My BIL called me over to help him fix a leaking circulator pump on his
system which was an easy swap and fixed the leak. But he still has a
big problem with his system, here's the current setup:
Boiler in basement
Split level house with all zone loops higher than basement
Three zones - all thermostats working properly
Circulator pump on the cold/return side of boiler mounted just above
comes on with furnace (zone independent)
Flo-control valve on the hot/supply side of boiler mounted near ceiling
Air separater right after main flo-control valve with bladder expansion
Three additional zone circulator pumps connected to the thermostat
Three zone flo-control valves, one right after each zone pump
The problem is that whenever any zone calls for heat there is flow thru
all three zones. I verified that each of the zone pumps are working
indepently and correctly. He told me that the system has always
operated this way and he just sets the thermostat on the upper level to
50 so it never kicks on because he always gets heat up there. On the
zone I changed the pump the flo-control valve stopped the water from
coming out when I pulled the pump. I'm assuming the other two
flo-control zone valves are also properly preventing back flow. But
the problem is they are are always allowing hot water to flow forward
even if the pump for that zone is off. There are no zone valves on any
of the zones, only the flo-contral valves. The zone pumps, flo-control
valves and thermostats appear to be add-ons to the original system.
Does this system need a circulator pump for each zone?
Should there be zone valves installed for each zone?
Why? You have three zone valves and three circulators. The individual
circulator for the zone should be doing the ork.
Was this a single zone system that was converted to a multi-zone system?
Sounds crazy to have a main circulator plus the individual zones. Could
also be the zone valves are not operating properly. Have you checked to be
sure they are closed?
Should be one way or the other. Any thermostat calling for heat would start
the pump and open the valve for that zone. My house has two pumps, one for
each zone. The thermostat starts the pump for that zone only and heats
that zone only. The boiler is controlled by an aquastat that starts the
burner when the water temperature gets below the set point.
System doesn't have any zone valves. Flo-control valves are supposed
to stop 'gravity circulation'.
Looks like it to me.
Again, no zone valves just the flo-control 'gravity flow' preventers.
I'm guessing the _main_ circulator pump is left-over from before the
system was zoned. My previous house had only one pump and three zone
valves and always worked fine. The pump was on the cold side of the
boiler. I think whoever did the zone work did not set up the system
properly. From what I read about these flo-control valves they will
allow flow with a minimal amount of pressure just not gravity flow from
rising hot water.
Unless I'm misunderstanding, aren't they designed to prevent backflow,
but allow flow from pumps, which appears to be the problem? When
circulator(s) are running, they are indeed allowing forward flow of
water through entire system. I think you need zone valves. As you say,
appears to be retrofitted system by someone who didn't quite know what
they were doing. Don't know how large the loops are, but main and zone
circulators seem redundant, though don't see why that should be a
problem(doesn't appear to be excessive electrical load at present),
once zone valves are put in.
You got it right. If you look at this page about halfway down they
show these valves installed after the zone pumps.
I think the reason his are allowing flow all of the time is 'main' pump
is on the return side of the bolier and forcing all three flo-control
valves open even though the zone pump isn't on.
I'm thinking of disconnecting the main circulator and then running each
zone to see if that cures the problem. Although having the pumps on
the outlet side of the boiler _could_ lead to a boiler overheat more
easily than if the pump was on the inlet side.
If it were my house I would disconnect the zone pumps and install zone
valves and run it for a season just using the main pump. If all went
well I would pull the zone pumps and have three spares.
I don't understand the multiple circulating pumps. If there is a manifold
with zone valves, when a zone thermostat calls for heat, the zone valve will
open, and that turns on the circulating pump. Only that zone will get the
hot water. The same for the other zone. The circulating pump won't shut
off until all the zone valves are closed.
Like Ed said, you either use circulators and flow controls or circulators
with zone valves and no flow controls. When you buy the boiler, it comes
with one circulator mounted on it, if you need more zones, you usually
remove that one and build or buy a manifold and mount them all together. So
you have a total of 4 zones, and I'm assuming 4 thermostats and relays. What
concerns me is what is controlling the boiler? Ed mentions an aquastat
maintaining his boiler temperature, some boilers maintain temperature and
some are wired for cold start, which means each zone control would turn on
its circulator and fire the boiler as well. What do you have for domestic
hot water? If it's a coil built into the boiler, you will have a triple
aquastat relay mounted on the boiler to maintain temperature, but if not,
you may have issues with the original circulator becoming energized when any
of the others come on.
This is exactly what is happening, every time an individual zone calls
for heat the 'main' circulator pump kicks on with the boiler as well as
the zone pump. The pressure from the main circulator is enough to lift
the flo-control valves off their seats in every zone.
The biggest problem is my BIL makes Tim 'the tool man' Taylor look like
Tommy Silva. So I can't try things like disconnect the main circulator
and let it run for a few days. I told him several times after I
changed the zone pump and refilled the system to check the pressure a
couple times a day for a few days. He still hasn't checked it (he
I'm thinking there are three options:
1-Have him buy three zone valves and replace the flo-control valves
with zone valves and leave everything else alone.
2-Put in the zone valves and disconnect the three zone pumps to see if
the single circulator pump can move enough water. If it works then
remove the zone circulators in the spring.
3-Tell him to call in a heating guy who will sell him some fancy
interconnected thermostats with ambient temperature probes along with
with cyclonic self-equalizing pumps. Oh yeah and a new boiler since
the old one isn't up to the task of properly heating the house
Ray, Did you check to make sure that the top nut of the check valve
was closed tight? Most times people forget to tighten this nut. If
not tight, it will allow for the hot water to enter into the other zone
causing ghost heating.
Yes. After I replaced the pump I fully opened (bypassed) the
flo-control valves and ran all of the circulator pumps to hopefully
flush any dirt from the seats and get the air moving. Then I closed
all of the flo-control valves. They were all closed when I got there
and hadn't been touched in years if ever.
Well, then if they are tight and have been there for awhile and you
are getting ghost heating you may want to try and replace one of the
check valves. There really isn't much to forced hot water system.
I was thinking about trying that but all three flo-control valves are
allowing flow no matter which of the zones is calling for heat. That
would mean all three of them have failed or are stuck, he also told me
that he has always gotten heat everywhere in the house since he moved
in 8 years ago. This has to be an incorrect zone job done for the
As Doug and Sev said, disconnect the wire to the "main" circulator and see
what happens. If the problem stops and this main circulator is not part of a
manifold, but instead, is inline in the return, I'd remove it altogether
Sorry....Disagree!! If you are NOT using zone valves then you need a
circ for each zone...PERIOD. If your using zone valves then one circ
wil work as long as you have the proper controller for the zone vavles.
How else are you going to get the hot water to each zone when there is
a call for heat by the thermostat? In my house I have two zones. I
choose to plumb my heating system with individual circulators because I
don't like zone valves. I have a Taco 503 controller that turns on
each individual circ when each thermostat calls for heat. In a basic
hot water boiler setup the only component that will prevent "Ghost
Heating" into a zone that is NOT calling for heat is a check
So, don't remove the circ. I would make sure that the valves are
working properly. You should be able to open up the valve without
removing it completely form the system. Now, if your still confused on
this issue all you have to do is call a professional. They will figure
it out for you.
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