March pump frustration

I'm trying to get my new brewstand running and have run into an issue with my march pump. I got the pump from a coworker who bought a bunch of homebrew gear but never got into the hobby, and it seems to work fine. I have mounted it with the motor axis horizontal and the inlet/outlet horizontal, with the outlet higher than the inlet. I've mounted it under a table, so I had to flip the pump head 180 degrees to keep the outlet higher than the inlet.

The first picture I've attached shows my kettle connected to the inlet and the outlet connected to a hose that's slung over the edge of my MLT. I used it in this configuration to successfully pump 4 gallons of hot water into the MLT in preparation for mashing.

After I pumped the hot water into the MLT and turned off the pump, I spent about an hour screwing around with some thermometers and during that time, the temperature dropped well below my strike temp. "No problem," I said to myself, "I'll just reverse the hoses, pump a gallon or two back up into the kettle, and fire up the burner for a few minutes. Boy, this pump sure is great."

The second picture shows how I plumbed the MLT outlet into the pump inlet, and the pump outlet to the kettle. I opened up the valve on the MLT, the valve on the kettle, and the valve on the pump outlet. Very little water flowed from the MLT down to the pump. It was as if I had a stuck sparge, or had pinched the hose shut near the pump inlet. I had expected the tube leading from the MLT to the pump inlet to quickly fill with water, but lots of air remained in both lines. I turned the pump on and although it appeared to fill the lines with water, it failed to pump any water up into the kettle.

With the pump still on, I disconnected the hose from the kettle and dropped the free end below the height of the pump. Quickly, the pump primed itself, blasted some air bubbles out of the hose, and started shooting a healthy geyser of hot water onto the ground. Lifting the free end of the hose back up to the kettle level, it continued to blast lots of water all over the place. So, clearly disconnecting the hose and dropping it below the pump for a second cleared up whatever was wrong. Obviously, this isn't a long term solution.

I can't figure out why this is happening and it's quite frustrating. I'm a mechanical engineer (which makes it extra frustrating, I'm supposed to be the expert, dammit) so feel free to go as technical as you want if you've got advice to offer. It seems to me that there is no good reason why it would work one way and not the other, considering both vessels are located well above the pump head, and the pump outlet is definitely higher than the inlet which should allow it to clear any air bubbles. Do I need some kind of bleeder valve? Is the orientation of my pump wrong?

Your outlet in the second picture is not providing a path for the air to escape. The air acutally gets the the highest point in before turning downward, which in this case is your pump. If you can orientate the pump so that the outlet is facing up and not allow the outlet hose to sag below the pump the air should escape and liquid should flow.

Notice in your first picture the outlet hose doesn't sag below the pump and it works. I would try that. Another option would be to put a tee on your outlet side and just bleed out the air like you mentioned, but you still wouldn't want the hose to sag below the pump.

Exactly right. Air has to have an easy escape from the pump head in order for liquid to flood into it. When you dropped the outlet hose down, the water that was in it pulled a vacuum on the pump and evacuated the air.

also add a ball valve to the pump discharge. Mount the pump vertically. Using the valve bleed off any air to prime the pump. start the pump with the valve closed then open slowly to the required flow

l3asturd said:

Your outlet in the second picture is not providing a path for the air to escape. The air acutally get's the the highest point in before turning downward, which in this case is your pump. If you can orientate the pump so that the outlet is facing up and not allow the outlet hose to sag below the pump the air should escape and liquid should flow.

Notice in your first picture the outlet hose doesn't sag below the pump and it works. I would try that. Another option would be to put a tee on your outlet side and just bleed out the air like you mentioned, but you still wouldn't want the hose to sag below the pump.

Click to expand...

Good advice. As a side note, you don't have to remove the whole pump to re-orient it. The motor can stay where it is. Simply remove the four screws from the front of the pump. Turn the pump head and reinstall the screws.

Just adding a bleeder valve will make life 100 times easier. I wouldnt use a pump without the bleeder valve....... i tried once it was an extremely frustrating brew day.

I have found that orientation of the pump head is not that important. Both ways prime and maintain prime just fine assuming you get the input line flooded.

Maybe if you dont add the bleeder valve it matters more???? Not sure.

I have it mounted horizontally like you have shown and havent had any issues since adding a bleeder valve.

Easiest fix would be to simply lift the hose up above the pump. Someone already mentioned it bug its worth repeating. On My set up I lift the hose till I get it flowing then I'm done.

Out of all the pump threads I've read, I really think this one is the simplest about just getting to the point of what 99% of people's problems are with pumps. Plain and simple. Good answers guys.

A T fitting in the inlet and outlet s of the pump will ease priming to the point of simplicity. I planned this into the overall design and ran the two lines into another T so they combined and could be routed to the drain. No sense having hot sticky water all over the area youre trying to work in. The reason I did it to both sides of the pump is to allow me to bleed the in line, then bleed the out line and minimize waste and time. I used the clear silicone heavy wall tube from Austin Brew supply so I can see exactly what I am doing and again minimize waste. It's very easy to plumb the two T's and related ball valves and will cost arount 20 bucks with brass ball valves and stainless T's. Hope this helps.
Wheelchair Bob

Thanks for the responses, everybody. I tested it out and I was able to get it to work properly first try by holding the hoses such that the pump is not at a high point in the circuit. I will probably install a bleeder valve as well, as it seems like the more I search around, the more I find that people are using them.

I'm using Watts FV-4M1 bleed valves, they work great. Picked up 4 of them for $20 on ebay.
http://www.watts.com/pages/_products_sub.asp?catId=64&parCat=251

You only need a priming valve on the outlet- not the inlet. An inlet bleeder is really a waste of liquid. Any air trapped will be expelled at the outlet priming valve. And a little air is not going to hurt - you just can't run the thing dry.

outside92129 said:

I'm using Watts FV-4M1 bleed valves, they work great. Picked up 4 of them for $20 on ebay.
http://www.watts.com/pages/_products_sub.asp?catId=64&parCat=251

Click to expand...

Can you maybe show a pic how you have that hooked up?

I'd like to add something like this mine.

Here's the setup, it's been modified since dec-2011 but the concept is the same.
The air bleed valve is on the output before the ball valve so it always has access to any air. Since wort will be going into the unit you should run clean it out after each use, i run hot water through the entire system anyways so no biggie for me. There is a little black screw on the top of the unit, make sure that's open, that's where the air vents out. If it's tightened then it doesn't work.

Thanks, that's how I imagined it would be hooked up. My only concern is the extra height having another tee and two more nipples adds.
I'll give it a shot though. Thanks.

Cool idea - but I'd still just use a ball valve with a nipple on it. It's simple, which mean it's less prone to fail. And also it is a great way to take a sample. You can also mount it horizontally so it takes up less room. Just my two cents.


photo by brewerJP, on Flickr

jcaudill
I know this is an old post but I was curious how you got your threaded fittings to line up. I'm trying to build a similar set up for my march pump. But can't seem to get the fittings straight. Thx for te pic btw. Very helpful

Haha, well this is an old setup for me but still - it took a lot of wrenching to get things lined up. I did a lot of disassembling and reassembling until I got it where I wanted it! Hindsight, really glad I don't have threaded fittings anymore. It's amazing how gross those threads get fast.

the trick to getting the fittings straight is to add teflon. An example would be if you need it to be 30 degrees less turn add a few extra wraps of teflon