In article , frank1492 wrote:
Sorry I wasn't clear. This is a *closed leg* with a circulator,
pressure tank and gauge. (Runs through a heat exhanger or tankless
heater, heat supplied by circulating steam boiler water- old boiler.)
Has always worked perfectly with identical components until the old
tank sprung a leak. I realize the ideal situation would be to have a
pressure reducing valve and backflow preventer permanently attached
but letting in the water manually on rare occasions has always worked
fine.
So the only thing that's new is the new pressure tank, same
capacity, style as before. As I say, when you let water in now, the
pressure rises very quickly as if there was no air cushion.

That suggests strongly that there is not in fact an air cushion. By any chance
is there a valve between the gauge and the air tank? And is that valve open?








On Wed, 30 Dec 2009 03:06:45 -0800 (PST), ransley
wrote:

On Dec 30, 12:38*am, frank1492 wrote:
Just heard a loud "whoosh" and the pressure has gone to zero again.
Nothing is leaking. Add that to the clues.

On Wed, 30 Dec 2009 01:25:50 -0500, frank1492
wrote:



I just installed a new pressure tank in my hydronic system. It said it
was pre-charged to 12 psi. When refilling the system I think I did a
good job of eliminating the air as there is little noise when the
circulator is running, plus there is a Spirovent installed.
* I like to keep the system pressure at between 15 *and 20 lbs. but I
noticed the pressure seems to drop back to 0 quite often. Then when I
add water, the pressure seems to rise very quickly. The only thing I
can think of is that I have no air cushion.
* I did not check the tank pressure before installing.
*What is wrong and what should I do? I'd like not to have to drain
the system again.
*Thanks in advance.
* * * Frank- Hide quoted text -

- Show quoted text -

Do you mean the pressure gauge on the boiler, how much does pressure
change from high to low, is your house 1 or 3 story, with radiators I
can not go to zero unless my system is empty, to keep my 3rd floor
radiator full of water I need near 12-15lb and only increase a few
pounds as water heats. Maybe a bad gauge, what was wrong with old
tank, to small a tank and pressure can jump when heated and be
erratic, when our boiler was changed the attic expansion tank was
eliminated and a basement tank installed, but we eventualy needed two
tanks as one was to small and pressure jumped 15-20lb with every
heating cycle. www.heatinghelp.com "the wall" is where boiler pros
are.