Pumping Water From Basement To Roof

I have a 50 gallon water tank in the basement and a solar tank on the roof. The roof tank is 35 ft above the basement tank and the top of the basement tank is connected at the bottom of the roof tank with 1/2 inch Pex with valves.

Is there a simple way of pumping the basement water to the empty roof tank. Unfortunately I can't use city water pressure to force the basement water up to the roof. I am trying to transfer the basement water to the roof leaving the basement tank empty.

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ArthurOakley2 months ago

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Someone already posted a solution to your problem:

The Ram pump.

Here in the AU outback they are widely used to get water from a creek into the storage tanks that are often 20m above ground level.
If your pressure in the lower tank is not enough to get the water to the roof you can add a small pump with an expansion tank (to prevent the big pressure build up in the RAM cycles) so the initial pressure before the Ram pump is high enough.
It should be possible to match the dimension of the Ram pump to your needs so you would be able to pump the water without the need of additional pumps or electricity.

Qcks2 years ago

To bring some light reading to what RedneckEngineer was saying:

I've seen them used in a number of situations, but not usually with lots of rise.

You mention the basement tank is 50 gallons, how big is the roof tank?

Something else... If this is for heating make sure that the PEX is rated to the correct pressure while it's hot. Crosslinked Polyethylene can fail when heated, so you'll want to make sure it all works nice, and that there's a way to protect it from over heating.

The pressure of the water in the PEX pipes can be calculated, but it's somewhat complex to be real exacting. Suffice it to say, it is dependent on the height difference of the tanks.
The simple form is H x g x q. h = height of water colum, g = gravitational acceleration constants, and q is the density of water.

This gives you the hydrostatic pressure at the bottom of the water colum.

Roughly, from what you've said, a 35 foot rise on a 1/2 line should put close to around 36 pounds per square inch of pressure on it. It might be more if you have hard water or a giant cylinder of water sitting on the roof. It might be less if you have very pure water (almost distilled) or if you're very far from sea level. Atmospheric pressure and dissolved particulates both effect this calculation.

atw58 (author)  Qcks2 years ago

The roof tank is the same (50 gal).

I think the pex is rated for 85 C. The system has circulated up to 90 C water from the roof to basement and has been in operation for 2 years.

Air lift probably won't work because both the hot and cold lines are connected to the bottom of the roof tank. Air bubbles would have to carry the weight of 50 gal constantly. The bubbled water does not spill into the top of container which can keep filling

Hope my explanation is understandable.

Qcks atw582 years ago

The air carrying the weight of the water constantly is alright.. As long as there's air being pumped into the line it should be okay. (Air always rises)

If an airlift makes you nervous, you might try a one way valve and a traditional water pump. The only thing about doing it that way is a water pump with a 35 foot rise is usually somewhat expensive, both to buy and operate, and loud.

Not sure why you can't use the city pressure and want to leave the bottom empty but here is an idea. First turn off the supply line to the bottom so it doesn't refill. Then remove the connection for the supply and add a connection that allows you to hook up an air compressor to force the water up the piping. Not sure I would want to try this with high pressure but it could work with proper use of valves. Or you could always use a separate pump type tie in from the drain to the supply line to the roof. Just a few ideas.

atw58 (author)  RedneckEngineer2 years ago

My configuration is a bit complicated.

The basement tank is used to either preheat water for a regular natural gas hot water tank or feed the hot water supply directly. To heat the basement tank, I connect the 50 gal roof tank to the basement tank through valves. A small DC pump circulates the water between the roof and basement tank so the temp of both tanks even out about 45-50 C after 1 hr of circulation. Then I flip the valves to connect the basement tank back to the hot water supply. The solar water heater is non-pressurized evacuated tube which means it cannot withstand city water pressure. That's the reason for all these steps.

The drawbacks are loss of heat 4-5 C in the pex from roof to basement during circulation, time to circulate and not using the full temp of the roof water (up to 70-90 C in the summer). My idea is transfer water from roof to empty basement tank. After the basement tank drops to 35-40 C, transfer basement water to roof leaving basement tank empty then repeat the cycle.