Bleeding air from gas boiler
I have a gas boiler by Weil-McLain model 75H and have noticed gushing water sounds and loud water flowing throughout the upstairs pipes. At first I thought it was leaking somewhere, but there are no leaks! I did some research online about this and learned it was "air" that needs to be "bled out". I called a plumber in my area to get a general quote on this procedure. He said it would take anywhere from 1-2 hrs for about $130! Is that a correct estimate?
Also, I noticed the PSI gauge is not reading anything. The needle is completely all the
Way to the left where there are no numbers. My question is do I need to replace the PSI gauge or is this part of the reason why I have air in the system? I read online about zero or below PSI readings, and read it's caused by lack of water and the mechanism responsible for regulating this may need to be replaced. However, someone suggested to fill the water manually and bleed the system of air first. I would like to learn how to do this, hopefully it corrects the problem!
In addition to the gushing water noises and PSI gauge issue I've noticed that my baseboard heaters are noisy & click a lot.. almost pound & thud at times. I was told this is d/t the expanding & contracting and the fitting being too snug against walls. Is there anything I can do about this noise?
Oh, and I don't have any pressure release valves or screws at the pipe segments the lead downstairs. I took the casing off my baseboard to check. I have copper piping with metal or aluminum fins encasing most of the pipe. So where am I supposed to bleed the air from?
Any help would be greatly appreciated guys!
Thx,
Shan