold weather service but that rating should be taken to mean "within reason". Also, that rating doesn't stipulate the lowest temperature possible before things begin to freeze. It also makes no attempt at quantifying interior comfort for varying degrees of cold weather. Even with its winter rating, our bus had a light freeze up in one of the PEX lines that runs close to an exterior wall in the bathroom. It's just an anomaly of how one particular line was run in one particular bus. It calls attention to knowing where your plumbing lines are and anticipating a freeze up. In our case, the freeze up happened during a -20F cold snap. Luckily no damage was done and we were able to get the line thawed out with a hair dryer. Now we know about this and will take steps to prevent it next cold snap.

     Moreover, the construction of a bus doesn't allow thick walls full of insulation like that found in a house. Most cold weather rated vehicles do have insulation in the form of styrofoam, like that used in coolers. It works reasonably well. Luckily, our bus is very tight which reduces what's called infiltration loss. Infiltration loss simply means cold air leaks in and chills already heated air. To overcome infiltration, more heat capacity is required to heat the constant flow of cold air coming in from the outside. A leaky vehicle will have cold spots and just be more expensive to keep comfortable. Keep in mind that some fresh outside air is good for ventilation. Ceiling, walls, floors, vent openings, windows and your access door all lose heat. This is especially true for window glass. It's been said your best window isn't as good as your worst wall regarding heat loss. Any ice cold surfaces presented to the inside will chill air. Cold surfaces also collect frost with some thawing and dripping. Keep an eye on these. Luckily there are some simple things you can do to help your bus hold onto its heat better.

Stock Heating System

     During the winter of 2009/2010 we hit temperatures of -20F overnight and in the early mornings. Luckily it didn't go on for more than several days. Weeks of time, however, did go by not seeing temperatures much above 5F during the warmest part of the day. Using supplemental heat, we did remain reasonably comfortable through it all. Finally, it only takes one really cold night to freeze and bust something. The message is make sure you have enough heat in the right places to stay ahead of freeze ups. And stock heating systems aren't enough to handle bitter cold. Making repairs in bitter cold weather is usually problematic, unpleasant or just impossible. It's something to avoid.

     Our bus has a Hydro-Hot system and 3 heat exchangers inside to produce forced hot air. A heat transfer fluid is circulated through the heat exchangers which then warms the air. In mildly cold temperatures (let's say 30F-60F) it works fine. In really cold temperatures (low 20s and colder), however, the system is inadequate. Meaning it runs constantly and can't stay ahead of the heat loss. Not only does this put needless wear and tear on the components, the interior temperature falls and becomes uncomfortable. The heat exchangers aren't designed well and I found this out upon disassembling them. The heat exchanger core isn't sealed well around the metal box it's installed in. Leaks mean cold air "blow by" around the heat exchanger fins resulting in reduced efficiency. I fixed this problem by stuffing insulation in the leaks. It helped a little bit. Dust clogs the fins too and reduces efficiency. It's a good idea to keep the heat exchangers clean and tight. Make sure your heating system (Hydro-Hot in our case) has been properly serviced before the winter heating season. Discussing annual maintenance procedures for heating systems is beyond the scope of this article. As a start for Hydro-Hot owners, replace the burner nozzle, fuel filter and all plastic parts in contact with the heat transfer fluid. An overlooked part is the plastic tank level switch which often breaks at the worst time. In a pinch you can jump out this switch but I don't recommend it. Hydro-Hot was an $8k option, so why would one expect anything more than cheap plastic parts prone to premature failure?? Go figure!

Heat And Heat Loss

     Heat loss is something that occurs in all vehicle interiors. It's impossible to create a perfectly insulated cabin and for ventilation reasons you wouldn't want to. When heat loss is greater than heat input, temperatures inside drop. When heat input exceeds heat loss, temperatures inside increase. Assuming you've got your stock heating system in order it still won't put out enough heat to handle a really cold winter. That said, you'll need to add heating capacity and also reduce the heat losses to control interior temperatures with the least amount of heat energy. To achieve maximum comfort, plan on it being a two fold proposition. Reducing the heat losses is the easiest and cheapest place to start. Let's take a closer look.

     The photos at right give a pretty good visual idea of what steps can be taken to tighten up your bus. Insulation is pretty cheap and well worth the extra effort to install it. Slide floor insulation was covered in Part I of this series and installing some makes a HUGE improvement. Each bus is slightly different, however, so you need to investigate and inspect your specific interior space carefully. Look for places to install insulation with good effect. Chances are good you'll find many places for significant improvements that will boost comfort and save on heating costs.

     We made custom insulation blankets for many windows from duct insulation and a good quality adhesive tape. Cut, fit, tape together and install them over windows as required. Keep in mind that duct tape doesn't hold up well when exposed to sunlight. Using a tape rated for sunlight exposure to join panels avoids doing the job over again.

     The front windshield was a bit more of a project. Our first attempt used 3 long horizontal runs (left to right) of 16" fiberglass insulation. We taped it together (horizontal runs) to make one large blanket that completely covered the front window. This quick and easy "test" allowed us to see how much improvement could be realized. The results were much better than expected. Our final (and current) method was to make semi-rigid insulation pillows about 3-4 inches thick. Vertical strength comes from making the sides from 1/2" polystyrene foam board. Front and back panels were made from silvery duct insulation like that available in a home center. The interior cavity was filled with fiberglass insulation and the top and bottom ends sealed with tape. All other joints were simply taped together. These pillows are easy to install and remove. They are tight, clean and store well on the bed during travel. Insulation properties are excellent. A bonus is in summer. They help reduce heat coming in which saves money on your air conditioning. They also help reduce outside noise and quiet the interior. I'd say insulating windows produces the best results for the time and money invested. Be complete, however, and don't just stop with the windows. Every little bit helps.

     Once you've got your bus insulated and tight you've pretty much covered the heat loss problem as best possible. From this point it is what it is and you just run with it. With good insulation in place, you'll find less drafts and a more even heat which makes a winter stay just that much more comfortable. As mentioned, the insulation will also help reduce outside noise. In the really cold climates, however, all the insulation in the world isn't going to allow your stock heating system to keep you warm. You will need to install supplemental heat.

Supplemental Heating

     The most common sources of energy for heat are diesel fuel, kerosene, heating oil, propane, wood and electricity. If your bus is painted a dark color, consider the sun as another significant source of heat. Obviously you need to be parked in direct sunlight and have the long side of your bus facing due south for maximum benefit. The closer you are to the equator, the stronger the sun will be. Depending on where you stay and where you can park this might not be an option or practical. And forget about the sun at night when it really gets cold out.

     If you have a Hydro-Hot system you'll be using diesel. Kerosene heaters are out of the question. An oil burner furnace won't work owing to its shear size. (The Webasto heater is sort of a miniature oil burner that runs on diesel fuel.) And I can't imagine using a wood burning stove either but I wouldn't put it past some people. What's left are propane and electricity. Consider any heating that comes from the sun a bonus.

     Combustible fuels all have BTU ratings. A BTU (British Thermal Unit) is the amount of energy required to raise one pound of water one degree farenheit. Thus taking one gallon of water at 60F to a boil (212F) would require 1,200 BTUs. This assumes that a single gallon of water weighs 8 pounds which is a small over statement. But it's good enough for us here. The table below gives a rough idea of what you can expect from various fuels. Diesel, of course, produces the most amount of heat. But it isn't as easy as just picking the most powerful fuel or energy source. As for diesel burned in a Hydro-Hot, for example, there are efficiency considerations. Those that own a Hydro-Hot system already know how much of the heat goes out the exhaust pipe. I'll come back to this later in the article and try to make some sense of it.

     We decided to use electric space heaters and they have worked well over the past two winters we've spent in Utah. As I write (winter 2011/2012), we are in our third Utah winter season using the methods I'm describing. Most others in the park are using propane. Personally, I'm not comfortable burning a pressurized fuel in a confined space. Burning propane consumes oxygen and produces moisture which are potential problems in a bus interior. Plus I don't like the exterior propane tank which tethers your bus via a gas hose. Both systems of heat have their advantages and disadvantages so I'm not knocking propane. A complete treatment of them is well beyond the scope of this article. I'm merely presenting what has worked for us and hope that information will help others make an informed selection. Several good heating options exist so do your homework. What I do like about propane is your heat isn't affected by a power outage. We lost power here back in the winter of 09/10 for 5 hours. Luckily our generator started. Last winter (10/11) there were no significant power outages. Although our Hydro-Hot system won't keep the bus comfortable, I think it will keep us from freezing up. An untested theory at this point. It remains then, a good back-up system (I hope) should the lights go out for an extended period of time. With proper thermostatic control, I don't think heating a small space with electric heat is terribly more expensive than propane. In fact, it might be cheaper if you consider all the factors. Whatever its cost, I certainly think electric heat is cleaner and safer for a bus interior. That, of course, assumes a proper installation and good quality heaters. Please don't install Walmart junk and/or cut corners with power feeds.

Installing Supplemental Electric Heat

     As mentioned, a proper installation and use of good equipment is key. Sadly it's just so easy to buy a cheap electric space heater, plug it in and fall asleep. This I strongly discourage. One of the down sides with using an electric space heater is making sure you have a safe power source. A good heater will run you $60 and up. Like I said before, it isn't as simple as just buying a cheap Walmart heater and plugging it in.

     Our bus has two 15A house outlet circuits. They are referred to as passenger and driver side circuits which are nothing more than a daisy chain of outlets that run front to back on each side of the bus. Sadly these are cheap plastic outlets mounted in wood with no metal containment box. They are fine for short term loads like a hair dryer, toaster, mixer, lights, PCs, small battery chargers, etc. I wouldn't even think about using them for long term high amperage loads like a space heater. Just because you can plug things in doesn't mean it's a good idea. With our house outlets, out of sight are connectors mid stream in the 14 gauge house outlet circuit wiring. I've already repaired one connector under the refrigerator that caused all the outlets forward to go dead. Pulling high amperage, any one of these connectors could over heat and present a fire hazard. These connectors are plastic and mounted to combustible materials with screws. Wire connections within them are via push down strips. In a house, this would never pass a building code.

     In our case the house outlets have an additional problem, that being they are run from the inverter sub-panel. What this means is if utility power is lost, these outlets immediately get switched to inverter power. If utility power remains out for several hours, thousands of watts of space heater loads will trash your house batteries in short order. If you aren't home to attend to this, plan on returning to a dead bus, possible inverter problems and potential house battery damage. Some inverters can be shut off but that defeats having a small amount of back-up power to run clocks, PCs, small chargers and HiFi gear.

     Even a small space heater will use most of a 15A circuit up. That means no toasters or hair dryers can be plugged in without snapping a breaker. You tell yourself you're going to remember to unplug the space heater but we both know you'll forget. Finally, for an entire cold winter season, I don't recommend using house power outlets to run space heaters. For all the reasons stated above and more, doing so compromises safety and crosses lines of practicality and good judgement.

     Our bus has two 20A air conditioner circuits (front and rear) which go unused during the winter months. It's wasted electrical capacity that could be put to good usage. With a little effort this can be brought into the living space as two dedicated outlets. And this is exactly what we did. Yes, running wire in these busses is generally a pain in the ass. In my opinion the increased safety easily offsets the labor required to make the installation. I used a good grade of 12 gauge copper wire with a ground. The run from outlet back to the circuit breaker panel is less any splices, wire nuts or connectors. I used a standard duplex 20A outlet mounted inside a steel junction box. Coming back to the breaker box, I simply paralleled the air conditioner circuits. I've included pictures of the outlets for reference. In the front zone, I installed a good duplex outlet into the existing mounting area of the passenger side house outlet hole. The cheap plastic outlet got tossed in the garbage. I split the outlet circuit so as not to lose my house circuit up front. Make sure to clearly label the functions.

     In the bedroom (rear zone) I needed to cut a new hole and mount the outlet there. Access wasn't too bad from under the closet bottom in the sink area behind the wall. See pictures at right for a look at the finished outlet installation. Both these zones provide solid 20A service without any safety issues. They are good for about 2,400 watts of continuous power each. All connections and outlets are within steel junction boxes. I used the box style that mounts into a blind hole which saves time and effort. Look for these in your favorite home center.  

Space Heater And Thermostat Control

      Once you have your power outlets run in you can begin dealing with getting your space heaters setup. This can be as easy as purchasing a good quality unit and plugging it in to your newly installed outlets. That's exactly what we did and found some additional operational issues that deal with the heater's internal thermostat. Depending on what model you are using, there may be some additional problems as we found out later.

     The space heaters we are using (see photos) can be purchased from Grainger (P/N 1VNW9) for around $56/each. They put out 5,200 BTUs on high (1,500 watts) and can be set to medium (1,000 watts) or low (650 watts) for those early winter cool days. On high they draw 12.5 amps. They have a ceramic heating element and a fan with a removable dust filter. The heaters are reasonably quiet. There is a safety switch that shuts the heater off if it gets knocked over. An internal overheat switch will shut off the heater if the ceramic element gets too hot. For example, from a blocked air flow and/or dirty filter. These are pretty good heaters but there are some issues you should be aware of.

     The fan inside is injection molded plastic and some run out of balance. Over time the vibration causes the heater to squeak which is obnoxious. Grainger was very good about replacing them, with no questions asked. For those inclined toward tinkering, you can take apart the heater and balance the fan blade. I did so by drilling a small hole in one of the blades and crimping a small bit of a paper clip through it. That worked well. Otherwise these heaters are reasonably well made.

     The biggest problem with these space heaters is the internal thermostat location. Floors in a bus usually get a little drafty. What this does is cause the heater to short cycle. The internal thermostat doesn't have an anticipator either like a standard home thermostat does. The anticipator helps reduce overrun by shutting off the heat a bit early in the cycle. This helps save energy. Heating systems work best when heat comes from a low point in the room and the thermostat is mounted on an inside wall about 5 or so feet off the floor. Thermostats should never be mounted in a cold air draft. If thermostat and heater are in one unit, as they are in most space heaters, optimal performance can't be achieved. It's a problem which boils down to wasting energy.

 


Dug Out In Park City, Utah 12/8/2009 10F Degrees

 


Typical 4 Slide Layout On A 40' Bus


Simple Way To Insulate A Window


Insulation Panels For Front Windshield


Pipe Insulation Fills Gaps


Gaps Between Floor And Movable Slide Panels
Can Be Plugged With Pipe Insulation


Bed Frame Gaps Closed With Pipe Insulation


Closet Door Needs Sealing


Adhesive Foam Makes Closet Door Tight


Frost On Aluminum Window Frame


Sun Melts Frost Which Produces Water Drips


Using An Electric Heater In The Bedroom



A Light Duty Electric Heater w/Fan
Available From Grainger



An Extra 20A Outlet Installed In Bedroom



Split 20A Outlet Installed In Front



Front Zone Low Voltage Thermostat


Bedroom Zone Low Voltage Thermostat


Heater Control Box (Custom Made)


Heater Control Box (Rear View)


My Outside Temperature Gauge


Heater Control Box Circuit (click for large view)

Heater Control Box

      To solve this problem, you'll need to make a heater control box. (See photo above for a suggested circuit diagram.) One for each zone will be required. We needed two of them. Basically what this box does is allow a 20A resistive load to be controlled by a low voltage thermostat. All that's inside the box is a power relay, 24 VAC transformer and fuse. These are pretty much the same components found in home heating systems assembled into a small portable box. The idea here is to physically separate heater and thermostat which allows controlling the heat source from a more optimal thermostat location in the room. In theory you could use an "electric heat line voltage" wall thermostat but then the wiring gets clumsy and you've got a thermostat screwed to the wall. The idea here is to be able to remove the supplemental heating components when they aren't needed. The mobility of the components also allows playing around with the best location for the thermostat. Why junk up your bus with a clunky thermostat screwed to the wall. To that end, we kept it as simple as possible and prioritized portability. I used a clear plastic adhesive wall hook for the mounting and vinyl tape to hold the thermostat wire in place. All we need to do is unhook the thermostats, coil things up and stow it away with the heaters for next season. Setup for the next cold season is also easy. Also, low voltage thermostats offer a much better selection and many models are programmable. If you want to go for the fancy stuff you can. Night set backs and 7 day programming might offer some energy saving advantages for some. It certainly is something to think about when selecting your thermostat. The approach presented here will afford you many options.

     As for building a control box, many configurations exist and with a little imagination I'm sure you can come up with something that works for you. The most important thing is make sure you build something that's safe! DON'T USE JUNK OR CHEAP UNDERRATED PARTS!! See the circuit diagram above for a reference and suggestion. Make sure to use 12 gauge wire on all power circuits, line cord, internal connections, splices and outlet. Put all your parts inside a sealed metal enclosure and fuse the primary of the transformer for added safety. Use proper strain reliefs on all wires entering and leaving the box. A low voltage thermostat has a set of "dry" contacts that close when the thermostat calls for heat. This completes the circuit and closes the power relay. You'll notice I have three wires (not two) indicated as the thermostat leads. What I did was run a 24 VAC source up to the thermostat just in case I needed a constant source of "low voltage" for some reason. You may opt for just two wires which will be fine for almost all thermostats. Using a light gauge wire here that's flexible will help with the cable routing. Wall thermostats usually mount in a box recessed into the wall with wires running through the wall as well. I surface mounted our thermostats and you'll need to play around with the lead in wiring to facilitate this. If you do run an "extra" third wire that isn't used, make sure to tape it off so it doesn't short to anything it isn't supposed to. Other than that, it's all reasonably simple and straight forward.

     On the Grainger heaters, there is a model that looks similar to the ones we've installed. This unit features an oscillating mechanism and digital control albeit at an increased price. I don't recommend using this heater or any other similar one. The oscillating mechanism usually fails over time and the digital control doesn't remember its setting when the power goes out. When the heater's power is resumed, the digital control comes back in the off position. For obvious reasons, this type of heater won't work from an external control like the heater control box presented here. If you depend on these heaters they need to be restartable. Consider a loss of utility power when you're out to dinner. When the power resumes, all your heaters need to restart properly. Digital controls that come back "off" won't restart which means you come back to a freezing bus. If you are a heavy sleeper you may wake up in the morning to a freezing bus. Either one isn't going to be pleasant.

     Many space heaters run at 1,500 watts or close to that so they can be used on a 15A circuit. On a 20A circuit you can handle a 2,400 watt resistive load. (For reference a 1,000 watts equals 3,412 BTUs.) If your heater has a low and medium setting you can combine two heaters for increased heating capacity. If you exceed 20A, however, you'll trip the circuit breaker. You'll need to set the power levels properly to stay within your circuit's capacity. On the Grainger heater (used in our application) that would be one unit on high and a second unit on low for a total of 2,150 watts or 7,336 BTUs.

Conclusions & Next Steps

     Going back to the notion that increasing the temperature of a space simply requires injecting more heat energy into it than is lost puts us back in touch with the basic idea. This implies that increasing heat input, cutting heat losses or doing both will allow us to heat our living spaces. Accurately controlling the temperature, staying ahead of winter's chill and maintaining comfort require us to dig deeper into details, methods, innovations and adapt products. Of course, the simplest (and cheapest) solution is to avoid winter altogether but that isn't an option for those that want to be close to winter sports and activities on an extended stay basis. For the small group that relies on their bus for a winter home we have some special needs. Whether you select propane or electric heat to stave off winter's chill, the ultimate goal is to be comfortable and avoid damage due to freezing. The challenge is to figure out how to adapt available products and safely address the heating problem. And make safety your number one concern. Safety has direct importance to you, to your neighbors and the community of mobile travelers at large. You don't want to heat your bus by burning it down. Chances are slim your neighbors will respond with smiles and marshmallows.

     It would be nice if dedicated tried and true products were available right off the shelf. The market just isn't big enough to support such a product line. How many folks are living full time in a bus? Of that group, how many decide to stay in a cold climate? It seems like only a handful of people. But for those few, getting the products and solutions they need is important. The information presented here is by no means exhaustive or the advice of experts. It's a single approach that's worked well for two travelers in one bus model. I offer it as something not to stupidly copy but to study, consider, adapt, evolve and learn from. Perhaps for some it's an example of what not to do. For others I hope it motivates a solution and makes your implementation an easier task. If you can go deeper with this subject, hats off to that. Just take the time to publish your findings for others to benefit from. The information super highway works better as a give and take proposition.

     Money can make people weird so I'll keep this subject simple and to the point. We were not blindly looking for the low cost heating solution as other criteria needed to be considered. I've learned over the years that certain forms of cheap can be really expensive. So it's important to look at the whole picture over time. Also, personal preference items guide decisions and choices which everyone needs to figure out for themselves. That said, the cost of your heating solution (and the proper solution itself) is something you need to arrive at on your own merits. I offer no advice on that beyond the example presented herein. I did, however, compile a table that compares the cost of propane, diesel fuel and electricity as sources of BTUs. It's by no means a complete treatment of heating costs and is offered for general interest only.

Cost Per 10,000 BTUs For Common Fuels (Nov 2011)

Fuel - Standard Sale Units

 

Market Price

 

BTU Rating

 

10K Cost

 

Diesel Fuel (7.15 Lbs/Gal) $3.89/Gal National Avg 157,300 Per Gallon $0.25
Propane (4.23 Lbs/Gal) $2.82/Gal Residential Avg 63,450 Per Gallon $0.44
Electricity (Sold by kWh) $0.09/kWh (in Utah) 3,412 Per kWh $0.26
Values shown above are approximate.

     How the above forms of energy are converted to heat is very important. Diesel, for example, doesn't burn clean so it needs a combustion chamber and flue vented to the outside air. A certain amount of heat is thus lost in the flue gases. Propane burns clean which means an open flame could be burned inside a living space. We know this from looking at a propane kitchen stove. All the heat produced by this method of combustion would go off in the living space meaning very little waste occurs. Electricity also converts cleanly and efficiently to heat via a resistive element. Again, very little of it is wasted in the conversion process. The equipment required to convert fuels (or any energy source) to heat should also be considered. In some cases, it's expensive, bulky and requires routine maintenance. More parts means more opportunities for a breakdown which ultimately costs money. The cost of energy is constantly changing by region and by season. For example, electricity was about $0.04 more per kilowatt in Colorado than in Utah. Even so, the costs presented in the above table make electric heat for small spaces reasonably competitive with common "fuel" heating options.

     Another point that needs to be made is some of our winter preps don't lend themselves to short term stays. If you travel around, staying only for short periods of time in one location, doing a proper winter setup just isn't practical. The information presented here assumes you'll be staying in one place for an entire winter season. The payback on efforts to winterize become less cost effective for the short stay travelers. Below a certain point it isn't worth the bother. If you are a short stay traveler, pick what you think will work and leave the rest of it behind. One of our cardinal rules is we don't drive in winter cold, snow, ice and salt. That mandates a long term winter stay for us and winterizing becomes just another part of our setup ritual. Also, installing insulation all over the place means you won't be able to clam up your bus quickly. Consider the safety implications, if any exist, before you bog yourself down.

     There's no such thing as green energy plain and simple. All forms have advantages, disadvantages, environmental foot prints and hazards. As for solar, the government's meddling in the industry has done it more harm than good. The Solyndra scandal is a good example. I think as a niche industry solar has potential and in my view the industry should be left alone to address those small markets. When the government begins dumping large amounts of money into technology that isn't ready for its call of duty sooner or later it all comes crashing down. Plus it runs the risk of labeling the technology with a scarlet letter which hurts it for everyone. The solar system that's installed on our bus is quite extensive and documented elsewhere on this site.

     I've done some thinking about how to use the solar electricity we can generate to offset our heating load. At its best we're talking nickels and dimes. One immediate problem comes to mind. When you really need the heat (which is at night) the sun isn't shining. Presently no practical and efficient means of storing the energy exists. Adding insult to injury, the winter sun is weak and that's why we get winter in the first place. From a natural perspective everything about winter is setup to be cold to include a low sun angle and reduced daylight hours. I could make a 1000 watt DC space heater and let it run during the day as a small boost. I could also heat the water in my fresh water storage tank during the day. That would require making a special heat exchanger and employ a circulating pump. Doing so would help keep the plumbing bay warm. I'm not sure whether the effort is really worth it. All these are merely "concept" ideas perhaps best implemented under the colored lights of a trade show. As for solar heating, I recommend just parking your bus in the sun and soaking up the heat. A dark colored bus works better and you do get a surprisingly good amount of heat that way. The best part is it's quick, cheap and easy. On many sunny days we get enough solar heat to click off the electric heaters which is a direct saving of energy. Using the heater control box you can position its thermostat to "feel" the sun to better control your heat source. It all saves money which is a good thing. Here's wishing everyone safe travels and a warm winter. Over and out for now.