I have a crazy idea to pump water

[turnkey4099]

Quote: As to pipe sizes 'to restrict the flow' as others keep mentioning. Why? A simple valve on a 1/4" or 6" diameter pipe would do the same thing. Engineering with a valve is a lot simpler than trying to determine what pipe size will do the job.


The problem with sucking on water is that you slowly inexorably form a bubble that floats at the high point of the system. As long as there is flow in the system there is a fresh source of water containing dissolved gases. The inherent vacuum in a siphon draws these gases out - - the source of the bubble. As the bubble grows it increasingly blocks flow past it. The bubble is pushed downstream, but this is downhill toward the output of the siphon. Since the bubble is in the descending water column it lightens that column and lessens the ability of that column to pull water over the top. So, if the flow velocity of the water is too low the bubble will not flush thru, but continue to grow until it is large enuf to resist all the surplus head in the system and then flow will stop. With a six inch pipe several gallons of bubble would form while the 2GPM allowed by the throttle valve continued past it. As it continued to grow it would reach a level of blockage where even 2GPM wouldnt sneak by on he fringes of the bubble. You may notice this and open the throttle valve thereby restoring flow. But this is only temporary because the bubble continues to grow. It will finally stop the flow because in cannot be flushed out with a low flow velocity. With a 1/2" pipe at 2GPM there is good flow velocity. In a constant flowing system bubbles would be driven out as soon as they began to obstruct even a small percentage of the pipe cross section. The bubbles would be expelled before you even could notice their effect. Not only is larger pipe more expensive, it will turn into a maintenance problem in this flow capacity system. Use a pipe size that self limits to the flow rate you want considering the surplus head pressure you have - - Im guessing that is in the neighborhood of 8 feet of water. It will be trouble free if run constantly. If you were to turn it off - stop flow - for a week of so you may have to reprime.
Larry

Very good points. I hadn't considered the 'outgassing' problem. If his spring has as much disolved gases in it as my well...

Harry K

 

[turnkey4099]

I have a different question, how do you prevent freezing in a gravity system. With a pressurized system, you lower the freeze point of the water by a few degrees for every PSI, and at that altitude you are going to have some pretty cold days and nights. Just want to make sure you consider all possibilities before you venture into this too much.

Derek

I hadn't heard of the lowering freeze point. Sounds logical tho as the boiling point goes down with increasing altitude (lower pressure).

Harry K

 

[Doc_Bob]

I have a different question, how do you prevent freezing in a gravity system. Derek

Darn good question!
Bob

 

[MikeD74T]

Not true, it just has to get allot colder for it to happen. Many of the bigger rivers in Northern Canada and Alaska become highways when they freeze. The truckers drive 80,000 plus loads over them all winter long. Same thing with waterfalls. When it gets cold enough, they freeze and some people even find it fun to climb them. Of course, a few die every year in the process.

Eddie

All is not as it seems, I've seen -55F and entire months of -30F in NH. While those rivers freeze on the surface they're still flowing underneath. In fact most "ice roads" require significant effort to keep snow removed & periodic flooding to keep them passable by heavy vehicles.

We can get 30" of ice on lakes & still have open water at the outlets. Whether the water freezes is also a function of it's velocity. Horse loggers used to freeze a section of a fast stream by floating a string of big logs across the stream to create a dead pool at the surface. Ice would form & the river runs under the ice/log.

Water coming from a well should be about 55F. It takes a while to loose that heat. Unless the flow is stopped most of that heat will remain at the discharge. MikeD74T

 

[Doc_Bob]

Water coming from a well should be about 55F. It takes a while to loose that heat. Unless the flow is stopped most of that heat will remain at the discharge. MikeD74T

So, will the exposed pipe need insulation???
Bob

 

[MikeD74T]

So, will the exposed pipe need insulation???
Bob

Not if the pipe size is matched to the best flow rate to maintain the velocity thru it's entire length. If oversized pipe is used with a flow restrictor insulation might become necessary. Burying most of the pipe would be the best all around insulation.

I'd experiment with hose to find the ideal pipe size to maintain an acceptable flow rate at an elevation just below the well bottom that would not deplete the well, but would provide adequate water for daily use. I'd then trench a pipe that size at least 4'deep (based on NH weather, others may vary) from the well over the bank & downhill to the elevation just below the well bottom & install a tank with an overflow. I'd size the tank to 1/2x -1x daily need. Pipe the overflow to an out of the way drainage point. Pipe from tank downhill to house to pump suction or regulator as necessary for ideal pressure. If total drop is sufficient no pump would ever be necessary. This pipe would have intermittant flow thus need to be buried/insulated. Around the tank I'd build an insulated spring house, again based on weather demands. i.e. 1gpm into tank would bring about 11k BTU/hr. ( based on 55F water ) Base insulation requirement on that.

With the tank at an uphill location if it were over drawn water would be lost at the house but only untill demand was reduced to below the capacity of the siphon and immediate recovery would begin. With 1 or 1 1/4" pipe from tank to house there might be no need for any pump at all, might even need a pressure regulator to reduce the pressure. Full time water for free forever.
MikeD74T

 

[CurlyDave]

While there is no doubt that a siphon will work, to me the problem is going to be that sooner or later something will cause the siphon to break (stop flowing) and then it will have to be re-primed.

While you might get lucky and have the tank run dry while you are watering the lawn at high noon on the 4th of July, a more likely scenario is that it will fail at 10 P.M. in the middle of winter, while you are out of town for a week, and your wife is in the middle of a shower.

If you think she is going to like toweling soap suds off, driving up there in the dark & rain, and then repriming the siphon, go for it.

I would be inclined to go for a more conventional system, even if if costs a bit more, just to prevent that from happening.

 

[MikeD74T]

CurlyDave, If reliability was a concern I'd put a float alarm in the tank to sense a specific level. That would leave you some water for necessities while fixing the problem. An alarm would be cheap and you'd still have a no power required system. MikeD74T

 

[hilld]

So, will the exposed pipe need insulation???
Bob

If I understand the scenario correctly, he will be using a gravity feed system to fill a tank, once the tank is full, the flow will stop and the pipe is now subject to freezing. I have seen broken water pipes (from freezing) at 25 degrees F that were installed in walls (not insulated, but protected from wind). So the argument of moving water not freezing won't really work as the water in the pipe will only be moving when the tank is not full. Speaking of tank, now you need to figure out how to properly insulate the tank as well, the water coming in could be extremely cold, not taking much to turn into a block of ice.

I just want to make sure all the possible scenarios are taken into account in order to prevent problems down the road. I really hate fixing things in the worst possible weather, the one doomesday scenario I could think off when you are trying to put out a fire and your pipes are frozen.

Derek

 

[MikeD74T]

If I understand the scenario correctly, he will be using a gravity feed system to fill a tank, once the tank is full, the flow will stop and the pipe is now subject to freezing. I have seen broken water pipes (from freezing) at 25 degrees F that were installed in walls (not insulated, but protected from wind). So the argument of moving water not freezing won't really work as the water in the pipe will only be moving when the tank is not full. Speaking of tank, now you need to figure out how to properly insulate the tank as well, the water coming in could be extremely cold, not taking much to turn into a block of ice.

I just want to make sure all the possible scenarios are taken into account in order to prevent problems down the road. I really hate fixing things in the worst possible weather, the one doomesday scenario I could think off when you are trying to put out a fire and your pipes are frozen.

Derek

Derek, You missed the part about the tank overflow. Flow from the well never stops. When full the tank overflows to a second location where water won't be a problem. The tank constantly receives ground heat from the water passing thru either to the house or the overflow. Groundwater from 20' below grade is cold relative to showering but is hardly extremely cold. An insulated well house will maintain a nearly constant temp regardless of weather outside. Your assumptions are correct as applied to the line from the tank to the house,it must be insulated, but that remains the case even with a deep well pump. MikeD74T