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Manually Adjustable Humidistat for Power Vents

$3878
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  • Adjustable humidistat
  • Suitable for all Master Flow brand power attic fans
  • Pre-wired for installation
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Product Details

The GAF Master Flow Adjustable Humidistat is used with all GAF Master Flow power vents. The humidistat helps reduce the likelihood of damaging moisture or heat from accumulating in your attic. Manually adjustable for varying climate conditions.
  • Humidity-activated humidistat can be adapted to accommodate all climate conditions
  • Designed for use with all GAF Master Flow and LL Building Products power vents
  • For use with power ventilators rated not more than 7.5Amps
  • Constructed from galvanized steel for a durable design
  • Manually adjustable setting from Stop to 20% humidity
  • Pre-wired for simple installation
  • Return Policy

Additional Resources

From the Manufacturer

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Specifications

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Questions & Answers

18Questions
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Q:Do I need to install it parallel to the thermostat?
by|Apr 26, 2020
2 Answers
Answer This Question

A:  Yes, you can email warrantyllbp@gaf.com and request wiring instructions. If you have any other inquiries about our Master Flow products please call Technical Services at 800-211-9612.

by|Aug 29, 2022
    1 found this answer helpful

    A:  It depends on how you want it function with the thermostat. If you want to turn on the fan with either the humidistat OR the thermostat then wire them in parallel. Wire them in series if you need both humidity and temperature threshold met (logical AND condition).

    by|Oct 12, 2022
      1 found this answer helpful
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      Q:Does this turn on when the Humidlty gets over the setting on when the Humidity gets under the setting
      by|Apr 8, 2020
      5 Answers
      Answer This Question

      A:  When it gets over the setting

      by|Apr 9, 2020

      A:  Over.

      by|Apr 9, 2020

        A:  It will turn on when the humidity level rises above the setting

        by|Apr 9, 2020

          A:  When set this switch will turn the fan, or whatever device is wired to it, on when the humidity reaches that point. Example: if you install this switch in a crawl space, set it to 60% and wire a crawl space vent fan to it, the fan will turn on at the 60% humidity level and stay on until the humidity level drops below 60% automatically.

          by|Feb 12, 2021
            2 found this answer helpful

            A:  This will turn on the fan when the humidity reaches the set point and will run until it is approximately 10 % below the set point. If you have any other inquiries about our Master Flow products please call Technical Services at 800-211-9612.

            by|Mar 22, 2021
              3 found this answer helpful
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              Q:Can this humidistat control be added to a Master Flow model 1600 powered ventilator unit that no...
              by|Feb 2, 2019
              3 Answers
              Answer This Question

              A:  Yes you can add the H1 to any of the Master Flow Power attic Fans. You could also replace the thermostat with the HT1 Thermostat/Humidistat Combo Unit. If you have any other inquiries about our Master Flow products please call Technical Services at 800-211-9612.

              by|Feb 4, 2019

                A:  Yes. If you want the fam to work only for humidity and not for temp then set the temp level on the fan to the highest setting.

                by|Apr 9, 2020

                  A:  The fan pulls 1.65 amps with a 1/9th horsepower motor. Yes, this humistat will work with this fan. Remember though, a humistat is a moisture control switch, works when the humidity reaches a certain percentage, not temperature. If you are looking to control crawl space moisture levels I'd pair this switch with a couple of foundation vent fans.

                  by|Feb 4, 2019
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                    Q:Why do fans run 24/7 or off 24/7? Can't find happy medium for crawl space.
                    by|Oct 3, 2018
                    5 Answers
                    Answer This Question

                    A:  well mine runs when humidity is high might run for two three days, when dry its off that is what it should do. but i am no expert...

                    by|Apr 15, 2019
                      1 found this answer helpful

                      A:  The fan will run, as necessary, trying to get the humidity down to what is selected. If the ambient humidity is high it takes longer. Also, if there is a lot of humidity coming up from the ground it will contribute to the ambient humidity, again, requiring the fan to run longer. Once the value, selected, is reached it might take a while for it to build up enough for the fan to restart. I see the same thing with mine. I just let it do its thing.

                      by|Oct 8, 2018

                        A:  Humidistats are made to work with one fan. Should you have any further questions, please contact Master Flow Technical Support at 1-800-211-9612.

                        by|Oct 3, 2018

                          A:  My setup has two humidistats. The first is at the "intake" side of the house and does not supply power to the second humidistat if the outside humidity is above a certain percentage since you don't want to pull in more humid air. So the first gate only opens when humidity is at a certain level outside to allow the second one to engage the fans and vent the crawlspace by pulling in less humid air. In your case, it may be running continuously because the outside air being pulled in is also more humid than the setting which will make things run continuously until the outside air humidity drops.

                          by|May 18, 2020
                            1 found this answer helpful

                            A:  One, make sure you have a 6 mil vapor barrier installed over the crawl space soil. Two, set the thermostat on 60%. If your fans are running 24/7 7 days a week you have: 1. Not enough foundation vents to allow the proper air flow through your crawl space. 2. A moisture or water penetration issue that needs further remediation by a licensed professional - your house is set low or the grading around your house is improperly done allowing rainfall to flow to and under your house.

                            by|Aug 7, 2021
                              2 found this answer helpful
                              Showing 1-4 of 18
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                              Customer Reviews

                              4 out of 5
                              (24)
                              • 4
                                out of 24 reviews
                              • 86%recommend this product
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                              Showing 1-10 of 24 reviews
                              Humidistat integrates and works perfectly with a Masterflow fan. ...
                              Humidistat integrates and works perfectly with a Masterflow fan. Call Masterflow to get the specs to connect the wiring properly - it can be tricky otherwise.
                              by
                              Response from Master FlowMay 2, 2022
                              Thank you for the feedback. Glad you were satisfied with your Master Flow purchase. MasterFlow
                                IS NOT PRE WIRED !!!!...
                                IS NOT PRE WIRED !!!!
                                by
                                Response from Master FlowSep 27, 2021
                                Please give us a call at 1-800-211-9612 and we can walk you through properly wiring this unit. MasterFlow
                                  Rating provided by a verified purchaser...
                                  Rating provided by a verified purchaser
                                  by
                                  Response from Master FlowOct 4, 2022
                                  Thanks for the feedback. Glad you were satisfied with your Master Flow purchase. MasterFlow
                                  • Verified Purchase
                                  screws protrude out the back, so surface-mount requires considerations. Seems...
                                  screws protrude out the back, so surface-mount requires considerations. Seems to work fine.
                                  by
                                  • Verified Purchase
                                  Rating provided by a verified purchaser...
                                  Rating provided by a verified purchaser
                                  by
                                  • Verified Purchase
                                  Hookup is easy and works very well....
                                  Hookup is easy and works very well.
                                  by
                                  • Verified Purchase
                                  The humidistat works great. It was easy to install...
                                  The humidistat works great. It was easy to install and it seems to work great.
                                  by
                                  • Verified Purchase
                                  1 found this review helpful
                                  I installed one of these a couple of weeks ago and subsequently found that it had no variability ...
                                  I installed one of these a couple of weeks ago and subsequently found that it had no variability as claimed, but is instead frozen at around 40% humidity, which renders it useless for automatically controlling a crawl space vent fan, since the humidity will never get that low to turn the fan off except during the most extreme winter weather. I contacted the vendor's tech support email and got no response. I ordered another one and installed it only to find that the second one had the same problem, except frozen at around 55% - still too low to be useful as an automatic crawl space vent fan controller. In looking over the reviews I see that others are having the same problem. In both cases I tested over a period of hours using a hygrometer to verify ambient humidity, just in case these were some unusually slow reacting humidity sensors. No change of switching point in either case, 40% for the one and 55% for the other, with crawl space humidity readings between 70 and 90%. This is a difficult installation in a shallow crawl space, taking significant chunks out of what paltry bit of free time I have, and it is very frustrating to have to go through the whole thing twice with the result of facing a third installation and tying up more time. I'm going to return them both and will be avoiding this brand going forward.
                                  by
                                    2 found this review helpful
                                    Was used and did not work. Looked new till...
                                    Was used and did not work. Looked new till you opened it. Extra Holes drilled in bottom with no order and shavings left in. No ground screw. After checking it, was a thermostat but marked as a humidistat. I lost time and money on this for a job. I had to order this.
                                    by
                                    • Verified Purchase
                                    Couldn't get Humidistat to work. No matter what setting fans...
                                    Couldn't get Humidistat to work. No matter what setting fans would run 24/7 or off 24/7. Master Flo said you need one for each fan. Must not be able to monitor whole crawl space by using one because specs are it can handle a 6.5 amp load. My total load amounted to a little over 2 amp. Used the CMF formula to move air needed in description and using more I'm than double required
                                    by
                                    • Verified Purchase
                                    Showing 1-10 of 24 reviews

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