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Aprilaire 700m + Nest (without humidistat and transformer)

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02-12-18, 08:42 AM

mikkadim

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Aprilaire 700m + Nest (without humidistat and transformer)

Trying to understand the right way to connect Aprilaire 700M without humidistat to Nest 3.0,
and a bit confused about relay, should I used or not. Found two schematic on this site:

From here: https://www.doityourself.com/forum/h...ml#post2282604

PS: Have a ordinary HVAC control board HK42FZ047(CEPL131011) with has HUM 24VAC 0.5A terminal.
Thank you.

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02-12-18, 08:53 AM

PJmax

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There are two 700 models. Makes for some confusion.
Plug yours into the wall. Short the two solenoid wires that get connected to the humidistat. Does the unit start to run ? It doesn't have to be connected to water for this test.

If shorting the wires turns the unit on.... you need a relay.
Most likely yours is a newer style and nothing will happen which means you follow the bottom diagram. That doesn't require a relay.

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02-12-18, 08:59 AM

mikkadim

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Thanks PJmax for quick reply!

I have a new model (grey) and I tried to short solenoid wires - nothing happened.
So my concern is - is switch inside Nest powerful enough to handle solenoid and fan relay in 700M?

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02-12-18, 07:48 PM

PJmax

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Yes.... the nest can handle the switching fine. I believe the nest is rated for 1A or 24va of switching current. The 700m should use under 10va.

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