[usarmy]

How to acurate check PSI in home expansion tank

[massplumber2008]

Hi USARMY!

Here you go... as quoted from www.doityoursef.com (easier than me typing it all out, for sure! ):

1. Shut off boiler and allow to cool to under 100°F.

2. Shut off water supply line to boiler.

3. Drain only enough water from the boiler drain (note: this does not have to be THE boiler drain. It can be ANY drain valve on the system. Use the one that is most likely to be able to not leak when closed again!) to drop the system pressure to ZERO. [COLOR=#ff0000]REPEAT: DO NOT COMPLETELY DRAIN THE BOILER! ONLY ENOUGH TO DROP THE PRESSURE TO ZERO![/COLOR]

4. With an ACCURATE tire pressure gauge, check the air charge in the tank on the air valve opposite the end of the tank that's connected to the system. If ANY water comes out of the air valve, the bladder inside the tank is shot and the tank needs replaced. If no water comes out the air valve, and the pressure is less than 12-15 PSI, continue to step 5. If the pressure is OK, turn the water supply to the boiler back on and repressurize the system, turn the power back on to the boiler, no service is necessary.

5. Using a bicycle pump, or a small air compressor, add air to the tank until you have 12 PSI air charge.

6. Check the boiler pressure gauge again, and if it has risen off ZERO, drain some more water from the boiler drain until it is again at ZERO.

7. Check the air charge on the tank again. If it is below 12 PSI, add air to the tank until it is at 12 PSI.

8. Repeat steps 6 and 7 until the boiler stays at ZERO and the tank stays at 12 PSI. At this point, the tank is properly recharged and the water supply can be turned on to re-pressurize the system, turn the power on to boiler and return to service.

Read more: Pressure Relief Valve leaking? Service your bladder type expansion tank! - DoItYourself.com Community Forums


Best of luck! USA

[ma0641]

Is this a boiler or house water pressure unit? If boiler, follow above advise, if house water pressure follow my advise. First you need to measure house static pressure. Then with all the water pressure released, measure the air charge in the expansion tank and adjust it to match house static pressure. Remove the blue cap and a Schrader valve is underneath.

[massplumber2008]

Yup, boiler expansion tank VS potable water expansion tank (domestic water) definitely have different procedures. Thanks for the backup, ma0641!