DIYbanter - View Single Post - Bleedingh radiators and the expansion tank...

wrote:

Greetings brothers ~

I have been searching for a while now on bleeding radiators...since the
bleeding I did last night seemed to cure about 75% of my insufficient
heat issue, I want to be sure I am doing it properly going forward.

Do you go from nearest to the boiler to farthest, or vice versa?
Somehow I would think farthest 1st...

Boiler should be running at normal operating temp when you bleed,
right?

Bleed at least a quart at each radiator? Less? More? How often when
a system shows trouble? (I am figuring a quart each, done every week
until the insufficient heat problem is gone?)

What about the expansion tank? Mine is a metal cylinder maybe 5 gallon
capacity, sitting just above the boiler. Should this thing be bled as
well? I understand they can sometimes become water-logged...

I hope that is comprehensive as far as what Q's come up for bleeding
FHW radiators so those that come searching can be helped.
Let's hear from the experts!

First, the expansion tank is there to act as a cushion against sudden
pressure changes such as the automatic filler clunking on and off.
Also, it accomodates changes in air pressure. The expansion tank is
only a chamber with a flexible diaphragm halfway up. That diaphragm
will last about 20 years, but can rupture.

Second, the pressure in your system is largely set by the automatic
filler valve. A typical range is 6 to 22 psi. It's built into the valve.

Third, air in the system should escape via a relief valve, typically on
the stem up to the expansion tank. Some systems have little air
separators on local high points around the system. These are valves
that have cardboard in them. Air escapes while the cardboard is dry but
when water hits the cardboard it swells up and stops the flow.

Fourth, it sounds like you could benefit from an hour of a friendly
plumber's time. Have him explain all the parts of your system and
answer your list of questions. In the end this will save you time
trying to guess what's going on.