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Discussion Starter · #1 · (Edited)
recently installed a third heating zone off my two-zone system and am having some trouble getting it to work (hot water circulating)

here's a shot of the boiler:

it's old but is nicely tuned and works well. i recently installed the water heater, fed hot water from the boiler during the winter, in the summer boiler is shut off and just feeds it town cold.
i believe the thing on the right is the circulator pump.

previous, my original two zones were plummed in with a "Y" fitting off the 1 1/4" pipe.

i installed the third zone similarly, with a Y that i wound up taking OFF the return of the original two (explained later).

here's the new zone, with the existing two:

the one branching off to the right is the new zone.

now, the return:

the two in the foreground were the originals, and the one on the right came in with the "y" fitting that i used on the supply.
originally i put in the new zone with regular T's. it didn't seem to get any water flow, so a friend recommended i use the Y.

along with getting rid of the Y here on the return end (because of needing to add the third), i replaced both the old drains and shutoff valves.

here's what's going on. i manually open the third zone valve (it's not wired to a t-stat yet.), with one of the other two open and calling for heat with it's t-stat.

the pipe immediately past the zone valve for maybe a foot or two is decently hot, but then turns cold. after i installed the Y i bled the radiator and the pipe at the top was hot, and i thought all was well.
now it appears again that nothing is circulating through.

is my problem the fact that i have regular T's on the return, creating some sort of turbulence with the returning water from the zone that comes in straight? my zone is turned off, the tenant has the two upstairs zones.
if i put Y's on the two returns that now have T's, will this fix it?
i have no doubt my circulator pump can get the water up to the attic, as it bleeds out with plenty of pressure.
what about using a monoflo T versus a Y at the return? is there an issue wit the T reducing the flow of water for everything it connects? with the Y, it doesn't reduce anything, as i understand it.

the upstairs zone that happens to return on the straight run without a T, i believe is working fine. the pipes are scalding hot to the touch, and even pretty hot on the return pipe.

FYI: my existing two zones have a large loop running around the basement and second floor, with monoflo T's branching off to each radiator (possibly on the return, i'm not sure).

the new third zone i installed is only leading to ONE radiator up in the attic, with all 3/4" pipe. the radiator is brand new. there are no leaks anywhere, etc...

any help on this would be greatly appreciated.


· Registered
579 Posts
Discussion Starter · #4 ·
What is the PSI reading at the boiler?
The new line goes to the attic?
What is the vertical rise?
the pressure reading is between 15-20.
the vertical rise is roughly 20 feet.

talked with a few hvac pros on the phone. both said they thought i had an air bubble trapped near the return end. recommended i purge about 5 gallons with the pump running. so, will install a purge valve.

thanks fellas.
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