Outside Air Reset Controllers

sopcopotoptop

I have a Weil-McClain HE-6 hot water boiler on a single zone primary/secondary circulating gravity conversion system. The boiler is ran by a Honeywell 8910U Hot Surface Ignition controller. I would like to add an outdoor air reset, particularly the wireless Honeywell W8735ER1000 or equivalent controller. I don’t believe my current ignition controller is enabled for outdoor air reset control. Any suggestions in upgrading? Thank you.

EdTheHeaterMan

the W8735ER1000 gets connected to the aquastat. the S8910U is not an aquastat, it is an ignition control. The HE boilers came in several versions, what Series is your HE boiler, that will let us know if you have a compatible aquastat for that reset control. or perhaps suggest a different one

sopcopotoptop

The boiler was installed in the fall of 1993 and the tag is very faded but I’ll try to read the series number tonight and I think I still have the book as well. Thanks so far.

EdTheHeaterMan

If it is a series 3 then you may have the boiler control that all the controls are connected to like this

This would be your wiring diagram for a Tekmar 256

 If you have an earlier version, then the S8910U control is not the original ignition control. That boiler may have had the obsolete Fenwal control that is no longer available (out of production). In that case you have a different diagram on your boiler.  More like this one. And there should be a sticker added for the S8610U, but it may not be there.

When you get home, look at the boiler to see if there is a wiring diagram on the inside of the front cover. A picture of that diagram will help.

EdTheHeaterMan

https://www.supplyhouse.com/Tekmar-256-Boiler-Control-One-Stage-Boiler-4150000-p

This control has warm weather shut down WWSD and boiler minimum temperature settings that are important to keep the flue gs from condensing and causing damage to the vent system and the cast iron boiler sections.

sopcopotoptop

It is a Series 3 and the ignition controller is later…the second or third one in 30 years.

sopcopotoptop

sopcopotoptop

EdTheHeaterMan

Your diagram is easier to read than the one from the WM website I used. You did have the Fenwal Control originally as expected

Here is your new wiring diagram with the S8910U and the Tekmar 256. Print it out and tape it to your boiler somewhere.

The instructions for Tekmar are somewhat ambiguous until you understand the way they draw the diagrams. I have included ALL the wires in my diagram, and do not assume you know where the missing ones go.

 The Honeywell S8910U has all the same wires as the Fenwal but Fenwal combines some of the (GND) wires so there are only 2 (GND) on the Fenwal but there are 3 on the Honeywell.  Don't worry about that, because the 3 (GND) lugs on the Honeywell control are connected internally. So you only need to connect one of them.  I included all three in the event your boiler is connected that way

sopcopotoptop

Thank you much Ed! This is very helpful and I shouldn’t have any issues. You’ve laid it out beautifully!