Replacing Convector/Rad on old MonoFlo Tee system

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jjjaaammm

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Hey guys - so I had a radiator fail on me - flooding my wood floor a bit. Had to shut my oil burner down and drain the system. My oil burner service company came in an cut the steel 1/2" supplies to the rad and installed two brass compression fitted ball valves to cap the lines. The exposed open ends are threaded.

I plan on replacing the convector/rad myself and already bought all the supplies.

Here is my question:

Should I take the 1/2" steel supply lines all the way out and PEX from the Tees on main loop or should I PEX from the temp ball valves that are already in place on the 1/2" steel supplies?

After the tech put in the valves, one of them was weeping a bit from the compression fitting on the pipe connection forming a drip - I put a bead of epoxy "weld" putty on the joint and it stopped. It has been 3 weeks and there is zero sign of any moisture.

I have easy access to all the connections and the monoflo Tees.

I have 3 options:

1)Drain my system - rip out the steel pipe to the Tees and pipe in the PEX to the new convector. (Most work)

2)screw my 1/2" threaded PEX couplings right to to ball valves currently in place and plumb in the convector. (least work, no draining the system, valves remain in place if I ever need to isolate the radiator again).

3)Drain the system, cut back the pipe on the one ball valve with the weld putty on in and put he ball valve back in with a new ferrule and then pipe in the PEX as I would in 2). (A bit more work, but I re-seat the compression valve that was leaking a bit on install)

My supply guy said the supply lines I have in place are not galvanized but are steel.

And advice?
 
Last edited:
Remove the valves and pipe from the tees. The compression fittings that are used on steel pipe are sealed with rubber gaskets that will not standup to temperatures of a hot water system.
 

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