Feed tank height aand size questions

[bison1973]

Due to adding a preheater I had to move my feed tank higher. Because of limited overhead space I'll have to go down to a 150 gal (from a 210 gallon). Also I'll only have about a drop of 9"-10" to the inlet on the preheater (I lost several inches there as well). Do anyone see any potential problems here? Previously it worked fine. The evaporator is a 3x10 drop flue.

[Bucket Head]

No, you should'nt have a problem. I can't see where you would. Theres still a lot of volume in the smaller tank. That, along with good ole' gravity should be more than enough.

My feed tank is very small and is only about five inches above the inlet on the pre-heater and it feeds fine.

Steve

[Sugarmaker]

Bison,
Doesn't sound like you will have any problem with a 150 gal feed tank.
Our 3 x 10 has the feed tanks about 4 foot higher than the float box. And with 750 gallons of sap storage available, I can easily over power the float.
With the smaller tank you will just need to monitor your sap level a little more often. What rate are you boiling at? We can get about 80-90 GPH with the preheater on this old rig. So your 150 gallon feed tank should be OK for about 2 hours of boiling before refilling. Also you may get low pressure on the float when your feed tank gets low.

Keep an eye on the preheater for possible problems, like air trap, resulting in lack of sap flow to the float box.

If I can help let me know.
Regards,
Chris

[Haynes Forest Products]

Dang Im starting to have sap tank envey. I feed my 3X10 with a 70 gallon tank. With the peak in the sap shack its tight to the rafters and has about 30" of drop and it works fine. Yes it keeps you on your toes. I have never had a problem from it running low. Its the other end of the pans that has me screwing up:emb:

[jrthe3]

i feed my 3x8 with a 55 gallon drum that is 10 inches higher then the preheater witch is 4 inches higher then the float box

[maple flats]

I feed my 3x8 from a 415 gal tank on the outside north wall with the tank valve about 10" above the float valve. Never had flow issues, even for the last few gal of sap in the tank. If in doubt just use a larger feed line. To test this need, mount your tank and set up and fill with only a few gal of water, and open the valves. Make sure with the float valve about 1/4 open you can get enough to match your boil rate with a safety factor of 3-5X. This is so you can catch up quickly if needed. If a pan gets low you need to get more sap in very quickly. Also a good idea to have a bucket of sap (or water if needbe) to dump in for emergencies. Remember, if any part of your supply system is outside lines can and sometimes do freeze during late night boils. You need an instant fix of sap before you can take time to thaw a line unless you can shut down instantly (oil or propane?)

[ibby458]

If you vent your feed line before and after the preheater, that'll eliminate vapor lock worries. I put in a Tee, with a clear poly tubing that extended higher than the feed tank max level. You can mark on it sap levels in case the steam obscures the feed tank sight gage.

I've had more problems with too much head causing the float valve to leak than lower head. I've got 100 gallons only 10 inches above the preheater outlet.

[bison1973]

Chris, I could get 100 gal/per hour without the preheater doing everything exactly right. So even the last 10-15 gal it sounds like I should have sufficient head pressure?

[Haynes Forest Products]

I see everyone is talking head pressure. Why if the evap is running low the float valve will open and sap will run in. You dont need alot of head pressure to have a smoth running float box. To much head pressure will drive you crazy. Now if you need alot of sap fast then you should go with bigger diameter feed lines and inlet valve. I also see that people are worried about to much head pressure causing the float valve to leak.......LEAK or free flow with little control of the level. If your evap is calling for sap and your float is leaking a small stream sap and then opens and closes all is well. Now if you stop boiling and the float allows the pans to over fill then put a shut off valve in the line and dont worry about the leak.

[Beans Maple]

Best thing I can mention about feed tanks is to take all the headaches away worrying about head pressure, tank size, and location. I have a 3.5' X 10' D & G, Oil fired w/ pre-heater and I feed it with a 7 gallon feed tank that has constant head pressure and COLD sap. To do this put a bilge pump run off a 12 volt batter charger into your large holding tank. Plum a line into a small feed tank that also has a return line. Now you never have to worry about adjusting floats or running out of sap. I have been using this for about 12 years. Even when we were wood fired with highs and lows we have never had a problem.

[Sugarmaker]

Beans,
So the bilge pump runs all the time to keep the 7 gal tank filled, using the return line the allow any extra sap to feed back into the holding tank?

Regards,
Chris

[Brent]

think beans logged off for the night.

Put the float switch in the feed tank and the bilge pump in the holding tank.
When the level goes down in the feed tank the pump kicks in and shuts off when the float switch goes up.

[brookledge]

The bilge pump runs constant with overflow line returning to the storage tank. The nice thing about that type of set up is a constant head pressure.
Also if height is an issue you can put in a small feed tank and not need the room or height over the evaporator
Keith

[Sugarmaker]

Yes, another good idea to solve a problem.
Thanks,
Chris

[KenWP]

It also will not freeze up on you as the sap is always moving. Same principle we used back in Alberta for spring fed water troughs. Put a pipe out the side to move the water away from the trough and keep it dry and it didn't freeze up on us all winter.