6 Zone Valve Control Module with Priority - Expandable

The Tekmar system worked very well for all these years only a few minor replacements. I could not expand the unit any more, like changing to programmable thermostats etc. So I went to a trade show and spoke to both reps, can't tell you the difference in both companies attitudes, I will not go further with this. Spoke to Taco, did my research, found Taco was less expensive with quality. Technical support was great and the ZVC406 was exactly what I needed and was easy to install. I can pick and choose what thermostats I want to pair up to the unit and will eventually buy the outdoor indoor sensor. Oh,and your company is always right on target.

I used this control ZVC406-EXP and ZVC404-EXP for a 10 unit building with ten separate zone valves and PC700 boiler reset. After changing all the values, installing new t-stats, controls and reset I found out that my pump runs even if outdoor reset temperature is not met. I contacted Taco and they said this is normal operation "the control will not fire the boiler however the valve(s) or pump will run because a demand is present. No one typically would turn the heat on if it was 80F outside". If one of the units has their t-stat set to call for heat the pump will run regardless of out door temperature. This can easily happen in a multi unit building if tenants accidentally set or change t-stat. Let me make that clear, if it's 80 degrees, middle of summer, with a reset of 60 degrees and one of your t-stats happens to be calling for heat, your pump will run all summer. What good is this reset? This is not standard operation for other controls, Tekmar control does not operate like this. Don't purchase this control. Some of these reviews look suspect to me. Taco service was not helpful. Valves seem okay, but I'm waiting for that gotcha.