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Small Cabin Forum / General Forum / Pump options for inline on-demand propane water heater
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KevinA
Member
# Posted: 1 Nov 2020 12:23
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I'm looking to get an L5 from eccotemp and their recommended pump is a 12v DC pump. Could I use a submersible pump with AC power instead? I have an on-grid power source so this seems like a simpler option but I'm pretty ignorant about pumps in general and the specific requirements for the system. I've been trying to enlighten myself but I could use some help.

Many thanks!

razmichael
Member
# Posted: 1 Nov 2020 12:45
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The L5 is marketed as a portable, outdoors only system so the most likely environment would be a 12 volt pump - hence the recommendation. In reality, as long as the capacity/pressure is within specs it does not matter. A regular pressure tank would work as well. Not sure on your location but keep in mind the L5 cannot freeze!

KevinA
Member
# Posted: 1 Nov 2020 13:04
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Thanks for the reply. I live in Ontario so I'd be leaving the system inside when not in use. I found a pump (vivosun 1600 gph) that looks decent, but I was having trouble determining the pressure based off the flow specs. Also I saw in another post that the shurflo pump has an internal pressure switch and I was wondering if that is a requirement.

Thanks again

razmichael
Member
# Posted: 1 Nov 2020 13:57
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Most 12v pumps, as they are aimed at RVs and boats, have a pressure switch that can be used along with the option of a micro switch in the faucet (or both). So how you use it really depends on how the rest of the system is set up. The heater just reacts to water flow through it, regardless of why/how.
I have screwed up two of them by not draining and disconnecting them until too late in the season. It only takes one freeze to split the pipes.

KevinA
Member
# Posted: 1 Nov 2020 14:27
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So the impression I have is that the flow from the pump needs to be compatible with the heater and I'm wondering if I'd be able to dial in the necessary flow with a submersible. I guess I could put a valve in the line to the heater to regulate it. As long as I get a pump that's strong enough

Brettny
Member
# Posted: 1 Nov 2020 14:38
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Dont get the ecotemp. It's got pretty poor temp rise vs GPM specs. Every manufacturer should state or have a graph of the temp rise vs GPM for every water heater. The L5, L7 L10 is just a name that dosnt really mean much as theres no standard I have found.

At the time I bought our eater heater the iheat from homedepot was about $140 and had quite a bit better heat rise as well as a lower burner on water pressure setting. It has been about 6yrs since I bought ours. Having a water, gas and high/low burner setting on the heater really helps dial things in.

Brettny
Member
# Posted: 1 Nov 2020 14:42
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I see that the iheat brand is no longer sold. There is a new brand that replaced them.

As for a pump pick one well bigger than your heater can support. As almost all these pumps GPM spec is at no head. Even the 6ft height of a shower head can really drop the flow. Not to mention the small opening of the heater and other fittings.

KevinA
Member
# Posted: 1 Nov 2020 14:57
Reply 


I'll probably keep water inside so it would be starting from room temp. I think temp rise won't be an issue, but I'm always open to better ideas. Eccotemp is just the one that I keep seeing everywhere.

Right, the vivo 1600 is supposedly 27 GPM and can rise water 14'. I think that would be sufficient but I'm no math whiz. If we have 27 GPM at zero head what do we have at 6'?

gcrank1
Member
# Posted: 1 Nov 2020 19:25
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Fwiw, while remodeling our only indoor bathroom I set up the L5 (we had for the Aliner camper) on the back deck with the outdoor water hose as the supply. Then my back went 'out' in the midst of the remodel.....we used the outdoor L5 until the leaves started to drop and my wife said it was time to get that bathroom at least functional or the neighbor kids were gonna be getting breakfast and a show.
But my real point is that if you emulate the water supply input as from a house with whatever ya got it should work fine. Btw, our old house system aint the big high pressure thing that many have and the pressure varies up/down quite a bit, dialing in the temp for the water flow-through took a little tuning.

darz5150
Member
# Posted: 1 Nov 2020 20:32
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Something to keep in mind is how big is your tank that you'll be pumping out of. If you got a 55 gallon barrel, and use a 27 gpm pump. Could equal a 2 minute shower. Lol. I found out the hard way.😫

gcrank1
Member
# Posted: 1 Nov 2020 21:56 - Edited by: gcrank1
Reply 


What will an L5 flow at max at the temp you like?
My thinkin is that no matter how oversized a pump might be it can only flow so many gph though the unit at a given pressure but you may need to be using a pressure tank rather than just a pump inline; ie, keep the pressure reasonable for that 55 gal. and be good for a lot of use IF you do the fancy version of a 'Navy shower'. I know we have been able to get a decent shower apiece that way out of a 2.5 gal bucket left in the sun all day through a 4 D-cell Coleman shower pump. One day I was feeling self indulgent and still didnt use all of the 2.5 gal.
Or am I missing something? (plumber I aint).

Brettny
Member
# Posted: 2 Nov 2020 06:37
Reply 


27gpm dosnt sound right. Do you mean 2.7? Most household shower heads are 2gpm.

My thoughts on a bigger pump is you can always choke it down with a gate or ball valve. You cant make it flow more later. We actualy use a garden hose shut off on ours for the corse GPM setting.

KevinA
Member
# Posted: 2 Nov 2020 09:14
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The L5 is rated at 1.5 GPM. I thought I should go bigger with the pump because lifting the water 6' will bring down the flow (unfortunately I don't know by how much) and I could dial it down with a valve. So I was looking at that vivosun 1600 (27 GPM at zero head) but I'm open to suggestions.

jhp
Member
# Posted: 2 Nov 2020 10:29
Reply 


The L5 has two dials - one to adjust the heat output which just regulates the flame like on a grill.

The second dials the water pressure up, if I remember right the lowest setting is around .5gpm and the highest is 1.5.

mj1angier
Member
# Posted: 2 Nov 2020 11:09
Reply 


I just had to put a new one on our camp shower this weekend. I used a 5.3 gpm. It is only for our shower and because the 55 gal barrel is outside in night temp of 35, you have to use the propane heater's flow control to slow the flow down enough to get it in the 101-108 degree zone. When its get colder, I will switch to our 20 gallon barrel and have to recirculate it to get it up to those temps.

mj1angier
Member
# Posted: 2 Nov 2020 11:17 - Edited by: mj1angier
Reply 


Quoting: gcrank1
My thinkin is that no matter how oversized a pump might be it can only flow so many gph though the unit at a given pressure but you may need to be using a pressure tank rather than just a pump inline; ie, keep the pressure reasonable for that 55 gal. and be good for a lot of use IF you do the fancy version of a 'Navy shower'.


We have this shower set up:
https://www.amazon.com/gp/product/B000UD7D7K/ref=ppx_yo_dt_b_search_asin_title?ie=UTF 8&psc=1

55 gal will last 4 folks a long weekend with them taking 1 shower a day navy style
Shower
Shower


KevinA
Member
# Posted: 2 Nov 2020 11:45
Reply 


Ok that's good to know. What kind of pump did you use? How high is the water being lifted? I'm trying to get a sense of how much the flow drops with height. Thanks

Brettny
Member
# Posted: 2 Nov 2020 11:45
Reply 


Quoting: mj1angier
switch to our 20 gallon barrel and have to recirculate it to get it up to those temps.

This is where the temp rise spec really matters..in the cold temps. I have had it snow at night with our water in a 55gal barrel on a trailer and we dont recirculate.

Nobadays
Member
# Posted: 2 Nov 2020 14:22
Reply 


Quoting: KevinA
I'm trying to get a sense of how much the flow drops with height.


It takes 2.31 feet of elevation (head) to equal 1psi. So theoretically for every 2.31 feet of head you have to overcome you will lose 1psi of pump pressure. Centrifugal pumps... at sea level will lift water from ~25', you will lose lift depth at about 2' per every 1000' of elevation.

Hope that helps

mj1angier
Member
# Posted: 2 Nov 2020 16:05
Reply 


Quoting: KevinA
What kind of pump did you use? How high is the water being lifted?


This is the pump:
https://www.ruralking.com/catalog/product/view/id/23989

We are off grid so 12 volt pump was needed

The 55 gal barrel is just on the other side of the tin wall on the ground
shower.jpg
shower.jpg


mj1angier
Member
# Posted: 2 Nov 2020 16:16
Reply 


Quoting: Brettny
This is where the temp rise spec really matters..in the cold temps. I have had it snow at night with our water in a 55gal barrel on a trailer and we dont recirculate.


Looks like IHeat is still around
https://tankthetank.com/collections/iheat-tankless-electric-water-heaters

But they all need 110ac supply. And are more $ than what we are using. But for here in NC there might be 2-3 weekends that we swap to the recirculate barrel.
We are more apt to have 80+ degree water in that black barrel in the summer time and don't even use the heater.

Biggest pain is draining it at the end of weekend when there is a chance of a freeze. Been thinking about using a small 5 gal bucket and running RV antifreeze in it instead.

Brettny
Member
# Posted: 3 Nov 2020 08:12
Reply 


Those arnt the portable ones if they take 120v.

Either way I wouldn't be locked into any specific brand, afterall there more than likely all made in china. Look up the specs and buy because of that.

KevinA
Member
# Posted: 5 Nov 2020 00:30
Reply 


Thanks for the help, everyone. Something I can't figure out is why the pumps generally sold with the system are diaphragm pumps. Won't a simple, cheaper centrifugal pump work fine?

Also they have internal pressure switches. Is that just so they turn off to save power when the flow is stopped from the heater unit?

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