hello all. i have a single zone hot water heating system with an
external coil. the circulator is continuously run for domestic hot
water. it appears that air may be getting in the system. i had a
"heating prof" in and he filled sysem and bled it from a valve located
near the boiler. i live on the first floor and the heating pipes run
from boiler, overhead, and then down to baseboard radiators. when he
first filled and bled the radiators i heard nothing from radiators or
boiler. the next day i heard some bubbling noise from the radiators
when the mech zone valve opened. the noise became progressively worse
each day. i have since bled the system again, and the radiators are
much quieter. however, i now hear a gurgling/bubbling sound from the
expansion tank each time the burner comes on. the burner comes on at
170/180 and goes off at 200 degrees. could the expansion tank be
faulty and somehow letting air into sysem? i believe the expansion
tank is one of the newer ones with a bladder. thanks for any
help.email me at email@example.com just remove the 5 for spam
purposes. or post message with any help. thanks again.
You either have an air control system or an air elimination system. If you
have a bladder type expansion tank you have an air elimination system.
Running pipes overhead and then back down creates a place for air to collect
that has separated out of the water. In an air elimination system the
highest point in the piping is where you should have an air eliminator to
prevent this kind of thing. It's a little tin can-looking thing about the
size of a shot glass that has a float inside. It lets air out but not
If you have the non-bladder type of expansion tank you have a air control
system. This means air is continually moving back and forth from the
expansion tank to the circulating system. For this you need a boiler
fitting to separate the air and return it to the tank, and a Automatic Tank
Fitting on the tank. Also the piping must be pitched up to the tank.
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hello mm. it is an air elimination system. if there is such a device
on the system is it possible it could be in the ceiling? because it is
nowhere else to be found. i live in a condo complex of garden apts.
everyone has the same system so i don't believe my problem should be
on of configuration. although the configuration of all the systems may
make them moe succeptible to problems. thanks for your help. jim
The air eliminator may be near the boiler. In many systems, a device such
as Taco Air Scoop separates the air bubbles from the water as the water is
pumped through the system. The air eliminator screws into the top of the
Air Scoop. This arrangement only works if the system has sufficient
velocity to keep air entrained in the circulating water. If the flow is
too low, the bubbles rise to the top of the system where they eventually
trap the flow of water. Wiring the pump to run all the time and cycling
only the burner may help. Adding an additional air eliminator to the top
of the boiler may help.
I've seen air eliminators installed in attics and crawlspaces - not the
preferred locations, but sometimes you have to. Good practice requires
these devices to be accessible for service.
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