[RFI] Grounding of A Rinnai RC80HPI Tank Less Water Heater

David Robbins k1ttt at arrl.net
Sat May 9 06:46:44 EDT 2015

Sounds like you have some rewiring to get done to get stuff right.  But that
said, that is not the fix to the rfi.

I also have a rinnai water heater, it took 2 chokes to fix it's noise
problem, though 1 may have been enough.  Most of the noise I found was
coming from the remote control cable.  a ferrite with a few turns quieted
that down.  And for good measure I took an extension cord and wound a choke
with that for the power line.  It is normal for rinnai heaters to just have
an outlet nearby that they plug into, they really don't draw much current
since all the real work is done by the gas.  In my case they rewired the
220v box that had fed the electric water heater to 110v and put an outlet in
it for the rinnai.

David Robbins K1TTT
e-mail: mailto:k1ttt at arrl.net
web: http://wiki.k1ttt.net
AR-Cluster node: 145.69MHz or telnet://k1ttt.net

-----Original Message-----
From: RFI [mailto:rfi-bounces at contesting.com] On Behalf Of Wm.Glenn Pearson
Sent: Friday, May 08, 2015 23:59
To: rfi at contesting.com
Subject: [RFI] Grounding of A Rinnai RC80HPI Tank Less Water Heater




I have a major rfi problem to which I have devoted enormous time
investigating. I will shortly prepare a query to ask the group once I can
get my thoughts organized. But I have made several discoveries which may or
may not be important. I have a Rinnai RC80HPI Tank Less Water Heater which
was installed several years ago. I discovered that it is not grounded except
through its outlet ground. The product manual indicates that NEC, ANSI/NFPA
70 be referred to for grounding (separate ground)  it or not.


Even more interesting is that my plumber used long drop cord (sold by Home
Depot) to its final destination at an outlet box wired to my breaker panel.
The actual 3 conductor AC cable from the unit is rather poor looking now.
Furthermore, he had wrapped excess drop cord cable around a nearby natural
gas conduit and an electrical feeder line. When I move the wrapped bundle
the water heater started making "squawking noises." I rerouted the drop


This led me outside to investigate our 3 gas Heat and Air Systems to see
whether or not they were grounded. There is an outside sub breaker box for
the system with a single fed back to my breaker panel. Today a service man
was by for the seasonal inspection and so I asked him whether or not the
units should be tied to a earth ground. He indicated they were depending on
the ground in the wire back to the panel box.


The next item along this same line is that we have a commercial
de-humidifier under our house as well. It too is fed by a long drop cord and
plugged into the same circuit as the water heater. Its distance from the
panel box is about 20 feet. The same is true for the water heater as well.


Over all I have been going thru the process of cutting house power and
monitoring for problem circuits and devices as I turned each back on. I must
note that unplugging the heater and de-humidifier has no effect on resolving
my problem.


I am of the mind for each device, a separate circuit should have been run
with its own outlet box. I am unclear with regards to separate grounding of
the HVAC units. Your thoughts and advice is most appreciated. Hopefully
shortly I will be able to fill in more of the details of my killer rfi




Glenn Pearson, WU2G

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