Call me crazy....A new indoor heater concept

[enguneer]

I have an indoor heater concept and would love you smart people to pick it apart. Vehicle is a 2000 Yukon XL 2500, which has a nice built-in bedroom. High elevation backwoods camping, so I expect cold nights & mornings, and a grumpy wife unless I can keep it warm inside! No money spent yet, other than for propane tankless water heater, which will work with my DIY pressure tank--separate project. As this would be a 2nd/separate fluid circuit, imagine valves here & there around the water heater, which I'd toggle at the right times. Hot water during the day, hot air during the night via a heat exchanger contained in a toolbox.

Pictures are worth many words, so have a gander & let me know what you think. Would this work? Would it produce enough heat to warm the interior of a vehicle? Gotchas? I do need to ensure that the coils aren't so restrictive as to overtax the pump...but I'm loving the concept and looking for the holes



Summary.... Hot water comes out of the water heater, into the vehicle & toolbox (which is just for containment), and into the radiator. Fan draws air through the toolbox, pulling heat off the radiator coils. Water returns to the burp tank, pump draws water from the bottom of the burp/expansion tank & sends back to the heater. Closed loop.

Thoughts? Thanks!

 

[enguneer]

Thanks! Here's the blow-by-blow that I envision:

1. The thermostat (inside the vehicle) detects ambient temp below desired setting, flicks the "on" switch to the system, activating the 12V pump and 12V PC fan(s)
a. I would probably use a relay so the thermostat doesn't have to push a lot of power)
2. Pump, now active, draws from the bottom of the burp tank, pushes into the water heater, creating flow (pump is rated for 2.1GPM, min flow for water heater is ~1.5GPM)
a. This location for the pump also ensures it's always primed
3. Water heater detects flow, fires up the burner, hot water makes its way back inside to the heat exchanger
4. Fan draws air through the heat exchanger, pulling the heat to the vehicle interior
a. Cooled water drops back into the burp tank, gets cycled back to the water heater by the pump
5. Thermostat eventually detects minimum ambient air temp, turns off pump and fan (would be nice to figure out a way to keep the fan running for a min....)
6. Water heater turns off when flow stops
7. Thermostat cycles the system on/off as needed to keep ambient temp

I agree very much that I don't want the water heater to run constantly. It wouldn't last long. The idea would be to dial in the heat exchange to ensure that everything runs efficiently, and keeps us warm with reasonably short cycles. One big caveat...this would be risky if outside temps drop below freezing. If the whole thing quits while we're sleeping and pipes freeze/burst in the water heater, that's a bad day....would need to keep the water heater inside and duct the exhaust out, with CO detectors..... That starts to get messy.....

 

[Billiebob]

Cool idea, seems maybe complex for an RV. Heating water so you can heat air.
Have you looked at Espar or Wabasto Diesel/Sleeper/Coolant heaters used in trucking and marine applications? Lots of research there which might answer some questions.

 

[enguneer]

Cool idea, seems maybe complex for an RV. Heating water so you can heat air.
Have you looked at Espar or Wabasto Diesel/Sleeper/Coolant heaters used in trucking and marine applications? Lots of research there which might answer some questions.

Yessir, I have looked into those. Price and depth of installation scared me off. In part, I'm looking to broaden the use of the tools I already own (like a tankless water heater). I like multitasking tools.

Forced hot water/baseboard heating is certainly a thing too...lots of houses are heated that way, so I'm not reinventing the wheel entirely. All the same concepts, just making it smaller and self contained (well, almost).

My RV has a very nice forced hot air system, and I thought about searching the junkyard for a similar/small propane furnace from a conversion van. But again, installing a furnace in an SUV feels like a bit much. If I play my cards right, this will be completely portable, and no bigger than a toolbox.

I may just have to buy the parts and try. It may fail. Then again, it may not....

 

[Scott_Milk]

So it sounds like you are making a custom PC water cooling system, accept you replace the CPU/GPU with a propane water heater. In my experience, the hottest running CPUs (say 200 watts of heat generation) can heat a small room a decent amount but that's in an insulated room and takes a good hour or 2. Now you have a dedicated heat source that probably outputs a whole lot more heat I'm assuming so I'm sure it could make enough to work, the problem is if you use PC water cooling hardware, like the radiator and fans you pictured, it will more than likely not be able to dissipate the heat as fast as it's generated, until it starts boiling the coolant. I would look into something rated for more heat output like a transmission cooler. Only problem is trying to keep the fan quiet.
I've seen a video where a guy uses an old steel amo can as a reservoir for the hot water that he gets up to temp with a campfire and then it radiates heat the rest of the night. This was in a much smaller room though so maybe you could use 2 or 3 in parallel. Just heat them up for an hour or so then shut off the heater and let them radiate all night long.

If you want to check out those videos, he has 3 videos building then improving them if you have the time to watch.

Just another idea

 

[enguneer]

So it sounds like you are making a custom PC water cooling system, accept you replace the CPU/GPU with a propane water heater. In my experience, the hottest running CPUs (say 200 watts of heat generation) can heat a small room a decent amount but that's in an insulated room and takes a good hour or 2. Now you have a dedicated heat source that probably outputs a whole lot more heat I'm assuming so I'm sure it could make enough to work, the problem is if you use PC water cooling hardware, like the radiator and fans you pictured, it will more than likely not be able to dissipate the heat as fast as it's generated, until it starts boiling the coolant. I would look into something rated for more heat output like a transmission cooler. Only problem is trying to keep the fan quiet.
I've seen a video where a guy uses an old steel amo can as a reservoir for the hot water that he gets up to temp with a campfire and then it radiates heat the rest of the night. This was in a much smaller room though so maybe you could use 2 or 3 in parallel. Just heat them up for an hour or so then shut off the heater and let them radiate all night long.

If you want to check out those videos, he has 3 videos building then improving them if you have the time to watch.

Just another idea

Thanks! Great input and much appreciated. I'll check out the videos. I've actually settled more on a transmission oil cooler, like you said. The PC radiator was interesting, but I've never handled one and in this case I'm more familiar with the automotive side. I'm not able to determine the pipe diameter the PC stuff uses, so it left me concerned about back pressure on the pump.

The tankless water heater will regulate the max temp, so no concern about boiling. Just not sure what that max temp will be, so your point about how long it would take to warm the space is certainly a good one. It's a pretty small space, but poorly insulated. So I'm unsure if I'll be able to get enough volume of air (at a sufficient temp) to actually make a difference on a cold night. Maybe Google will find me a BTU calculator of some kind. Hmm...

 

[eriefisher]

I applaud your ambition! You have some great ideas here and looks like it will work in theory. One problem I see would be component location. You would want the pump and the burp tank/reservoir/expansion tank at the lowest point in the system and an air bleed at the highest point to prevent vapor lock and air bleed the system. Can you achieve that? It just seems quite complicated to me. I think an easier solution would be a couple 100ah batteries, a solar panel and a inverter to run a small electric heater. Heck, there are even 12v heaters and lose the inverter. Just a thought. Good luck on your adventure.

 

[old_man]

A diesel forced air heater meant for Semi Truck cabs can be had for less than $200 and will run much cheaper and easier, as well as safer.

 

[Slack]

Yep drove over the road 26 yrs.Had one of them last three trucks.work great will run you out if you turn it up to far
Slept in some cold places with no problem.Planing on doing in my 4runner.

 

[lhoffm4]

I second the notion of a Chinese Diesel Heater. While space is always a premium, a tank less propane water heater is mutually exclusive to a space heating system, but since you already have it, keep and use it for its intended purpose. If you didn’t have it, a diesel water/air combo would be a good idea, if you were needing to save space. That said, a water heater heats water and an air heater heats air. With separate systems, you won’t lose both if one goes down. I’ve never owned/used a high end parking heater, but I did purchase one of the CDH models. After playing with it and surfing some CDH forums, I can say I believe they can be finicky if you are not schooled up. While I expect they CAN be reliable, they may not. After all, do your harbor freight tools hold up as well as snap-on? Some may, some may not. If you need it to work, will it?
Final thought- build for fun, but build for reliability otherwise you are wasting your hard earned money!

 

[MSD]

I like the ingenuity, but like others have mentioned a Chinese Diesel Heater is going to do the best job. Yes, they have a different learning curve from the webasto & espar heaters. But once dialed in they are just as good. Best thing to do is get an all in one heater like this - (no affiliation) 12V 8KW Warmtoo All In One Diesel Air Heater Car Parking Heater for Boat Lorry b | eBay. Once you get it, bench test in the garage, once it’s dial in install in your rig.

There are 3 major manufacturers of diesel heaters in China. One makes 80% of the parts for Espar, so you can get a quality heater & not pay the high mark up of name brands. All I’ve used is a Chinese heater in the last 6 years, have them in both my vans & getting ready to install one in my Jeep soon, plus an off road trailer too. I like to run a mix of diesel & kerosene or straight kerosene since the diesel fuel here in Colorado has additives that will clog the fuel pump & the glow plug.

 

[Jim SoG]

SO "diesel" heaters run on kerosene? Did not know that......

 

[eriefisher]

Yes. The two are very similar. You just need to decide which smell you prefer. Cost is an obvious factor as well.

 

[Boostpowered]

There are lots of ways to heat, look into sailboat/ yacht heaters.
Your idea will probably work but there is likely a similar system out there that is more efficient.
I've seen all kinds of heating in the back of rigs from small wood burning stoves to diesel heaters and everything in between.
This isn't the worst idea I've seen, atleast your not asking how to put a rocket stove in a roof top tent.

 

[lhoffm4]

SO "diesel" heaters run on kerosene? Did not know that......

Yes, they will, but there is a potential to damage the fuel pump as it is lubricated by the fuel. Most folks will do a 50/50 or even 70/30 mix of kero/diesel to ensure the pump doesn't seize up. Based on what I'm getting from the "gurus" on the F/B CDH forums...

 

[old_man]

SO "diesel" heaters run on kerosene? Did not know that......

You can even get these types of heaters to run on petrol.

 

[DANNER]

What kind of hot water heater are you using? I've got a Joolca and water doesn't get more than 110F and takes a bit of time to ramp, so I can't imagine getting much radiant heat from that.