[Iliff Ave]

Does anyone use this and a false bottom for a mash tun? f so, what is your dead space? I just replaced my Rubbermaid cooler and transferred over all of the existing hardware including the false bottom. I had 0.41 gallons of dead space in the Rubbermaid.

To measure my new dead space amount I am putting 1 gallon in the mash tun and draining until it stops while tipped. I subtract the collected volume from the original gallon to get what is left in the cooler. I have done this about 5 times and have gotten dead space measurements ranging from 0.50 gallons to 0.63. I feel like I have gone crazy right now. Any idea what I could be doing wrong? The new cooler is slightly more narrow and the spout appears to be lower than the Rubbermaid but everything else seems pretty much the same.

[Stevie]

A pint variance is pretty small in the grand scheme of things.

[JT]

Three things:
1) What happens if you don't tip? 
2) Could you be losing suction somewhere? (hose or nipple unclamped/untaped and exposed) Without wet grain packed on top of it I could see a small leak possibly stopping suction. 
3) Try it with 4 gallons to start. 

[trapae]

My rubbermade 10gal MT deadspace is 0.25gal.  I was getting higher volumes when trying to measure it until I attached my hose and drained it like I would while brewing and realized that the suction from the siphon decreases the amount greatly as opposed to just opening the valve.

[Iliff Ave]

Three things:
1) What happens if you don't tip? 
2) Could you be losing suction somewhere? (hose or nipple unclamped/untaped and exposed) Without wet grain packed on top of it I could see a small leak possibly stopping suction. 
3) Try it with 4 gallons to start.

Thanks for the suggestions. I will try these things.

It will not start to drain if I don't have at least a gallon. I may be losing suction somehow. I do not have clamps on the ends of the tubing since I have used it before and not had issues. I did have to cut the tubing about 1/2" shorter to make it fit better. I have also noticed that when the valve is fully open that it doesn't seem to drain as rapidly.

[Iliff Ave]

My rubbermade 10gal MT deadspace is 0.25gal.  I was getting higher volumes when trying to measure it until I attached my hose and drained it like I would while brewing and realized that the suction from the siphon decreases the amount greatly as opposed to just opening the valve.

I would prefer to have less dead space although I realize it is not a big deal.

So you connect a hose to the end of the valve for draining the mash tun? Just trying to understand your process.

[JT]

Three things:
1) What happens if you don't tip? 
2) Could you be losing suction somewhere? (hose or nipple unclamped/untaped and exposed) Without wet grain packed on top of it I could see a small leak possibly stopping suction. 
3) Try it with 4 gallons to start.

Thanks for the suggestions. I will try these things.

It will not start to drain if I don't have at least a gallon. I may be losing suction somehow. I do not have clamps on the ends of the tubing since I have used it before and not had issues. I did have to cut the tubing about 1/2" shorter to make it fit better. I have also noticed that when the valve is fully open that it doesn't seem to drain as rapidly.

Yeah you don't really need the clamps and thread tape when there is grain in there and really it would be the last thing I'd try doing when doing a water only test as well.

[S. cerevisiae]

What kind of false bottom are you using?  A domed false bottom with a right-angle hose barb should not result in that much dead space.

[Iliff Ave]

What kind of false bottom are you using?  A domed false bottom with a right-angle hose barb should not result in that much dead space.

I am using exactly what you described. I may experiment with starting with more water and a hose attached for draining to a bucket below. Maybe I will just have to brew a batch and see what I end up with...

[Stevie]

Yeah, a hose on the outside does certainly help with maintaining suction.

[S. cerevisiae]

I am using exactly what you described. I may experiment with starting with more water and a hose attached for draining to a bucket below. Maybe I will just have to brew a batch and see what I end up with...

You do not use a hose?  That's a recipe for lipoxygenase oxidation.  How is the non-refrigerated stability of your beer?

[Iliff Ave]

I am using exactly what you described. I may experiment with starting with more water and a hose attached for draining to a bucket below. Maybe I will just have to brew a batch and see what I end up with...

You do not use a hose?  That's a recipe for lipoxygenase oxidation.  How is the non-refrigerated stability of your beer?

Never noticed an issue.

[JT]

Yeah, a hose on the outside does certainly help with maintaining suction.

Guess I didn't catch this.  I'd say this is your problem.  Put a hose on the outside, fill it up with more than a gallon and see if it solves. 

[flbrewer]

Use a hose. Same thing happened to me while testing. Also you have to have a gallon or so in there to start the flow. I end up with about a quart.

[coastsidemike]

Does anyone use this and a false bottom for a mash tun? f so, what is your dead space? I just replaced my Rubbermaid cooler and transferred over all of the existing hardware including the false bottom. I had 0.41 gallons of dead space in the Rubbermaid.

FWIW, I don't measure deadspace.  I feel like the cooler needs to be warmed up before using, so I run 4 gallons or so through the system first.  I heat to 160 in the HLT, transfer, and then let it sit in the Rubbermade for at least 20 minutes before using.  By doing so, the deadspace measurement really doesn't matter as it's added in to both tanks by then.  I use a weight to hold the Rubbermaid lid on tight and am able to keep the mash temps of 148 to 154 within a degree for a full hour long mash.  I'm using a bazooka screen (not that it matters), and also tip the mash tun and give it plenty of time to drain.

Hope it helps.