Help with my Closed Loop

[IslandCrow]

Well, it looked simple enough, but I'm obviously doing something wrong. I just built a closed loop for my tank, hooked up to a Velocity T-2 pump and going through an Arctica 1/10 HP chiller. Once I got a couple leaks out of the system, everything was looking good. I ran it once without the chiller hooked up, and it looked like water was flowing out of the hose that would be going to the chiller at a pretty good rate (I haven't actually measured the flow). The T2 is rated at 650 gph at 3 feet of head pressure, and it's all routed through 3/4" PVC and flexible tubing. Running the specifics through the headloss calculator, I should be getting right around 600 gph, not counting the chiller (I'm just not sure how to account for that). What I am getting is little more than a trickle once the whole thing is hooked up. Even if I close off one of the outlets, I'm getting almost no flow. I'm also noticing that I'm getting about 50% water and 50% air actually going into the pump (one bonus for having that section of tubing there). I am closing off the cap for the priming hole before I start the pump if you're wondering. I'm wondering if it's just not able to suck in enough water, though that doesn't seem to be a problem if I don't hook it up to the chiller and return tubing. There are a total of 76 1/8" holes in the PVC that's taking the water in from the tank, and all the holes were submerged when I was testing it. The only thing I haven't tried yet is to test it with the chiller hooked up but not going through the return PVC to isolate the problem there. Anyway, here are some pictures of the system. The arrows indicate the water flow, with the red arrows being pre-chiller and blue arrows as post-chiller:

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<a href="http://photobucket.com" target="_blank"><img src="http://i51.photobucket.com/albums/f368/IslandCrow/Closed-Loop/Front-View.jpg" border="0" alt="Photobucket - Video and Image Hosting"></a>

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[wuelfman]

did you prime the pump ?
my c/l always shoots out air when it was first setup or when i take the pump offline for cleaning.
i have some air in the pipes ill the pump forces it out

[bubblethumper]

oops, never mind

[IslandCrow]

Yeah, I made sure to prime the pump. Of course, there's some air in the PVC in the small section where I add the water to prime it (above the elbow leading going down to the intake). I'm assuming that's fine, since I don't see any way around it. I'm planning on doing some more trouble shooting today, so hopefully I'll be able to come up with some more info. Now, I don't think this should matter, but my returns haven't been submerged while I've been testing this out.\

[RichConley]

The intake is just that spraybar looking thing right?

Its probably way too restrictive, and sucking air through a not too well sealed fitting because of that.

[wuelfman]

you will have some air when yo first turn it on
the pump should expell it so it will come out your two returns. but should quickly go away.
everytime you take it out of the water and then restart it the same will happen.
the other thing to check is you flexable tubing. it does not seal that great. you might put a couple tie wraps around each inlet and outlet on the braided hose.put it around the hose where the hose and hard pipe meet and pull tight usally a couple tie wraps will fix it i have this problem before.

[wuelfman]

also put some plummers tape on the place where you prime if it threaded there. that could also be sucking in air

[bassnman11]

Put clamps on the hose fittings. Also, remove the cap from the bottom of your suction strainer to check for restriction. You may need to enlarge the holes in the intake if it works with the cap off. Use 5 or 6 wraps of teflon tape on the cap after you prime. Tighten the cap slightly with a wrench.

[IslandCrow]

The bottom cap on the strainer is actually glued in place, so it will be no easy task to remove that. I've used teflon tape on everything threaded. I'll try putting clamps on the sections where the tubing is attached, but I think it's actually pretty airtight. It's a nice, snug fit, and I also added some silicon to the fitting to help there as well. There are absolutely no leaks when I run it, so there's probably not any significant amount of air getting in from anywhere. When I remove the top cap, you can definitely feel that there's a vacuum in there, so I don't think it's a source for leaks either.

I've checked the water pressure coming out of the hose leading directly from the pump without connecting it to the chiller. It's an absolute torrent of waterflow. I then tried connecting the chiller, but disconnecting the hose leading from the chiller to the outgoing PVC that leads up to the nozzles. I get almost no flow, so the holdup seems to be in the chiller. How much loss in head pressure are you generally going to see running through a chiller? I'm going from what I would guess is my 600+ gph to definitely less than 50 once it goes through the chiller. I'm going to give the company a call, but are there any gotchas I should be aware of? It's an Arctica chiller by the way.

[PJSEA]

The JBJ 1/10 HP chiller is rated for a minimum flow of 240gph and maximum of 960gph so it shouldn't be restricting flow like you describe.
I would look for an obstruction in or around the chiller. Try reversing the flow to see if you can flush anything out.

Do you have a pic of the hookup for your chiller? If you have valves in line maybe one of them is not working properly.

[IslandCrow]

I'll get some pictures with the chiller hooked up. I can't visually see any obstructions, but I'll try your idea for reversing the flow. It's really a straight shot from the pump to the chiller back to the closed loop, with no check valves, ball valves, etc.

[IslandCrow]

Upon further investigation, it doesn't appear to be a chiller issue. I tried just running water from a hose through just the tubing going into and out of the chiller, and there's no noticable reduction in flow. I'm off to Lowes to get a connector to directly mate the hoses leading into and out of the chiller, so I can just bypass that part of the system and run it through everything else. I'm a little concerned about my connections from the PVC to the outgoing nozzles (the two black ones). They're made for slipping onto flexible tubing, and not PVC, so although I don't see any leaks, I wonder if I'm losing pressure at that point and if I am whether or not that would cause the problem I'm seeing.

[wuelfman]

on the flexible tubing you wont really see leaks. it will suck air in.
i would still put clamps on it

[IslandCrow]

That makes sense. I tried bypassing the chiller and directly connecting the two hoses that were going in and out of it. Works like a charm that way, so I'm not entirely sure what's going on. I'm going to try putting clamps on those connections and see if that helps. I'm also changing out the flexible tubing leading into the into the pump for rigid pipe (using flexible tubing wasn't my original plan anyway). Thanks for all the help by the way. If you couldn't tell, I don't exactly have much experience when it comes to plumbing.

[IslandCrow]

Alright, I tried it with the modified inlet and hoses clamped, and we have success! I'm thinking it was a bad seal where the flexible tubing connected to the PVC like everyone was saying. I was thinking that since I didn't have any leaks, the problem must've been elsewhere.

Thanks, for all the help. I knew it would end up being something fairly simple. By the way, I love this Velocity pump. Talk about quiet. It says less than 30 db, and I think that's an understatement.

[wuelfman]

:thumbsup: :thumbsup: :thumbsup: :thumbsup: :thumbsup: