Purging air from monoflo tee's

Heatman_2

We repaired a boiler system with 3/4" Weil Mclain copper fintube baseboard divided into 5 zones. All zones are 3/4" copper supply and return. We have one zone in 1" pipe that will not heat, purges great, but no flow through radiation. All system piping is hidden in drywall, but we are quite sure this loop is using monoflo tee's. What is the best way to purge this air, the baseboard has no bleeders.

Heatman_2

anyone?

Plumdog_2

Purging without bleeders

I have been able to get air out of monoflow systems by using a glycol pump and re-circulating the water into a bucket. You must be able to isolate the loop, pressurize it, and then dump pressure suddenly to force out the air. Repeat as required. Be careful not to blow the relief valve (and maybe put on a new one beforehand, as an old one will surely leak once it blows).

oil-2-4-6-gas

if it purges great --and you dont get any air out --well// its probably not an air problem --is this their first season? you will either have to open the wall to see whats there or you can put a bleeder on --or quick and dirty you can put a saddle valve from an ice maker kit and use that as a bleeder --is the customer giving you the usual bs --it worked fine until you did ___________/

mtfallsmikey

My method

With any Monoflo system...bypass the feeder, do not use circ.pump..start closest to the boiler, work your way around and up (if more than one floor). This method can be disputed, or argued but has worked for me...that's the way the Dead Men taught me.

[Deleted User]

Bottom fill, top purge...

Monoflow systems HAVE to be bottom filled, and top purged. It is a parallel circuit, and the chances of force purging successfully are slim to none.

Take the time to install base board tees with coin key vents, and the system will purge the way it was designed to purge, bottom fill, top purge. Simply explain to the customer that this is the way it works, and that it MAY eventually self purge, but to do the job correctly and professionally, they MUST pay you to correct the deficiencies. If they balk, you walk and it becomes someone elses problem.

ME

Uni R_2

Add a ball valve to the main?

I'd try adding a ball valve to the main if you can't get a bleeder on the branch to do it first. Place it somewhere along the piping between the tees for that branch such that you can divert up to the full flow through the heating branch and push whatever bubbles through and out of that branch and to the air eliminator. Once purged, then reopen the valve.

I would be tempted to try the ball valve or a globe or balancing valve played around with to see if you could balance between more velocity on this one branch while keeping sufficient velocity for the other monoflos to all heat the space in a predictable desired manner.

Eric_32

Split loop

Im willing to bet this is a 1" split loop zone, follow that 1" line both on the return and supply end, and see if it splits to 2- 3/4" lines. if so your only bleeding the shorter loop. Ive seen jobs all the time that have gotten sheetrocked by anxious homeowners not realizing that "PB-56"(purge/balance valve) at that split was needed to bleed the heat properly. Open the sheetrock at the end of the 1" line and you'll see your pot of gold!!Run the heat feel both lines, 1-will get hot, 1-will not, you'll know which loop is air bound.

FYI: monoflow system with fin baseboard will bleed air out with "force bleeding" as in a loop system, water is pushing through both sides of the tee not just going straight. I've done it. Just takes a little longer than a loop zone. Rads are taller so air will be trapped even with force bleeding.

Plumdog_2

Exactly

Like I said, you have to Isolate the loop, it should be fin tube without any tall risers, and then run water thru it repeatedly with a lot of velocity. The air will come out. I have done this when Bookcases or gigantic furniture is blocking access, or the bleeders are rusted and time is critical.