At the beginning of the winter season my boiler wasn't turning on, but I got it to work by turning on the inlet valve and just letting it feed water until the gas burners kicked in. The sight glass completely (over)filled with water to the point I couldn't see any air in the top. I was happy because my heat was working.

Now, the boiler is not engaging again. I was going to try the same tactic, but without knowing anything about boilers, let alone the kind I have, I'm afraid I might damage it. So, I just drained the water (from the rear at the inlet valve) until the low water light came on (the water in the sight glass was near the bottom). I then let in new water until the sight glass showed 4/5 full. Still no engagement of the gas burners. The pressure is floored, too. The gas pilot is burning, too.

I'm pretty sure if I just let the inlet valve feed water to the unit things will start to work again, but then what's the point of the sight glass? I don't want to try that until I know for sure it's the right move.

I'm attaching some photos of the boiler and it's readings, and I hope you can help figure out why I have no heat.

Boiler Front Boiler Front

Boiler Right Side Boiler Right Side

Boiler Info Sticker Boiler Info Sticker

Sight Glass Sight Glass

Water Pressure Gauge Water Pressure Gauge

Water Pressure Cutoff Switch Water Pressure Cutoff Switch

Inlet From Hot Water Heater Inlet From Hot Water Heater Inlet From Hot Water Heater enter image description here

  • The problem was that the system had to be reset from a reset switch inside the gas grate, but was triggered by the exhaust damper motor not working properly. Got the damper fixed and reset the boiler. Everything works fine now.
    – John Manko
    Commented Dec 20, 2018 at 2:10

2 Answers 2


If this steam boiler has not been serviced in a while I would recommend that you have this done to insure safe operation this winter. Using this boiler with too little or too much water in it can damage it and can be very dangerous. Without knowing more about how the boiler is connected into the heating system and what type steam system it is, it is hard for anyone to give a further explanation of how to fix your problem. I can say however that some of the return piping looks wrong. It does not have a "Hartford loop" in the the return at the boiler. That doesn't mean that it will not work and heat your place. Also, post a picture of a typical radiator or baseboard installed in your home so the piping in and out can be seen. Also, send a picture of the return piping that can be seen in the next to last picture or the one before the radiator so I can see how the return is piped. One last thing, the piping that is connected to the pressure control and the low water cut out needs to be removed and cleaned. They both could keep the boiler from firing.

  • I added an image of the radiator. I hope that helps. I tried to find the boiler model online, but it must be too old.
    – John Manko
    Commented Dec 18, 2018 at 13:34

Here are some facts that may help: You have a steam boiler. All steam boilers have what is called a low water cut-off. This devise makes sure that the boiler never fires dry or without water covering the cast iron exchanger. This would destroy your boiler in short order. The Mfg's install literature will tell you how high the water should indicate in the sight glass to protect the boiler. Mark the side of the boiler jacket with a magic marker. You don't want to overfill the boiler because empty space at the top of the boiler is required to allow the steam to shed excess moisture before heading out to the house. We want dry steam going to the house. Now the low water cut-off should be adjusted to hold the water in the boiler at the point indicated in the sight glass. Good Luck.

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