Water Pump for a 3" Boka Still

['SideWinder']

Hi guys,

I'm slowly finishing off my 3" Boka still. It'll have a 200mm double wound condenser using 3/8" tubing and the total length of the column including condenser is 2m.

I have a 50L S/S keg with the spear taken out & a 2200W S/S heating element.

So the question is, what flow rate does the water pump need to be? The pumps I find at my local hardware store don't look like they can be adjusted.

I can get a 350W commercial pump for $79 = 3000L/hr or 750W commercial pump for $79 = 12,500L/hr

or

250W private pump for $49 = 8000L/hr or 550W private pump for $79 = 15,500L/hr.

this is the link to Bunnings which shows the different water pumps they sell - http://www.bunnings.com.au/search-produ ... nce&page=1" onclick="window.open(this.href);return false;" rel="nofollow

or I could go with a http://www.westbrew.com.au/showProduct/ ... ent/700015 for $49 which looks like a pond/aquarium pump :/

any help is much appreciated.

Edit: the guy at brewcraft doesn't have any specs on the pump he sells & they aren't adjustable either. Think I will cut that pump out of the equation.

I was thinking going with one of those commercial pumps cause if it has to run for hours it'll have a longer life. The price are the same for a 350W & 750W, should I just go with the 750W or could too much flow rate cause problems?

[HolyBear]

I don't have a boka. I run a cm 3" PSII. But from my experience, pump height ability is probably what you should be looking at, not so much the volume.
A pump might be able to push alot of water volume at level or down hill, but if it doesn't have the (torque?) to push it up to the top of your column, it won't do you any good.
I would also suggest getting one that is rated a at least couple feet higher than your column because they do seem to get a little weaker over time...

['SideWinder']

I don't have a boka. I run a cm 3" PSII. But from my experience, pump height ability is probably what you should be looking at, not so much the volume.
A pump might be able to push alot of water volume at level or down hill, but if it doesn't have the (torque?) to push it up to the top of your column, it won't do you any good.
I would also suggest getting one that is rated a at least couple feet higher than your column because they do seem to get a little weaker over time...

Thanks mate. I've found the website that supplies the pumps to Bunnings - http://www.commercialelectric.com.au/water_pumps.html" onclick="window.open(this.href);return false;" rel="nofollow & checking out the manuals

350W (commercial) @ 2.5-3m pushes out 2,500L/hr (41L/min)
550W (private) doesn't specify at different heights (think ill def go with a commercial pump then lol)
750W (commercial) @ 2.5m pushes out ~10,000L/hr (166L/min)

Would there be too much pressure through the 3/8" copper condenser? or at the pump end and damage either? using the 750W? What kind of rate of flow and I aiming for?

They are both priced the same - $79. This makes me want to get 750W.

This is the page for the 750W pump - http://www.commercialelectric.com.au/Su ... _750W.html" onclick="window.open(this.href);return false;" rel="nofollow

['SideWinder']

anyone?

[maheel]

you can push a lot of water through 3/8 tube with not much back pressure

a 250 mm single coil of 3/8 knocks that 2200 with ease that i was using for a while
i also have a double 3/8 in a 3" and it has no problems

get a pump that will push to say 4 or 5m head height as flow rates drop as head increases normally

my pond pump is happier on the 3/8th than on 1/4...

[maheel]

some use 12V boat bilge pumps and say they work well but then you need a 12v suplly..

['SideWinder']

you can push a lot of water through 3/8 tube with not much back pressure

a 250 mm single coil of 3/8 knocks that 2200 with ease that i was using for a while
i also have a double 3/8 in a 3" and it has no problems

get a pump that will push to say 4 or 5m head height as flow rates drop as head increases normally

my pond pump is happier on the 3/8th than on 1/4...

so are you recommending to go with the 750W pump? 6800-8000L/hr @ 4-5m head height (113L - 133L per minute) is ok to run?

[maheel]

no i am not recommending anything...

i was running a 2" bok the other day with about 2L a min... at +-120L a min your going to have way to much pressure i think and will need to divert some but still ensure you get the flow you need

build it 1st and do some test runs on the garden tap to figure out what sort of flow rates you need
a small pond pump that lifts to 4M may be all you need rather than to much pressure causing you drama

[620rossco]

Mine is a dirty water pump which means I don't need to change the water so often and I don't need to worry about leaves and stuff in the tank.
I use controllers to manage the voltage of the elements, so I made a third one to control the speed of the pump.
I use a ball tap Y piece with a return to the tank to bleed off some of the water pressure. I bought it at a garage sale ex-hydroponics set up but its one of these:

http://www.ebay.com.au/itm/Submersible- ... 2c63609002" onclick="window.open(this.href);return false;" rel="nofollow

Specs say 10m head, recon that is about right.

[HolyBear]

Not sure what kind of hardware stores you have in OZ, but here we have big box stores that cater to the home "do it yourselfer". One project people like to do around their homes is building small ponds with waterfalls. The pond acts as a reservoir for the pump that pushes the water up to the top of the waterfall, it then gravity feeds back down... (I've heard that water goes backwards below the equator, does it flow uphill down there? ) these pumps are rated by their pump height ability as well as flow rate...these work very good since they are made to run for long durations and pump to atleast rated heights...

[620rossco]

these work very good since they are made to run for long durations and pump to atleast rated heights...

Yeah so the head height is the important consideration consideration right?
Almost any decent pump will need a bleed when it is hooked up to a 6mm cold finger (dimroth) condenser.

[emptyglass]

Would there be too much pressure through the 3/8" copper condenser? or at the pump end and damage either? using the 750W? What kind of rate of flow and I aiming for?

It seems all the pumps you are talking are all centrifugal style. You generaly cant hurt this style of pump by resticting the flow. They are a non positve displacement pump. This means you can throttle it back with a simple valve.
A positive displacement pump can be damaged by restiction.
If it has an impellor (propeller kind of thingy inside) its centrifugal. Disadvantage with them is their performance drops off real quick once you start trying to lift with them.
Get the biggest centrifugal one you can within reason and throttle it back. A 3"bok is going to need a good bit of cooling. No need to go above a 1" outlet on the pump.

['SideWinder']

Would there be too much pressure through the 3/8" copper condenser? or at the pump end and damage either? using the 750W? What kind of rate of flow and I aiming for?

It seems all the pumps you are talking are all centrifugal style. You generaly cant hurt this style of pump by resticting the flow. They are a non positve displacement pump. This means you can throttle it back with a simple valve.
A positive displacement pump can be damaged by restiction.
If it has an impellor (propeller kind of thingy inside) its centrifugal. Disadvantage with them is their performance drops off real quick once you start trying to lift with them.
Get the biggest centrifugal one you can within reason and throttle it back. A 3"bok is going to need a good bit of cooling. No need to go above a 1" outlet on the pump.

Sweet. This is what I was hoping for!

I'll get the 750W pump because it costs same as the 350W pump. If I can just restrict the flow & it's fine, it's the better option.

[620rossco]

If I can just restrict the flow & it's fine, it's the better option.

Bunnings sell a Y piece that has a ball valve in each outlet. Run a return to the tank from the other and use the valves to adjust flow. This avoids restricting pressure from the pump.