Posted by jtown on October 08, 2001 at 20:48:43:
In Reply to: Re: expanssion tank draining, seal posted by Chadwick T. Morgan on October 08, 2001 at 10:10:39:
Water will rush in fast at first as there is no pressure in the tank to hold it back, once it compresses the air enough the water will slow. To check the PRV, heat the house up good and then shut off the boiler for a couple of days. Check the pressure and see if it rises due to just the PRV and not thermal expansion of water. After a day of holding steady, shut off PRV line and drain boiler 'til you see five or so psi drop on gauge. Open up PRV and check that it brings system back to what it was at. The make-up to the boiler might come from the water heater so cold water doesn't shock the hot boiler. Or you may be looking at the domestic water going through the boiler to pick up heat before going to the water heater. Whichever, if you are going to mess with the water temp while people are in the shower - be thinking "What am I going to change my name to". Always check the water temp when done. Being able to hold your hand in it with a little discomfort is hot enough. A heating technician will have a thermometer.