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Navien NCB-240 Internal Circulator Variable or Single Speed
axeyal
Member Posts: 8
I'm trying to balance my Primary / Secondary flow and would like to understand if the internal circulator in the Navien NCB-240 runs on a single speed or does it have more than one speed to modulate with the firing rate?
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Comments
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It's probably single speed. Do you know what model the circ is?"If you can't explain it simply, you don't understand it well enough"
Albert Einstein0 -
Thanks Zman,
The model number is 30012768A Circulation Pump.0 -
Its 3 fixed speeds manually adjustable only. Similar to a grundfos 15-58 3 speed. Its flow rate is only good enough for about 7 Gpm max I think. So the flow is about 4-7gpm
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That’s one huge limitation of a combi. Depending on desired supply temp, the capacity is limited by primary loop flow. So if you have a bigger cast iron system and have lets say 14gpm on the secondary, if 150 gives you let’s say 15f delta t across the system and it comes back at 135f, you have to supply 165f water. Not a big deal but something to keep in mind.0
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The installation manual does not mention an adjustment on the circulator. That makes me believe it is a single speed. Do you have any documentation showing otherwise?motoguy128 said:Its 3 fixed speeds manually adjustable only. Similar to a grundfos 15-58 3 speed. Its flow rate is only good enough for about 7 Gpm max I think. So the flow is about 4-7gpm
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I read somewhere in this forum before that the flow rate of the circulator is 5gpm. I am getting lower water temperature reading at the secondary loop supply than the primary loop supply temperature on the boiler. This makes me think that I need to reduce the flow in the secondary loop so there is less mixing of return water across the closely spaced Ts0
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