Off Grid Water Heating

[TheWire]

I'm looking for ideas on water heating for the cabin I'm building.  The cabin has no electric service and somewhat poor solar exposure due to a lot of trees.  I plan on having propane. 

The cabin has an artesian well (through a 20' deep sand point) at the bottom of the hill the cabin sits on.  We sunk a 50 gallon plastic tank in the ground and the artesian well fills it at about 5 gallons an hour.  The well won't however push water any higher than a foot above ground level.  I planned on using a 12v pump to pump water from the tank that the well fills to fill a 30 gallon tank in the space above the collar ties in the rafters of the 1.5 story cabin.  The cabin's kitchen sink, RV toilet, bath sink and shower would then be gravity fed. 

We mainly use the cabin on weekends and would like a water heater that can heat 5 to 10 gallons in an hour or 2 after we get there.  I'm not having a lot of luck finding a 5-10 gallon propane water heater other than ones made for RVs which won't meet code in a house. Also, we only really need hot water for showers and washing dishes both of which we could anticipate an hour ahead.

Any ideas for heating 5-10 gallons of water in an off grid cabin? 

[Redoverfarm]

TheWire don't know if this will help but recently they came out with a small propane heater to use to assist in outdoor furnaces while the owner is away and unable to fire the convientional wood fire.  As I understand it is a rather smaller unit that is a line installed unit. They are used in conjunction with the regular AC circulating pump which in your case could be substituted by your DC RV pump.  I don't have any namebrand only have talked to some owners of outdoor furnaces that it exist.  Maybe a search or google might turn something up.  Maybe informal correspondence with the major outdoor furnace manufacturers like, Hardy, Taylor, Hicks, Unon boilers and the like might give you a direction to look

[hnash53]

I use just what you said you had found..and RV propane-fired hot water heater.  Works well enough.

Another person in the area of my cabin uses a 10 gallon electric water heater.  He connects his generator to it for about 1.5 hours and that gives him hot water.  They use it when they anticipate the need for hot water, sort of like what you have described.

The Atwood company makes a good 10 propane heater.  My cabin is like an RV that doesn't move...I use a 12volt water pump, RV toilet, and RV hot water heater.  Seems to work well enough for us.

Best wishes,

Hal

[glenn kangiser]

Coleman and others also make the portable water heaters that would not have to be considered part of the house.

Are you having inspections? - ie need to meet code? If not I'd use an RV one.  Otherwise the Bosch Aquastar HX125 (has since been upgraded) is pilotless - no standing pilot -- has it's own generator to light- but makes all the water you want on demand - about $600.

[davidj]

Coleman and others also make the portable water heaters that would not have to be considered part of the house.

We just got our Eccotemp L5 working in our outdoor shower this weekend.  It's something like $130.  It's as cheapo and tacky as the price implies, and not exactly high flow (I'm guessing <1 gpm for show temperature heating straight from the well).  And the 50psi from the well pump actually blew a hole in the shower hose!  All that being said, running hot water at the flick of a switch is hard to beat and you could pay that much just for a gas valve.

[John Raabe]

When I was in the Peace Corps, much of the third world heated water with kerosene or oil. It does have a higher energy density than propane and may make sense when carrying it into a homestead or remote cabin.

Here is an updated version of a tankless heater:
http://www.houseneeds.com/shop/heatingproducts/waterheating/toyotomi/toyotomi-water-heater-mainpage.htm

[fritz]

One of the things to consider is not only how much water flow but also how many degrees in temp rise.  a 40 degree rise is great if you start with 70 degree water...not so great if you start with 40 degree water.

[peternap]

If you have sun, think about a solar heater. Use an RV pump to move the water.

[MountainDon]

IF you don't have the inspection bugaboo, the RV water heater works well. That may be a big IF, though.

A "trick" we use with the RV water heater is to light the pilot and leave it sit there on pilot only. After a time, 12 hours+ the heat from the itty bitty pilot is sufficient to heat the water in the tank to the equivalent of the "Lowe" setting. After a day it's nearing the "High" setting. This works well when the major hot water uses are for a shower every other day or three and the in between uses are small volume. It wouldn't work for water hogs. It works well enough for our use though; sink washups in the AM and PM, dishes done in a small wash basin, not the big sink, and showers, with uses spread over the day.

Also the RV heaters can be bought with an electric heating element as well as propane.

But, yep; they won't meet code.

One thing that caught my eye in your original post was the placement of a water tank in the attic. That won't give you much pressure or flow. You get .433 lb of pressure per foot of elevation; source to point of use.

Also the gravity flow rate would probably not be sufficient to activate some of the tankless type of heaters. You would likely be better off using a 12 VDC RV style water pressure pump.

[MountainDon]

I just wanted to add that there are also direct ignition, no pilot, RV heaters.

[TheWire]

Don,

I guess I was going to wait and see how much flow I got from 10' of head.  When I see how much flow comes from a water jug with a tap, commercial coffee pot, or box of wine, I was hoping 10' / 4.3 psi of pressure with oversized PEX would suffice.  At least for the sinks and a 1 pint per RV flush toilet.  It looks like I may have a holding tank and figured I could get a years worth of holding capacity if we didn't waste water.  Low but usable flow would help "enforce"  that with the kids.   

I may have a problem with the shower though.  I know tankless water heaters need pressure to prove flow and turn on the heat.  If 10' of head isn't enough or I want a tankless water heater I know I may need a pump.  I'm going to need one anyway to get the water up a hill from an artesian well anyway.  I might use it for a pressurized shower also.

Thank you,

Jerry

[ScottA]

I'd set it up like a well system. Use a large pressure tank to streach the time between pump cycles and limit the pressure to about 30 psi. I bet somebody makes a 12v pump. The rest could be done just like a well system.

[NM_Shooter]

I visited an outpost cabin in Canada a few years ago that had a sweet offgrid setup. 

For water, they had a honda pump with the wet end in the lake.  Once every 3 or 4 days we would run the pump to fill up a tank that was lifted up on a structure.  Here is a picture of the tank (and the privvy)



The tank was perched on the highest point on the island, but even so it was only maybe 6 feet above the shower head.  It fed a standard propane water tank in the cabin and the pressure was fine.  Not a blasting, needle like shower, but very adequate. 

To prove to yourself how well water can flow with just a little head pressure, take a piece of 3/4 PVC, put a valve at the bottom, and experiment with filling it with water, holding it vertical, and draining the water.  You can get good flow with just a little bit of head pressure.

BTW... if you want to see more pictures of what I think is the best cabin in the world, feel free to check out a web shrine I made for a fishing trip:

http://home.comcast.net/~a.wirtz12/Monroe/Monroe.html

[Bishopknight]

I just read glenns reccomendations on the HX125 Bosch tankless water heater. I looked it up , its been replaced by the 1600H now.

I just found it factory reconditioned online for $449, that may be the cheapest I can find it.

Great thread here, found the info I needed though.

- BK

[NM_Shooter]

What about this?


http://cgi.ebay.com/LP-PROPANE-GAS-TANKLESS-WATER-HEATER-Concession-Kiosk_W0QQitemZ120293517405QQihZ002QQcategoryZ115967QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

I searched ebay for "tankless water heater propane" and a bunch popped up...

[TheWire]

I found a Marey LPG Propane Gas Tankless Water Heater for $179.   It needs 1.3 GPM to switch on.  I wonder how well it would run with a RV water pump running a shower.

http://tankless-water-heaters.ecrater.com/product.php?pid=1450945

[JRR]

I know the Coleman unit has already been mentioned:
.
http://www.coleman.com/coleman/colemancom/detail.asp?product_id=2300B700&categoryid=2200
.
I have seen a similar, all-inclusive, Coleman camp shower rig at Costco's about a year ago.  I believe it was for less than $200.  I haven't looked/noticed them at Costco's this year.  Coleman has some discount outlets in various locations.

[NM_Shooter]

For the tankless water heaters, what sort of venting is required?  what height of vent pipe is required?  I am wondering if you can vent them directly out a wall under an eave, or if you have to vent through the roof?

Anybody have any experience with these?

Thanks,

-f-

[glenn kangiser]

The Bosch can vent horizontal but needs a fan kit if I recall correctly - probably varies with application.

[NM_Shooter]

Here's the Marey install manual.  Looks like you need a 92" vent stack:

http://www.tanklesshq.com/marey-gas-owners-manual.pdf

I just looked at the instructions a bit.  They are written by an ESL person.  Looks as though the outlet of the heater should probably be a run of metal pipe for a bit.  Probably the heat exchanger has the potential of overheating the fitting which might soften pex?

Power for the auto-ignite is only two AA batteries!

I think that the down side of the on demand is that temperature regulation is a bit poor if you are trying to conserve water.  These appear to be better if you turn them on and let them run, instead of turn on, get wet, turn off, soap up, turn on, rinse off.  Dunno for sure though.  I never used one.

[MountainDon]

Here's the Marey install manual.  Looks like you need a 92" vent stack

Oh! That's the length.   


I didn't read the manual but wanted to add that some tankless heaters draw combustion air from inside the building, some from outside. Inside draw and small buildings that are well sealed don't get along together very well.

[muldoon]

Sorry to bring up an old topic, but I have been looking at the Marey propane heater for water with intention to use it as a portable ourdoor shower.  A summer shower of sorts to have hot running water, especially for use in the summer when the heat is unbearable and showers would be so so nice.  I searched the forums and this was the only thread it came up in.  Curious if anyone did buy it or knows anything else about it.  (regarding the venting noted above, I would be using it outdoors only). 

Here is it reviewed on youtube
http://www.youtube.com/watch?v=nGy-fofLk2A

And I have found them online a few places in the 179 range.  Seems to me it would be a pretty simple (and cheap) setup to use as an interim shower until real plumbing and bathroom is intact. 

Any thoughts on it? 

[Redoverfarm]

Muldoon you might check out the one mentioned in the following thread.  I saw it in Sportsman Guide.  Sounds like it would be ideal for temporary shower. It can be run off of a 20# cylinder.

http://www.sportsmansguide.com/net/cb/cb.aspx?a=477229

http://countryplans.com/smf/index.php?topic=5748.msg74112#msg74112

[glenn kangiser]

Looks pretty good, muldoon.  Coleman makes one too.  I think the Marey looks a bit better.

The Sportsmans Guide ones look good and hard price to beat.  I buy lots of stuff from them and have always been happy with them.