i have a gas, hot water system that uses radiodors, circulator and
expansion tank, i guess its a standard type of system. the boiler is
in the basement, there are two additional floors above, each floor has
two units, with a total of 6 units with six heating zones. i'm having
a weird problem, i have heat going to the top floor two units, 1st
floor two units are also ok, the problem is the two basement units,
the heat is not circulating to the bottom two units. i checked the
zone valves and the electrical power to them, this seems ok, i also
get no circulation to these units when the zone valve is set to open,
i know the zone valve is not stuck because i can open the system to
bleed out the air. So i've also blead the system, each unit
individually, i did this for the second time yesterday using a bucked
which a friends suggested, although it took longer i could see the
bubbles better, i did also notice the water being almost black with a
lot tiny black particles, i guess this is soot from the boiler, is
this normal? So it seems like i still have air in the system, what
could be causing the air to enter the system, and why would the bottom
two units not get circulation and the top floors are ok, thanks in
The basement loops may be air-bound. This is a factor to consider
when loops travel below boiler level. It's addressed with a
appropriate way to bleed the whole loop at one time, usually
when the system is installed, as opposed to individual bleeders
that you have elsewhere.
Not something you want to tackle by written instruction only,
for the very first time. You have six families depending on you
to get it right the first time.
So I strongly advise you find yourself a highly recommended
boiler service tech to A) fully diagnose/confirm what IS wrong
and B) IF it's air-bound, watch him/her bleed the basement loops
and let them know you would like to bleed this yourself next
time so they can offer you any other instruction needed. And don't
be too surprised if you'll need a new PRV (pressure reducing valve).
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.