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View Full Version : Put humidistat on timer?


lastlight
11-03-2011, 06:07 AM
So my humidistat is connected direct to the power and fan like you'd normally expect it to be. Is there a device I can put inbetween the two so I can avoid the thing starting/stopping so often?

I guess I could splice the power into one of my indoor/outdoor timers I have kicking around and then wire the fan to a plug-end and insert that into the timer's outlet. Looking to see if there is a better device/way first though...

wingedfish
11-03-2011, 12:59 PM
No cheap delay on make/break timers that can be used with that kind of load. What is your humidity? Depending on the vintage of your home, when your exhaust fan comes on it can be interlocked to the furnace fan also. Is this so?

I would try another dehumidistat. They are far from accurate.

lastlight
11-03-2011, 02:39 PM
I'm not sure my question was clear here.

I have one of these wired to a dedicated fishroom fan (bathroom fan):

http://img.ehowcdn.com/article-page-main/ehow/images/a04/oq/ff/a-humidistat-work-800x800.jpg

I just want to place the fan on a timer in addition to the humidistat. The humidistat works great and I'm keeping my room at 50% but the fan cycles too often for my liking right now.

StirCrazy
11-03-2011, 03:00 PM
I'm not sure my question was clear here.

I have one of these wired to a dedicated fishroom fan (bathroom fan):

http://img.ehowcdn.com/article-page-main/ehow/images/a04/oq/ff/a-humidistat-work-800x800.jpg

I just want to place the fan on a timer in addition to the humidistat. The humidistat works great and I'm keeping my room at 50% but the fan cycles too often for my liking right now.


If you put it on a timer you are defeating the whole purpose of having a humidistat. it cycles on and off so often because you need it to. the less humidity added to a space the less it will go one and off. the more.....

I would just be happy it is doing its job and preventing any mositure related problems.

if it is the noise that is bothering you look to a better fan.. I had a panasonic fan in my old house that ran at 1.5 scones and unless I was in the bathroom I could not hear it. granted a better fan costs more but it would solve your problem.

Steve

Delphinus
11-03-2011, 03:27 PM
The only thing a timer could really do is just make it so that it's off longer, if you tie the two together the fan will still be cycling like crazy during the timer's "on" cycle. The problem is just like with a topoff, you have a setpoint and a tolerance and the smaller that tolerance is, the more on/off's you'll get in order to keep the feedback at the setpoint. Whereas with a larger tolerance the value can drift farther before the controller kicks it back on.

I am not sure if a dehumidistat exists that gives you a variable tolerance.

What you could do is just take the dehumistat out of the picture altogether and just use a timer (assuming you can find a timer with enough programmable settings and can handle the load and all that good stuff) and then you become the humidity meter and adjust the on/off cycles or durations. Sort of like dosing with a peristaltic pump and a timer. :lol:

Maybe that's a kooky idea, I dunno...

mike31154
11-03-2011, 03:39 PM
Most modern digital thermostats have a tolerance setting that allows you to adjust whether the furnace kicks in within more or fewer degrees of the set point. I haven't seen a humidistat like that, but I haven't looked for one either. If you can find such a beast, that might be your best option. Don't think trying to incorporate a timer into your current setup is a good solution either. Another piece of hardware making things more complex & one more failure point, although I guess the result of a timer failure would not be as catastrophic as with some of our tank related gear. I'd probably choose Delphinus solution of more or less manual control of the fan. Or let it be, like Steve says, it does the job, don't mess with it.

sphelps
11-03-2011, 03:40 PM
A timer is actually a good idea. Those humidistats typically connect to the furnace in such a way the humdifier or exhaust fan will only turn on when the furnace fan is powered by your thermostat. In addition many humidifiers also have a function to only activate when warm air is being pumped through the furnace. So my point is those humidistats aren't really designed to work alone, the furnace typically also contributes to the control which prevents them from turning things on and off too rapidly.

So if it were me I'd wire in a timer to control the duty cycle, this wouldn't eliminate the purpose of the humidistat it simply mimics it's designed purpose. You could also just wire it into the furnace so it only turns on when the furnace turns on which would eliminate any negative pressure effects, not that there would be.

An alternative would be a different controller, something like this is probably better suited to the application:
http://www.canadiantire.ca/AST/browse/8/KitchenBath/RangeHoodsExhaustFans/BathroomExhaustFans/PRD~0528200P/Dew+Stop+Humidity+Sensing+Control.jsp?locale=en

lastlight
11-03-2011, 04:57 PM
the way i see it using a timer would be adding the variance that the humidistat lacks. i wouldn't set the thing to be powered a couple times a day... i'd have the power to it every 30 min or hour.

Seamazter
11-03-2011, 05:27 PM
I would think if the timing of the fan coming on and off is a bother, you could perhaps try for a quieter fan and save yourself all the other troubles your experiencing.

lastlight
11-03-2011, 05:36 PM
The fan is not noisy I was thinking more about prolonging the life of it. It was only $40 tho... maybe I'll allow it to maintain a constant humidity as is and just replace the guts if she fries. Time will tell I guess.

StirCrazy
11-03-2011, 06:30 PM
The fan is not noisy I was thinking more about prolonging the life of it. It was only $40 tho... maybe I'll allow it to maintain a constant humidity as is and just replace the guts if she fries. Time will tell I guess.

when I did mine it ran for 1 week pretty much constant untill it drew the humidity of the house down from 98 to 45% after this it would come on and off for the next 10 years. never hurt the fan at all. so I wouldn't worry about that. if you fan does fail, like you said it was 40 bucks, and buying just the motor that fits inside the housing is probably about 25 bucks.. and takes about 10 min to switch out. deal with it when it dies.

Steve

lastlight
11-03-2011, 07:09 PM
Yeah good call that's what I'll do. It's doing it's job perfectly as is. Still feels humid in there relative to the rest of the house... as soon as you exit the fishroom and you're in front of the tank you get that awesome calgary dry-air-nosebleed feeling again.

cwatkins
11-04-2011, 12:16 AM
You could look at getting an IAQ digital humidistat. Search on google or Amazon for digital IAQ. I think Honeywell makes a bunch. The digital ones should do what you want I think.