How to Drain a Boiler Expansion Tank

If your heater has a boiler tank connected to it, than it is going to have an expansion tank as a matter of course.  If your boiler system utilizes a closed vent, then you are going to have to drain the expansion tank.  This tank is filled with air, and allows for air within the boiling tank some place to go as it gets hotter and expands.  The whole system is an exceptionally interesting process, and economical in certain areas, but it does lead to the necessity of draining from time to time.

Water will get inside of the system, of course, which means that you are going to need to drain expansion tank to make sure that the pressure that the tank absorbs is always at an optimum.  This task shouldn’t take very long, and should be done a couple of times a year by you or a professional.  Sometimes, depending on the system, the expansion tank can be a bit tricky, so if there is any doubt, call Dr. Pipe Drain & Plumbing immediately.  To make sure that you should do the task, tap the tank a bit to make sure it has collected enough water to need a drain.  If there is only a small amount of water, then don’t worry about it, but make sure to check it again in a month or two.

First place a bucket beneath the purge valve on the tank, or attach a hose.  If nothing comes out, there is the possibility that you have a big of a vapor lock.  Be very careful at this point, as the best way to do away with this problem is to blow into the faucet of your expansion tank.  Water at this point might come rushing outward, and there is the potential that this water is very hot.  Do a touch test on your tank, and see what the temperature is like.  If it is too hot to touch, then do not use the ‘blow system’, and instead use a long enough hose that you will be able to move your mouth away before the water begins to flow.

Keep an eye on the water and once there is no more coming out of the expansion tank, close the valve and restart your boiler tank.  That is how simple this job can really be, but there are some things (like hot steam and air) to worry about.  Always keep yourself properly shielded from such problems by calling the professionals the minute there is a concern about the job.

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