Want to build a climate controlled drying cabinet, need humidistat or dehumidistat - created 07-12-2005

Hokanson, Erik - 07/12/2005.12:16:40

Hello, I'm in plate cracking hell over here. I want to make a cabinet with a 100 watt bulb with some holes at the bottom and holes at the top and a way to measure the humidity in there in such a way that the light will go on when the humidity is too high and off when just right or too low, I think it's more humid than not here so I'm not too worried about increasing humidity, I think a plate of sponges would do that if it were an issue. My question is how do I explain this to the guy/gal at Home Depot or somewhere? Does anyone know what exactly the device is that I need?

There is no way for me to effectively control the humidity in my studio.

Any ideas would be most appreciated.

Its called a humidistat. You probably won't find one at Home Depot but you may find one at Graingers.

Thank you, Barry - I couldn't think of the name and it was driving me nuts!

I think you mean a dehumidistat, Barry. A humidistat turns on when the humidity is too low (unless it has both normally open and normally closed contact but few do), a dehumidistat turns on when the humidity is too high.

Barry is right, Erik. You'll just get blank stares at Home Despot. Do a google search for line voltage dehumidistat.

Humidistats come in two varieties, high rh on, and low rh on. The first is for dehumidifiying and the second for humidifying. you will want one that runs on line voltage rather than one of the ones that require transformers and relays.

They are often available on ebay very cheaply.

Airconditioning and dehumidifiers will keep the studio controlled, just cost a lot.

If you do find an internet source, post it here! I'd like to look into one of those units myself.

A place where you can buy house ventilation or bathroom furniture would have that.

You can probably get a reasonably low priced one from Sears as a replacement part if you can find a parts #. (I'll look see if I still have one of their humidifier parts list). I used a Sears dehumidifier for a lot of years - during the big San Francisco quake of 1989 (epicenter really was about 6 or 7 miles from Santa Cruz) electric lines down the street got crossed over, and when electricity was restored I was getting 220 volts on 110 volt service to the house - everything electric burned out - except my Sears dehumidifier - it ran for several more years before giving up the ghost. Bought a new one the lasted about a week beyond the warranty date. Being too lazy to go out during Christmas rush to pick up a new one locally, I ordered one through the mail -- it got lost in shipping - they sent a replacement - it didn't work!! As a temporary measure, I removed the humidistat from the broken down dehumidifier, wired it up to a 100-watt light bulb in my closed in Go-bar and have been using this ever since. Works fine - no reason to even purchase a new dehumidifier. I use a high quality hygrometer in the closed in Go-bar to check for accuracy, it holds just about perfectly.

Thank y'all, I think my question is answered. I just did a little search and found at Grainger's website:

Autoflo humidistat -Grainger item 2E453 $28.00!! -is that the thing? If it is, grainger will be wondering why there is a sudden rush on humidistats. I'd include a live link, but I'm not sure how.

Here.

Wrong switch action, Erik. You want switch close.

Try Nuton-Broan DH100W (scroll down to bottom of page) or Ranco J10-810

Of the two, I'd go for the Ranco, only because I can't find a current rating for the Nutone-Broan.

Honeywell makes a pre-wired one, part # H46E1013(plug it into the wall, and plug the lamp into it), but it is much bucks.

Thank you, Ms. Suran.

Mr. Alexander, Thank you too.

We're pretty informal around here, Erik, and we're all on a first-name basis.

I bought a humidistat off of ebay. It was a honeywell unit. When I opened it up I found a place to solder a wire to change it to a "dehumidistat" which I have connected to a dehumidifier, or when it is colder, to a heater (to raise the temperature to control humidity - much as a light bulb does). I can rewire it to use it as a humidistat if I want to connect it to a humidifier.

It was not very expensive.

I just went the cheap way and wired my bulb to a dimmer switch and put a hygrometer in the box. On my way out in the morning I'd check the RH and adjust the brightness of the bulb and then check it again when I got home. My hygrometer keeps track of highs and lows reached and my completely un-high tech method kept in within ranges I was happy with. But a dehumidistat sounds way, way cooler. I'm now in another damp house without a dedicated workshop, so I'll likely be building another box. And probably buying one of these. Thanks for finding this information.

This is just something I was wondering about on the cabinet construction. If the humidity outside of the cabinet was say 60%, and the cabinet had holes in the top and bottom, Wouldn't the humidity inside the cabinet still remain at 60%,even with a heat source. I mean wouldn't the humidity inside the cabinet be continually trying to equalize to the outside Humidity?

Unless your cabinet is air-tight you don't need more than one small hole, or so I found. Not sure I even needed that hole, but it's where I threaded out the power cord. And no, that equalization doesn't seem to happen. As long as the air inside is warm enough, the humidity stays down.