Click here to Find a Contractor in your area.
Welcome! Here are the website rules, as well as some tips for using this forum.

If you've found help here, check back in to let us know how everything worked out.
It's a great way to thank those who helped you.
Need to contact us? Visit

Oil on the boiler room floor

I have a Prestige Triangle Tube boiler, going on 5 years old, feeding into a network of hot water radiators. Southwest Montana. Five years old. So far flawless performance. Until now.

Late today I noticed a large pool of thick clear oil on the boiler room floor. I'm not certain where the oil came from but there is a copper pressure relieve valve on the top of the boiler, feeding into an open-ended copper pipe that points down almost all the way to the floor.

The inside of that pressure overflow relief pipe feels wet with oil. So this must be coming from within the boiler somehow. This does not sound good.

I have not yet been able to reach my plumber. After 5 years I'm not sure he is still in town. Good plumber. But for all I know he moved to Seattle. Or Denver. Or Timbuktu. The phone number I have is not working.

If I cannot reach him tomorrow I'll look for another plumber.

In the meantime what is your best guess (anybody)? How serious is this? How and why does thick heavy oil squirt out through a pressure relief valve?


  • SWEISWEI Member Posts: 7,356
    Is there glycol in the system? Is an automatic water feeder in use?
  • pittendrighpittendrigh Member Posts: 4
    Thank you. Glycol. Yes of course. It's glycol not oil. Automatic water feeder yes.
  • Jamie HallJamie Hall Member Posts: 12,695
    If it's glycol, then the TPRV has opened, either on temperature or pressure. Neither one is good.

    If on pressure, it could be a leaking autofill. It could also be a failed expansion tank. Take a look at the system pressure when the boiler is off and cold for your static fill pressure. Also observe what happens when the boiler fires.

    It could also be opening on temperature, which suggests that the aquastat may have failed. What is the boiler temperature when it is operating?

    As I say, neither is good. You must find the source of the problem and fix it -- and I I recommend replacing the TPRV as well, once you have fixed the problem. Cheap insurance.
    Br. Jamie, osb

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • pittendrighpittendrigh Member Posts: 4
    Thank you. I really appreciate the feedback. My plumber still doesn't call back so I'll find a new one. He's apparently made a transition to commercial construction and seems to be.....less interested in his old residential customers.
  • SWEISWEI Member Posts: 7,356
    I would start by testing the pH and glycol percentage.

    Are you certain the system actually requires glycol?
  • pittendrighpittendrigh Member Posts: 4
    Requires glycol? Maybe maybe not. We do have some pipes in a hidden ceiling in a garage, that heat an over-the-garage room. We worried about those pipes freezing if the thermostat in that room was ever turned off. I have a plumber coming. I'll ask him about the "aquastat." Thank you again. The internet is such a good resource.

  • SWEISWEI Member Posts: 7,356
    Glycol is expensive and fussy. It's worth finding out if you can safely run the system on plain water. Pipe freeze-up can be prevented using a number of different strategies.

    Good luck with the project.
  • unclejohnunclejohn Member Posts: 1,525
    TT has a anti -freeze parameter in the set up menu. It runs the circ. at low temps. Also pretty much any problem other then to much water or bad extrol tank would have shown up as a error code.
Sign In or Register to comment.


It looks like you're new here. If you want to get involved, click one of these buttons!