www.fueloilnews.com | FUEL OIL NEWS | JANUARY 2015 45
HVAC/ HydroniCs
doing this to their bellows in the cutoff, and so, don't
do it and I strongly recommend that if you find one of
these hack jobs you get it off!
Speaking of that float bellows, in 2015 it's worth
noting that M&M states that you must inspect the float
and switch mechanism every year and has since 1995.
M&M goes on to state in their Publication MM-825E
that a #67 low-water cutoff should be blown down
weekly and inspected and tested annually. That annual
inspection includes: "Visually inspect the inside of the
float chamber during the annual inspection. Partial
disassembly may be required". And finally M&M rec-
ommends that the entire unit be replaced on a 10-year
interval. In other words you probably should remove it
and upgrade the technology with a probe type.
Now a few questions:
1. Who pays for the gasket that will be needed during
the annual cleaning and inspection?
2. Who pays for the complete cutoff assembly every
ten years?
3. Do you know how to really test a low-water cut-
off?
The answer to the first and second questions is you
do, if you cover low-water cutoffs under a service con-
tract. The answer to the third question has to do with
those test procedures that I'll come back to. Now, the real
answer to all of these questions is, as always, education.
That education thing is the key and this is for my
brothers and sisters, the burner techies. When you
service steam boilers, do you just flush the cutoff, or
do you really check them? There's a big difference!
If you just flush them, how do you know the cutoff
really works? How do you flush a probe type cutoff?
You must run the boiler to a point where you simulate
an out of water condition and see what happens. If
you don't, you just flushed it and during the flush the
burner went out.
Well, a good lawyer could argue that was just a coin-
cidence, because it is! There is no guaranty that it really
worked. Are you 100% sure all of the piping, Figure 3,
leading into and out of the cutoff is clear? Is that brass
"upper tube assembly" from the top of the cutoff back
to the trim piping totally clear? It turns out that the only
correct way to test a float type cutoff is the only way you
can properly check a probe type, by draining the boiler
with the burner running. By the way, did you noe the
mercury switch?
What we teach at Firedragon Academy is the fol-
lowing:
1. Do a test by lowering the boiler water level from
the boiler drain valve with the burner running.
2. If the burner goes out at the "minimum safe level"
drain the cutoff by opening its drain valve. On probe
types this step isn't required.
Figure 4
Figure 3
