FHW overflow valve letting go

Bill_38

I have a three year old Weil McClean FHW 3 section boiler. Temp set to 200 degrees and presure reads ~20 pounds. The 30 pound releif valve on top of the system lets a bit of water off periodally, this just started this season. Boiler has never been shut off in three years.

You think the presure valve is shot?
Expanion tank?
Water feed control valve?
Other?

How do I test each?

Thanks, Bill

john@TR

relief valve

Most likely it has to do with the expansion tank. If it's a steel tank (up btwn the ceiling joists) you can usually just drain it. Hopefully the valve on the bottom has an air bleeder. If it's one of the newer diaphram tanks you're probably going to have to have someone change it out for you. Don't try to do it yourself because it could also be a feed valve problem or a pinhole in the domestic coil. It needs to be diagnosed in person by a pro, sorry.

Bill_38

relief valve

Okay fixed problem! It was the bladder type expansion tank that had failed. There was no air pressure in the tank once system was brought to zero psi and it was full of water. (checked this with tire gauge on bottom) Quick run to Home Depot and spent $30 an 10 minutes later all is okay.

Unknown

What was the pressure in the new tank?

Unknown

C'mon

It's always 12 psi from the store Noel , aint it ?

I've seen some as low as 5 psi brand new , and one was over 20 psi . It's a good practice to check the pressure before it goes on the system . I check by listening to the pop in the tank when we fill the new boiler .

Maine Ken

Had one last year that went off the chart on my gauge. It only reads to 60psi. HO couldn't understand what the problem was!!!!!!