Idling engine to power AC or heater

[Overland One]

Another heat source I have wondered about is the bottom air space below large rigid solar panels. They get really hot and need ventilation to function well. Maybe close in the sides and circulate the air in that space into the van at floor level in winter with a couple of computer fans in a couple of PVC pipes during the sunny days?

That's a good idea. Also, as we all know, the cooler we keep those panels, the more efficient they are. Except for the tiny power draw from those little fans, that would be free heat. Even if it was not enough to do the job by itself, it's free so even a little free heat is still good. I have seen people experimenting with running cooling lines under the panels in a grid form and then pumping the heated water though a heat exchanger, like a transmission oil cooler. They do this in the summer to cool the panels, in the winter, they could stick that heat exchanger inside the van and add antifreeze to the water and get heat. I just realized I would have to "spoof" my thermostat on the window ac unit, or just move it inside in the winter otherwise the unit would never turn on when it got pretty cold outside. PS I just looked up a comment from an ac/heat/air guy on another forum and he said turning a window unit around backwards will work but only down to an outside air temp of about 40 degrees. Not sure if he knows what he is talking about but this might be the case. He also mentioned the thermostat and figuring a way to weather proof the electrics. I have a 10,000 btu kerosene heater and a 5,000 btu propane heater so I probably won't need to do this but, it still might be a good project.

 

[RonDean]

In this whole conversation it would be good to keep our apples and oranges straight.

Just as there is a big difference between coolers and refrigerators, there is also a big difference between ACs and evaporator (swamp) coolers. Sometimes the cheaper device works fine for some situations, other times not.

I do have a window ac that fits a window exactly. And when I am somewhere for multiple days with power, I'll go ahead and install it. But, I prefer boon-docking and that restricts that option. I have sometimes resorted to a swamp cooler. They take water (or ice) to evaporate and that is in short supply in most boon-docking locations. And many of them don't work well enough to bother with.

What is not in short supply on hot desert days is sunlight. So, I am seriously looking for actual AC systems that won't break the bank. If anyone hears of any, please pass that info along.

 

[LoupGarou]

I used to idle my diesel truck to charge up the batteries. The emissions hardware didn't approve, don't do it anymore.

 

[RonDean]

On a slightly different tact, I have often wondered about passive systems. In desert regions like ancient Persia they used wind-catchers - https://en.wikipedia.org/wiki/Windcatcher.

I am thinking that once I am parked (think rural desert location) I connect a tower of some kind on top of my RV. As I understand it, such a tower allows cooler air to sink into the structure and hot air to rise and be expelled. Maybe couple that with some kind of vent to capture the cooler air from underneath my RV? I already have added lots of extra insulation to my RV. Add some fans and Bob's your uncle. edit: Maybe also add some kind of over the top tarp to provide shade?

I looked online but so far can't find where anyone has tried this on an RV. Maybe because it just won't work? But, maybe worth thinking about. Just throwing my idle thoughts out into the cosmos.

Another edit: While looking for wind tower info, I did find the following link which I thought was worth passing along. https://cheaprvliving.com/passive-cooling-how-to-beat-the-heat-in-a-van/

 

[Overland One]

I do have a window ac that fits a window exactly. And when I am somewhere for multiple days with power, I'll go ahead and install it. But, I prefer boon-docking and that restricts that option. I have sometimes resorted to a swamp cooler. They take water (or ice) to evaporate and that is in short supply in most boon-docking locations. And many of them don't work well enough to bother with.

What is not in short supply on hot desert days is sunlight. So, I am seriously looking for actual AC systems that won't break the bank. If anyone hears of any, please pass that info along.

If your window unit is efficient (think Energy Star rated) then you should be able to run it from solar with all that sun. The cheap 5,000 BTU window unit that I posted about several times now, (about $200) draws only 446 watts and can be easily run from solar and/or a cheap gas inverter generator. I designed my setup for boondocking and I can stay out as long as I want, within reason. I got the gas generator because I will be spending more time in National Forests than in the desert and tree cover sometimes makes the solar input not so great. Great info on Bob's link, thanks. He has covered most of this in the videos of his I have watched but nice to have it all in one place so, good to have. Also, Bob has 2 videos of him and Jim In Denver testing some wind towers and they were not impressed with the results especially considering the cost. You should look up those videos if considering trying them. Here is a link to the first one. The one with the testing comes a little later:

 

[abnorm]

Zero Breeze uses a 24 volt battery system......................

 

[wayne49]

The windcatcher mentioned in #24 is a passive tower that redirects air flows to where they can be used to cool by air movement without using any other energy. The wiki entry explains how they function without outside power. The problem would be what does one do with the tower while traveling.

The wind towers in the video that Jim Bob were talking about are wind powered bladed generators that supply electricity.

 

[RonDean]

Wayne... exactly!

I was suggesting a wind TOWER similar to that described on the Wiki page. Not a wind generator! Interestingly, when doing a search, you get lots about the generators and nothing about the towers. My questions would include how high or large would a tower have to be to actually do anything. Since I can't find anyone having tried this, I can only assume it is not feasible, even working in tandem with other cooling methods. Too bad.

Back to reality...

 

[Overland One]

The windcatcher mentioned in #24 is a passive tower that redirects air flows to where they can be used to cool by air movement without using any other energy. The wiki entry explains how they function without outside power. The problem would be what does one do with the tower while traveling.

The wind towers in the video that Jim Bob were talking about are wind powered bladed generators that supply electricity.

Ah, thanks for pointing that out to me.

 

[Overland One]

Wayne... exactly!

I was suggesting a wind TOWER similar to that described on the Wiki page. Not a wind generator! Interestingly, when doing a search, you get lots about the generators and nothing about the towers. My questions would include how high or large would a tower have to be to actually do anything. Since I can't find anyone having tried this, I can only assume it is not feasible, even working in tandem with other cooling methods. Too bad.

Back to reality...

Yes, sorry I "assumed" you meant windmill towers. I have never heard of wind towers so I have no research or links to them.

 

[jacqueg]

If your window unit is efficient (think Energy Star rated) then you should be able to run it from solar with all that sun. The cheap 5,000 BTU window unit that I posted about several times now, (about $200) draws only 446 watts and can be easily run from solar and/or a cheap gas inverter generator. I designed my setup for boondocking and I can stay out as long as I want, within reason. I got the gas generator because I will be spending more time in National Forests than in the desert and tree cover sometimes makes the solar input not so great. Great info on Bob's link, thanks. He has covered most of this in the videos of his I have watched but nice to have it all in one place so, good to have. Also, Bob has 2 videos of him and Jim In Denver testing some wind towers and they were not impressed with the results especially considering the cost. You should look up those videos if considering trying them. Here is a link to the first one. The one with the testing comes a little later:

Slim Potatohead was also less than impressed with using a wind turbine system on his A-liner. IIRC, it turns out that in order to generate sufficient power to make it worthwhile, the turbine should be at least 20 feet above the ground. That's a pretty tall post to carry around and anchor temporarily.

 

[eDJ_]

Some time ago I advanced the idea of a circuit that used a mechanical thermostat in the rig that worked with a relay that would start & stop the vehicle engine. I wanted to use baseboard hydronic heat and a pump from a Toyota Prius to circulate the engines coolant. I didn't go into using the engine A/C similarly as the topic was focused on heating. I think this would require an insulated rig.

I even considered using a propane on demand water heater that would both heat and provide hot domestic water.

 

[RonDean]

Some time ago I advanced the idea of a circuit that used a mechanical thermostat in the rig that worked with a relay that would start & stop the vehicle engine. I wanted to use baseboard hydronic heat and a pump from a Toyota Prius to circulate the engines coolant. I didn't go into using the engine A/C similarly as the topic was focused on heating. I think this would require an insulated rig.

I even considered using a propane on demand water heater that would both heat and provide hot domestic water.

eDJ, I love your "out of the box" thinking. I remember visiting Minnesota years back and noticing many people had hot water baseboard heaters. I assume they were all 110 V ac. Maybe there are gas ones that could be converted to propane? Or take one of the electric ones and just hook the water connection to a propane hot water heater and ignore the dangling ac wires? Anyway, another interesting thought.

 

[Gr8ful]

My ambo with the last 7.3 non computer diesel has a rear hot water heat so it would just be a matter on adding remote start & stop which was $79 installed on my last 1 ton 5.9 cummins dodge,even had a delay before starting. Also has very good rear air.

 

[Gr8ful]

With a circulating pump you could shut the engine off & still get heat for quite a while. It would also charge the house batteries with it's 250 amp alt while heating & it's well insulated & built to idle & if you have shore power it keeps the water hot when plugged in. Just can't beat an Ambo!

 

[eDJ_]

Ron, the baseboard heating may be done in a house with a boiler and a pump and several zones each with a thermostat to regulate the temps as and where needed. (I've seen hot water tanks with a domestic water coil in them used for heating too) In smaller applications there are fixed length heating elements that have an electric element in one end which can be regulated with a thermostat set to desired temp. These usually use 110 VAC and could be adapted to a Van if one had shore power. My house originally had hydronic heat & boiler but I converted it to forced air to get AC. The heat from hydronic is nice mellow heat and I liked it better than forced air.

I looked on an old jump drive and found the floor heat sketch that used the on demand water heater. One could install a small insulated hot water tank especially if they could find one with a "domestic coil" built into it. (where the hydronic heating water mixed with with non toxic antifreeze could circulate thru it to have a domestic hot water tank. I originally wanted to use the vehicle engine as a heating source which may work well with cast iron engines that would hold heat longer than aluminum engines.

The pump in this sketch is from a Toyota Prius which is built for this duty.



The Toyota water pump has a brush-less design and is generally a $25 dollar replacement part. It has good pressure and can move a lot of fluid. The on demand water heater ignites when it senses movement of fluid thru it. This concept sketch uses propane gas & house battery to power the pump. It could be set up for baseboard if not using the floor area as shown.

Free standing hydronic electric heater strip here:

Hydronic Heating Strip

 

[Gr8ful]

You could run the pex in the floor & pour lightweight concrete over it made from vermiculite instead of gravel. We did a small wood fired sauna stove that I welded a sideways U in the firebox & piped to a large beer keg. It would boil water in the keg with no pump needed as the inlet & outlet were different heights so it would syphon.

 

[eDJ_]

I had originally started the thought process with a rocket stove which would have a built in coil. I was considering it for an off grid tiny house. The floor would be a plywood sandwich using boards from shipping pallets to create the labyrinth the PEX would travel through. Linoleum flooring would cover the top.

The problem ? How to auto feed the rocket stove and scavenge the ashes that would build up in it.

 

[abnorm]

^......and you would need an expansion tank.......

 

[bullfrog !]

And an over pressure relief safety valve!