We have had an increased number of Tech Hot-Line calls recently dealing with the issue of wiring of power venters with the Carlin controls. With the new Weil-McLain version of our control now available I thought this was a good time to revisit the issue of power venter wiring and clear up any and all misunderstandings. Regardless of whether you have a Field or Tjernlund power venter, if you are connecting it to any hot water boiler that cycles through an aquastat (TT terminals jumpered) you DO NOT need an isolation relay in the circuit. If you are connecting the power venter to a heating appliance that utilizes the TT terminals directly on the cad cell relay (TT NOT jumpered) then and only then will you need an isolation relay.

Following you will find four wiring diagrams. The top two are for Tjernlund Power Venters. If you have a hot water boiler application (TT jumpered) refer to the wiring diagram on the top left, you DO NOT need an isolation relay. If you have a steam boiler or furnace (TT not jumpered) refer to the diagram on the top right. You will need an isolation relay installed as shown. Tjernlund is introducing a new power venter within the next few months that will have a solid state internal switch eliminating the need for an isolation relay. The bottom two diagrams are for Field Power Venters. If you have a hot water boiler application (TT jumpered) refer to the wiring diagram on the bottom left, you DO NOT need an isolation relay. If you have a steam boiler or furnace (TT not jumpered) you will refer to the diagram on the bottom right. You will need to install Field RJR-6 add-on isolation relay. It connects very easily to the Field Power Venter and comes with all the necessary wiring complete with terminal ends.

As always, if you should have any questions regarding this bulletin or any other Carlin questions, PLEASE do not hesitate to call the Carlin Technical Service Hot Line at800-989-2275 (CARL).

Technical Hot Line 800-989-2275
www.carlincombustion.com

If you would like copies of the above wiring diagrams please contact Carlin at 800-989-2275.