Too much humidity?

[Jay Yoder]

I recently lost my dehumidifier and was in the shop tonight and noticed that there was alot of condensation on my well pressure tank and it was dripping on the floor. I checked my gauge and it was at about 80%. The question I have is what damage will this do? Unfortunately, the budget is tight and a new dehumidifier is not in the picture at this time...:(

[Lee Koepke]

I would say thats too much.

With my overhead door open, I was getting 70% + this weekend. closed its not so bad.

[Frank Drew]

To keep the ultra-high Virginia summertime humidity out of my shop, I one year kept the shop doors closed, stifling as that was (even with a ceiling fan). When I realized I was dripping sweat onto a piece of furniture I was finishing, I decided then and there to air-condition my shop, and it was one of the best decisions I ever made.

[Scott T Smith]

The question I have is what damage will this do? Unfortunately, the budget is tight and a new dehumidifier is not in the picture at this time...:(


It will have two negative impacts - first moisture can condense on the metal portions of your equipment, and second the moisture content of the wood stored in the shop will rise well above 10% (if the RH% is 80%).

[David Thompson 27577]

Make a redneck dehumidifier.

Find some calcium chloride -- its the ice melting stuff that isn't rock salt.

Put a few pounds of that in some sort of tight-mesh sack (pantyhose are great, but getting hard to find -- cheesecloth would probably work too).

Suspend that bag directly above a bucket.


Empty the bucket as needed, cuz it's gonna get full.

[Dave Lash]

The only time I had to fix a dehumidifier that stopped working was when the fan bearings froze up. I could hear the compresser run when the dehumidifier was pluged in, but the fan didn't run. Oiling the bearings got the fan running, and the dehumidifier did its job again.

[John Keeton]

Jay, a couple of years ago, I had an interesting phenomena that sounds a little similar, but much more damaging. It had been rather cool, and I had been working in the shop with the door open and both windows open. Temps were in the 50 range.

Suddenly, a front came through with a sudden increase in temps of about 25 degrees, with a humidity level approaching 100%. It nearly rained in my shop. Every surface, metal, formica, toolboxes, every tool I had hanging in the shop on the walls, and all of my machines were instantly dripping wet.

It took my hours to get everything cleaned up. I had to turn on my heat just to dry everything out.

I learned a valuable lesson - be aware of the weather!! If we have fronts coming through, I never leave my shop open.

[David G Baker]

One of the major problems with dehumidifiers is the fan no longer working. I have tried to find replacement fans and have not had any luck. If your dehumidifier is a high end brand name unit then replacement parts may be available.
The calcium chloride idea is a very good idea and works well.

[joe milana]

Make a redneck dehumidifier.

Find some calcium chloride -- its the ice melting stuff that isn't rock salt.

Put a few pounds of that in some sort of tight-mesh sack (pantyhose are great, but getting hard to find -- cheesecloth would probably work too).

Suspend that bag directly above a bucket.


Empty the bucket as needed, cuz it's gonna get full.

Interesting, how long does the CC last?

[Paul Ryan]

Jay, a couple of years ago, I had an interesting phenomena that sounds a little similar, but much more damaging. It had been rather cool, and I had been working in the shop with the door open and both windows open. Temps were in the 50 range.

Suddenly, a front came through with a sudden increase in temps of about 25 degrees, with a humidity level approaching 100%. It nearly rained in my shop. Every surface, metal, formica, toolboxes, every tool I had hanging in the shop on the walls, and all of my machines were instantly dripping wet.

It took my hours to get everything cleaned up. I had to turn on my heat just to dry everything out.

I learned a valuable lesson - be aware of the weather!! If we have fronts coming through, I never leave my shop open.

John's phenomenon occurs yearly around here. At least once every spring some times twice. I have been trying to find ways to keep the condensation out of the shop and have resorted to celing fans circulation the air, that is about all you can do. And that doesn't do everything. The tools still have to be covered and coated. But normal even 100% humidity when the machines are warm isn't too much to worry about. It is the drastic change in temps cold machines and floor, warm air that is the real killer. If you don't have those problems I would just put couple of good coats of wax on your tools and you will be ok. The pressure tank was sweating because of the cold water inside. When your floor starts sweating get the air moving and cover the cast iron surfaces.

[David Thompson 27577]

Interesting, how long does the CC last [on a redneck dehumidifier]?

We had one in a rather small room that was in the center of our house. The room had, many years prior, been the boiler room -- the house originally had hot water heating. We now have heat pumps, mounted outside.

The house is on a a crawlspace, but the boiler room was at grade level -- it was three steps down to the concrete floor, which was the "rat-slab" of the crawlspace.

The boiler room (we actually called it "the pit" for many years) was rather small, maybe 8' X 8', but it had probably a 12' ceiling.

We put a redneck dehumidifier in there, with maybe a pound of calcium chloride. It was still working a year later, when we remodeled the space into a laundry room.

Note -- this is not an optimal method, but it will take some moisture out ofr the air.

[David Giles]

You can lower the relative humidity by reducing the amount of water in the air (dehumidifier or adsorbents). Or you can lower the relative humidity by increasing the temperature. If the surface temperature is hotter than the dewpoint, then the water won't condense. Heat lamps or halogen lights shining on cast iron surfaces will do wonders to reduce condensation. Long periods of cold followed by a quick, moist warm front is the worst.

[Frank Drew]

... you can lower the relative humidity by increasing the temperature. If the surface temperature is hotter than the dewpoint, then the water won't condense. Heat lamps or halogen lights shining on cast iron surfaces will do wonders to reduce condensation.

Given that we're probably already taking summertime, this suggestion is good in theory, maybe not so good in actual practice :eek:!

[Keith Avery]

I have a serious humidity problem in my new pole barn. Eventually I plan to put ac in but it isn't yet in the budget. I found a salvage type place through craigslist that was selling new Kenmore 50 pint dehumidifiers for $75 and 30 pint ones for $55. Humidity is now about 50 percent inside, outside yesterday was 85%.

[Thomas love]

John ,
Down here in TX, I have experienced this ,
what a nightmare.

[Jay Yoder]

This is in my basement and unfortunately is creeping over 80% today!:eek: my quick solution is the dehumidifier route, there goes a max of 240! What numbers should i look for? The highest pints per hour rate? or one that is sized to fix my shop and lower pints per 24 hours?

As for the redneck dehumidifier...how much would one actually use? not sure I want to create more of a headknocker in an already too low basement...

[Frank Drew]

If this is largely for summertime use, I'd look for a Kenmore window rattler a/c that I could afford rather than a dehumidifier, as many (most? all?) of those give off heat, don't they?