GV90+ Boiler Plumbing Problems

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BoilerEE

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So I'm completely stumped on my GV90+5 install. I'm asking the internet for answers because the friend of a friend licensed plumber I had helping me seems to have screwed this up and I just don't trust him anymore (plus I don't want to pay $100/hr anymore when I'm not sure he can fix it).

It should be a pretty simple setup - just running a single-zone for a large garage - one manifold and 5 loops of 1/2" PEX, all loops about 150'. This plumber told me that the GV90 didn't need a circulator pump because it had them built-in, which I didn't bother to double-check since that's what he does for a living. So this is the way he installed it initially:
15335106197_81ac1bd1b9.jpg

So, it didn't work, and we did find that the brand-new boiler had a rusted/seized circulator pump, which I replaced, but then as I was reading the install manual I saw: "NOTE: The system circulator pump must be supplied by the installer" and upon further inspection saw that using the internal pumps only works for a baseboard system, not for radiant. So I took a hack at re-plumbing it myself and came up with this:
15518534991_8b5575bec1.jpg

Which worked, but it made it so the Taco 5000-series mixing valve didn't really work right - I was getting about 120 degrees at the input to the PEX manifold and about 100 degrees on the return with the boiler set to 140.

So then I thought I needed the "closely spaced tees" primary/secondary loop setup, so I just tore it all apart and made it look like this:
15521704475_0e0b6b6d23.jpg


Which I really thought was going to work great, but it's not working at all!!!! I've got 180 at the output of the boiler, and the pipe is so hot you can't touch it right up to the first tee, then it gets cold right away, and my input output temp of the PEX manifold is just staying right at 65 degrees even though I've got .75 GPH showing through each of the 5 PEX loops.

Anyway, I'm extremely frustrated and wondering if anyone can point out what I'm doing wrong.

Thanks!
 

Tom Sawyer

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Leave the manifolds and tear everything else out. This time follow the piping diagram supplied with the boiler. There's too much wrong there to bother explaining.
 

BoilerEE

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That's just the thing though - I followed the instructions for radiant from the Taco mixing valve - it looks a little funky because of the space available. So I guess you're saying my 3rd attempt is just totally a mess, but I just don't understand why. Maybe I'll sit down and try to draw out a way to make it match the schematic in the drawing 100%
 

BoilerEE

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A quick update -- turns out the piping was just fine - it was just chasing all of the air out of the system that I hadn't found. I was so convinced it was something wrong with my circulator pump that I neglected the internal primary loop circulator - it seemed like it was flowing, but it really wasn't. Once we cracked the lines at the output of the secondary heat exchanger, then filled, tightened, and worked our way up it started running like a champ! I thought I had confirmed the primary loop was flowing, then turned on the radiant loop and it made it quit - what I was missing was that must have forced some air back into the primary loop and locked up the system circulator! Anyway, the Taco valve is working as advertised now - the boiler is putting out 180 degrees into the primary loop, and the taco valve/circulator pump is mixing that down to 100 degrees at the PEX manifold input. I can still hear some air moving around, but I'm hoping the Spirovent will eventually work it all out.
 
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