Injection issues

[Clarkbug]

You can get any of the pumps with a standard or rotated flange, just depends on the model number. I got those nifty Webstone isolation flanges that rotate, so you can use whatever. Havent had to use them yet for a pump change, but Ill bet they will be nice when I do.

One more thought... Rather than the balancing valve (which I know restricts the flow in your injection loop) what about partially closing a valve right after the pump? This would increase the head, reduce the flow, and potentially trick the controller into keeping things above 50% instead of the dip.

You are right that its potentially a hydronic issue coupled with the lower % driver of the pump. I would say to hook up the 008 to the controller without connecting it to the piping, and see if it will still spin at 30%. (Thats probably not so good for the pump unless you can hook it up to some temporary piping and pump into and out of a bucket or something). It might help isolate if its truly an electronics issue, or if the hydraulic effects of your system are also playing a large part.

 

[Chuckcrj]

That is a symptom of an oversized injection pump. The 15-58 has much more flow than necessary for the large temp delta you have (the difference between the source supply and the load return).

Try a taco 005. But first throttle down the valve on the supply side of the injection pump like Clarkbug suggested to see if this diagnosis is correct.

 

[Chuckcrj]

Or you could do it the easy way and install an ECM circulator with setpoint control such as the Taco Bumblebee. That pump will slow down all the way to a crawl if needed.

 

[Karl_northwind]

Or you could do it the easy way and install an ECM circulator with setpoint control such as the Taco Bumblebee. That pump will slow down all the way to a crawl if needed.

actually, you only get speed one, two, three or four. not less than speed one/curve one in the install manual. they aren't really variable speed, just 4 speed. at least that's my observation based on quite a few installs.

and you can't install an ECM circulator on a tekmar 356 style variable speed controller.

k

 

[Chuckcrj]

You wouldn't need the tekmar with the bumblebee. Set the pump for setpoint control, sensor on supply pipe to radiant heat.

It works the way you describe if put in CP mode, only runs on 4 speeds.

In setpoint mode it works very well for injection mixing, no 3rd party control needed.

It just isn't a great idea to try and vary the speed of a PSC motor, shortens motor life.

 

[Smoothride]

I just finished installing the Taco PC705-2…same as the Tekmar. First…it requires a certain style capacitor motor. The Taco 008 works. Second, the variable speed controller may not give enough juice to the injection pump motor to over come the head/distance from the storage tank to the system loop. If the tank loop circ pushed all the way to the system loop and then you had the injection there, the low speed/voltage could overcome the head and not stall. Use the storage circa to move the water the distance and the variable speed circa for just injection. Pumps also like to push rather than suck.

 

[Karl_northwind]

You wouldn't need the tekmar with the bumblebee. Set the pump for setpoint control, sensor on supply pipe to radiant heat.

It works the way you describe if put in CP mode, only runs on 4 speeds.

In setpoint mode it works very well for injection mixing, no 3rd party control needed.

It just isn't a great idea to try and vary the speed of a PSC motor, shortens motor life.

In setpoint mode it may work just fine, but it still only operates in speed 1, 2, 3, or 4, not infinitely variable as with an injection control. you still need to power or un-power it for mixing, and you get no outdoor reset function in that configuration. if speed 1 is too high and delivers too hot of water to the primary loop under certain conditions, you are stuck. not saying it won't work, just that I'll probably stick with the 356 and an $85 circulator rather than a $200 circulator.