Head bowl backfilling from holding tank

[ybrad]

Working on the plan to install a holding tank in our 37C. Intended install will have the head discharge directly into a y-valve. One path goes to a MSD that is lower than the head, so there is no back-fill problem. The other will go to a holding tank that is a foot or so higher than the head. Just replaced the joker valve so that that will help minimize backflow from the uphill discharge.

Anything else need to be done to minimize backflow?

Anyone using a vented loop to minimize the amount of exposure (i.e. 2' of hose verses 8' of hose)?

Or is it not that big of a problem in the real world?

Thanks for input!

 

[thinwater]

a. Take the discharge hose up above the holding tank top as quickly as possible and then slope toward the holding tank.

b. Flush with enough water to clear the line; only clear water can run back.

 

[ybrad]

OK, makes sense. Since not a siphon problem, don't need the 'vent', just the 'rise.' Thanks for the clarification.

 

[thinwater]

OK, makes sense. Since not a siphon problem, don't need the 'vent', just the 'rise.' Thanks for the clarification.

Actually, if the discharge is below the water line (normal) and the bowl is below the water line (typical), a vented loop is still needed. This can be located only on the direct discharge leg of the Y-valve, where is may be less prone to plugging if that option is seldom used.

On the other hand, if the head were plumbed only to the tank with pump-out by land or macerator pump, then the loop goes on the macerator pump discharge.

 

[ttac]

On our boat ( 42 Passage ) the aft head would always drain out after flushing. I had to put in a ventilated loop to fix that problem! We have about 12 ft of hose from that head to the tank! We just replaced the hoses also and the low spot is where the hose was plugged! With our layout there is no way to not have a low spot in this line. It must go under the tub and fridge!

 

[FastOlson]

One suggestion, since you are in the planning stages...
Design your new tank with All top fittings. i.e. the waste enters on top, and the exit(s) are mounted in the tank top with a plastic pipe that goes down to the bottom. Ronco can easily build this style for you and provide all internal piping and an inspection port as well.

We did this for a new HT for our boat. This configuration has no tank fittings on the side at the bottom to ever potentially leak. We have one exit tube (aka "dip tube") for shore pumpout and a separate one for overboard discharge where legal.

All these options are cheap and easy for Ronco to do when constructing the new tank, and a lot more difficult to retrofit later...

Regards,

 

[KD3PC]

It must go under the tub and fridge!

Wasn't it fun to replace that one??!! I wish I had my wife take pics of me laying and contorting on both ends to fish a line and then pull the new hose in...I tried using the old hose as a pull, but that failed where it went under the tub...I think I pushed it more than I pulled.
Next time I will pull from the bath instead of from the galley grid and see how that works.

Then getting to the loops against the aft head wall, had to take batteries and charger/inverter out to get close enough, still did a lot one handed and stradling things. I did lube and service the cockpit drain thruhull real well while I had things out.

 

[ttac]

We were able to pull the new hose thru with the old hose! I used a barbed connector and put a screw thru the hose into the connector so they could not pull apart! We started from the aft head and pulled it to the tank thinking the worst spots were under the tub for getting hung up! All went well! We were done with both head hose's in about 2 hours!

 

[Dalliance]

Good advice

One suggestion, since you are in the planning stages...
Design your new tank with All top fittings. i.e. the waste enters on top, and the exit(s) are mounted in the tank top with a plastic pipe that goes down to the bottom. Ronco can easily build this style for you and provide all internal piping and an inspection port as well.

We did this for a new HT for our boat. This configuration has no tank fittings on the side at the bottom to ever potentially leak. We have one exit tube (aka "dip tube") for shore pumpout and a separate one for overboard discharge where legal.

All these options are cheap and easy for Ronco to do when constructing the new tank, and a lot more difficult to retrofit later...

Regards,

Wish I had this - all top fittings and a "dip tube". Still have the original fiberglass holding tank with inlet and vent on the side near the top and the pump out hose fitting on the side near the bottom. This allows waste to sit lower 3 ft of hose, and eventually permeate it.