Circulator selection

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I am tearing out my existing hydronic system in the boiler room. Short answer to why? Copper piping looks like crap because of bad batch of antifreeze and no support from crimp tool manufacturer or antifreeze manufacturer. Second Aluminum boiler core failure. Manifolds failing with no manufacturer support for parts. How do I love this! Winter commeth.

All Copper will be replaced. Some alterations will be made on the Copper design and attached devices to improve performance, usability, and eliminating butt ugly seeping press fit joints used for the expensive piping.

System flushing (again), cleaner, and corrosion preventive material (per WM) will be applied.

Overall, there is a possible 6500 sq ft of in-floor/slab heated space. Heavily insulated in a Pacific NW climate. This includes a green house not built and two garages not heated, and a basement not heated. System has worked well for 10+years except for components failing. More than half of that area has never been heated.

A lo0p off the primary controls a large priority DHW tank. This uses a Grundfoss fixed speed pump.

And now:

New boiler will be a WM EVG 110 with a stainless steel heat exchanger. Appropriate alterations will be made to fit in the existing boiler location. The EVG includes a Taco circulator. Actual model of pump not known. I would like to know; but I have not found the answer. I am hoping it is a VR1816.

The system is primary/secondary. The new EVG circulator will run the primary loop. A separate secondary loop pump is attached to the primary loop and services the DHW. This will not be altered.

There is a large buffer tank between the boiler and the heat distribution part of the system. Many individual loops controlled by motor (thermal devices) controlled by a Tekmar control system. Overall, this will not be altered. A Grundfos fixed speed pump transfers heat from the primary loop to the buffer tank.

The buffer tank is monitored by the Tekmar controllers.

The large secondary loop has 6 taps for heating loops. These secondary loops are driven by a Grundfoss pump that was put in to handle the entire distribution system. Since only about 40% of water flow is actually used, this pump is vastly over kill.

I originally wanted a Taco Veridian pump here, but they were not ready yet. Now they are. As well as some competitors.

If you are still reading this; there are pumping questions. And the basic reason I am posting this.

It seems to me that the circuit between the primary loop and the buffer tank requires a smarter approach to pump circulation and water temperature management. The effectiveness of the current fixed speed pump between the primary loop and the buffer tank would seem to be in question.

The fixed speed pump in the large secondary really needs supervision. There is currently a pressure management device at the end of the big loop. I have never believed it was doing anything useful. I simply can not see the information on the bypass device adjustments. It is behind a bunch of stuff. Playing with it has not been useful.

So we are now to the crux of the issue. You probably thought we would never get here. Thanks for the persistence.

I am down to two alternatives for the pump in the secondary feed loop for all the loops. I want to remove the way over capacity Grundfos pump. There are, in my mind, two major contenders for replacing the existing pump. The Taco VR1816 and the Grundfos Alpha2.

Both of these pumps are pretty much the same until we get to the issue of smart control. The Alpha2 has an additional function that appears to be a good thing, not handled by the Taco. Each pump supports fixed selections of pump parameters, but the Alpha2 claims to provide an additional intelligent solution which the Taco does not.

It would appear to me that the Alpha2 approach provides a more effective approach to flow regulation. I have not found real detail information on how this works. If the Grundfos is sufficiently clever, it would win. Both Taco and Grundfoss are a bit information deficient. The apparent approach is significant enough to specify the Alpha2.

Is there anyone out there that can provide an evaluation of the Taco vs the Grundfos in terms of selecting a solution. I am currently leaning toward the Grundfos (ignoring the price differential).
 

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Follow up of my own question.

The circulators will be AquaMotion AM55 pumps.

The Alpha2 has a magic function selection. I am unable to see the merit. It wants to nose around your system for a week or two and then it will adjust to your usage pattern. That just does not seem right. A variable speed pump here needs to respond to continuous changes; not how it used to be a week ago. In many systems (including mine) I am thinking there are no "patterns of usage. So, out of the competition.

Taco VT1816. This was my initial selection. I don't think you can go wrong with this one.

However, the AM55 became my favorite. If you go to their web site, look at the curves. They have selectable fixed speed choices. They can do a bit more pressure vs flow range than the same thing in Taco. But look at their curves for variable speed. Interesting. The AM55 pump has what I perceive as more robust materials used. And easier to fix if it needs it. They are not really generous on describing things. The company is relatively new. It is pretty much a bunch of ex-Taco people that wanted to do it better.
 
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