Early in 2003 we received
a call from a distressed new building owner. The three story
single family home was purchased in the summer and the heating
season seemed far off. As winter approached they fired up the
boiler for the first time and found that it banged so badly
that sleep was next to impossible. They immediately contacted
a plumber who came in a did some work, upon firing the boiler
again the family realized that the banging was actually worse.
It was at this point that A Real Good Plumber Inc. was contacted
to do a complete survey of the entire heating system, and implement
picture shows the original piping configuration at the time
of purchase. The vertical white lines represent the original
take offs. This piping arrangement causes banging because the
two steam risers from the boiler are aimed towards each other
with the two take offs in between. The steam from each riser
actually bumps into the steam from the other riser. This collision
along with the fact that the left riser has no where to dump
water, causes water to follow the steam through the pipes. Water
in steam pipes is a prime cause of banging. (see line to banging
pipes and velocity charts)
plumber they called in realized this problem and removed these
two take offs and capped the two tees, which was the appropriate
thing to do. The goal is to get the steam a from both risers
going in the same direction. The problem was that they left
the main header (see #2) back pitched and only installed one
new 2” take off which they then split into two 2”
take offs. This actually made the banging worse because all
of the steam for the entire building now had to travel through
one 2” pipe which doubled the velocity of the steam traveling
in this one 2” pipe. Steam traveling at high velocity
causes the steam to carry water along with it and once again
water in steam pipes causes banging.
Here is the actual
proposal that we sent to the customer.
These next two pictures show how we corrected the boiler piping.
#1 shows the two risers from the boiler. We brought them up
high so that we are at least 24” above the water line
in the boiler. This prevents the water from coming along with
the steam up into the header. As long as the two risers are
sized adequately almost no water will come along with the steam.
#2 shows how we bring the two risers together before installing
any take offs to the building. #3 shows the two vertical take
offs to the building.
If you look closely
you will see that we increased the size of these two take offs
from 2” to 2 ½”. The two overheads that travel
the length of the basement, one going towards the front and
one going towards the rear were 2” in size and pitched
down. The original take offs were done in 2” so the “normal”
thing to do would have been to use 2”. However, we did
some calculations and found that 2” takes offs were a
little too small to carry the amount of steam created by this
size boiler. Thus we increased them to 2 ½”. It’s
the little things that sometimes make a real big difference
in the end result. When we left the building the boiler was
quiet and the owners were now able to sleep through the night.