Gas and Oil Home Heating Furnaces - Humidity Causing Cans To Rust

Evidently the humidity in our home must be extremely high in certain rooms. Some of my canned goods are rusting and I notice the master bath has heavy condensation on the vent cover after I take a shower. First off, are the canned items good if the tops of the cans are rusty and secondly, what can we do to make it less humid?

Need more INFO here where are you. Do you have heat and cool. full basement or crawl way.Vent cover is that inside or out? Not seeing the cans Id say if they are not puffed up they are good. You should see cans that or on a boat for a time;) ED

We have heat and air. No basement, only crawl space. We live in Georgia. The vent (register) cover is inside on ceiling in bathroom. I have never seen cans rust like that so that is the reason for my concern. How exactly could we find out what the humidity level in the house is?

OK Now is it wet in the crawl way? Do you have any poly down on the ground at all in that crawl way?????Lets get this humidity stoped and fine out where it is comeing from. Do you have the heat and cool duct work down in the crawl way?;) ED

No it is very dry underneath. There is nothing on the ground from what I can see. The duct work is underneath as well.

I dont know if you have looked at any of the post on here about the grawl way or not.What I have done over the years on a crawl way. Put a 6 mil poly down on the ground. Over lap it about 12" and tape it. go up the walls 12" with it.Put a 2"polystyrene on the wall from the ground up to the floor joist. cut like blocks of R 19 fiber glass and put them in the joist space on top of the sill plate all around the home. Cut two small register out lets in the duct work and one in the return. Block all the vent openings. If you take and go to this www

http://www.ornl.gov/roofs+walls/facts/index.html

You can see that this is the way the Gov said to do it.
Even if it feels dry down there its not and I think that is where all of your moisture is come from and goes up in the home through the floors. Also make sure you have good gutters on the home and all water can drain away from the home;) ED

Do you have an adequate exhaust fan in the bathroom? And if so, do you run it long enough? That is the biggest cause of indoor humidity, next to unvented clothes dryers and cooking.

There also as to be some place for air to enter the house as you exhaust air from the bathroom. Is the construction of the house such that air can get in or is it relatively air tight?

Get that humidity out as :) Ed says or you will end up with sick house syndrome. :(

Ken

Back again??????????????? do you have insulation up in the floor joist now?????????????The duct work is it insulated or duct board???? ;) ED

You said certain rooms...besides the bathroom you mentioned, what are the other rooms? It could be you just have poor venting (exhaust fans, inadequate ductwork, improper airflow, etc.) in those rooms if other rooms seem ok. As you can see from the replies, their can be a multitude of reasons for you problem. I think more specific information is order to better help you.

ventilation problem. does the vent hood over the stove go outside? how about the bath fan if there is one? you never said. how about the dryer...this is the cause in most of the cases i see, not vented outside, or pipe loose from the back of the unit.

http://www.epa.gov/iaq/molds/preventionandcontrol.html This is an EPA site that will give you some tips on how to control moisture. All the previous replies are correct because there isn't enough information. In most cases like yours it is a combination of factors that is creating the condensation. There are basically 2 methods of controlling moisture. One is to make sure conditions do not exist that promote condensation. The rule here is warm air condenses on cooler surfaces and not vice-versa. Example a soda can will sweat but a cup of coffee will not. The other is to limit the amount of moisture in the home. There are 2 ways this applies to your home, one is air transported and the other is heat transported moisture.

Heat transported moisture is carried in heat as it transmits through solid materials. In bathrooms a common source is the drop ceiling above the tub/shower enclosure. Insulation has the tendency to drop in this area allowing the ceiling to get cold. This increases the probability for condensation in the bathroom considerably. Properly insulating this area prohibits the conditioned required for condensation to occur.

Air transported moisture is more common. This is because the source of the moisture can be either from inside or outside the home. Ed's reply concerning covering the dirt floor in your crawl space is an example of moisture source from outside. Though the ground may appear to be dry, there is moisture in it and it will evaporate. Outside the home it evaporates into the atmosphere, in the crawl space it evaporates into the floor of your home and increases the humidity level throughout the home. Doing Ed's solution limits the amount of moisture in the home.

Plumbing leaks also increase the humidity levels in the home, which is an example of a source within the home. Other concerns are duct leakage in unconditioned areas like the crawl spaces or attics, openings around plumbing vents and pipes. Making sure your bathroom vent dampers close, duct is sealed and exits the house. These limit the amount of moisture and prohibit the conditions required for condensation to occur.

Many of the replies given, you should heed. What I am saying is not one of them will probably solve your problem, all of them probably would.