Greetings. I have a Burnham Revolution gas-fired boiler plumbed to converted steam radiators; circulator-zoned with two zones. Currently uses a Taco 2-zone switching relay to operate the boiler and the circulators. I'd like to add more sophisticated control-- e.g. outdoor reset, etc. I'm looking at something like the Tekmar 336/420 combination.

My question is how to wire control of the boiler. Most of the reset controllers indicate that they should be wired to the T-T terminals of the boiler control. Seems easy enough, but...

The Revolution uses an L8148 aquastat which manages the burner and an internal boiler circulator. Closing T-T energizes the boiler circulator and the L8148 cycles the burner off the high limit.

So just wiring a reset controller to T-T isn't going to do the right thing. It seems like the reset controller replaces some of the L8148 functionality, but there does not appear to be any documented way to integrate external reset control.

Looking at the wiring diagrams, I think I see how I could jerry-rig things to work, but that clearly isn't the right answer.

I've looked at all of the Burhman installation instructions, but they don't discuss reset controls. What am I missing here? Surely there's a "proper" way to hook this up...

Thanks for any help.
-Chris

 

Off the top of my head and without looking at any diagrams I think that the reset controller could be wired in series with the existing two-zone relay and the T-T terminals on the L8148.

 

Thanks for the reply, furd.

My concern is about the internal boiler circulator: the Revolution has an internal loop which mixes boiler water with return water. If the reset breaks the T-T connection, this circulator will shut down too.

I've been assuming that the "right" thing would be to shut down just the burner and leave the boiler circulator running to try an capture as much heat from the boiler as possible.

-Chris

 

With an 8148, you need to remove the circulator from the aquastat's control. It can be wired thru a switching relay to energize whenever any zone is calling. If the zone relay has X terminals, they should provide closure for the switching relay.
Something here may help:
http://www.taco-hvac.com/uploads/Fil...ry/100-9.0.pdf

 

Hey y'all. Happy fall.

I have this setup. Revolution with a tekmar 260 and a Taco SR-503. There is a simple trick to wiring this setup that I received from Burnham, which is on another computer. I'll see if I can post it tomorrow.

The upshot is that the internal circ and aquastat need to do their own thing in order to provide the right circ speed and thus internal temps for boiler protection.

 

I knew you were out there just lurking & waiting for an outdoor reset question so you could pounce on it like a striper on an eel.