Hot water heating system water pressure question


  #1  
Old 10-14-23, 08:34 PM
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Hot water heating system water pressure question

I have a gas hot water heating system. It is about 14 years old. I am in MA. I tested my system today. I found that there is about a 10 psi pressure difference between when the water is cold and when the water is hot. Is that normal or the pressure tank is not working properly now?



 

Last edited by PJmax; 10-17-23 at 02:46 PM. Reason: resized pics
  #2  
Old 10-15-23, 11:21 AM
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D,
You should only get maybe 2-3 psi difference in your pressure from cold to hot. Ten psi is excessive. If your pressure stays stable when cold then your extrol tank could be the problem. It may be undercharged or the bladder may be gone. To check the tank it must be isolated from the system. Yaou are looking for at least 12 psi in your tank.
 
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  #3  
Old 10-16-23, 05:47 PM
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I checked the expansion tank by knocking it with a metal stick. It sounds fine. I plan to check the pressure and recharge it tonight. Should I take it off the system or I can just shut off the expansion tank and recharge it online?


 
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Old 10-16-23, 07:26 PM
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I just bought a 120 volt Inflator from the Homedepot. The air pressure from the expansion tank is 18 psi. My house water pressure is 60 psi. where is the issue?

When I checked the pressure, there is no water coming out from the expansion tank.




 
  #5  
Old 10-17-23, 06:22 AM
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What type of radiation do you have? Cast iron radiator systems (especially if a converted gravity system) may need a larger expansion tank or a second tank in parallel.
 
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Old 10-17-23, 11:13 AM
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Your house pressure is irrelevant because you have a pressure regulating valve on your cold water feed to your boiler and the pressure only rises when the water gets hot. As 2j mentioned your tank may not be large enough for your system. If you have any cast iron radiation you may need at least a #60 extrol or an other #30.

Could you post more info about your system.
.
 
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  #7  
Old 10-17-23, 05:07 PM
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Thank you guys. I just figured out the issue. The tridicator is bad. It doesn't show the real value.




 
 

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