RBM (remove this) wrote:
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?

Separate water heater.

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
forgot).
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
efficiently.