2 radiators on one set of monoflo tees?

Ron S

I am a plumbing & heating contractor on Cape Cod, MA. Recently, I sent 2 younger licensed plumbers to disconnect 2 cast iron radiators and replace them with copper baseboard and a kickspace heater. The cast iron radiators were connected to a monoflo system, the monoflo tees and main heating line is in the basement. The apartment is on the second floor. The piping runs through a finished first floor apartment. What they ended up doing is: removed one radiator and hooked the 2 pipes to a piece of copper baseboard with a coin vent. That radiator is heating fine. They hooked one pipe from the other radiator to a piece of copper baseboard (with a coin vent), then the other end of the baseboard went down 6 or 8 inches below the second floor, and a few feet away hooked up a second radiator (this one a kickspace heater), with a coin vent, and then back under the floor to the second pipe from the previously removed cast iron radiator. These 2 heating units are not heating (surprise, surprise!). We bled and bled the air from the coin vents, to no avail. Then the boss (me), came up with the brilliant idea to install a ball valve on the pex piping behind the kickspace heater (which we could get to), with a boiler drain on each side of the ball valve. The idea here was to purge the air out of the piping in each direction. Didn't work.
Of course there is a nice finished wood floor in the second floor apartment now, and we cannot get at the piping. Does anyone have any suggestions to try to get these 2 units working? Thanks in advance.

Jamie Hall

You may have some trouble. Monoflo Ts are very sensitive to the flow resistance in the two circuits -- one straight through and one going through the radiation. Further, two parallel circuits -- such as your radiator and your kick space -- are going to have very different resistances, and the one with less resistance is the one which will get the flow.

retiredguy

I am not sure how the radiation that does not work is piped by the description you gave so maybe you could draw a picture of the piping and post it here. One idea would be to replace the elbows at the entrance to the radiation (both sides), with Tees so you could install vents everywhere the piping goes up/down and forms a trap. On the up part of the tee you could add a short stub and a reducer to install coin/key vents. Also, make sure that the mono-flo tees are facing the right way for the flow. That kick space heater will most likely need a mono-flo tee on both the supply and return.

EBEBRATT-Ed

@Ron S you added too much restriction to the second part of the monoflow tee loop. The kick space heater has too much restriction so the water will not flow.

How to fix it? That's the issue. You might try a ball valve or balencing valve on the single raidation that works and close that a smidge might work.

I am sure the kickspace heater is the issue.

You could put a pump on the monoflow tees as you can do that in the basement, may be the only way to go. Then balance the flow between the three (2 baseboards and 1 kickspace)

Ron S

Thanks guys, I will try adding a pump in basement.