First time poster...avid reader. In november the oil furnace tech came
to do the annual inspection and cleaning. Apparently, he needed to
replace the transformer, which he did. So the other day I happen to be
down near the furnace and notice a humming sound. It is the circulator
pump. It seems even with the heat side of the boiler off, the pump is
still running. It never used to be that way. When we turned the heat
off, the pump was off as well. It also looks like something is missing.
Just from memory, I think there was either a relay or a seperate
transformer wired in before the pump to prevent it from running all the
time. Does anyone know what is missing and hoe it's supposed to be
wired in. I would call the oil company again but were in the country
and don't have a choice who to use and I don't like who were stuck
with. I really don't want to pay for another service call.
Almost forgot... it's a John woods JWF 307V boiler
White-Rodgers 8A05A-101 transformer
thermostat is wired to the R and G terminals of the transformer, Com is
Mine is wired so that the thermostat applies power (24 vac) to a relay.
The relay starts the boiler (flame) and applies 120 vac to the
circulator motor. The circuits are simple and you should be able to
figure them out. It sounds as if the relay thinks a thermostat is "on"
all the time. Get out your meter! Use a clip lead to simulate a
You could wire it to a separate relay, however the relay you have is a
double pole relay and should be able to control the circulator. If the
thermostat does not control the circulator, I'd call the service company
back and correct their mistake
There are variables, depending upon the specific equipment, but in general,
if you only have the one circulator pump, and one heat zone, the thermostat
should control the circulator. Thermostat up-pump comes on, thermostat
down-pump goes off. The boiler may be started by the same relay that
controls the circulator, or it may just start and stop to maintain a
predetermined boiler temperature. In any event, the boiler will go off when
the water temp reaches its limit of around 190 degrees, if the room
thermostat , which controls the circulator is not satisfied at that time the
circulator should continue to run
There's no reason why it needs to be that way, really.
You don't necessarily have a problem. The circulator and the boiler operate
more-or-less independently. The circulator runs when the thermostat calls for
heat; the boiler runs when the water circulating through it is cooler than the
boiler's cut-in temperature. It's perfectly normal for the circulator to
continue running after the boiler has shut off -- or for the circulator to
start running before the boiler turns on -- as long as the water is hot.
Do these two tests with the boiler switched ON:
1. Turn your thermostat(s) down to several degrees below room temperature. The
circulator should stop promptly. If not, there's a problem.
2. Turn the thermostat(s) back up to several degrees above room temperature.
The circulator should start up promptly, followed quickly by the boiler. If
not, there's a problem.
Doug Miller (alphageek at milmac dot com)
Get thee a basic book on Hydronic heating and controls.
From the sound of things, you will be needing it to
forestall another visit from this tech.
Look in your local libray, BigBox or Amazon.com maybe.
Audels has some good ones.
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