I want an electric water pump on my chaser

[REasley]

Other than the price... I got the hot water unit for the same price as a on demand pump. That being said, I may replace the pump with an RV unit if I can't figure out how to hook up the pump to my bulk tank. I wouldn't use an on-demand unit though. I'll use the power supply from the Coleman system.

I am using the same Coleman unit on my trailer. I have not disasembled the Coleman pump, but it looks to be a centrifugal. and must have a flooded suction or or be submersed. Since my tank is mounted in the frame and has a very low profile, the Coleman pump won't work very well. I am using a Shurflo demand pump. I'll simply wire around the switch. That makes it open flow and will only build pressure based on the friction thru the water heater. I will measure the flow with the original pump and then select a pump that closely matches.

As to cost, Shurflo RV pumps if purchased thru an RV supplier have a high margin. You can buy an AG pump from a farm supply store for a lot less. The pumps are the same with the exception of the valves. The RV version uses EPDM valves and the AG version uses Viton. You can find these pumps for under $50.00

 

[R_Lefebvre]

I looked at the AG type pumps at the farm stores, but wasn't sure if they'd be clean enough to drink from? I think a lot of the cost of the Shurflo pumps is the "on demand" part. I think I saw some that were just simple pumps, no pressure switch or anything for less? The pressure switch/on demand part is not needed for this setup, which I think is what you meant.

 

[REasley]

Rob

The RV and the AG pumps share the same Santoprene diaphragm and ususally the same polypropylene housing. Some of the smaller ag pumps and some of the RV pumps have housings that are unique to the their series. When it comes to polys, the FDA requirement is that it be made from virgin material and these pumps comply.

The pressure switch is not needed for this application. The pump without the switch should retail for about the same price, since the costs are within $0.15 of each other.

I do think that the flow rate of the pump should be similar to that of the Coleman pump. I don't know whether the unit is thermostaically conrolled. It might be possible to push too much water thru and not get a good heat transfer. One of the accessories for these heaters is a flow control for use with pressurized systems.

Tonight when I get home, I will fire up my unit and check the flow rate.

 

[ddog45]

water

I knew I would get some ideas. I remember camping with my parents when I was a kid and everytime someone would turn on the sink it would growl and you knew there was water being used. I was hoping I could mount somekind of pump inside my water tank and flip a switch or turn on a faucet and water would be flowing. The best part of all of this adventure trailer camping is that I was a wilderness ranger for three years and never thought I would need a faucet while camping my how things change.

 

[REasley]

I knew I would get some ideas. I remember camping with my parents when I was a kid and everytime someone would turn on the sink it would growl and you knew there was water being used. I was hoping I could mount somekind of pump inside my water tank and flip a switch or turn on a faucet and water would be flowing. The best part of all of this adventure trailer camping is that I was a wilderness ranger for three years and never thought I would need a faucet while camping my how things change.

Setting up a pump for your application is easy. Just plumb in an external demand pump at a low point on your tank. Then run a 3/8" hose to a faucet or valve at the location of your choice. When you open the valve the pump will provide water. When you close the valve the pump stops. Most demand pumps are somewhat adjustable as to pressure. The lower the pump starting pressure, the lower the amp draw. The starting amps on these pumps are anywhere from 3 to 15 depending on volume and pressure. The wiring for these pumps is simple. You can find these pumps with both a switch and a fuse built in. Just run a hot and a ground from your power source. I doesn't really matter which wires you hook your leads to, because the motor is happy to turn in either direction.

 

[REasley]

I fired up the Coleman water heater this evening and measured the output. It delivers right at 1 gallon per minute.

The pump supplied by Coleman is a very tiny open impeller centrifugal pump. I will replace mine tomorrow with a Shurflo SLV series 1 gpm pump. http://www.shurflo.com/pdf/industry/general/911/911-SLV10-AA40.pdf These pumps can be purchased for less than $50.

The water pump and a few led lights will be the only things drawing current from the onboard battery. Since this pump will have a draw of less than 2 amps, I can get away with a pair of very small gel cell batteries and a relatively small solar panel to keep them charged, thus saving dramatically on weight. The batteries will also power breakaway circuit on the electric brakes, but that is a zero draw.

 

[R_Lefebvre]

I was shopping last night and ran across a small RV pump at the local auto store for $15 on clearance. I almost bought it, but wasn't sure. It was all white and looked kinda cheap and like it had been there a while.

Are you saying the FDA rules for cleanliness apply to ag pumps? How can I be sure? I get really nervous buying things made in China as some of these stores. Probably have an impeller made of lead with a housing of depleted uranium and melamine seals.

My Coleman pump has curved vanes, so it does care about direction/polarity. So just be careful of that part. But re-reading your post, I think you're saying most RV pumps are diaphram pumps? Even still, I think most DC motors typically have "timing" built into the brush alignment, and as such will run better in the design direction. They will run backwards, but will run better forwards.

 

[REasley]

Rob

I think I would stay away from import pumps. As you say, you just don't know what they are made from. Besides there are several North American manufacturers that produce pumps and will stand behind their products.

FDA regs are only concerned with the materials that go into the manufacture of the product not the cleanliness. There is no certification process (deja vu). i.e. The polypropylene housing will consist of polypropylene and carbon black, but no recycled material. In fact manufacturers of quality plastic products won't use repro, even if it is inhouse stuff because it will imbrittle the finished product. Often times cheap plastic products break because of the repro that goes back into the product. Repro is mucho cheaper than virgin. I do know that Shurflo uses the same parts for AG as for RV. On some of the pumps the only difference is the label (& price). I have dealt with Shurflo since 1983, less 6 years I spent in the plastics industry.

Centrifugal pumps are very direction sensitive. Kinda like a drill bit. As to DC motors, I am sure that you are correct, however I have seen wired in reverse pumps run for years, under the most adverse conditions, with out motor failure. They usually come back to us with switch malfunctions.

 

[REasley]

Oh.. yes, most RV pumps are diaphragm. They are positve displacement pumps and will self prime to several feet. The santoprene diaphragms are very elastic and will run dry for extended periods.

These pumps are very durable. The only real problems, that are not user induced, are switch failures from rapid cycling and motors under continuous duty cooking off from operating at high motor temp (over 150) in high ambiant (over 100).

 

[R_Lefebvre]

I don't doubt a DC motor would run forever backwards. It'll just make less power, and in a pump application, many probably wouldn't notice. I don't know if all DC motors have timing built in, or just the high performance ones I've dealth with. It's probably worth the few seconds it takes to find out which is supposed to be positive and negative.

Thanks, I'll probably stick to a reputable brand then.

It's bad but... my babysitter recently gave my kid some candy from the dollar store. I need to talk to her because I don't want my kid eating anything from an unlabeled or unknown manufacturer made in China.

 

[ddog45]

thanks Mike

TheMike found me this faucet it may be what I am looking for I just thought I should show everyone else I think it may work perfectly. Im not doing anything till camping season is over but I will post up a review as soon as I do the install.

http://www.westmarine.com/webapp/wc...64?&cid=chanintel&ci_src=14110944&ci_sku=2064

Hopefully that link works it doeasnt really look right.

 

[R_Lefebvre]

REasley, I found this pump at the local RV place, $99 CDN, think it's a good one to use? Any idea if that price is crazy (probably is).

http://www.shurflo.com/pages/RV/rv_product_sum/rv_sum_docs/general_purpose/nautlius.html

With these water heaters, it's important to try to keep it to the original flow rate, or the water won't get hot. You said 1 Gal/min, so that what I'm looking for. I don't think you can "throttle" a diaphram pump with a valve can you?

 

[REasley]

Rob
That pump is a wobbler. It's kind of a crude centrifugal. It requires a flooded suction, so it needs to be mounted at or below the bottom of the tank. It delivers 1 gpm at 0 psi. At 5 psi the flow drops to .75 gpm. I don't know what the friction loss would be, but if you push the water up three feet above the pump, you will lose 1.29 psi to head. That alone will drop your flow to .9 gpm.

I did not measure the flow from the Coleman pump. The 1 gpm was measured at the outlet of the heater. Just for grins and giggles I will measure the pump output tonight.

As to cost. That pump is only sold thru the marine industry, so it is not in any of my catalogs. In looking at the spec sheet from Shurflo, I see that they do not offer repair parts for this pump. That means that it is a very very low cost product.

On the West Marine website that ddog45 referenced, there is a Shurflo that delivers 2 gpm for US$99. What's that...about CA$110? http://ecatalog.westmarine.com/full.asp?page=328

While you can't restrict the pump output on a diaphragm pump, you can divert it. Add a small poly tee to the inlet and outlet and divert a portion of the flow thru a valve back to the suction side of the pump. The valve allows you to adjust the final output.

If you can mount the pump at or below the tank, then the unit that ddog45 found might be a good choice. The price is ok and it delivers 1 gpm at 5 psi. It has a 3/8 hose barb built into the pump in addition to a 3/8 mnpt thread that could be screwed into a bulkhead fitting, but on an offroad trailer that thread might be a point of failure.

 

[R_Lefebvre]

Hmmm... thanks... That $99 becomes at least $200 by the time it reaches my hands, so I'll keep looking around locally. Good point about the pressure and flow and diverter valve, maybe I need more than 1gpm open flow to get the 1gpm after the restriction from the heat exchanger, head, etc.

 

[REasley]

Rob
The Coleman pump delivers 2 gpm with no lift. With 3' of head it pumps 1.75 gpm.

The flow thru the heater looses 50% to friction.

A 1 gpm or larger diaphragm pump would probably be the best choice. It will produce enough pressure to overcome the friction thru the heater and self prime.