Welcome • User Guide
ToS • Privacy • Canary
Donate • Bugs • License

©2025 Poal.co

1.1K

I changed the expansion tank today and now I'm wondering if I need to bleed the system or is it ok to turn it back on. The last time the heater ran was during the home inspection when I was buying the place in spring.

Steps I took.

  1. Turned gas off to the heater
  2. Turned the heater off (turned off electric to the unit)
  3. Turned off water to the heater
  4. Removed and replaced expansion tank (old tank was rusty and weak at the inlet)

The old tank had quite a bit of pressure/water in it. I definitely got wet. I'm not sure about all of the components. I know one is the reducer valve for the water pressure and I'm pretty sure the other is a purge valve/bleeder, but I don't know if it's auto or manual. And if it is auto do I still need to do a manual bleed after changing the tank? If so what steps do I need to take?

Here's some pics of the system. If you need more pics of specific areas let me know.

Old Tank (pic8.co)

Reducer Valve (pic8.co)

Purge Valve/Bleeder ??? (pic8.co)

Whole System

The box on the pump is open because some water got in there so I'm trying to dry it out before turning the power back on. Any help/input is appreciated.

I plan on replacing the boiler next summer with a forced air system. At least then I'll know how to work on the damn thing if something goes wrong. Just gotta make it through this winter.

I changed the expansion tank today and now I'm wondering if I need to bleed the system or is it ok to turn it back on. The last time the heater ran was during the home inspection when I was buying the place in spring. Steps I took. 1. Turned gas off to the heater 2. Turned the heater off (turned off electric to the unit) 3. Turned off water to the heater 4. Removed and replaced expansion tank (old tank was rusty and weak at the inlet) The old tank had quite a bit of pressure/water in it. I definitely got wet. I'm not sure about all of the components. I know one is the reducer valve for the water pressure and I'm pretty sure the other is a purge valve/bleeder, but I don't know if it's auto or manual. And if it is auto do I still need to do a manual bleed after changing the tank? If so what steps do I need to take? Here's some pics of the system. If you need more pics of specific areas let me know. [Old Tank](https://pic8.co/sh/84X3Ku.jpg) [Reducer Valve](https://pic8.co/sh/oFYaBg.jpg) [Purge Valve/Bleeder ???](https://pic8.co/sh/mT5Jnk.jpg) Whole System - https://pic8.co/sh/a6FOA9.jpg - https://pic8.co/sh/XGrqg8.jpg The box on the pump is open because some water got in there so I'm trying to dry it out before turning the power back on. Any help/input is appreciated. I plan on replacing the boiler next summer with a forced air system. At least then I'll know how to work on the damn thing if something goes wrong. Just gotta make it through this winter.

(post is archived)

You are currently inside a comment thread.
Click here to see all the comments (12).
[–] • 1 pt

I had a professional work on my boiler once. He forgot to bleed the lines. Even I knew to do this. The result was the circulator pump stopped circulating the hot water. Instead, the boiler created super hot water which destroyed a pipe joint causing water to flood my basement. This in turn ruined my floor. It was quite a mess.

[–] • 1 pt

Well so far everything seems to be ok. As far as I can tell the automatic purge valve did it's job. One of my sons told me this morning he thought he could hear water dripping all night. After a quick inspection of all the radiators and the basement I came to the conclusion that he was just hearing the water circulating through the pipes. Fingers crossed I can at least make it through this winter without problems. Come next spring/summer I'll be replacing it with a forced air system.