Outdoor reset Tekmar to Taco ECM?

marcomjl

Hi, I have a radiant pex between the joist floor system powered by a heat exchange to 3 way taco manually set mixing valve to a Taco ECM vt2218 pump to 4 zone valves controlled by a taco zone controler. Looking into an outdoor reset setup. Interested in the Tekmar 256 or 356. Looking for others experiences with these or similar.

The tekmar 256 would only turn on the pump on/off. The 356 would additionally control its speed.

I spoke with tekmar and the issue is that the 356 controls only 3 speed wet rotor pumps, not the ecm variable pumps (unless I turn off the ecm function which would make this pump a non ecm pump). Also I might have to change the mixing valve for the 356 to control?


Any input? Just trying to get the most economical but efficient outdoor reset setup.

Zman

Have you looked into the Taco I series? You can do outdoor reset without the extra pump.
Injection mixing works OK, it can be a pain to balance out so it doesn't over/under shoot.

Dave H_2

marcomjl

Unfortunately, you will not be able to use an ECM style circulator for variable speed injection mixing by using an external controller that is going to chop the sine wave of the AC going to that circulator. ECM circs need the 120 AC power not changed in order to work properly.

As Zman said above, your best bet would be the i-series mixing valve. This valve has the controller built right into the power head, so no external controller needed. All you need is a source of 24 volt power and it fits exactly into the space that is there with the thermostatic mixing valve.
It will give you the outdoor reset control of water temperature that you want. taco-hvac.com/products/systems/radiant_systems/pressure_valves/i_series_mixing_valves/index.html

I currently have two in my house, both with variable speed circs, one VT2218 and the other with a 006-VDT


Dave H

marcomjl

Just read up on the Taco I-series and Dave H that's much simpler than what tekmar was suggesting.

How is the tuning/balancing on the mixing valve so it doesn't under/over shoot like Zman mentioned?

Dave H_2

There is a reset curve you can use for fine tuning and then there are a couple of dip switches that you program min and max water temps.

Zman

marcomjl said:

Just read up on the Taco I-series and Dave H that's much simpler than what tekmar was suggesting.

How is the tuning/balancing on the mixing valve so it doesn't under/over shoot like Zman mentioned?

The nice thing about the packaged valve/control is that Taco took care of that for you.

Do pay attention to the CV values for any mixing valve. Taco provides a chart to assist with sizing in their installation manual.

marcomjl

Nice, thank you guys. I guess it was good all my components are in the Taco family. That and the main headquarters is 10 mins from me. Lol