Circulating pump causing noise
Posted by Jerry Doyle on July 28, 1999 at 18:02:32:
We installed a Lennox complete heat system severy years ago. Because of
many problems during that time, the Lennox company had the local contractor
replace the main furnace and water heater unit several times (we have lost
count). After the last installation, we noted a hammering noise when
especially the hot water was turned off at a sink. Our heating contractor
seemed to be of the opinion that it was not related to the furnace
installation, but that probably the water pressure was too high. So we had
a local plumber install a pressure reduction valve in the line to the house,
since the pressure was originally about 100#. They turned it down to about
85#, the noise continued, I turned it down to about 55#. The noise
continues. The same plumber installed a 3/4 inch Sioux water hammer
arrester in the hot line from the water heater. It seemed to reduce the
noise, but the sound seems to be telegraphing from another location. Prior
to the arrestor installation, we installed a Laine hot water circulator at
our utility room basin (all piping seemed to come from that first). As you
can guess, we were confused by the fact that we were getting the noise at
times when we were not turning on and off hot water.....finally coming to
the realization that the circulating pump was also causing the noise when it
completed its cycle.

1. Do you have any suggestions? We have been told that a loose pipe could
cause it. If that is the case, it means unloading some storage space and
getting down and dirty....OK, if really necessary.

2. Should I put an arrester in at the recirc pump? If so which one. As
you know, there are 1/2 and 3/8 pipe fittings in conjunction with that.

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