Options for humidity sensor or exhausts with heater + humidity sensor

5 years ago

last modified: 5 years ago

We are rebuilding our home and I really like the idea of having bathroom exhausts with heater. I have one in my current home and everyone wants to take a shower in that bathroom :)

I was planning to use the following that had everything until my contractor told me that legally I need one with humidity sensor (I am in CA where they have special requirements for everything!) https://www.homedepot.com/p/Panasonic-WhisperWarm-110-CFM-Ceiling-Exhaust-Bath-Fan-with-Light-and-Heater-FV-11VHL2/203762030 - for master which is bigger

https://www.homedepot.com/p/Delta-Breez-Radiance-Series-80-CFM-Ceiling-Bathroom-Exhaust-Fan-with-Light-and-Heater-RAD80L/205088881 - for kids bath that are 8X5

I cannot find any exhaust with heater and sensor both, so I explored the option of installing sensor separately, but there was none that had even decent reviews. I read some options about other means of heating the bathroom, but we have really small bathrooms so I really didn't want to have multiple units in there. I am hoping some experts here have better suggestions.

- For California, is humidity sensor really required by law? If yes, do I even need one for powder bath (with no shower) and master toilet (which is a small enclosed room by itself)

- Is humidity sensor required even with the heater combo? (Just hoping someone gives an answer I am hoping for ;)

Thanks so much!

Featured Answer

Mini-Split Warehouse

3 years ago

HUMIDITY SENSOR:

Fundamental vs. Secondary

https://www.centralacwarehouse.com/

Fundamental measurement devices depend on some intrinsic physical phenomenon to provide consistent, high performance measurement. In the world of humidity, chilled mirror hygrometers achieve this by controlling the temperature of a surface so that condensation remains in an equilibrium state on that surface. The temperature of the surface is measured, yielding a very accurate dewpoint measurement expressed in the International System of Units.

By contrast, the capacitive humidity sensor is a secondary device. It relies on a dielectric material and how that material changes as a function of relative humidity. The dielectric material can be “fooled” into responding to substances other than water vapor, and it can drift over time due for a variety of reasons. The tradeoff between the two technologies: users of capacitive sensors sacrifice some performance for price, simplicity and ease of use.

Simplicity

Capacitive humidity sensors are simple. They consist of two plates sandwiching a dielectric material. Each plate has a “leg” for an electrical connection. The sensor is attached to an appropriate device for measuring capacitance. What could be easier? Well, it’s not really that easy. First of all, the plates have to be permeable to water vapor or the response time of the sensor would be far too slow. The plates are typically very thin layers of metal, often sputtered onto a base material. This requires sophisticated equipment and process knowledge. Some sensors are manufactured in clean rooms to obtain uniformity and consistency. This is not simple. Furthermore, the actual change in the sensor’s capacitance is quite small over the humidity range of 10 - 90%. Electronic circuits for measuring the sensor have to be designed carefully to measure this small change, and stray capacitance has to be eliminated in all wiring that connects the sensor to the electronics. These are not issues for users, but knowledge of these details might help users understand the differences in price and performance between instruments that appear to be the same.

Contamination

All humidity sensors must be in contact with the gas that they measure. Anything in the gas that “disagrees” with the sensor can alter the sensor’s performance. For example, small oil droplets in aerosol form can coat the sensor, forming a barrier that limits water vapor permeability. Dust can accumulate on the sensor with a similar effect. The most difficult contaminants are chemicals that interfere with or change the nature of the dielectric material.

https://www.ductless-mini-split-air-conditioner.org/

These contaminants can be sneaky. When the sensor is exposed to them, they create measurement error. In some cases, when the sensor is removed from service for calibration, the contaminants may outgas and the measurement error disappears. Other contaminants may cause permanent damage to the dielectric. Sensors from different manufacturers may react differently because of differences in dielectric material or sensor design. All sensors have strengths and weaknesses when it comes to contamination, but sorting them out is nearly impossible without direct testing. This is the nature of capacitive humidity sensors. Unfortunately, every humidity measurement technology is also subject to degradation due to contamination.

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Comments (19)

wdccruise
5 years ago
last modified: 5 years ago
- Per Air King, here are the requirements for a ventilation fan that meets CA Title 24.
- The fans have to be Energy Star.
- The fans have to be controlled by a humidistat.
- Here are the Energy Star fans and the Energy Star 2019 fans.
- As far as I can tell there are no Energy Star fans that contain heaters.
Pooja Maheshwari
Original Author
5 years ago
Thanks so much Lawrence for pointing me to the right information. I couldn't find it with my searches.
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my contractor told me when we start in may we can finalize location and what units i want. i guess that means everything is in stock, no supply issues. he said i def dont need a light on it because of the lights he will be installing above the shower, the tub, and then the vanity has 2 sets of lights. so i can get just a humidity sensor fan. so if you have specific models you are happy with id appreciate those numbers.i see people mentioning panasonic whisper and appreciate it i need to delve into manuals to see but i was wondering if the fans also have manual override to turn them on for X minutes then turn off. since my fan will be near my window (joist issues) i was thinking if i found a suitable heater i could mount it in the center of the room. even if it had a fan i guess just not wire up the fan. ive seen heaters with lights but since i dont need a light. thats kinda pointless.
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Nancy in Mich
5 years ago
If it helps you at all, here is a heating alternative that we are loving here at our house.
See the white panel up by the ceiling, above the door? It is a cove heater. It is an electric heater that is run with a thermostat. Hard wired, so you need an empty slot on your electrical panel (or two slots if you want the money-saving 240 volt version). It silently radiates heat down into the room, much like sunshine does, heating up objects in the room. If it is on and you stand still, you soon feel that the side facing the heater is getting warm. We leave the room door closed now and the thermostat set for 72 degrees (the rest of the house is 64 to 68 degrees, depending on the time of day). When you need to disrobe, it is toasty! I have no idea if this is okay in California. We also have a Panasonic fan with both the humidistat and motion sensor. Comfort Cove Heater
Pooja Maheshwari
Original Author
5 years ago
Thanks Nancy! Never knew about cove heaters. Glad to hear you love it. I will check with our contractor regarding this.
catbuilder
5 years ago
DewStop switches work great.
wdccruise
5 years ago
last modified: 5 years ago
You can always just install a simple infrared bulb heater. (I'd put it on a timer.)
Nancy in Mich
5 years ago
I almost went with the infrared bulb heater. When my contractor said we could eliminate the soffit above the vanity, though, we had room for the smallest cove heater. It is my experience that the infrared bulb heats you up if you are standing under it. It probably will dry your hair really well, too! The cove heater heats the objects in the room, so the whole room becomes warm.
wdccruise
5 years ago
If your vanity sits on the floor, you could put a kick space heater under it.
Pooja Maheshwari thanked wdccruise
pattyl11
5 years ago
last modified: 5 years ago
https://na.panasonic.com/us/home-and-building-solutions/ventilation-indoor-air-quality/ventilation-controls-switches-3

https://na.panasonic.com/us/home-and-building-solutions/ventilation-indoor-air-quality/ventilation-controls-switches-1

Condensation Sensor Plus FV-WCCS1W Dew Point Sensing, On/Off Wall Control, White Wall Plate Included

The Condensation Sensor Plus is the next generation in moisture control and healthy indoor air technology. Condensation Sensor Plus works with any single speed vent fan, automatically turning the fan ‘on’ before condensation forms, and off when the room returns to the optimum dryness level. Unlike competitive units that only monitor humidity levels, the Condensation Sensor Plus features advanced, built-in intelligence that monitors both temperature and humidity — actually anticipating the dew point — making it the most effective, proactive solution on the market. Additional features include a blue LED light to indicate when the fan is on and a matching wall plate for a decora style design. Can be used to comply with ASHRAE 62.2, LEED, CALGreen, and ENERGY STAR® 3.0
catbuilder
5 years ago
Those Panasonic switches are actually DewStop switches with a Panasonic label slapped on and the price tag to match.
Pooja Maheshwari thanked catbuilder
dchall_san_antonio
5 years ago
If I ever think about moving back to California, someone please slap me. I can't believe they mandated a humidistat.

Living in Texas, in the influence of the Gulf weather, I just leave the ceiling fan on 365/7.
Nancy in Mich
5 years ago
dchall, sometimes you actually need to remove that moist air from the home, not just move it around.
Pooja Maheshwari
Original Author
5 years ago
Lawrence, thanks for suggesting so many options! Really appreciate it! We did think about an infrared bulb heater (rather preferred it more at some point), but then thought it might look dated. Was a little nervous about any safety issues kick space heater with little kids around etc. Will discuss again with my husband and contractor.
Pooja Maheshwari
Original Author
5 years ago
pattyl11 - thanks for the links. Is Panasonic a brand you recommend if we do decide to go switch route. The reviews on Panasonic/Leviton etc seem to be really mixed.
Pooja Maheshwari
Original Author
5 years ago
catbuilder - haven't heard of dewstop switches. Is dewstop a brand?
Pooja Maheshwari
Original Author
5 years ago
dchall_san_antonio - humidistat and 1.8GPM showerheads just to name a few of crazy CA requirements :) People seem to cheat and work around inspections because of these.
pattyl11
5 years ago
pmgzb, I have no personal knowledge of this switch, sorry.
Pooja Maheshwari thanked pattyl11
catbuilder
5 years ago
DewStop is the company that makes the condensation-sensing switch. You can buy a DewStop directly from the company itself or from Amazon or hardware stores, Menards, etc. Or you can buy a Panasonic brand condensation-sensing switch, which is actually a DewStop switch (not a copy of one, or an upgrade of one, but it actually says DewStop on the switch) and pay a whole lot more for the privilege of saying you have a Panasonic switch. There is a timer on the switch, which you can adjust for the length of time you want it to run after it turns on. If it still senses moisture after the time elapses, it will stay on for that period of time again. You can also turn it on manually if you like.

Options for humidity sensor or exhausts with heater + humidity sensor

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wdccruise

Pooja Maheshwari
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Options for humidity sensor or exhausts with heater + humidity sensor

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