High Speed Draining

[conrad]

Anybody tried draining a tub using a sump pump? I spotted one rated at 1300 gallons per hour for $70 at Home Depot. I want to use this pump to shorten the drain time to 30 minutes and decrease the risk of freezing pipes when temps are near 32F. I understand normal drain time is 3-4 gallons per minute for my 580 gallon tub (Maxxus) which would be about 3 hours to drain! Won't my pipes start to freeze in 3 hours if temps are near 32F? The sump pump seems like a better alternative removing water at 22 gallons per minute, and seems more reasonable compared to just waiting for mother nature to cooperate and give me warmer temps to conduct a slow drain. A fast, 30 minute drain would probably leave an empty tub with enough residual heat to prevent leftover water from freezing. Then I could start my fill with a fresh water supply whose temperature is usually 45 to 50F, warm enough to stave off a freeze during the 2.5 hour period of refilling.

The pump is encased in a hard plastic housing, but I wonder if pump vibrations would damage the shell of the hot tub? Guess I could always tie off the pump so it is suspended an inch or so off of the tub surface.

Any experiences with this type of high speed draining procedure?

[Chas]

Get one of these - they work great.

Little Giant pump - Amazon.com

[Dr. Spa]

That little thing? I liked something closer to 10,000 GPH when I was doing maintenance. Drain that sucker in 5 minutes... Then run hoses from all the neighbors houses to refill in 15 - 20 minutes.

[conrad]

So I tried this idea of high speed draining this afternoon. The results are a little mixed, however it might be help to those who are interested, especially for those of us in colder regions.

I bought Flotec 1/6 HP pump (Model 1300x) from Home Depot for about $70. The specs on the pump claim 1250 gallons per hour maximum output. Hooked up the pump to a 5/8 inch garden hose which drained directly over the ground. Here are the results:

Time to drain:

Used sump pump method, Maxxus 580 gallon tub

Start time: 3:00pm, tub temp 104F, ambient temp 38F

End time: 4:27pm, tub temp 70F, ambient temp 35F

Total time: 87 minutes (1.5 hours)

Flow rate: 6.7 gallons per minute

Conventional draining normally takes at least 3 hours or more. The sump pump worked FASTER than conventional draining with only 1.5 hours time. This allowed me to drain the tub quickly on a cool day where temperatures were close to freezing and allowed me to refill by the time the sun went down. By the way, overnight temperatures will be plunging to 19F or less as a cold front is moving in. I was able to drain and fill the hot tub in 4 hours total, more than enough time to avoid exposing the tub to freezing temps. This would have taken 5.5 hours or more without the pump.

Only one downside, I expected a faster flow rate from this pump since it is rated at 21 gallons per minute (1250 gallons per hour), I didn't see that flowrate! Did some research and found out the flow rate is limited by diameter rather drastically. The pump has a 1 inch outlet, and comes with a garden hose adapter. I used 5/8 inch garden hose, and probably should have used a 3/4 inch hose which was recommended by the pump manufacturer, Whoops! I will try the 3/4 inch next time. Wish I could get 1 inch flexible hose but that might be overkill.

[Dr. Spa]

Use the shortest hose possible. Cut it if you have to. Even better, rig up your own hose using one to 1-1/2" diameter pipe. The bigger the pipe and the shorter the distance, the faster it will drain. Done right, you should be able to get the drain time down to about 1/2 hour.