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rugercpl
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# Posted: 27 Jul 2012 10:23pm - Edited by: rugercpl
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Okay here goes.............
equipment list........
1. manual hand pump well outside of the cabin
2. some shape or form of a cistern in the attic of the cabin. 50 gallon or so
3. Fixed fill hose leading to attic cistern (probably pex-type tubing)
4. detatchable outdoor hose leading from hand pump well to attic cistern fill hose
5. tubing from attic cistern leading to bathroom and kitchen below
6. separate on-demand propane hot water heaters for bathroom and kitchen
7. drain valves for cistern and kitchen/bath tubing
How I imagine it will work is the manual hand pump pumps water to the attic cistern. The attic cistern gravity feeds kitchen and bath with two lines each (one line to hot water heater and one ambient temp line)
My concerns are this........
Can a manual hand pump pump 50 or so gallons to an attic cistern...i'm guessing it would be about an eighty linear foot run plus a 12 foot or so incline.
Is there enough pressure from this gravity fed plan to push water through an on demand propane hot water heater? cistern may have to be more wide than tall to distribute the weight in the attic across a few trusses
How do i make or buy a cistern for an attic. what type of material (rigid plastic, or other)
How do I know when the cistern is near full or empty as not to overfill or run out mid-shower
how to install the propane water heaters (outside the wall, inside the wall and vented)
How to make the cistern and hoses freeze-proof for an overnight during the winter. Cistern will be filled day of arrival to cabin and drained on the day of packing out.
.....there is no access to the attic other than vent panels outside the building (aproximately 18" x 24"). This cabin is new to me so I will be climbing in to investigate the quality of the insulation and looking for any unforeseen issues. it is possible that i will be redoing the ceiling in the cabin and may gain access by taking down some sheet rock to asess the attic....may be a good time to install a pull-down staircase to get up there to store stuff and inspect the cistern once its installed. Cistern shape and placement may be tricky as i dont know yet how the studs or trusses run. If the only way to get a cistern up there is to take down sheet rock, i will. I dont know how i would get one through an 18" x 24" vent.
Your advice I am grateful for. Thanks
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MtnDon
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# Posted: 27 Jul 2012 10:56pm
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Gravity water pressure can be calculated at 0.43 PSI per foot of vertical height from the water level in the tank down to the point of use. That is pretty much always not enough pressure to operate an on demand water heater.
A better deal, IMO, is to use a water tank inside the heated area of the cabin; under a kitchen counter for example. RV parts suppliers have a variety of sizes. Then use an RV water pressure pump. Shurflo and Flojet are 2 common brands. Most are 12 VDC but I know Shurflo also makes 24 VDC and 115 VAC versions. They usually supply about 40 PSI. We use a 15 gallon tank under the kitchen counter with a Shurflo 2088 pump.
We use an RV heater installed as in an RV, through a wall, under the counter.
Most hand pumps I've seen will not push water up to an attic. They have an open "head". There is one made by Oasis that can push water through a hose uphill. We have one. We use a 1 1/2" dia fire hose to deliver the water from the in the ground cistern to the tank in the cabin. If there is much of a rise to the destination tank a backflow preventer valve at the pump output can make the job a little easier. But remember you are pushing the volume and weight of that water in the hose uphill. Maybe not as easy as you think it might be. I also use a submersible sump pump to move water from the cistern to the cabin tank through a 5/8" hose. It only delivers a gallon a minute but it's nice not to have to hand pump.
How to tell when full or empty. Empty is easy. Full is another matter.... I have a vent tube from the inside tank to the outside. I can tell by the change in the sound when the tank is full. If not paying attention the vent will spout water... that's full!
Position all outside hoses so they will drain back to the source. To alleviate worry we pump air into the hose from the cabin end to make certain the water all returns to the in ground cistern.
If you are off grid you will want to use on demand heaters that are mounted inside and vented to the exterior. They should also have a combustion air intake from the outside. There are some that can be mounted outside in the winter. They however, have an AC heating element to keep them from freezing. Not good off grid. Some on demand heaters are difficult to properly drain. Blowing out with volumes of compressed air can help.
In winter if we are at the cabin for only a few days we do not bother with the indoor plumbing. We heat water in a stock pot on the wood stove, maybe raise its temp on the propane range as necessary. We then bring water from the outside cistern pump inside by filling gallon jugs we have on hand.
I also leave plastic jugs, filled to about 3/4, in the shower pan when we leave. They've never burst from freezing when left 3/4 full. If they did the water would go down the drain. The shower drain does not have a P trap; it goes directly to the grey water leach field. No danger of it freezing.
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rancid
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# Posted: 28 Jul 2012 12:04am
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love this stuff, im hoping somthing similar with my 2 40ft container cabin. but with a glass covered solar gain on my holding tank above my container but below the outside roof.
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rayyy
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# Posted: 28 Jul 2012 05:43pm
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It's true,Rug.Your water flow would be to inconsistant for that heater.Mtndon has the answer.You need consistant pressure and flow for the water to stay a constant temp.
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reugercpl
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# Posted: 28 Jul 2012 09:32pm
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If a manual hand pump well is able to push water from the well to an attic cistern, then how about pressurizing the attic cistern to about 10 pounds psi to push the water through the on-demand propane hot water heaters below?
If I can find a pressurizable cistern I can easily bring in a tank of CO2 and a regulator to pressurize the cistern. Only pain i can figure is opening the cistern when its filling up to displace the air, then closing it up when filled. A tank of CO2 is only about $30, and it would last a very long time at low pressure.
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MtnDon
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# Posted: 28 Jul 2012 10:18pm
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I can buy a Shurflo 2088 water pump for about $70 delivered to my home. The one in my RV was 15 years old when we sold the RV. We've had one pumping water in our cabin for over three years.
To me it seems simpler to buy a water pump to supply pressurized water than to rig up a pressurized supply tank that uses something you have to replace as it runs out. Plus a tank that will safely be pressurized may be more expensive than a water pump.
If you have batteries for lights, you can run an RV water pump.
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rugercpl
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# Posted: 28 Jul 2012 10:31pm
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My likes for my design plan is that it doesnt require electricity, and a pump wont have to be turned on and off to get water, or wires for a battery run.
I have a regular supply of CO2 at all times....I'm in the restaurant and brewery business. That is not an issue for me, and I calculate that one standard tank may last me a very very long time.
With all due respect.....the cost of two batteries, two pumps, two reservoirs, a means to recharge the batteries, a means to fill two indoor reservoirs, and the wiring for all of it is cost prohibitive to me right now.
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MtnDon
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# Posted: 28 Jul 2012 11:02pm
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Quoting: rugercpl and a pump wont have to be turned on and off to get water, or wires for a battery run.
The Shurflo 2088 like other RV water pumps have a built in regulator and pressure on-off switch. Just give it power (we use a disconnect switch to make it easy to service things like the filter system). It goes on and off with demand or no demand.
As for the cost of the electrical it was my assumption that there would be some DC power at least for a few lights. My error if that is not the case. Assumptions brew trouble.
Why two pumps two reservoirs in your scenario above, though? A single interior tank can supply the entire cold and hot water system.
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