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How to 'water' fill Weill Mclain oil boiler

OllyOlly Posts: 11

I need to fill up my Weill McLain oil boiler with water. Do I use the drain valve for that? I have not drained the whole system because way above the boiler, a leak was repaired.

Can I simply connect a water hose on the drain valve and fill up to the right pressure?



  • EddieGEddieG Posts: 150

    Can you post a picture of your boiler and the near boiler piping? That would make it much easier to explain. Your boiler should have a connection to your domestic (cold) water piping, that should have a feed valve (PRV). It is probably the line you shut off to drain the boiler to make the repairs. If it does you should be able to turn it on to refill the system. But the key will be getting the air out of the system, if it is hot water and not steam. Do you have radiators or baseboard heat? Also need to know if it is steam or hot water? What kind of expansion tank (if any)? Need a lot more info to help you.
  • OllyOlly Posts: 11
    edited April 2011

    Hi Eddy,

    It is indeed hot water with three zones and baseboards. I added a picture and there is indeed already a fixed water connection direct to the left of the three circulators but that seems to be for the warm water. I have to fill the heating zones.
  • IronmanIronman Posts: 3,280
    Fill Valve

    There is an automatic fill valve (prv) in the 1/2in. copper line that tees in above the expansion tank. Open any isolation valves in the line that are closed and the system should begin to pressurize to about 12psi. As Eddie said, you'll have to bleed the air from the system and since the isolation valves on the zones are open, the loops will have to each be purged of air.

    You can purge the loops by doing the following:

    1.Close the 3 isolation valves on the return manifold on the left side wall near the boiler. The right side is the supply where the pumps are. Close those valves also for now.

    2. Connect a garden hose to the first boiler drain (hose valve) above the isolation valves on the return manifold. We're gonna be purging air and draining water, so the other end of the hose needs to go to a drain or outside where the water can be discharged. Open this boiler drain valve.

    3. With the boiler pressurized and the fill line open, go to the supply manifold and open the isolation valve that is on the same loop as you have the garden hose connected to. We're letting water from the boiler go up through the supply and out of the hose on the return. Make sure all the isolation valves on the return are closed as well as the other two isolation valves on the supply. You have to do one loop at a time. Let the hose purge until the the water runs clear out of it. If the pressure drops alot, close the drain valve for a minute til the pressure builds back up and then re-open it. Do this until you have clear water discharging.

    4. Once you've purged that loop, close the boiler drain and then the isolation valve on the supply and move to the next loop and repeat the process. The only isolation valve that should be open at any time is the one on the supply loop to which you're purging.

    5. When you've done all the loops,  and all your boiler drains are closed, open all of the isolation valves and start your boiler. As long as you have circulation in each loop, the auto vent on top of the air scoop should remove any residual air. Make sure the small valve stem cap is open 1 turn on top of the auto vent.
    Bob Boan

    You can choose to do what you want, but you cannot choose the consequences.
  • this is your water feed valve

    the item with the flip lever is the boiler feed valve.
    Cost is what you spend , value is what you get.

    cell # 413-841-6726
  • IronmanIronman Posts: 3,280

    How do you draw on an existing pic like that? I'm too computer illiterate to know.
    Bob Boan

    You can choose to do what you want, but you cannot choose the consequences.
  • I just figured it out

    my self Iron man. I downloaded and saved the photo and brought it up in my photo shop type program. This must hurt the computer guys as much to read as when I read customers describing their heating systems.
    Cost is what you spend , value is what you get.

    cell # 413-841-6726
  • OllyOlly Posts: 11

    Hey guys,

    Thanks so much for helping us out again!

  • IronmanIronman Posts: 3,280
    That's Exactly...

    What I was was thinking when I was typing the question.

    Thanks Charlie.
    Bob Boan

    You can choose to do what you want, but you cannot choose the consequences.
  • EddieGEddieG Posts: 150

    Sorry, I was away from the computer for a while. Looks like Ironman and Charlie got you through just fine. Glad it worked out. You need to pipe that relief valve on the front of the boiler down to the floor. Before you get a HOT surprise in the crotch one day!
  • OllyOlly Posts: 11
    edited April 2011

    Don't worry! I am amazed about the number of people, the speed of responses and the knowledge people have and share! Truely amazing! 

    Indeed we need to change that to point it to a safer place:-)
  • icesailoricesailor Posts: 7,265
    Service Switch:

    It's nice to see the service switch within arms reach so that you can turn off the burner while looking at it through the flame inspection port. That switch and plate came mounted on the 4" square box above the burner with the blank plate on it. I bring that up because my arms aren't long enough to reach it on the wall.
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