"cool tub" idea - need a pump
"cool tub" idea - need a pump
(OP)
ok gents, I had an idea the other day which I might pursue farther if I can find some parts. I have an outdoor hot tub on my deck in the back yard. Houston is hot enough as-is without sitting in hot water most days in the summer ... so I was thinking I might like it better as a "cool tub." The tub itself is about 240 gal. I would guess that watering my lawn uses up to 4000 gal/mo in the peak season, which would be a full volume change every 2 days for my hot tub. The water might be cool-ish, especially if I make sure that my sprinklers run on saturday and sunday mornings to change out the water on the days when I'm (kids really) more likely to hop in the tub.
The missing part from this scheme is a pump which runs on supply water pressure and can achieve a similar head & flow rate for return water - so that the city supply pressure, emptying into the tub, can drive a pump to take water from the tub and put it back up to (nearly) line pressure to run the sprinklers. I know I wouldn't get all the pressure back ... but I don't need ALL of it to make the sprinklers work. Any such thing already out there? A quick google didn't net anything (wrong terms?).
If I had the pump, the piping, wiring, and solenoid valve would be easy.
The missing part from this scheme is a pump which runs on supply water pressure and can achieve a similar head & flow rate for return water - so that the city supply pressure, emptying into the tub, can drive a pump to take water from the tub and put it back up to (nearly) line pressure to run the sprinklers. I know I wouldn't get all the pressure back ... but I don't need ALL of it to make the sprinklers work. Any such thing already out there? A quick google didn't net anything (wrong terms?).
If I had the pump, the piping, wiring, and solenoid valve would be easy.





RE: "cool tub" idea - need a pump
RE: "cool tub" idea - need a pump
http://www.waterdamagedefense.com/products/basepum...
Here's another type:
http://www.grainger.com/product/ZOELLER-Pump-12U35...
And another:
http://www.sourceforbusiness.co.uk/papa
John R. Baker, P.E.
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RE: "cool tub" idea - need a pump
1) combines the streams and seems to be for low-pressure release of the water - don't think I could use this to draw hot tub water into the sprinkler supply line
2) same story as 1? spec was hard to find, but it seems to give back less than 1/2 of the pressure at best http://www.zoellerpumps.com/en-na/product/65-home-...
3) converts high flow/low pressure into low flow/high pressure ... but I want similar flow and pressure on both sides (or else the idea doesn't work).
RE: "cool tub" idea - need a pump
RE: "cool tub" idea - need a pump
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P.E. Metallurgy, Plymouth Tube
RE: "cool tub" idea - need a pump
The first pump suggested may be overkill, you may not need a backflow preventer but you may need a siphon break.
If you water your lawn through a venturi you can suck some water from the tub.
You can then use a float valve arrangement to maintain the level in the tub.
Bill
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"Why not the best?"
Jimmy Carter
RE: "cool tub" idea - need a pump
You didn't supply the GPH needed for the sprinkler system so I could spec out the model, I did notice the ~120GPH were about $100 each
http://www.proconpumps.com/brands/Standard-Vane-Pu...
RE: "cool tub" idea - need a pump
Just watch out, though- the volumetric flushing isn't enough to keep the water in the tub pure. A pump-around with a filter is probably also a good idea.
RE: "cool tub" idea - need a pump
The sprinkler system already has anti-backflow and siphon breaker features near the connection to the water main, and the hot tub already has a filtration system and a bromine dosing system (although I imagine I'd need to adjust the chem rate to compensate for much higher water loss and/or not to kill the lawn ... but the bromine evaporates rapidly so maybe not a problem).
Haven't flow tested the sprinkler system (I didn't install this one) but I imagine it's somewhere just below 8 GPM, so I'm probably going to need bigger pumps.
I am thinking that there are more applications for this concept than just "cool tubs"... if you could make the recovery pump sets cheap enough, then anyplace where you don't need much pressure (bathroom sink, toilet tank, etc) you could use the water flow through your supply pipe to re-pressurize gray water for lawn use ... would need an accumulator or tower to save it, though. I could imagine a case where you had an inconveniently placed piece of plumbing, and you wanted to pump every bit of water back up the hill that you sent down the hill to it, maybe this would work. Not totally sure what that'd be ... maybe it's a solution looking for a problem?
RE: "cool tub" idea - need a pump
http://www.douglas-self.com/MUSEUM/POWER/waterengi...
I tried to find a piston design, but the mechanics for the engine adds complexity
If you could find one of these (and afford to put it to work), these would be extremely cool to have
https://www.youtube.com/watch?v=AJpZNBXEeUc
RE: "cool tub" idea - need a pump
I found something else that might work, use a pnematic double diapragm. Using non compressiable water (the yellow sections) as the operating fluid should give it increased power. Just would have to determine if those components would be water compatable
http://www.hammer-alleviators.com/images/double-di...
Nortern tool has a 10 gpm around $300 for the complete unit
http://www.northerntool.com/shop/tools/product_200...
RE: "cool tub" idea - need a pump
You have a lawn when so many people don't?
RE: "cool tub" idea - need a pump
RE: "cool tub" idea - need a pump
You have a lawn when so many people don't? eh? I have an automobile and smartphone too, and so many people don't. Maybe you're suggesting I should box up the water and mail it to California instead? An interstate pipeline is well out of scope for my home projects.
I've only got the bromine dispenser set at about 4% opening at the moment to maintain the recommended concentration, but yeah, the levels would definitely swing around wildly if I went ahead with the plan.
I'm definitely still intrigued by the concept of mechanically "swapping" clean for dirty-ish water without much pressure loss.
RE: "cool tub" idea - need a pump
RE: "cool tub" idea - need a pump
RE: "cool tub" idea - need a pump
How about running your filter system at the same time that you water the lawn with some type of heat exchanger between the filter recirc. line and the lawn water line?
Don't exchange the water, just cool it.
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: "cool tub" idea - need a pump
RE: "cool tub" idea - need a pump
It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.
RE: "cool tub" idea - need a pump
RE: "cool tub" idea - need a pump
Many people here have removed their lawns because of the water usage cost. Never mind how much it costs to heat their hot tubs.
The concern is that the water from the tap maybe too cold to enjoy. So the heat exchanger might be a better idea, so you can control the temp.
With chlorine you need to keep the PH in a specific range to be effective. Is it the same with Bromide?
RE: "cool tub" idea - need a pump
RE: "cool tub" idea - need a pump
More seriously now, your musing about pumping water uphill reminded me of a "ram pump". Not the same application here, though.
STF
RE: "cool tub" idea - need a pump
RE: "cool tub" idea - need a pump
I was thinking about this after reading it the other day and thought it might be a good idea to make a cooling pool as it's going to be a hot summer this year in western canada. (hey, hot for you guys in the south is completely unbearable in the north. that heat just wrecked me when last visited) I think I'll be making due with some simple waterproofed cheap material and a small flowpump to circulate the water. Something easy to setup for el nino summers and takedown for the winter. great ideas though.
RE: "cool tub" idea - need a pump
RE: "cool tub" idea - need a pump
RE: "cool tub" idea - need a pump
However, in the real world...
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: "cool tub" idea - need a pump
Go to your irrigation store, tell them you want a pump that will irrigate from surface water (like a pond) and properly charge your irrigation system. You may need to provide them some basic details of your irrigation system.
Attach that pump to your drain line of your tub.
Install a float switch to the inflow line of your tub from city water, so whenever the tub dips below a certain depth it fills it back up with city water, like a toilet does.
Done.
Hydrology, Drainage Analysis, Flood Studies, and Complex Stormwater Litigation for Atlanta and the South East - http://www.campbellcivil.com
RE: "cool tub" idea - need a pump
energyrcovery.com
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P.E. Metallurgy, Plymouth Tube
RE: "cool tub" idea - need a pump
RE: "cool tub" idea - need a pump
1. Couldn't you rig up a quasi geothermal unit to cool the tub
2. Couldn't you run some lines back into the house to get some indirect cooling from your house A/C?
3. Couldn't you blow pressured air (or use an air compressor) into the water for cooling