Water Pump for Remote Cabin Application

Google "12 volt water pump". There are many used in boats and RVs. that should be suitable.

Like an automotive windscreen washer pump, perhaps?

I thought about that too, but then I thought it might not be really rated as "continuous duty", since those pumps are used very intermittently. Might be worth a try, if you get one cheap/free at the salvage yard. If the price was right, you could even keep a few on hand as replacements for the inevitable failures.

Tom

You might try an inverter for 12VDC to 120VAC and a Taco brand pump. Taco has been making pumps for solar hot water systems for decades so they have proven their design to tolerate the 180F which is the same as the stagnation temperature of many solar thermal systems. You'll want one of the brass versions (not cast iron) because of the potable water requirement. Taco is MADE IN THE USA and is less expensive than the European brand pumps.

GA, Mainly -- Previous replies have missed the point that most inexpensive consumer type pumps are not suitable for 180F water. This application should really be suitable for boiling point temperature since this is a likely failure mode of the system involved here.

Critical to the pump selection is both the flow rate and the pressure (head) it must pump against. Presumably the cabin hot water tank will be mounted high to provide a good 2 gpm flow for the shower. If plumbed with 1/2" pipe between the tank and the stove the friction head loss will be minimal so figure whatever friction loss will be what you can get through the tubing length you are able to wrap around the stove flue. So let's say you've got a 6 inch flue and you want to wrap maybe 25 feet of 3/8 inch soft copper tubing around it. That's maybe 13-14 turns. At one GPM you may get around a foot or so of head loss. That suggests that the little Taco model 003 stainless steel circulator pump is a good bet. One source at $180 is in the link below.

http://www.pexsupply.com/Taco-003-ST4-003-Stainless-Steel-Circulator-1-40-HP-15059000-p

This has a 1/40 hp motor which suggests the draw on 115 volts would be around 30-40 watts. Around 4 amps draw from a 12 volt battery to feed an inverter box is probably the most you'll need. I suspect it may be half of that if you throttle the flow with a globe valve back to 1 gpm. These are real ballpark numbers but they tell me that your idea is feasible if you want to invest the money in it. Sounds to me like you'll be into it around $400-$500 if you have to buy everything new including a 26 gallon water heater.

If you were a craftsman pretty handy with machining I'd suggest experimenting with a small stirling engine to drive a little bronze centrifugal pump or possibly a piston pump that you could make yourself.

Ed Weldon

Excellent! I use a Taco in my house for exactly that purpose. Hot water jacket in in my wood stove, electric hot water tank as reservoir. In the winter I turn of the breaker to the tank. Pump is a about 1/16 Hp, uses almost no power. My electric bills go down in the winter./

Water when heated has a tendency to go up and cold water goes down. Can you think of a system with circulation based on this principle? (similar to solar water heaters)?

1. why not have a water reserviour on the roof (copper pipe is cheap enough) and gravity feed water past the heater and on t the shower...avoids a temeperature tolerant pump.

2. Any of the rubber/nitrile impellor type pumps...Jabsco, Shurflo etc can do this. They have 12/24v model that can handle chemicals and probably temperature. H

However, it is cheapest to pump cold water.

Please take a look at this one: http://www.laing.de/eng/products/pumps/dc_pumps_d5_solar/

Perfect match for your application: 12 VDC, suitable for hot water service, capable of continuous operation.

Regards, nudnik

Apart the pump from being continious type, it would also a heat water pump.

I see every offered pump is suitable for cold water. If the pump fails (melts), what you will obtain is the boiling water, not suitable for bathing.

On the other hand, you may check, whether you can use the benefits of Natural Circulation (Convection)

This sounds like a good application for a thermo-syphon and gravity loop. There are many examples on the internet of these installations, use google. The (simple) theory is that the hot water will rise as heated, so you would want to have the hot water tank elevated and to run a 1/2" to 3/4" pipe from the top of your heat exchanger coil to an inlet connection at the top of the hot water tank. The cold water line will connect from the bottom of the tank to the bottom of your heat exchanger coil. The denser, colder water will drop and feed into the bottom of the loop, rise as heated and run back into the top of the tank. A natural, gravity fed thermo-syphon loop.

Exactly.

This is what I wanted to describe as Natural Circulation (Convection)

For years John Deere tractors used a thermo-syphon system for their cooling systems. This principle could be enhanced with a 12 volt electric water pump as found in hot rod catalogs like Summit or Jegs. A pump of this type would take the temperature and should have good endurance, though I don't know about the cost compared to the others.

This may sound silly but...why pump the from the "hot" side? Why not push from the cold side? You can find a demand pump with variable flow at almost any RV place that is designed for both 12v and continuous duty.

I wouldn't reinvent the delivery system that works, just the heating system. There I think you have a brilliant idea.

Rick

Of course the pump is at the entry side.

It is cold water, passing inside the pump at the beginning.

What you do not imagine, it is a closed loop.

The pump is a circulation pump, and water is continuously circulating.

Therefore the pump side will be warm a short while later.

Hydromatic makes small condensate pumps rated to 180 the reason I say condensate is due to their small size flows around 1 to 2 gpm with approx. 15 to 20 foot of head.

Head means pressure or if you have a column of water 2.31 feet high that equals 1 PSI. Another way to calculate it is if you want to push the water up 10 feet in the air over to your shower the pump must exceed 4.3 PSI plus additional pressure to overcome friction loss in the copper tubing. Copper has a very smooth internal surface so losses will not be much.

Also look up Hartell pumps they are a division of Milton-Roy they have a pump rated to 200 degree F but the flows in gpm may be too high for your 26 gallon holding tank.

In closing I sure you have 120 volt single phase power in your cabin, these small pumps have small motors I.E. 1/4 or 1/2 or 1/5 hp they will all be 120 volt, single phase plug in type ASJ cords.

Good Luck

How about a pump from a fish tank. They run continuous for years, are cheap and readily available.

You could consider duplicating a travel trailer system and avoiding the hot water pump. That system being a cool water storage tank, 12 volt pump drawing from the storage tank, passing through a 5 to 8 gallon water heater to shower head. My travel trailer water heater is gas or electric, you could incorporate the water heater in the flue of the stove or as soneone suggested with coiled tubing with a thermo siphon to the reservoir. A travel trailer shower head has a cut off at the head where you can shut the water off without changing the temperature set by the hand valves to conserve water while you lather up. Five gallons is plenty for a shower if done this way.

Advantages of this system are:

1. Relatively low cost 12 V pump, with no high temperature requirement.

2. Said 12 V pump has a built in pressure cut off so you don't blow your piping apart.

3. No additional cost of an inverter, the inverter consumes power even when the pump is not running (I think).

4. No elevated storage tank (you have to get the water up there somehow, five gallons of water weighs over 40 lbs).

5. Everything you need to pump the system is available at a RV supply store, plastic tubing for the supply lines, pump, water saver shower head....

6. You can repair plastic tubing with a razor knife and channel lock pliers.

7. This system can be closed (with proper relief on the reservoir, again from a RV supply store) so you have proper water pressure, otherwise the hot water pump would be supplying pressure which would need to be regulated.

8. The single pump can supply hot water, and cold water for proper mixing, comfort and safety at the shower head.

Keep in mind that an open system would require a hot pump to supply pressure and needs to be regulated, and a second pump to supply cold water for mixing.

You may want to consider a propane powered water heater from a RV, my RV can heat 5 gallons of water in about 10 mins, is propane powered, with 12 volt controls.

There have been some good suggestions. Another source of circulation pumps is the Grundfos Series UP. Grundfos has been making circulation pumps for years. US made but you would have to do the inverter thing because Grundfos pumps are 115v 60hz.

I am looking at the pump curve for the UP 15-10SU7P/TLC and it pumps 0.5 gpm @3.2 feet of head or 1.0 gpm @2.8 feet of head, 115v, 60hz, 0.25hp, 0.23 amps, 25watts.

You will pay a little more, and you will have a pump that will last for 20 years.

You can contact me off line if you need additional help.

ccmoore@kasl.com

If you want to think a bit out of the box here below some links to look at that I came up with in a Google search for "water jacketed stovepipes" that perhaps could make a thermosiphon setup work better than a long small diameter copper coil would.

Also a couple of caveats on this. Make sure the whole system is reliably vented (i.e. closed off with a screen to keep critters out) to the atmosphere so you don't end up creating a high pressure boiler. And be aware that cooling the stovepipe can accelerate creosote buildup, especially if you burn softwoods. So be ready for periodic maintenance if you plan intensive use of your cabin stove.

Ed Weldon

http://www.tentsmiths.com/tent-camp-accessories-stoves.html

http://www.islandhottub.com/woodhtr.html

http://forums2.gardenweb.com/forums/load/strucs/msg1209560724118.html

http://hearth.com/econtent/index.php/QA_Templates/info/710/

http://www.cabelas.com/p-0005873513961a.shtml

Check Jabsco marine pumps. I've used one of them in my car for 15 years to circulate the coolant.

Look for "circulation pump". They are built for exactly this application.

Wangito

When I was a kid in Scotland in the 1950's we had a flap at the back of the fire.When opened it heated a water jacket.The water rose as it heated to the roof tank (about 40 gals as I remember),and was replaced by cold water which flowed from the bottom of the roof tank down to the jacket.After about an hour and a half of a good fire the whole system would started to bubble furiously with loud sounds coming from the roof.The water was boiling !

Dead simple , no pumps , no valves , just very old pipework

Guest -- Sure the setup in Scotland worked great. And also points up the need for a good vent or relief valve.

The problem in today's safety, environmental and lawsuit conscious world, at least here in the USA, is being able to buy the stove/chimney hardware that can do the job. I've already mentioned some of the issues that can easily keep good hardware out of the consumer market.

The ten or so percent of us that can build our own stuff (probably fewer in this case because you need to be a pretty good welder) don't sweat it. The rest are a lot more limited.

If I wanted to do something like this I'd go buy a slip roll for my shop, some 304 stainless steel sheet, some 1/8 plate that I'd lathe turn into annular rings. Turn a couple of threaded rings for water connections and TIG weld all three tubes together. (including the clamps on the outer one outer tube for holding the insulation). I'd do a little research into the subject of thermosiphons to find the optimum pipe diaameter for the vertical run to the tank and then go find the right (read cheapest)temperature resistant piping. I have a suspicion that I might end up with around 1-1/2" schedule 40 galvanized pipe with some good insulation on the outside.

If this thing transfered to much heat it might be necessary to have a valved branch for the heater section of the chimney so it could be taken off line once the whole thing got to high in temperature.

Ed Weldon

hi, mike

goodmorning,

u cann get this type of pump at laboratory equipment stokist at your area wrhere as it is special requirement butu can get probabilty of youer specification because in Chemical lab that of wtaer extracting as well as wter discharge pump normaly used for its pilot project.

thanks

tmp

"Mike: I am in central British Columbia and am building a wilderness cabin. My intention is to use a 45 gallon drum at ceiling height for storage of hot water to heat my cabin long after the flames have died, - and for domestic hot water, eg, sink, shower.

Have you found a way?

Frankinbccan