variable speed injection for radiant

[jgcool]

My plumber installed a brand new Buderus oil fired boiler with a Logamatic R2107 controller and FM241 bd for secondary low temp radiant heating. The system consists of a primary/secondary loop with an injection pump into the secondary low temp radiant loop. What he did not realize is that the FM241 can only control a mixing valve and not control the speed of the mixing pump. He is not suggesting to use a Tekmar356 to control the speed of the mixing pump instead of installing a motorized mixing valve. Any issues with this solution. Tks.

[SolarMike]

I would use the Tekmar as, i assume, it is all installed. As an option get a 3 or 4 way mixing valve, use the buderus control and call it a day. You still have the higher temp for the primary heat, whatever that will be.

[STEVEusaPA]

its 50/50. Pay for the new control, which will work fine, or go with the mixing valve. I think the plumber should put in the mixing valve, and pay for the labor, or buy you the tekmar, it was his oversight

[bobboan]

Using v.s. injection may require re-piping and an additional circ. It is, however, the best method of controlling a radiant slab.

[bobboan]

Second attempt to attach file.

[STEVEusaPA]

If you follow the Tekmar PDF, take special note, and follow, the piping notes regarding spacing, how many pipe diameters from elbow, etc.