Need to install and wire in a 24v vent damper and a 24 Louver actuator.

Mail4tommo

Hello all. This was brought up in a different post, and I appreciate everyone's input. I figure if it was under its own discussion it would get this figured out.

I have an lgb-7 series 2. We want to install a 24v vent damper and a 24v Motorized louver actuator for combustion air (to keep the elements out and other reasons) If the actuator does not have end switch's built in I would add a whisker or something of the sort.

The limit circuit is 120v and when satisfied it powers the 24v transformer for the burner circuit.

I know the end switch's on the damper and actuator need to be in series with the burner circuit to prove they are open.

How would I wire in both of these into this set up without killing power to the dampers when the 120v limits open. I'm assuming with a second transformer and a SPDT Relay? If so where on the diagram would these tie in? I've spent a bunch of time trying to figure it out but not sure how to do it properly.

Here are the diagrams. I appreciate everyone in advance.

LGB-7 Wiring Schematic.pdf

Vent damper Diagram.pdf

LGB 7 Ladder Diagram.pdf

Jamie Hall

The vent damper is on the exhaust vent? If it is, it must become part of the limit circuit, and prove open before power is applied to the rest of the boiler limit circuit. It's not a question of killing power to the damper when the existing 120 volt limits open — it's a matter of killing power to everything except the camper unless the damper is open.

Mail4tommo

@Jamie Hall Yes the vent damper is for the exhaust, and yes I agree power needs to be killed to everything except the damper so it can close. Thats why I was thinking a second transformer wired in right after the service switch- constant power going to the 1 terminal.

Steamhead

First things first. Wire the fresh air louver into the thermostat circuit. Get an R8285A fan center, like this:

https://customer.resideo.com/en-US/Pages/Product.aspx?cat=HonECC%2520Catalog&pid=R8285A1048/U&category=R8285&catpath=1.2.8.3.2&rank=0&v1=Sort.1.Product.Rank&asc=1

Mount it on its own 1900 (4" square) box. Feed it with 120V and route the two normally open relay contact wires (black and red) out of the box through a bushing to keep them from abrading.

Wire the louver so it gets 24V from the thermostat when it closes. The thermostat connects between R on the R8285A and the damper motor feed. If the thermostat needs a common wire, that goes on terminal C, as does the other side of the louver motor.

Feed the end switch with the same 24V that goes to the louver motor. Wire the other end switch terminal back to G on the R8285A. This will pull in the relay when the end switch closes.

And the two relay wires sticking out of the box? These go to TT on the boiler.

Sequence of operation: On a call for heat, the thermostat sends 24V to the louver motor. The motor opens the louvers. When the louvers finish opening, the end switch closes, sending 24V back to the relay to pull it in. This closes the thermostat circuit to the boiler, which then comes on, opening the flue damper as part of its cycle.