Which knob do I use to add water to my boiler?
It is easy to forget which specific knob or valve controls the water supply to repressurize a heating system. Because homeowners want to be careful and avoid mistakes, uncertainty about the correct controls stops them from safely adding water when the pressure drops.
What people tried
Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.
- 1Calling a technician for assistance
- 2Labeling valves with tape and a sharpie
- 3Using the bypass for the auto water feeder
In their words
Unedited, grouped by where they were said, most upvoted first within each place, each linked to the thread it came from.
“For the life of me I can’t remember which knob I’m supposed to use to add water when the level is low.”source ↗
“I just don’t recall which stupid knob and I want to be careful.”source ↗
“It says low p and its supposed to get pressure automatically (at least is has in the past) however i have two pressure guages that show two different things. One is from the main water supply and shows just above 15 and the other shows 10. How do I add pressure to the system?”source ↗
Where this came up
People with this problem also raised
- 4New water heater not getting hot enough
- 4Why does it take so long for hot water to reach distant bathrooms?
- 3Why are my cold taps running tepid after a water heater service?
- 2Air coming out of hot water lines only
- 3How to clean calcium and mineral buildup inside a glass kettle
- 4Why is there water on the floor around my new water heater?