Proper relative humidity for pellet storage

[orangecrushcj7]

I only have room in my shed for 2 tons, and I am certain I will need at least 1 more to get me thru the heating season. That said, I would like to purchase an additional ton should I come across a place that has some in stock, sooner than later. I have plenty of room in my cellar. The problem I have is I have a very high water table, thus a damp basement. It dries up entirely in the drier summer months and mid winter, but in the fall/early winter and early spring, my sup pump will run every few minutes. I am planning on buying a hygrometer to know exactly what the humidity is down there.

I would store the pellets on pallets, raised off the slab on concrete blocks.

Does anyone know what an acceptable high humidity threshold is? Has anyone any experience with storing in a damp basement? I have emailed the manufacturer, Lignetics, but haven't heard back yet.

 

[Jester]

Let us know how what you find out. Ive got one of those basements as you described. One of the improvements I made is a maytag dehumidifier and an HVAC drip pan pump to send the condensate to a rain barrel for watering the flowers and breedin the skeeters.
Ive got mine set to 45%, but if I can knock it back to a more reasonable 55 or 60 that's wear out a few less bearings on the electric meter.
E

 

[BubbRubb]

I've kept my pellets in 45% - 55% humidity for the last two years in my basement without any problems

 

[orangecrushcj7]

I have contacted both Lignetics and Pellet Fuels Institute. I am waiting for thier responses. Maybe I'll email every manufacturer I can think of.

45-55% humidity is pretty dry. The more I think about it, all summer long it is 70% -100% humidity all day everyday in any non conditioned space, i.e. sheds, garages, outside, etc.

Jester - Wouldn't that be a shame if the bearings went on your electric meter - free electricity!

 

[bostonbaked]

I bought a bunch of open head 60 gallon barrels on craigslist. Each one holds 7 1/2 bags. I got them lined up along a wall right near the stove. ( stove is in the basement) Snug as a bug in a rug. They have air tight seals and could sit there forever. The bags I got in the shed stay in the bags and I can get six bags in each barrel no problem. It may sound crazy but it is bullet proof storage. Now I don't worry about it anymore. 7 barrels hold a ton actually 49 bags.

 

[swimman]

I run my basement dehumidifier at 55-60% during the summer. Getting much lower than 50% will be a task depending on the size of the space as well as the rating of the dehumidifier as the unit will probably stay on never surpassing the threshold. I would say between 50-60% would be perfect but in the winter you'll find the daily humidity lower than 60% so it will be easier for the unit to take out moisture if set lower.

 

[orangecrushcj7]

Well, I put an old hygrometer in the cellar 4 hours ago, and it now shows 72% relative humidity. I don't know how accurate it is, but it showed 59% for the upstairs where the pellet stove is before I brought it down. I put a handful of pellets on a table down there too to see how they hold up after a week or so.

 

[orangecrushcj7]

well, it has been a week. The hygrometer reads a steady 87% now. The handful of pellets I put down there seem to be just fine though. I have a vernier caliper, and have been checking the diameter regularly. It hasn't changed. First blush I would have said 87% is way too humid, however the pellets seems to be fine. I think I'll try keeping an unopened bag down there for a few months.

 

[peirhead]

My current home is on a slab so humidity in the basement is a non issue, however my previous home did have a basement and we were always fighting with high humidity. First we tried the dehumidifier route but it an expensive solution and the water still has to go somewhere...then I heard about a basement ventilator, basically a bathroom fan ducted to pick up air off the basement floor and vent it outside (replaced by fresh upstairs air) all controlled by a a humidistat . This worked extremely well and cost peanuts in energy...the smell was mot musty either. Later on we finished the basement and since it was hot air I put in cool sir returns on the floor and ran the furnace fan full time (so we didn't need the ducted fan any longer). so I recommend 2 things:
1) if you have forced air put a couple of cold air returns on the floor of the basement (you probably will need a couple of warm air supply while you are at it) and try running the furnace fan 24/7
2) if not forced air then make up a fan assy to suck air from the basement floor and dump it out a window. All you need is a humidistat, and a ducted fan with the inlet end of the hose near the basement floor and the outlet dumping out a window.
good luck!!

 

[orangecrushcj7]

Peirhead,
I have forced hot water, so your first suggestion is a no go. I may try your second suggestion. Did you have to create an opening from the first floor to the basement for the upstairs air supply?

 

[packerfan]

I keep my pellets outside in my screen porch, and have not had a problem at all with humidity affecting my pellets.
Maybe the tiny holes in the bags are just too small to allow much moisture in unless the bags would be getting rained on, or actually sitting in water.

 

[peirhead]

Orangecrush----we had a door at the top of the stairs but there was a 1/2 inch or so airspace at the bottom of it...doesn't ned to be much. A typical bathroom fan is rated at around 100 cfm (probably actual preformance of say 50 cfm) say your basement is 1000 sq ft..x 8 ft high gives 8000 cubic feet..so 50 cfm represents an airchange every 3 hours or so. Pretty good actually...over a period of days it will bring the basement humidity down to that of the rest of the ambiant air around the house, plus no condensate from the dehumidifier to wory about, and waaayyy less energy!

 

[peirhead]

I found a link to a commercial unit that does the same as I described
(broken link removed to http://www.airtechhumidity.com/basementunit.php)
What I made was essentially the same thing except I scrounged most of the parts and used the 6" flex pipe (plastic vent pipe) instead of their fancy boxed in design...I believe these commercial units are are around $300

 

[orangecrushcj7]

I found a cheapo bath fan for $10 at Home Depot that I plan to run with a 4" dryer vent to a vent cap on the outside wall. It is only 50cfm, but that is an improvement to what I have now. I figure, for $10, I can't go wrong.

 

[peirhead]

Exxcellent I like the do-it yerselfer approach!!

 

[rap69ri]

I found a cheapo bath fan for $10 at Home Depot that I plan to run with a 4" dryer vent to a vent cap on the outside wall. It is only 50cfm, but that is an improvement to what I have now. I figure, for $10, I can't go wrong.

Just an FYI - I have seen two bathroom fans cause fires in the last year. They're not meant to be run 24/7 and when the bearings go they make a pretty light show that will burn your house down.

 

[orangecrushcj7]

I researched this more, and all search results from science websites, colleges, etc contradict what (broken link removed to http://www.airtechhumidity.com/basementunit.php) claims. Airtech claims that moist air is heavier and therefore settles into the lowest parts of the area in question, i.e. the basement floor.

(broken link removed to http://airtechhumidity.com/basementunit.php)

How It Works - AirTech Humidity Solutions

Moist air is heavier than dry air, and tends to settle in the lowest part of the home. Air Tech units draw moist, stale air from the lowest point of the structure, dealing with the root of the problem. Stagnant air is expelled outside through the unit vent.

At the same time, drier, fresher air is drawn down from the upper levels of the home. With this process, your home has a complete air exchange from six to ten times a day.

Using an adjustable humidistat, the unit will reduce or increase speed to address rising or falling humidity. Even on high, Air Tech units use on 38 watts of electricity, costing roughly $3.00 a month to operate

However, I can't find any results that agree with that claim.

http://www2.sunysuffolk.edu/mandias/met101/pressure_help.html

Assuming a gas (such as air) at a constant volume and pressure, the number of molecules is controlled by the temperature while the type of molecules is controlled by the atomic masses of the gases involved.

Density is important because it is what determines whether a parcel of air will rise or sink in the atmosphere. If a parcel of air is MORE DENSE than its surroundings it will SINK. If a parcel of air is LESS DENSE than its surroundings it will RISE.

Since cooler air has less kinetic energy and therefore less motion than warmer air it has more molecules (more mass) in any given volume so is more dense. Warmer air is less dense because it has more energy and more motion and therefore has fewer molecules (less mass) in a given volume.

As air becomes MORE HUMID (meaning more water vapor molecules) it becomes LESS DENSE. DRY AIR is MORE DENSE than humid air at the same temperature. Water vapor molecules have a lower molecular mass (18 per molecule) than dry air molecules (29 per "molecule.") Therefore, humid air which has molecules with masses of 29 and 18 (mixture) will have less total mass than dry air with all molecules having masses = 29. Therefore, at the same temperature and pressure, humid air is less dense than dry air.

In summary, a cool, dry air parcel is more dense than a warm, humid air parcel

also: (broken link removed to http://answers.yahoo.com/question/index?qid=20070121144258AA54nn9)

Humid air is air with a lot of water vapour not condensed water. Water vapour is a gas that is lighter than air so humid air is lighter than dry air. It might feel heavier but it isn't.

Heat does not rise, nor does cold sink. Denser air sinks replacing less dense air. Very often cold air is denser than warm air so it sinks but it is a question of density not temperature.

Warm humid air is usually less dense than the surrounding colder air so it will rise.

So it would seem that placing the vent intake higher near the cellar ceiling would remove the humid air, not near the floor.

 

[peirhead]

Circulation is the name of the game....you want to get out the stale air...most basements have very little temp variation from floor to ceiling so you won't find the humidity that much higher at the ceiling levels (although warm air does hold more water) however the key is air exchange ...you want to remove air from the place in the basement that gets the least ventilation.