Weil-McClain GV series system pumps and Tekmar Controls

convair580

A new GV series boiler for a heating system retrofit that I did on my home was installed, along with it was a tekmar 400 and tekmar 315 that we used for zone control. Baseboard heating, taco sentry zone valves with a separate system pump in addition to the system pump built into the GV series boiler. Originally I use just the 315, but the Tekmar rep talked me into a 400 as well for the outdoor reset. A new Taco Viridian pump is being used as a circulator on the supply side with Taco Sentry Zone valves. All is wired correctly, Taco Viridian pump comes on with a call for heat from the zone valves, boiler fires to target temperature and all appears to be working properly, no air in the system, etc.

Here is my difficulty that I am experiencing. TT from the boiler is wired to the 400 control on "stage 1" and this asks the boiler to fire based on outdoor temp and boiler temp, again all appears well from boiler firing, piping, etc. What is not happening is a good flow rate. Although I have chosen different speeds on the Viridian to get the desired effect I feel the most heat coming from the baseboard only when the integrated system pump on the GV is operating (call for heat) as soon as the boiler shuts down from a firing condition, you can FEEL the drop in the heat output at the fintube. Its still there, as the Viridian is trying to move the water, but is seems as if it is having a difficult time when the boiler pump is not operating. I dont THINK its an air problem, I have purged the system more than once, have coin vents at each downtown of the system, and vents at the top of the supply manifolds and return manifolds. As well as an air separator on top of the expansion tank.

There is no reason for this that I can come up with, as the return loop shares common piping with the supply (meaning it is not plumbed in such a fashion that it would be trapped in the boiler ) so Im wondering when you have a separate pump from the integrated GV pump is there a way to have it run when there is a zone call for heat as well? Or I am I doing something wrong. This is a very small system, 1700 Sqft home, with approximately 55 lineal feet of fin tube, and we are not using the DHW portion of the system at this time ( separate gas fired DHW heater). The GPM calcs match for the sytem pump, and there is no air in the system that I can find or hear that the air separator hasnt taken care of. FLuid is flowing, but moves much faster when the integrated GV pump is runnnig vs. just the Viridian when the boiler is not firing and the GV pump shuts down.

I'm probably not making much sense, but I certainly would appreciate any help anyone could offer.

CV580

EBEBRATT-Ed

We need pictures or a sketch of the piping to help you out

convair580

convair580

First pic is the integrated supply and pypass pump that are part of the GV series boiler
2nd is a overview of the piping, so is the 3rd. Supply header is coming off the boiler from the right and goes through air separator to expansion tank to Viridian pump then up supply manifold to zone valves, return manifold is pictured to the left.

Last is my messy wiring, it was all cleaned up until I started troubleshooting. I'll see if I can come up with my piping schematic, wiring is as described in the Tekmar 400 manual.

Thanks for taking the time to respond. I purged it again, at a higher pressure to make sure that i had no air starting with the highes zone valve and working my way down.

convair580