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[Roger2561]

Hi all, I was in the basement of my house on Saturday - cleaning the darn thing, it's my wood working shop - for some reason I decided to look over my oil furnace (it provides the potable hot water in the summer months) and I noticed the water pressure gauge on top of it shows 25Lbs.  I have no idea how long the pressure has been this high.  The auto-take up valve/pressure reducer is set to 12-15Lbs.  Can anyone offer me any ideas what to do to lower the water pressure?  And, what may have caused this spike in temperature?  Due to the high cost of hiring a plumber, I cannot afford to have him stop by and remedy the problem for me.  Thanks for the help.  Roger

[RSI]

What kind of expansion tank do you have? If it is the type that just has air in it, it might be filling up with water. If it gets too full of water then the fill valve will add water when the boiler temp drops and pressure will go high when it gets hot.

If you have an expansion tank with a bladder, it could have popped.
Or your fill valve might not be working properly.

I would let some water out and then watch and if the pressure goes up and down with the heating cycles it is probably the expansion tank. If it just goes up and stays, probably the fill valve.

[Roger2561]

What kind of expansion tank do you have? If it is the type that just has air in it, it might be filling up with water. If it gets too full of water then the fill valve will add water when the boiler temp drops and pressure will go high when it gets hot.

If you have an expansion tank with a bladder, it could have popped.
Or your fill valve might not be working properly.

I would let some water out and then watch and if the pressure goes up and down with the heating cycles it is probably the expansion tank. If it just goes up and stays, probably the fill valve.

RSI - Thanks for the reply.  When I get home from work this afternoon I'm going to remove some water from the system and see if that remedies this problem. 

I tapped the expansion tank this morning and the upper 1/3 of it had a distinct "thunk" to it.  The lower 2/3's sounded like it was hollow.  I'm guessing this normal.  Let  me add that the system will be 20 years old next year and I believe the expansion tank has never been changed. 

[RSI]

Does the fitting go into the top or the bottom of the expansion tank? If it goes into the top them it has to be a bladder type. The other kind have to have the fitting at the bottom.

[Roger2561]

Does the fitting go into the top or the bottom of the expansion tank? If it goes into the top them it has to be a bladder type. The other kind have to have the fitting at the bottom.

The fitting is on top.  Nothing on the bottom but an air valve that I'm guessing is to add/remove air?