Low vacuum with Shurflo

[Urban Sugarmaker]

I have about 70 taps on a Shurflo 4048 with 2 clusters of trees tapped with 5/16" laterals and 3/4" mainline. The land is fairly flat and there is a gentle slope to the mainlines which slope almost to ground level where they meet at a tee that goes to the pump inside a plastic container.

I have 3 vac guages - one just before the pump inlet, and one at each end of each mainline. I was getting 8-9" vac dry and about 13" when the sap started to run. I got 75-80 gallons over about a 24 hour run.

For the bypass I used a saddle, then a piece of 5/16" into a barb fitting, then into a needle valve, then 1/4" tubing. This was NOT setup and working during the sap run because I didn't have a weight to weigh it down. So to be fair, I missed a step here.

Anyway, 13" with sap flowing was the best I got. All 3 gauges agree.

My questions and concerns:

1) According to people here, 20+ inches is the expectation when sap is running and you have a bypass. Is the bypass all I need assuming no leaks? I thought once sap was running, bypass didn't help.

2) I have a handful of tap holes that are weeping and I fear I caused some out-of-round holes. I don't think I split any wood because I tap gently until the sound dulls. How much vac can I lose here if I made bad tap holes?

3) I just ordered a sight level to be absolutely sure there's no up slope where sap columns would form in the main. Could be the problem, but I won't know until I check.

Other than that the system works. It's on a 160 watt solar panel with a 12V deep cycle. It ran the whole time and maintained a charge.

[maple flats]

Could be low spots or could be a leak. A shurflo does not do well with leaks. With the pump running carefully check everything, from the tap into the tree, the drop into the Tee joining the lateral and the saddle as it enters the main. A leak will usually look different. If you see a slow progression of sap then air then sap out a tap, that is good, if you see tiny bubbles moving fast, it's a leak. Also at the end of the main, check the valve or plug, listen carefully someplace you likely have a leak.
When the pump is running you should have a slow flow thru a re-circulation loop to keep the diaphragm wet, adjust that needle valve to do that, it does not take much. If all 3 gauges agree you likely have no sags that are blocking the main, look for leaks.

[Urban Sugarmaker]

Thanks Dave. The sap will be running again this week so I will have an opportunity to look carefully. This time my recirc will be up and running too.

[bawplank]

Did it improve with the recirculation line? I have almost the exact same situation.

[Urban Sugarmaker]

Did it improve with the recirculation line? I have almost the exact same situation.

Yes I got some improvement and found a couple leaks but overall the system is tight. With no sap flow the recirc line is giving me about 15" of vac. When I close one valve or the other there is no change in vac so I am thinking everything is fine.

I had about 18" with a little flow yesterday, so it's really improved. People say their pumps do 20+ when "it's running good" so we will see. I haven't had a good run yet and I am also on pretty flat ground.

[Urban Sugarmaker]

After finally getting a good run and making sure everything was tight I am getting 20-21" on vac. One problem I discovered was my recirc line was frozen inside a block of ice in the tank. I was playing with the needle valve and could see how much difference it makes. It's much easier to adjust to optimal levels if you shut off the mainlines (I have ball valves on mine).

[Dlee]

I just hooked up a pump to a couple of my 3/16 lines and hear you talking of a recirculating line what does that involve I am just running it straight into the barrel.

[Urban Sugarmaker]

I just hooked up a pump to a couple of my 3/16 lines and hear you talking of a recirculating line what does that involve I am just running it straight into the barrel.

You tee off the line right before the pump inlet and run from there to the tank. Put a weight on it to keep it submerged. I use a needle valve to regulate the flow. Just a trickle keeps the diaphragm wet and it will pull much more vac. I was experimenting with it the other day and very small adjustments can mean a few inches of vac difference.

[Dlee]

Thanks a lot for the quick response will get that done first thing tomorrow. What about the pump at night do you leave it out or take it in at night I have been taking mine in.

[motowbrowne]

I never bring my shurflo pumps inside. No heat lamps either. The first one is going into it's 4th season with zero maintenance. I turn it on at the beginning and turn it off at the end if the season. Only other time it's off is if we have a few days of very cold weather.