View original topic: Hot Shower Install - GPM Pump Question Page: 1, 2  Next
scottjk Tue Mar 13, 2012 8:18 am

I find the only thing I miss when road tripping is a quick hot shower after windsurfing or kiting all day so I'm going to install a heat exchanger in my 13 gallon water tank tapped off my under seat heater hoses.

My question is does anyone have experience with showering under different GPM rated pumps? I'm looking at the Shurflo Marine pump at a rating of 1 GPM but I'm not sure if 1 GPM would be enough flow for a RV showerhead.

My goal is to balance water usage with enough flow to comfortably wash off.

Any input would be appreciated... other than "just use a solar shower" or "just use baby wipes". :lol:



SCM Tue Mar 13, 2012 8:48 am

I'm not very familiar with shower pumps, RV stuff, etc. However, as a frame of reference, a typical household garden hose is about 5GPM. That seems a bit harsh for a shower IMO. I want to say my household shower head restricts flow to 3GPM or maybe a bit less but my memory is foggy on that.

scottjk Tue Mar 13, 2012 8:55 am

I believe the standard flow rate from what I'm reading in RVs is about 2.5 GPM. I'd like to reduce this rate even further to conserve on water due to the small 13 gallon tank in the Westfalia.

The pump I'm looking at is 1 GPM but I just don't know how much spray I'll get out of the shower head.

joseph928 Tue Mar 13, 2012 9:10 am

:bay_blue: WE have a 1 GPM pump, seems good and at times I could use even less to save water. WE can take a shower with 1 min. of water , we just turn it on and off. PS we only have a 5 gal. tank. But I cary 5 gal. on the rear rack. When we want to soak we hit a campground. :D

spitsnrovers Tue Mar 13, 2012 9:20 am

I'm not sure of the GPM, but for my take on your project check out and look for the Westfalia link. I think the pump model is mentioned there.

We (particularly the Mrs.) loves this feature.

scottjk Tue Mar 13, 2012 9:21 am

Excellent info. Just what I was looking for.

splitsnrovers... nice write up. I have actually been studying your set up. I can't seem to find the GPM for that Proven pump though.

Joseph... what type of shower head are you using?

Sounds like a 1 GPM pump might be plenty.



dubbified Tue Mar 13, 2012 9:40 am

I have the same questions.. and then it comes to heat range.. where i'm getting heat from, heat dissipation in the lines...

That store has alot of great ideas.

Then, I got to thinking about these gizmos found when I was researching Biofuel..

I found these 1/4 and 1/2 GPM spray nozzles used for washing.. I got to thinking I could use these for the shower.

It isnt the most glorious looking, is Brass.. wont rust.. and low GPM, not what you'd typically use.. but super efficient.. you're only wanting to get wet, and this sucker covers a good area/fogging right?

I want to order this up, put it on a hose.. and test it out.

Temperature comes to mind.. I have a sprayer/fogger in my shower at home, but to get comfortable.. I have to turn it all the way HOT.

The aerating action of the nozzle cools the temp of the water quite considerably.. but its not horrible..

I'd just picked up a Miller MIG and spoolgun to do Alum or SS.. and have in mind a design for either an Aluminum or Stainless Steel heater core type deal.. which will sit atop of the RV cooktop on my kitchenette, or lay down in a firepit.. and provide me with hot water.. So.. kinda like a Zodi.

PDXWesty Tue Mar 13, 2012 9:52 am

Scott - You might want to use a 2-2.5 gpm pump if you can. You can always add a small valve to throttle the flow down to your liking. 1 gpm is really light for a shower spray. Typical sink sprayers are about 1.5-2.2 gpm. Those small pumps are also listed at a very low head pressure, so you want to get a pump for the gpm you want at the correct head pressure. You'll need to calculate the pressure loss through your piping, hose, and sprayer and have your pump rated for that.

70coupyel Tue Mar 13, 2012 9:55 am

My van came with a hand held shower head plumbed in so you could use it with the rear deck open. In tank submersible pump and that was fine for rinsing off after surfing. Sorry I don't have the spec for that pump handy.

edit: Looks like 1.5 GPM Here

scottjk Tue Mar 13, 2012 9:56 am

I'm going to do almost exactly what roversnsplits did. I'm going to tap the rear bench heater lines, run a copper coil 'heat exchanger' in to the water tank (I'm going to try and open the coil up more than 4.5 inches and squeeze it down so it looks more like a stove heating coil. This way as the water depletes there will still be a good portion of the coil toward the bottom of the tank). I'm planning on making a switch and indicator panel to install somewhere in my dash area to turn on/off the solenoid and monitor function of the system.

I'll also cover the entire tank with Reflectix insulation to reduce heat dissipation.

Pump will be 'on demand' at 30 psi hooked to both the front faucet and a quick disconnect off the rear back cabinet with the expectation of showering off the back end with the door up. I'm upgrading the sink faucet to the Shurflo kit that GoWesty sells.

dubbified Tue Mar 13, 2012 9:58 am

There is also a really cool device some of the espresso stands use.. its a pressurebladder you can rig inline.. keeps some of the stop/starts of the pump to a min..

scottjk Tue Mar 13, 2012 10:04 am

PDX... I spoke with a Shurflo tech about throttling the pump with some type of a valve system but he didn't seem to think it would be a good idea. Said it might be hard on the pump. That doesn't make complete sense to me because I'd image that people in RV's adjust their flow rates all the time via sink and shower controls.

It definitely makes more sense to go with the bigger GPM pump due to the flexibility. The way I see it is the pump shuts off when there is 30 psi in the system lines so if I restrict my shower down to the point of creating 30 psi in the lines it should just shut off, but it might cycle too much.

Guess I better buy a pump from somewhere with a good return policy.

dubbified... that accumulator looks interesting.

"Really helped to minimize resonating the noise through the trailer when the pump is running. Now the pump comes on only after the faucet runs for 3 to 5 seconds depending on how far open you turn the faucet. It doesn't do that on/off, on/off, on/off thing when you have the faucet on just a little bit. Very pleased with it. Worth while project".

That seems to answer the cycling question with the larger pump and restricted flow.

dubbified Tue Mar 13, 2012 10:07 am

That accumator will stop the start/stop condition when getting smaller amounts of water.. claims smoother operation.

My parents are on well water, and we had two rather large versions of that.. using air from an air compressor to pump up a bladder.

Pretty cool.

I "WISH" there was a way to coax some of the heat output from the Propex.. or they'd make a all in one answer.. shunt a vent one way.. heat your water... shunt another.. heat your cabin.

but.. being able to heat water on a campfire or alternate heat source is another idea altogether..

PDXWesty Tue Mar 13, 2012 10:20 am

Technically, what you are doing would not be allowed by the plumbing code if this were a house. There is a potential for contamination of the drinking water tank with glycol from the engine coolant system. Any leak in the heat exchanger or fittings would contaminate the water in the tank. It would be good if you could keep all your connections and fittings on the outside of the tank and not the inside.

derekdrew Tue Mar 13, 2012 11:41 am

General notes from hard experience: Unless you are planning to be always connected to external fresh water supply, I suggest an extremely small gpm flow, like maybe using the little pump for the drinking water supply. This will make your water last much longer with little wastage in showering. You can get many showers out of a tank that way, whereas if you use a big pump you may not get two showers out of the stock westfalia tank. Also, heat exchanger based pumps where the heat exchanger is in the flow line are intolerable because you are supposed to vary the amount of water flow as a means of controlling heat transfer and thus temperature. But it is much too hard to control the heat this way, and you would then have no control over the amount of flow, and have a lot of backpressure sometimes on the pump, thus burning it out maybe. Anyway, I found out the hard way not to do this. Instead, get a stainless steel coil, maybe from a windshield washer tank heater (mercedes?) and put that into your drinking water tank.

tschroeder0 Tue Mar 13, 2012 11:41 am

I did a mod for a shower that was very simple. I like some of the mods I have seen but I think that many are way to complicated and can have much potential for problems down the line.

I had a Zodi camp shower but hated that you had to have it running all the time as it would overheat otherwise (that is the copper tubing would get so hot it would melt the plastic tubing)

So, I tapped into my water tank(drilled a new hole) and with the install of some longer water lines to the Zodi a T and a valve all I do is have a full water tank, fire up the Zodi and hang it from my poptop latch, use the pump on the zodi to heat and recirculate the hot water right back to the water tank. Now you have nice hot water in the tank. The Zodi can really heat water fast.

Once hot I shut down the zodi and then just use the pump (that comes with the Zodi) to pump the nice warm water to my extra long spray nozzle outside and I can take my time and shower. You can obviously turn the pump on and off as needed and take your time.

Any water you do not use is not wasted as it just remains in the tank and cools down.

Very simple and it works very well.

davevickery Tue Mar 13, 2012 12:51 pm

This is my setup.;start=20

I started with a 1 GPM Shurflo Nautilus pump - $46.36 Found on It was fine, but the flow diminishes the higher the shower head is and maybe with the length of hose. So above my head it would not extend out very from the side of the van when attached to the sliding door. I plugged some of the holes in the shower head to get it to shoot out further, but it was still only about 1 foot out. I burned that pump out when emptying the tank (forgot it was on) so my replacement is a 1.1 GPM flojet that is an on demand pump so you can stop flow without turning it off and it doesn't hurt it. It is better quality I think and supposedly can be run dry with no harm.

It shoots out enough farther now and I think it is perfect.

Medium hot water is a spawning ground for germs. You will have to empty the tank regularly and probably clean it out with bleach more often. My tank is only 4 gallons and is a nice compromise. The complete parts listing is in the thread above. It works great. Uses the rear heater fan switch, setting #3. Originally I removed the rear heater, but I have since put it back. Everything fits and still works great.

scottjk Tue Mar 13, 2012 12:58 pm

Nice Dave. I have been using your plans for my ideas also. Thanks for sharing.

joseph928 Tue Mar 13, 2012 1:58 pm

scottjk wrote: Excellent info. Just what I was looking for.

splitsnrovers... nice write up. I have actually been studying your set up. I can't seem to find the GPM for that Proven pump though.

Joseph... what type of shower head are you using?

Sounds like a 1 GPM pump might be plenty.


Scott :bay_blue: It's made by Texsport, has an on and off , has 21 holes of 2 different sizes ! :D

scottjk Tue Mar 13, 2012 7:13 pm

This looks interesting. Too bad they don't seem to make one with a handle and an on/off switch. Looks like good pressure and spray for .55 GPM

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