Circulator Speed?

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Kungur
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Post by Kungur » Tue. Dec. 27, 2022 8:49 am

As time passes I have forgotten why I did cer things when I installed my KA2! I retro fitted our home with radiant floor heating.
I have the circulators set on the Medium speed. But now can't remember why!
So with 3 speeds to select from whi h would be the "best" to use?
Thanks!

 
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Rob R.
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Post by Rob R. » Tue. Dec. 27, 2022 9:20 am

If your radiant install is typical with 300’ loops of 1/2” pex I would run the circulators on high.

 
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McGiever
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Post by McGiever » Tue. Dec. 27, 2022 10:21 am

K can you read your return water temperature?
20*F delta is ballpark.


 
Kungur
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Post by Kungur » Tue. Dec. 27, 2022 10:51 am

Rob, they are between 250&300'. I will bump it up to high.

 
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Lightning
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Post by Lightning » Tue. Dec. 27, 2022 11:29 am

Is there any cons to running it too fast?

 
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Rob R.
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Post by Rob R. » Tue. Dec. 27, 2022 12:26 pm

Lightning wrote:
Tue. Dec. 27, 2022 11:29 am
Is there any cons to running it too fast?
Waste of power and in extreme cases erosion at fittings, etc.


 
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davidmcbeth3
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Post by davidmcbeth3 » Tue. Dec. 27, 2022 12:41 pm

And what is the GPM difference between the 3 settings ?

Faster = more heat capacity of system I would assume

 
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Rob R.
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Post by Rob R. » Tue. Dec. 27, 2022 1:07 pm

It depends on how many loops you have and what circulator you are using, but you can get an idea by look at the pump curve chart for a common circulator like a Grundfos 15-58.

For a radiant floor you want to make sure you have enough flow to have an even temperature, otherwise you will notice some areas warmer than others when walking around barefoot. My kitchen has 4 300' loops of 1/2" pex in the concrete slab, and even with the Grundfos circulator on high I only observe about 0.5 gpm through each loop. I calculated that the circuit should have about 10 ft of pump head, but in practice it seems to be higher.

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