Model # H1

Internet #100023416

Store SKU #144657

Master Flow Manually Adjustable Humidistat for Power Vents

Master Flow

Manually Adjustable Humidistat for Power Vents

  • Adjustable Humidistat
  • Used with Master Flow Brand PG and PR Series Power Ventilators
  • Pre-wired for installation
$3027 /each
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Frequently Bought Together

Product Overview

Use the Master Flow Adjustable Humidistat with all 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 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




Warranty / Certifications

More Products With These Features


Customer Questions & Answers

How to set this Humidistat to run at 70%??

I installed this humidistat along with MasterFlow 1250 CFM Power Roof Mount Vent (Model # PR2DWW) with wires connection as directed on humidistat cover (white-white, black-black). I set the thermalstat to 105F and set the humidistat to 70% (as suggested). When temperature in attic above 105F, fan did NOT run. I had to tune the humidistat to DRY in order for fan to run. What should I do?
Asked by: sbinh
It sounds like you have the humidistat wired in series with the thermostat instead of in parallel with it. It is my understanding that the combined setup of those two control units, when properly wired, should create an either-or situation, meaning that if humidity gets above the set percentage and/or the temperature gets above the set level the appropriate control unit for that condition will energize the power vent's fan motor. You appear to have the humidistat wired so that it gets fed by the main power line but then the thermostat's main power input has been connected to (is being fed from) the humidistat's switched output instead of the thermostat's power input also being connected to (fed from) the main power line (you have them wired in series instead of parallel) so what's happening is that the thermostat isn't getting any power to be able to turn on the fan unless the humidistat's set percentage is already exceeded. Each unit has a power input connection and an internally switched output connection. Both units' electrical input needs main power, both units' switched output need to go to the fan.
Answered by: Hopethishelps
Date published: 2016-08-11

Will the H1 work to turn on a stand alone humidifier if the humidity drops below a certain level?

Asked by: Joe
No, other way around. Contacts close on rise
Answered by: goose
Date published: 2016-07-27

Is this wired in series or parallel with the fan's thermostat?

Asked by: LIShopper
done paralel
Answered by: goose
Date published: 2016-07-27

Which way do the contacts work? I want my fan to run when humidity is 40 percent or greater. I want to dehumitify

Asked by: Obie
Contacts close on rise. It will work for your app.
Answered by: goose
Date published: 2016-07-27
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Customer Reviews

Manually Adjustable Humidistat for Power Vents is rated 4.5 out of 5 by 8.
Rated 5 out of 5 by from 5 Star Review Rating provided by a verified purchaser
Date published: 2017-04-04
Rated 4 out of 5 by from Works as expected.... Works as expected.
Date published: 2017-06-13
Rated 5 out of 5 by from A "must purchase" for older homes This humidistat is a must have accessory for its matching gable mount attic fan which comes only with an adjustable thermostat. Especially in older homes with less or no attic insulation, it is critical to remove humidity which may leak from heated living spaces below into the attic during winter months. Unless this is done, damage to the underside of roofing underlayment will occur and it is conceivable that condensation and melting of ice formed inside the attic on roofing nails protruding through the underlayment will penetrate ceilings and leave water stains. My only issue with this humidistat unit is the wiring diagram stamped on the unit housing. It does not contemplate its use with a thermostat, so if one follows the diagram during installation the thermostat will not turn the fan on at the recommended 105 degrees in the Summer. Oddly, one must call the customer service number for the manufacturer and provide your email address at which they will email you the correct wiring diagram to connect the humidistat to the thermostat and allow them to work together properly. Seems to me it would be easier to just include a small paper insert in the box for either the thermostat or the humidistat to illustrate the combination set-up if you wish to use both units in series rather than the current "need-to-know" system.
Date published: 2016-08-17
Rated 5 out of 5 by from added to newly purchase attic ventilator Installation was made by a qualified electrician, but was quite simple. We did call the company to make sure how to properly wire it so the humidistat and thermostat worked separately. The instructions were not included for that. But, it works fine. It's come on several times in the early morning when it's very humid here in the South. I would definitely recommend including this if you install a thermostatically controlled attic ventilator fan.
Date published: 2016-08-10
Rated 4 out of 5 by from Worked well. The plastic grommet was different from a regular cable clamp but worked fine with th... Worked well. The plastic grommet was different from a regular cable clamp but worked fine with the armored cable coming from the motor. Very simple wiring and easy to install.
Date published: 2016-12-15
Rated 4 out of 5 by from not many to choose from. All that is needed for the application! What else besides t-stat is needed to control attic fan
Date published: 2016-07-12
Rated 5 out of 5 by from DUAL use! Great product! Let's you make DUAL use of your attic fan.
Date published: 2014-06-10
Rated 4 out of 5 by from great product Good product, easy to install, may need adjusting to your attic, buy over all OK.
Date published: 2015-11-10
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