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[juddspaintballs]

New house, new setup, lots of my old installed parts reused.  I have a Grundfos 26-99 (3 speed) or a Taco 007 (stainless) to choose from.  My boiler is 25' from the house, I'm using 32mm Logstor.  I'm feeding a 20x20 heat exchanger and a sidearm exchanger.  From the basement penetration to the two exchangers is about 20', and that will be plumbed in 1" PEX.  One big loop.  There's a few 90's in the mix, but nothing too crazy.

I *think* the 007 will supply enough flow to be adequate.  My concern is that it's internal bore is about that of 1" copper's ID, whereas the 26-99 is a lot larger.  Eventually, I'm upsizing the heating in this house with radiant floor heat, and I may even heat my detached garage at some point.  This setup is long-term temporary, if that makes sense.

I was initially going to go with the 007, but now I'm leaning towards the 26-99 running on low.  My last house had a much bigger heat requirement from a longer run (~85') of 1-1/4 PEX and that pump on low was more than enough to get the job done there. 

Thoughts?

I'm not buying a new pump anytime soon.  I want to use what I have for now. 

[willieG]

if you already have both the pumps, install valves on both sides of the pump so changing a pump is  "no big deal"
 

[RSI]

I would try the 007. Doesn't sound like you will have much head pressure.

[juddspaintballs]

007 it is.  There's only a 1/8" difference in the width of the pumps flange to flange, so switching between the two should be easy.  I'm obviously going to be using valved flanges.  Not having a valve on both sides is borderline stupid. 

[Sloppy_Snood]

Not having a valve on both sides is borderline stupid.

Hilariously true. 

[juddspaintballs]

It's been 65+ the past three days.  I shut my boiler down because of that.  I took advantage of the warm weather and switched over to my Grundfos 26-99 pump.  I think the Taco 007 was just a touch too small since my temp gauges showed the return line at the top of the boiler being a couple degrees hotter than the supply line off of the bottom of the boiler.  I don't think the 007 was flowing enough to mix the water in the water jacket thoroughly, but it was supplying plenty of heat for my house at least.  I'll keep it as an emergency backup and run the 26-99 on low until it dies.  I'll probably look for a smaller Grundfos pump after the 26-99 dies to save some money on electricity, but for now I'll use what I have.