Hot water idea for camping but don't want to blow up my radiator

[yotatake2]

Hey guys, so I'm planning on building a water tank where my spare used to be and I'm playing around with the idea of incorporating a hot water system. I'm planning on using this pump.
It puts out 55psi. Now, to heat the water, I'm thinking of using the trans cooler portion of my radiator since I now have an independent trans cooler. I'm just worried that the pump would put out too much pressure that it might burst the radiator. Anyone know how much pressure those things can handle?

 

[mark21742]

You be looking at about 20 psi MAX in the trans cooler safely. How about an inline heater that runs off 12 volts. You wouldn't have to run it all the time, maybe just turn it on a little while before needing the hot water

 

[mark21742]

Maybe something like this?

300 Watt 12 Volt DC Submersible Water Heater Element - - Amazon.com

 

[yotatake2]

Maybe something like this?

300 Watt 12 Volt DC Submersible Water Heater Element - - Amazon.com

hmmm. That could work. The only thing is I wanted to avoid having to heat up the entire tank. It's going to be about 20 gallons. I was planning on using a mixing valve and basically have it work like a normal faucet. Maybe I'll look for something like this but one that water can flow through. kinda like an electric heat exchanger. Or maybe I can use the heater you linked in a much smaller secondary tank that water will flow through to heat up.

 

[TheDurk]

I like your idea. The 55 psi is the max pressure output of the pump, but the actual pressure in the system can be much less than that. That will be a function of the feet of head in the system, which in turn is a function of the size and length of the piping, plus the number of turns and the degree of elevation change. The 55psi will only be reached if the system meets or exceeds the maximum head loss. I have no idea what the trans cooler is designed for, but I'm sure it is far more than the 15lbs of the cooling system. It has to take the trans system pressure not the cooling system pressure. Cooling system pressure actually protects the trans cooler piping. My pool filter pump has a max pressure of 46 psi but the system pressure never goes over 15psi because the system head loss is so low.

I take it you are trying to use it as an instantaneous heater. Your real issue is how much flow you can achieve with a satisfactory increase in temperature. I'd install a pressure gauge, hook up the pump to the trans cooler, and let her rip. See what the pressure is with no additional restriction. As long as it is under say 30 psi, I bet you are safe. I've never seen a metal tubing system that couldn't take 30psi. In fact, I bet it it can take all 55psi that pump can throw at it, but that's just my guess. Then see what the output temp is. If too low, install an output valve, and throttle it back until the pressure gets too high or the temp is what you want, whichever comes first. As flow goes down, pressure and temp will both go up. If you get it right, you can use the output valve as your temp controller. Every home in Brazil has an electric showerhead that works exactly this way.

If that doesn't work, you can consider a recirc heatup mode where the water goes back to a holding tank until it hits your ideal temp. then close a valve, take the cooler out of the system, and the pump sends the hot water to be used straight from the tank.

 

[mark21742]

Another option would be to get a peice of stainless steel exhaust pipe ( only need like a foot of it) and build a box around it for the water to run through. Use your hot exhaust pipe to heat the water like VW bugs used it to heat the air for the heater.....just a simple heat exchange right behind the catalytic converter should get hot enough.....then you could also put an electric element inline too like i posted above for backup/ secondary heat.

 

[HammerTime]

If you are worried about high pressure, could you add a regulator? I think you've got a great idea here! Best of luck pulling it off!

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[AZBub]

?
http://www.amazon.com/gp/aw/d/B0095...+exchanger&dpPl=1&dpID=41V6WmIVGFL&ref=plSrch


Sent from my iPhone using Tapatalk

 

[SilverRidgeRunner1]

Ever considered doing like a Solar heating sys that u could mount on the roof

 

[jeremyc74]

I like this idea a lot! I'd throw a regulator on it though. Something like this:
http://www.amazon.com/Pressure-Regu...4514&sr=8-5&keywords=water+pressure+regulator

 

[IBallEngineer]

I like your idea. The 55 psi is the max pressure output of the pump, but the actual pressure in the system can be much less than that. That will be a function of the feet of head in the system, which in turn is a function of the size and length of the piping, plus the number of turns and the degree of elevation change. The 55psi will only be reached if the system meets or exceeds the maximum head loss. I have no idea what the trans cooler is designed for, but I'm sure it is far more than the 15lbs of the cooling system. It has to take the trans system pressure not the cooling system pressure. Cooling system pressure actually protects the trans cooler piping. My pool filter pump has a max pressure of 46 psi but the system pressure never goes over 15psi because the system head loss is so low.

I take it you are trying to use it as an instantaneous heater. Your real issue is how much flow you can achieve with a satisfactory increase in temperature. I'd install a pressure gauge, hook up the pump to the trans cooler, and let her rip. See what the pressure is with no additional restriction. As long as it is under say 30 psi, I bet you are safe. I've never seen a metal tubing system that couldn't take 30psi. In fact, I bet it it can take all 55psi that pump can throw at it, but that's just my guess. Then see what the output temp is. If too low, install an output valve, and throttle it back until the pressure gets too high or the temp is what you want, whichever comes first. As flow goes down, pressure and temp will both go up. If you get it right, you can use the output valve as your temp controller. Every home in Brazil has an electric showerhead that works exactly this way.

If that doesn't work, you can consider a recirc heatup mode where the water goes back to a holding tank until it hits your ideal temp. then close a valve, take the cooler out of the system, and the pump sends the hot water to be used straight from the tank.

Yeah, I couldn't find a rating for an OEM cooler, but the consensus is the output of the trans is 20-30PSI before pressure drop. And the pressure drop can be HUGE based on the size of hose and length of run. Here is a pressure drop calculator that requires flow rate, and PSI.

Pressure drop in pipe calculator

So if you know the gal/hr and psi, length of pipe, including the cooler, and of course ID you can figure it out. My gut says the idea would work, and now I have to consider it myself if I end up making a trail rig out of my 99.

:fishing:

 

[0xfded]

Love the idea of putting a water tank down there. If I ever switch to a tire carrier, I might steal your idea!

But for the heater, is the idea to heat the water on the drive in and have a nice hot tank available for the first night? That could work, but you'd need to be careful--potable water is going to boil at a lower temp than engine coolant, so you definitely need to include pressure relief.

But after that first tank cools off, reheating by idling the engine seems pretty inefficient. First you've got to bring your coolant up to high temp to heat your potable water, and the whole while your fan and radiator are trying to dump heat. I'd wager that electric would be faster.

 

[AZBub]

I have pondered a set up as well, that is why I posted a link to a heat exchanger BUT in the end I have decided to stick with a HWOD like the Mr Heater Buddy series. A remote tank still comes in to play but you wouldn't have to run your engine forever to heat up the water and in terms of a solar set up, hope you are not under the trees and again wait forever for hot water. something to think about anyways.


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[0xfded]

Maybe something like this?

300 Watt 12 Volt DC Submersible Water Heater Element - - Amazon.com

That got me thinking about making a portable 12v hot water tank again, but the math sort of sucks, or I'm doing it wrong (please correct me!)

Say you want to heat 5 gallons (ie. you're using a blitz can as your tank). And say you're only trying to go from cool water ~10C to shower temperature water ~40C, so 30C difference.

5 gallons water = 18927.059 grams

You need 1 calorie to heat 1 gram of water 1 degree, so you'd need 567810 cal to heat your water, assuming no losses.

Here's where the idea stops being fun.

300 watt/sec = 71.66 cal

So it's going to take 7923.67 seconds (132 minutes) for that element to heat the water to 40C. Longer if its colder, or you want it hotter.

300w @ 12v is 25A draw, so you don't want to just do that off the battery. So you're idling for 1-2 hours heating your water. And that's assuming no losses, which there will be a lot of in 2 hours.

So that sucks.

How about inline, point of use heating? Looks like inline heaters (like this one) tend to be around 2500 to 3000 watt, so something similar running on 12v is going to suck ~250A.

Boo. Sticking to my campfire kettle for the time being.

 

[mark21742]

That's what made me think of the exhaust pipe heat exchanger idea to save electric power. I know the in home tankless water heaters can only be run safely after you upgrade to a 500 amp service so we would be looking at a major power draw on a 12 volt system.

Might be best to stick with your camp fire idea or just man up and take a cold shower lol

 

[BrianSD_42]

That got me thinking about making a portable 12v hot water tank again, but the math sort of sucks, or I'm doing it wrong (please correct me!)

Say you want to heat 5 gallons (ie. you're using a blitz can as your tank). And say you're only trying to go from cool water ~10C to shower temperature water ~40C, so 30C difference.

5 gallons water = 18927.059 grams

You need 1 calorie to heat 1 gram of water 1 degree, so you'd need 567810 cal to heat your water, assuming no losses.

Here's where the idea stops being fun.

300 watt/sec = 71.66 cal

So it's going to take 7923.67 seconds (132 minutes) for that element to heat the water to 40C. Longer if its colder, or you want it hotter.

300w @ 12v is 25A draw, so you don't want to just do that off the battery. So you're idling for 1-2 hours heating your water. And that's assuming no losses, which there will be a lot of in 2 hours.

So that sucks.

How about inline, point of use heating? Looks like inline heaters (like this one) tend to be around 2500 to 3000 watt, so something similar running on 12v is going to suck ~250A.

Boo. Sticking to my campfire kettle for the time being.

I could see this working if he just takes his showers after parking and hitting camp. Drive all day, keep the heater on the last 3 hours. Stop for camp. Setup tent and get out a change of clothes which will only take about 30 minutes, then shower with the warm water.

I would definitely prefer an electric water heater in an isolated tank as opposed to some type of coolant exchange which may put the coolant system at risk. If you modify the coolant system in some way and the coolant leaks out while driving you won't notice it until the dash gauge goes into the red at about 240F-ish and even then it won't trigger a CEL (at least not on my 97). Basically if the coolant system fails or leaks you stand a good chance of not noticing the problem until you are already overheating the engine.


:fishing:

 

[GangsterOfLove]

An electric instantaneous setup is not going to work - not at 12 volts - not at 120 volts for that matter. Heating up a tank will work if you insulate the tank well enough and drive far enough. Using the radiator trans cooling circuit sounds like a winner.

The pressure the pump makes isn't a big issue. Install a regulator, a good gauge and a thermostat. Make sure you install some sort of safety that will keep the water tank from blowing up if it gets too hot - I'd probably use a domestic water heater pop off valve.

I like the whole idea. Hope you'll post how well it works when it's done.

 

[yotatake2]

That's what made me think of the exhaust pipe heat exchanger idea to save electric power. I know the in home tankless water heaters can only be run safely after you upgrade to a 500 amp service so we would be looking at a major power draw on a 12 volt system.

Might be best to stick with your camp fire idea or just man up and take a cold shower lol

Shots fired! hahaha. This is all hypothetical. I don't really have a need for it, but I'm really just trying to see if I can do it lol. I'm thinking of an exhaust pipe heat exchanger. Maybe I can coil some copper tubing around the exhaust pipe near the end, right in front of where my muffler used to be. I really just wanted it on the fly without heating the water in the tank. Basically, I'd have the output from the pump with a splitter valve. One output would go straight to a mixing valve and the other would go through the heat exchanger and then to the mixing valve, where my final output would be.

 

[AZPartsGuy]

I called the Toyota Help line but they weren't able to answer my question I didn't really expect them to be able to so it's ok.

They submitted a ticket to the Technical guys so they're going to get back to me on Monday about what the max PSI of the trans cooler is. I'll post up what they say.


Edit: They got back to me already. They couldn't provide additional info but they did refer me to techinfo.toyota.com and helminc.com for references. The techinfo link requires subscription that I do not have access to, so that's a no go. Helminc I'm familiar with but I have no interest in ordering a repair manual at this time.

Larry is the guy that spoke to me and we both agree that Toyota most likely designed the rubber hoses to be the main failure point in the system, so whatever PSI those are rated for could possibly be a ball-park figure. Sorry I couldn't find out the exact number, but we gave it a shot.

 

[yotatake2]

I called the Toyota Help line but they weren't able to answer my question I didn't really expect them to be able to so it's ok.

They submitted a ticket to the Technical guys so they're going to get back to me on Monday about what the max PSI of the trans cooler is. I'll post up what they say.


Edit: They got back to me already. They couldn't provide additional info but they did refer me to techinfo.toyota.com and helminc.com for references. The techinfo link requires subscription that I do not have access to, so that's a no go. Helminc I'm familiar with but I have no interest in ordering a repair manual at this time.

Larry is the guy that spoke to me and we both agree that Toyota most likely designed the rubber hoses to be the main failure point in the system, so whatever PSI those are rated for could possibly be a ball-park figure. Sorry I couldn't find out the exact number, but we gave it a shot.

Whoa, wasn't expecting anyone to do that much research! Thanks man!