How can I change the water filter if the only valve to close the water supply is before the boiler? If I just close the valve and unscrew the filter the hot water from the boiler will flow back? Is this the standart procedure or is there some way that I can prevent the water from coming out of the boiler?

And also how to properly place the filter back? Im worried about air getting into the boiler.

2 Answers 2


Personally, I'd just install a ball valve on either side of the filter. With those ball valves in place, replacing the filter would take no more than two simple twists to shut off the water. This SHOULD have been done originally, and it is something not difficult to do. Plumbing is not difficult to do, though I will admit that my first attempt had me fearful. You can learn it quickly enough. If not, then call a plumber. This is a quick fix that will not cost more than an hour of their time under any circumstances.


Is your boiler the same as my hot water heater. If so you should be able to replace the filter without losing to much water as long as you keep the faucets closed the suction should keep the water from flowing back except for what is in the pipe. I would shut the water off at the pipe then open a faucet to relieve any pressure then close it. Put a pan under the filter and slowly open the housing some water should come out and then slow down. Air will just go through the system when you turn the water back on. On my water heater I have a shut off valve on both the hot and cold lines, does yours not have any shut off? If not you should put on in next time you have the system open.

  • Im not sure if my filter has any buttons to relieve pressure. Do all the filters have them?
    – roman
    Mar 17, 2012 at 19:31

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