I had my boiler inspected and cleaned recently and the tech found a few issues. He showed me how the valve on the expansion tank would leak when he would push it in, which means the tank needs to be replaced. He also showed me how there was water leaking out of the Taco air vent. Later when I inspected it on my own, I couldn't feel any water leaking from it. With the system off, should there still be water leaking? I am just trying to get a better understanding of the system and what needs to be done.

They were charging around $800 to replace the tank, vent and to drain/fill the system. We have a lot of noise in our pipes, so I assume air is getting in some place. Could it be either of these two places if they are indeed leaking?

  • get a second opinion from someone reputable, it's very easy to FUD a unknowing homeowner by fiddling with the bleed valves. – ratchet freak Mar 21 '17 at 11:27

The expansion tank probably needs to be replaced. Some vents can be forced to leak by depressing a manual valve on top of the vent. To replace the expansion tank normally the heating system does not have to be drained, although some water will be lost. Just make sure they add an isolation valve when installing the new tank. I can't comment on the cost of the job since I have never had service company in any of my residences. Doing a good job usually takes a lot of time.

  • With a new vent and expansion tank installed, would that eliminate air that is in our pipes currently? Or would we still need to flush the system in order to resolve that issue? – junta Mar 23 '17 at 14:07
  • You would still need to get the air out of the heating system. I am guessing that you have copper finned baseboard heating since you did not indicate which type heating system you have. How you remove the air would depend on how the installer installed the system. You could have a purge system and automatic or manual vents or you may have only manual vents. In order to give advice on air removal we would need to know the type of system you have. – d.george Mar 24 '17 at 10:06

If water came from the expansion tank recharge valve, the diaphragm is leaking and it needs to be replaced. You should be able to get water from the air scrubber. If you depress the pin and nothing comes out, then the system has been drained or the scrubber is seized up. Honestly, its been 13 years since I worked as a plumber( truck drivers don't have to play with poo-poo), but $800 sounds like a rip-off. I'd think it would cost half that price.

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