Mono flow kicking my butt....

kcopp · October 2013

I was asked to install a panel rad and kick space heater in a remodel.... I

The existing set up is fairly old but has a new boiler installed by someone else. The loop is driven by a grundfos 15-58. I added two red ring 1.25" x 1/2" tees. Spaced 20" apart. The panel rad is a short run maybe 6'total run and below the main. The toe kick above the main and maybe total 10 feet total run. Run in pex for both. I ran them in series against my better judgement.. Not getting flow... Added a bleeder at the end of the run bleed out everything. Still no flow. Ideas anyone?

Alan (California Radiant) Forbes · October 2013

You may have to

install a ball valve between the two venturi tees. Use it once to purge the air out and then leave it open for operation.

Twenty inches is too close; they should be 10 feet apart, otherwise the flow of water will not want to go through the branch.

kcopp · October 2013

Thanks...

I have a ball valve on the return line w/ a bleeder on it. bleed it a lot. Will 10' make that much a difference? Would a set of reducer couplings be a better match to divert more water to the branch?

Im also having an issue getting water up to the 2nd fl. 2 mono flows yes 10-12' apart and the bleeder up there is getting bled of air. No ball valve in the return. It worked fine until I touched it.... ugh. There is an air scoop there but not installed as I would have done. (only 4 inches off the 90) I jacked up the pressure to 25 and let it run all night. Wondering about adding the dish soap thing ME has done....that is if its an air issue.

GW · November 2013

I had this once

Are you sure you don't have a stray loop coming off the main/zone somewhere? If you disturb the pressure balance you will lose flow ( if you have two or more loops off the same zone)

Seems like you have a pressure drop issue, that's if you're positive it's not an air issue

Gary

GW · November 2013

And, it may be better to come off main twice

Both of those items may be too much pressure drop.

GW · November 2013

I had this once

Are you sure you don't have a stray loop coming off the main/zone somewhere? If you disturb the pressure balance you will lose flow ( if you have two or more loops off the same zone)

Seems like you have a pressure drop issue, that's if you're positive it's not an air issue

Gary

icesailor · November 2013

Mono-Flows:

The way you describe and I understand what you did, that both come off the same set of Mono-flows, the upper one will always take priority over the one that goes down. Mono-flow "one pipe" loops don't like to go down. You need a set of Mono-flows for each loop. And the ones that go "down" should have the branch's facing down and be 3/4". I've seen ones going "up" spaced with close nipples and worked fine for years. I've seen the same piped down that didn't work until they were spaced at least 18" apart.

Mono-Flows are like that little boy who was bad.

"When he was good, he was very, very good. But when he was bad, he was AWFUL".

kcopp · November 2013

I did finally .....

get it to work. I closed off the ball valve, and very quickly took the bleeder plug off and jammed a hose over the bleeder and directed it to a 5 gallon bucket. I made a bit of a mess (finished basement) but it did get the air lock out. I did add some dish detergent to further keep the air in check. Never again.....

Mono flow kicking my butt....

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