CD 30 Holding Tank Venting

[Don Metznik]

The material furnished by Peggy Hall on marine sanitation in response to several messages posted between 9/24 and 9/28 recommended increasing the vent hose diameter to as much as 1 inch if the vent line travles beyond 45 degress above the horizontal (and for other reasons). She also suggests adding a second vent line. In my CD 30, the single vent line appears to be five-eighths inch ID and goes straight up to vent in the bow. Has anyone tried the larger hose and/or a second vent line, and with what results to help eliminate odors?



dmetznic@ix.netcom.com

[Peggie Hall/Peal Products]

You don't have it quite right yet, Don (but whether you do or not, I'm delighted that you actually read it!)... a larger diameter vent line will NOT help much if the line rises more than 45 degrees. It prob'ly wouldn't help a vertical vent line at all. Reason: the gasses in the tank--even the odorless ones--are about 50% heavier than air...they aren't gonna rise, nor is the lighter air outside gonna fall down a pipe of any reasonable size to dissipate them. However, fresh air CAN travel in a 1" line that's absolutely straight (no loop, no bends or elbows other than an elbow fitting on the tank), and doesn't rise more than 45 degrees. And if the thru-hull is into the wind--i.e. in the bow--air will be forced down it when the boat is underway or on an anchor. A second vent is only necessary if the vent line has to be more than about 3-4' long.

We didn't invent anything new, btw...the principles involved are the same ones that apply to the breakdown of ALL organic matter: when it's oxygenated, there's no odor...when it's not there is. Compost piles are a good parallel...they have to be tossed and aerated or they don't compost, they compact and rot. Septic tanks don't get oxygen...that's why they stink. The same thing even applies to our bodies: blood carries oxygen to tissue...when the supply of oxygen to any part of the body is cut off, the tissue begins to decay and putrify. We simply apply that same principle to holding tanks: keep it aerobic and it won't stink....and the shorter, straighter, more horizontal, and more open (wider diameter) the vent line, the easier it is to keep the environment in the tank aerobic.


Peggie

The material furnished by Peggy Hall on marine sanitation in response to several messages posted between 9/24 and 9/28 recommended increasing the vent hose diameter to as much as 1 inch if the vent line travles beyond 45 degress above the horizontal (and for other reasons). She also suggests adding a second vent line. In my CD 30, the single vent line appears to be five-eighths inch ID and goes straight up to vent in the bow. Has anyone tried the larger hose and/or a second vent line, and with what results to help eliminate odors?

">Marine Sanitation: Fact vs. Folklore</a>

peghall@att.net

[Giles Morris]

>the shorter, straighter, more horizontal, and more open (wider
>diameter) the vent line, the easier it is to keep the
>environment in the tank aerobic.

Just a thought... Would a second vent, as far as possible from the first, combined with (gently) forced ventilation keep things moving along nicely?

Giles Morris

Peggie

The material furnished by Peggy Hall on marine sanitation in response to several messages posted between 9/24 and 9/28 recommended increasing the vent hose diameter to as much as 1 inch if the vent line travles beyond 45 degress above the horizontal (and for other reasons). She also suggests adding a second vent line. In my CD 30, the single vent line appears to be five-eighths inch ID and goes straight up to vent in the bow. Has anyone tried the larger hose and/or a second vent line, and with what results to help eliminate odors?

Giles.Morris@usa.net

[Larry DeMers]

We used Peggy's products (forget the name now..)for two years, and had no success at controlling the odors. Turned out that the products were stored in a metal shed (at the marina's store)until needed in the store. Then they were brought out for us to buy. Trouble is that heat kills these microbes off according to Peggy..and that is why it did not seem to work..at all. So we fought the smelly battle by changing the accordian hose used by CD as the head output hose for a thick walled, rather stiff but smooth finished white hose offered to us by West Marine. Guess what? 2 years of odorless head use..and I mean use. We will have 34 weekends aboard this year when all is said and done. The head area has zero odor. We went through and washed out the holding tank area well, replaced the hose (as well as the vent hose), tightened the clamps and voila', it worked well -so far. I do use a head treatment chemical in the tank now..it's probably formaldehyde..it's a blue powder in a very easily torn paper bag. Works ok from my viewpoint however.

Larry DeMers
s/v DeLaMer

The material furnished by Peggy Hall on marine sanitation in response to several messages posted between 9/24 and 9/28 recommended increasing the vent hose diameter to as much as 1 inch if the vent line travles beyond 45 degress above the horizontal (and for other reasons). She also suggests adding a second vent line. In my CD 30, the single vent line appears to be five-eighths inch ID and goes straight up to vent in the bow. Has anyone tried the larger hose and/or a second vent line, and with what results to help eliminate odors?

demers@sgi.com

[Peggie Hall/Peal Products]

>the shorter, straighter, more horizontal, and more open (wider
>diameter) the vent line, the easier it is to keep the
>environment in the tank aerobic.

Just a thought... Would a second vent, as far as possible from the first, combined with (gently) forced ventilation keep things moving along nicely?

'Twould...and we sometimes install a second vent and an exhaust fan. But it's a last resort and not always practical 'cuz the fan requires a power source. (Solar doesn't work too well during a week of hot rainy days)

A small caveat: People--especially engineers and scientific types--sometimes get so wrapped up in the minutae of the principles that they end up trying to over-engineer it It's not brain surgery or rocket science...it really doesn't have to be any more precise than: open a window to let fresh air in to dissipate the smoke if you burn something on the stove...the size of the window relative to the size of the kitchen (i.e. the exact volume and rate of exhange) isn't crucial...it just needs to be big enough and have enough direct access to the kitchen...same is true of the vent in a holding tank.

And unless a tank location makes it impossible to run a short straight vent line that doesn't rise more than 45 degrees, two vents are seldom necessary.

Giles Morris

Peggie

The material furnished by Peggy Hall on marine sanitation in response to several messages posted between 9/24 and 9/28 recommended increasing the vent hose diameter to as much as 1 inch if the vent line travles beyond 45 degress above the horizontal (and for other reasons). She also suggests adding a second vent line. In my CD 30, the single vent line appears to be five-eighths inch ID and goes straight up to vent in the bow. Has anyone tried the larger hose and/or a second vent line, and with what results to help eliminate odors?

">Marine Sanitation: Fact vs. Folklore</a>

peghall@att.net (NEW): peghall@bellsouth.net

[Peggie Hall/Peal Products]

>the shorter, straighter, more horizontal, and more open (wider
>diameter) the vent line, the easier it is to keep the
>environment in the tank aerobic.

Just a thought... Would a second vent, as far as possible from the first, combined with (gently) forced ventilation keep things moving along nicely?

'Twould...and we sometimes install a second vent and an exhaust fan. But it's a last resort and not always practical 'cuz the fan requires a power source. (Solar doesn't work too well during a week of hot rainy days)

A small caveat: People--especially engineers and scientific types--sometimes get so wrapped up in the minutae of the principles that they end up trying to over-engineer it It's not brain surgery or rocket science...it really doesn't have to be any more precise than: open a window to let fresh air in to dissipate the smoke if you burn something on the stove...the size of the window relative to the size of the kitchen (i.e. the exact volume and rate of exhange) isn't crucial...it just needs to be big enough and have enough direct access to the kitchen...same is true of the vent in a holding tank.

And unless a tank location makes it impossible to run a short straight vent line that doesn't rise more than 45 degrees, two vents are seldom necessary.

Giles Morris

Peggie

The material furnished by Peggy Hall on marine sanitation in response to several messages posted between 9/24 and 9/28 recommended increasing the vent hose diameter to as much as 1 inch if the vent line travles beyond 45 degress above the horizontal (and for other reasons). She also suggests adding a second vent line. In my CD 30, the single vent line appears to be five-eighths inch ID and goes straight up to vent in the bow. Has anyone tried the larger hose and/or a second vent line, and with what results to help eliminate odors?

">Marine Sanitation: Fact vs. Folklore</a>

peghall@att.net (NEW): peghall@bellsouth.net