water pumping issue

Need some help all. I bought an on demand propane hot water heater for the camp an Eco temp L5 flow rate 1.50 gpm. needs minimum 25 psi, I can not figure out what pump to get. I would prefer a 12 volt set up although we do have a generator. The heater and pump would be about a 2 feet t over the water in the boat house then pumped up to the sink directly above 7 or 8 feet for dishes. I would like to put another line to go out about 30 feet for an out-door shower. any help or advice would be greatly accepted as usual.
Thank you Don

If you can find a 12v pump from a house trailer you may be OK if the built in pressure switch is high enough.Not a lot of flow but some trailers had demand heaters. Talk to a dealer in your area, they might have someone on staff who can help.

Thanks patvetzal: With all the different types out there I have been looking at on the internet, I am really confused at to what is needed. Next time i am on a drive and pass a rv dealer ill stop in.

I have a 12 volt pump from princess auto that was really cheap, around 60 bucks if I remember. It would do the 1.5 gpm but I'm not sure about the p.s.i.
They also have a good selection of other pumps and most of them have the specs listed on them.



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This would do nicely:

http://shurflo.com/rv-products/rv-pu...12-vdc-3-0-gpm

species8472 Thank you very much, you have confirmed the 1 of 2 choices I have made, With all the research I have done on the net. It was this one as first choice or the flo jet 144a triplex 2nd choice. But I thought this one looked better for my needs but was still unsure as I know nothing of pumping water. We are a bit excited as we don't have to bring pails of water up from the river any more for dishes or the zodi shower.

Some simple things to know about pumping water. The smaller diameter line you have the harder the pump works because of friction on the inner wall. So pumping from a lake if you went 2 inch line as opposed to a 1 inch line the pump works far easier and gives you far more volume.
Then the higher you go in elevation and the longer the distance you pump, again the harder the pump must work.

Sawbill the heater states it is run with a garden hose as well as the pump. would this still be an issue or should I attempt to convert to a larger diameter hose or pex pipe... Thank you don

Most garden hoses are 1/2" or less. I'd just go with 3/4" Pex, that way all your bridges are covered....

Thanks patvetzal there was a deal for 20 feet of plex at the hardware store this week, the guy told me that he has to order the stuff in and I would need a special crimping tool for the fittings that was expensive. so I did not get it, Don't know how true this is but I am going to do some research on it.

I'll give you a 'for instance'. For $150 I bought a Southern piston pump with 3/4 inch discharge. It took almost 2 hours of running that pump off my generator to fill a 200 gallon water tank.
Fed up, I bought a Honda water pump with 2 inch discharge and filled that same tank in 5 minutes.

You can also pump to a gravity tank above the heater, to give volume and pressure..
The pump feeds the tank which gravity feeds to the heater, when you turn on the water. When you turn off the water the pump will top off the tank for the next time.
That way you can still use water if the power goes off. At least till your tank empties.

I can't remember the formulas for calculating water pressure generated by height and reductions ( 2 in to 3/4 in for example ).