I'm a new home owner. My house is heated with steam radiators attached to an oil fed boiler. The boiler is getting close to retirement. One concern I have is that I need to drain water from the reservoir every couple days. There's a glass tube on the front of the boiler with a sharpie mark made to indicate the level it should be at. It fills up slowly and I need to place a bucket under the drain and lift the lever to allow excess water out.

What happens if the reservoir fills up completely?

1 Answer 1


Eventually if water continues to fill the system, it will fill the pipes, and eventually come out the vents on the radiators. I saw a house that got flooded when someone was adding water to the boiler manually, forgot to turn it off, and left - made a big mess. Obviously that would take a long time with a slow leak.

I am not sure whether this also creates a safety issue.

There may be an automatic fill valve that isn't sealing off properly when the water reaches the full level that can be serviced or replaced. I believe these can also be retrofit if there isn't one on your furnace.

  • If you need recommendations on how to operate your steam system add another post. As long as you can see the top of the water line in the glass tube you do not have to drain the excess water. There are a few things you need to do during the year as regular maintence.
    – d.george
    Dec 22, 2016 at 21:12

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