How many circulators can a boiler controller run?

Bob_Engelhardt

I have a Weil-McLain CGs-5 boiler that has a United Technologies 1107-1 control module.  The module powers the circulators.  For multiple zones, the module output is switched through thermostat-controlled relays, but the module is still powering the circulators.



How many circulators can it power?  The boiler I&O doesn't say, there's no current rating on the module,  and I've found nothing on the web about it. I can put in a relay controlled by the module, but I'd rather not if I don't have to.



Thanks,

Bob

icesailor

Controllers:

I don't have it available to me at this moment because it is in my truck. But I have a book from Taco that shows just about every imaginable way to connect their controls to any boiler known to the imagination.

I'm not familiar with your control and how it works but usually, the control may send power to a circulator when there is a call but the control has no way nor does it care if a circulator motor is there or starts. Just that it gets a signal from some device like a thermostat to start the burner and controls. Zone controllers like a Taco SR 504 will control 4 circulators but the end switch makes it appear that only one thermostat is connected.

So I guess you could say that the control on the boiler, when wired up with a circulator zone controller has no limit to how many circulators the controller runs. The boiler control has no idea of the total. Just that "one" zone called and it sends current to a non existent zone.

Bob_Engelhardt

It's a matter of the current

"...you could say that the control on the boiler, when wired up with a

circulator zone controller has no limit to how many circulators the

controller runs."



It has a limit as to how much current it can supply.  If the controller is powering the circulators through the relay contacts of zone controllers, it's still supplying the circulator current.  My Taco circulators are rated at .7 A each.  If all were running at the same time (highly unlikely), that would be 3.5 A required of the boiler control.  That's not very much, but it all depends upon what the controller was designed for.



I guess that I should try to get an answer from W-M.  I suspect that it wouldn't be easy.



Bob

Paul48

No

For multiple zones, the module does not power the circulators. Pull up the manual for a Taco SR 504.

Paul48

#2

Zoning with circulators (Figure 6)

(return temp over 130°F)

1. Size each circulator to individual circuit requirements.

2. Do not install circulator on boiler (except for primary/

secondary piping).

3. Install isolation (balancing) valves to adjust fl ow to

distribute heat to all zones.

4. Install and wire a separate relay for each zone circulator

Paul48

In

the case of primary/secondary piping, the module could still control a boiler circulator, but the zones would still be controlled by a switching relay.

icesailor

Correcto:

Correcto.

You can have multiple electrical circuits running the whole mess as lomg as you don't get any phase switching, crossings.

Paul48

Answer

I guess to answer his question specifically.........I would assume the module is rated to run only 1 circulator, as they specifically say to use switching relays when zoning with multiple circulators.

Bob_Engelhardt

Follow up

I just discovered something that indirectly answers my question.



It turns out that the "circulator" output from the boiler controller is activated as soon as the "thermostat" input is closed.  I assumed that it was delayed until the boiler was at some "circulate" temperature (cold start boiler), but it isn't.  So, the circulator control is just a relay and is included in the controller to eliminate the need for a separate switching relay WHEN THERE IS ONLY ONE ZONE.  For multiple zones, the controller "circulator" output is redundant (the separate zone relays handle all the switching).



So, the answer is: one circulator.



Thanks for all the replies,

Bob

Paul48

Bingo!

That's right.