March/Chugger Pump Priming Port Location

So I'm a bit confused about the location for a priming/purge port with my pump. Here is how I currently have my pump oriented and setup.



In the picture you will see that the beer leaves the MLT from the LEFT, goes through a vacuum gauge, and then into the pump. It then exits to the right. To prime the pump I have both ball valves on the right open and slowly close the purge valve (the one with the stainless 90 attached).

As I do, the wort begins to flow up through the hose into my HERMS coil and back into the MLT to start the process over. I (like many) was having priming issues and added the purge/priming valve to solve this problem. It did.

But I was looking today at MoreBeer's March Pump assembly HERE and they have their purge/priming valve on the INLET side of the pump. Not the OUTLET side like I have. Here's a picture of their assembly:



And here is a picture of how they have it attached to their sculptures:



When I looked at the item description of the pump assembly, they actually answer the question of why the purge valve is on the input rather than the output. Here's what they say:

"Some people wonder why we put the “priming tee” on the inlet rather than the outlet. The priming ball valve is there to allow air pockets out, and if it is positioned after the pump head, the air bubbles would get caught in the pump head and continue to cavitate."

As you can see from the picture above, their pump heads are oriented vertically with with the inlet side down and the outlet side up. I've seen a lot of other guys here on HBT who have their pumps mounted this way as well. I assume it works and works well.

As you can see though, that's not how I have my pump head oriented. It is horizontal. Should I change where I have my purge/prime valve though? I'm trying to figure this out. Anybody using a horizontally oriented pump that has the purge valve mounted on the inlet that can give some input?

There is one issue I've seen with my current setup. Maybe changing up the location of the prime/purge valve will help. Here's what happens. When the mash is over, I unhook the MLT from the pump and then hook my HLT up to the pump. But the pump will not pump water from the HLT through the pump, up through the HERMS coil and out onto the top of the MLT for the sparge. To get the pump to actually pump, I have to siphon the remaining wort out of the HERMS coil. If I don't it won't pump.

So what I do is detach the output ball valve (not the purge valve) and allow a siphon to suck all the wort out of the HERMS coil. I collect this and dump it in the MLT. After that, I reattach the output ball valve, open both the output ball valve and the purge valve, turn the pump on, let the water begin to squirt out the purge valve and then slowly close it. Then the pump starts pumping sparge water through the output ball valve, into the HERMS coil and over into my MLT.

This is kind of annoying, but it's what I do. Will relocating the purge valve to the inlet side of the pump fix this problem? Will it allow me to simply unhook the MLT, hook up the HLT and go without having to siphon the wort out of the HERMS coil? Tell me your thoughts.

I don't know how a priming port on the inlet side would allow air to escape the pump... I have mine out the output and it works like a CHAMP. If the pump doesn't prime for some reason, I just turn it off, open the priming valve on the output side until water starts flowing and then it's almost guaranteed there's no air in the pump. Flick the pump on and it goes every time. I can't imagine how bleeding air before the pump would help. Also, it works great to take hydrometer samples from. I would think that opening a valve on the input side could possibly allow it to suck air in which would stall the pump again.

Man that's really pretty. I've seen this subject come up a few times with no definitive answer. I've personally never used a primer valve, as I really don't need one. Realistically either side would work, as you just need to get fluid to the inlet of the pump, hit the on/off switch a few times and your good, it'll prime.

One theory of not putting the purge valve on the output is when I do lose prime on my pump, it generally means the output side is full. If I put a purge valve on the output in this situation, I believe (not 100% sure), it would drain the output hose and siphon from my recirculation port in my kettle before the air from the inlet side would come out.

mpcluever said:

I don't know how a priming port on the inlet side would allow air to escape the pump... I have mine out the output and it works like a CHAMP. If the pump doesn't prime for some reason, I just turn it off, open the priming valve on the output side until water starts flowing and then it's almost guaranteed there's no air in the pump. Flick the pump on and it goes every time. I can't imagine how bleeding air before the pump would help. Also, it works great to take hydrometer samples from. I would think that opening a valve on the input side could possibly allow it to suck air in which would stall the pump again.

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I thought the same thing. But apparently LOTS of people do it that way and MoreBeer obviously does it that way too. And it does work (even though I don't understand why). One thing I did notice as I was doing more research is that Blichmann's Tower of Power has their purge port on the OUTLET side of the pump. It's toward the top of the tower, but it's after the pump, not before it. They do it for the reasons you mention, i.e. it allows easier sampling for hydrometers, tasting, etc.

I agree that lots of people do it. My roommate has his on the input side, but he'll tell you that that's just where he felt like putting it for pulling samples, not because it helps priming. When his pump stalls, it's harder to get going with flicking the pump on and off a few times to clear the bubbles. Opening that valve does nothing for priming his pump. That's not an issue with mine at all.

That being said, it's not hard to prime a pump and he rarely has issues.

I received a Morebeer 2100 back in October and had issues priming on the first few batches with the purge valve on the inlet side. I changed the configuration to have it on the outlet and have had no priming issues since.

dpmealey said:

I received a Morebeer 2100 back in October and had issues priming on the first few batches with the purge valve on the inlet side. I changed the configuration to have it on the outlet and have had no priming issues since.

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That's interesting. I'm seeing that like a previous poster said, there doesn't seem to be any real consensus. MoreBeer has it before...Blichmann has it after. Lucky for me I have tri-clamp fittings throughout. I changed it up this evening and tested it out. It didn't work nearly as we'll. I eventually got it primed but I had to flip the pump on and off 10+ times or more before it finally started pumping. I think I'll stick with what I've been doing.

How far below your kettles are your pumps mounted? That makes a bigger difference than where a bleed is located.
I work with industrial versions of our little pumps everyday. When you orient them sideways like your picture shows they tend to trap air easier. Best practice is to locate the outlet vertically. Would the center inlet pump head fit your application?
I've got a morebeer tippy dump and there is a bleed on the inlet side of the pump. It isn't necessary but I find I use it quite a bit. An easy way to avoid cavitation is to open the outlet valve fully when you prime the pump, then close it completely when you start your pump. Once it's running open your outlet valve until younger your desired flow.

fastev said:

How far below your kettles are your pumps mounted? That makes a bigger difference than where a bleed is located.

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Yeah, that's a good point. I don't have much height to my HLT above the pump. It's only about 16 inches from the outlet of my HLT to the inlet on my pump. I know siphons work better the longer the line. As far as using the center inlet pump, I thought about it initially, but ended up going with the inline for no other reason than that's what my LHBS carried. I've got a system that seems to be working at this point with the inline horizontal setup. If I have issues in the future, I may try re-orienting the pump head vertically like you say.

In your industrial applications, do they use priming ports or is there another method they use? If they do, are they before or after the pump?

Fact is air rises - so you want your bleeder (if you decide to use one) on the outlet side of the pump.

hafmpty said:

Yeah, that's a good point. I don't have much height to my HLT above the pump. It's only about 16 inches from the outlet of my HLT to the inlet on my pump. I know siphons work better the longer the line. As far as using the center inlet pump, I thought about it initially, but ended up going with the inline for no other reason than that's what my LHBS carried. I've got a system that seems to be working at this point with the inline horizontal setup. If I have issues in the future, I may try re-orienting the pump head vertically like you say.

In your industrial applications, do they use priming ports or is there another method they use? If they do, are they before or after the pump?

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16" should be plenty. If you can get it working then that's all that matters.

I'll get some pictures of our process pumps. Some of the centrifugal pumps I maintain move up to almost 600 gallons/minute, others run up to near 100 psi output. Big, BIG, brothers to our little March and Chuggers. However, none of them have bleeds on the outlets; well, unless there is a recirc loop. I am a proponent of leaving the outlet valve closed until the pump has spun up and built a little pressure.
Centrifugal pumps, mag-drive or otherwise, can be dead-headded without causing any damage. The reason I put a bleed on the inlet side of my pumps is simply so I know I have liquid at the pump head. Being able to see the liquid in the hose negates the need, but I use the bleed simply as a piece of mind.

fastev said:

I'll get some pictures of our process pumps. Some of the centrifugal pumps I maintain move up to almost 600 gallons/minute, others run up to near 100 psi output. Big, BIG, brothers to our little March and Chuggers.

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That would be way cool. Thanks in advance.

Take a look at this post I made a while back on pump orientation. If you look at the first picture, you will see that the outlet of our pumps is ever so slightly higher then straight and level (its actually a 13* tilt offset from 90*) As lpdjshaw said....air will seek its highest point, so as long as your output is at the highest point in you system and lets air travel continually up, then you should have no priming issues. Biggest thing I see wrong with most systems is that they have their discharges lines too long and have dips in the lines that can act like a trap when filled with liquid and not let air travel out and up. And we usually recommend any bleeds on the outlet side.

https://www.homebrewtalk.com/f11/short-pump-orientation-mounting-tutorial-306814/

WalterAtMarchPump said:

Take a look at this post I made a while back on pump orientation. If you look at the first picture, you will see that the outlet of our pumps is ever so slightly higher then straight and level (its actually a 13* tilt offset from 90*) As lpdjshaw said....air will seek its highest point, so as long as your output is at the highest point in you system and lets air travel continually up, then you should have no priming issues. Biggest thing I see wrong with most systems is that they have their discharges lines too long and have dips in the lines that can act like a trap when filled with liquid and not let air travel out and up. And we usually recommend any bleeds on the outlet side.

https://www.homebrewtalk.com/f11/short-pump-orientation-mounting-tutorial-306814/

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Thanks for the info Walter. That was really helpful. I had a friend PM me telling me much of what you said. It's good to remember to keep the lines short all around too. Any input on why MoreBeer would put their bleeds on the inlet if you guys recommend it on the outlet?

There are different ideas on where it should be....but most times when placed on the inlet side you are trying to purge as much air out of the intake line as possible.....assuming the orientation of the pump head is in the proper position that air will leave the pump head and you don't have any other issues downstream on the discharge to block things up.......when placed on the outlet side, we feel its the best of both worlds as you are letting the pump prime properly and you don't have to worry about anything on the discharge line as the pump should be able to push through it at that point...

WalterAtMarchPump said:

There are different ideas on where it should be....but most times when placed on the inlet side you are trying to purge as much air out of the intake line as possible.....assuming the orientation of the pump head is in the proper position that air will leave the pump head and you don't have any other issues downstream on the discharge to block things up.......when placed on the outlet side, we feel its the best of both worlds as you are letting the pump prime properly and you don't have to worry about anything on the discharge line as the pump should be able to push through it at that point...

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Thanks Walter. That's good information.

I still just don't get how opening a valve before the pump head would clear air from the pump itself. Opening AFTER still purges air, but now the pump is full of liquid. Works every time.

mpcluever said:

I still just don't get how opening a valve before the pump head would clear air from the pump itself. Opening AFTER still purges air, but now the pump is full of liquid. Works every time.

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I'm with you on this. Basic physics says it shouldn't work. I think what's going on though I'd that it does work (for whatever reason). That's why people do it. It doesn't make sense and it didn't work for me. Also March recommends a purge valve after the pump if you're going to use one. That's enough reason for me.

mpcluever said:

I still just don't get how opening a valve before the pump head would clear air from the pump itself. Opening AFTER still purges air, but now the pump is full of liquid. Works every time.

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A lot of priming issues have to do with the INLET hose or pipe size. If the air forms a bubble in the inlet supply line, and you have any restrictions in the line (valves, QDs, hose barbs, etc), it may not properly prime the pump even if you have sufficient height above the inlet and outlet (both are important). That is true even if you take a tube with the air bubble and hold the outlet at the discharge height of the pump. In this condition, the only solution is to put the purge valve on the inlet of the pump so that you can create a siphon and force the air bubble out of the line. After that, it doesn't much matter how the outlet line is configured, as the inlet fluid will now fill the pump at least to the top of the outlet. That assumes that the outlet is the highest point in the pump. It is..... Right?

The 2 things I find that eliminate the problem is using full port or oversized valves and fittings on the inlet, and to have the air bleed at the inlet of the pump. If you do both, you won't have any problems

Chugger partially addressed that with the center inlet pump by making the inlet a 3/4" fitting. Of course, if you reduce that back to a 1/2" at the pump, you risk the same problem further up your line.


Cheers

hafmpty said:

I'm with you on this. Basic physics says it shouldn't work. I think what's going on though I'd that it does work (for whatever reason). That's why people do it. It doesn't make sense and it didn't work for me. Also March recommends a purge valve after the pump if you're going to use one. That's enough reason for me.

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Actually basic physics, along with fluid dynamics, says it does work. Surface tension in the water allows it to form that air pocket in the inlet tube if there are restrictions for it to work against. With the restriction of a QD or hose barb, there is enough surface tension to resist the head pressure in the HLT trying to push it through the pump. Allowing the inlet plumbing to fully fill eliminates that problem.

drhawn said:

Actually basic physics, along with fluid dynamics, says it does work. Surface tension in the water allows it to form that air pocket in the inlet tube if there are restrictions for it to work against. With the restriction of a QD or hose barb, there is enough surface tension to resist the head pressure in the HLT trying to push it through the pump. Allowing the inlet plumbing to fully fill eliminates that problem.

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Thanks for throwing down some information. This is good stuff. Your recommendations are helpful.