Wiring a Tekmar 256

[Dr Atomic]

New to this forum, thought I would throw this out there. I am planning to install a Tekmar 256 outdoor reset on my solid fuel boiler. The boiler has a honeywell 8124A on it and my zones are controlled with 845A's on circulator pumps for each zone. It's wired just like figure 6 in the 8124 manual.

My question specifically has to do with the boiler demand signal for the tekmar. It requires a 24-volt input on a switch that kicks in when the zone t-stat closes. What's the best way, if any, to get that out of an 845A? Do I wire my 845A's to handle two loads (1 120 for the circ, 1 24v for the boiler demand) like figure 8 in the 845A manual?

Or is there an easier way to get there? Thanks for any thoughts.

[kingsotall]

Tekmar reps are outstanding when it comes to service.

[geno54]

You would have to add a transformer off of the service switch to power the 256 then rewire your aux contact wiring through this transformer to energize the 256 when any of the zones calls. Then the 256 would bring on the boiler (8124A) through (5/6). If not done this way you may end up with crossed transformers as each of the 845's has there own. Crossed transformers tend to smoke a bit. Tekmar has some wiring diags to go by but did not see this one specifically. good luck