# Sweating interior walls



## Bob Mariani (Dec 1, 2008)

maybe because it is colder now and you are using the propane heater more. Never use any gas heater that is not vented to the exterior. We try to not use these even for construction work since it will bring in unacceptable levels of moisture. Use a dehumidifer. It is your best choice now.


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## Maintenance 6 (Feb 26, 2008)

Caulking and sealing the house probably tightened it up somewhat, and now the air turnover rate has dropped to where the moisture is showing up. You do realize that propane heaters produce carbon monoxide as well as water vapor as combustion by-products. Unvented heaters that burn any kind of fuel are not safe to use indoors.


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## Daniel Holzman (Mar 10, 2009)

As previously noted, burning propane without venting is a potentially lethal issue because of the possibility of producing carbon monoxide. At a minimum, make sure you have at least one , preferably two, working carbon monoxide detectors in the house, if you insist on not venting the units.

Propane when it combusts produces water vapor, carbon dioxide, and carbon monoxide. The water vapor is condensing on the inside of the cold walls. Possibly before the painting job, the moisture wicked through the walls to the outside. I am going to guess that the walls are not insulated. After the painting, the exterior of the house may have become less permeable to water vapor, so the moisture is unable to escape the house, hence condenses on the inside.


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## MJW (Feb 7, 2006)

With the high humdity like the others have said, it condenses on cold surfaces. Reduce the humidity and find out why your walls and windows are so cold.

Never heat with ventless heaters. Very dangerous and puts a ton of moisture in the air.


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## mhpruitt727 (Dec 22, 2009)

We used vented propane furnace(s) years ago and the cost was astronomical, not to mention the fact that at least a third of our heat was going up the chimney!

These are ceramic brick propane wall heaters - made to be UNVENTED - and they have built in oxygen depletion sensor and flame failure safety features. We have used this kind of heater in our big old farmhouse for 20 years or more without any problem.

Have spoken to a carpenter in this area who has run into this problem before. He thinks that the vapor barrier between the laminate and plywood flooring, combined with the primer on the exterior of the house, and primer on the walls inside (forgot to mention that earlier) have made the room too airtight and is causing the moisture. His suggestion is to drill vent holes in the top of the outside walls and cover the holes with soffits.

I guess hubby will give this a try tomorrow!


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## firehawkmph (Dec 12, 2009)

It would really help if people on this forum would take the time to fill out at least the city where they are located at in their profiles. A lot of questions that get asked are area specific. Enough ranting.
MH,
I wouldn't start drilling holes in my outside walls. Even though your propane wall heaters are made to be unvented, they still add a lot of moisture to the inside of your house. I agree with what Maintenance said, the house got rid of some air leakage with the new floor and sealing up the exterior. That's actually a good thing. Is there any insulation in the walls? If there isn't, I think that would be a good place to start. Get rid of the cold outside walls and get a dehumidifier if you are going to continue with the ventless heaters. Your main problem seems to be the excess humidity due to the heaters. 
Mike Hawkins


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## jaros bros. (Jan 16, 2009)

I know that these non vented units are not allowed everywhere. I thought maybe by now they are outlawed in all 50 states but I guess not yet. I came across an interesting link with a quick google search. http://chimneysweeponline.com/hovflett.htm

"cost was astronomical"

I wonder, can you really have that low of a view of your life and health. A properly sized and installed system for your place will not cost you that much more to operate. They have gas systems running in the high 90s for efficiency. In the end, the added cost is negligible compared to your life and health.


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## Bob Mariani (Dec 1, 2008)

Do not cut holes in the siding. This will do nothing to address your problem. You have sealed the house more than it was. You are still using a bad heating system. This is what you need to address. But to be sure what to fix locate a local BPI professional auditor. (I am in CT) These guys are trained in inspecting the home as a system and will identify all of your heat loss and moisture control problems. And they can fix it also. Cost for inspections average around $350.00


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## drtbk4ever (Dec 29, 2008)

I'm always surprised how defensive and stubborn people get when informed that something they are doing is dangerous.

One possible reason they haven't had any health issues up til now is that the house was soo leaky that any poisonous gases were leaking right out of the house. As they slowly tighten up the home, the risks will only increase.

By the way, the solution for this problem (if not changing heat source), control humidity in the home and insulate the outside walls!


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## ccarlisle (Jul 2, 2008)

A good half of the states in the US (mostly in the east) _allow_ unvented propane heaters, so what's the fuss? OK, local jurisdictions apply - but without further info from the OP, we can't make *any* statements about legal or not, good or not, healthy or not - but there's no denying the fact that they _exist_, have performance specifications that some government body passed - and are therefore on the market.

They're only room-sized tho', not the big units for the whole house...


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## jaros bros. (Jan 16, 2009)

They have been heading in the direction of being outlawed because they have been found to be dangerous. It is only a matter of time before every state outlaws them.


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## user1007 (Sep 23, 2009)

Dehumidify the space with some portable units or something. They will be out of season where I am now and you should be able to pick them up online for chimp change. 

And I would definitely think about saving up for a safer heat source if that is at all possible. 

I know it seems counterintuitive, but leave a window open. Or I would make sure there was some flow through ventilation in that house year round and hopefully running through a filter system of some kind. I sealed my California house so tight it almost became sick and I had to add exterior vents I could open and close to an expanded HVAC system to make it healthy again. I tighten up all my projects here, where the temps have been frightenly comfortable and above freezing so far but headed to -20F come January or February, too but make sure that flow through concept is in place somehow.

Houses and buildings need to be able to breathe. Everything in them outgasses stuff on a second by second basis.


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## ccarlisle (Jul 2, 2008)

I don't think they'll be banned. 

Look at their performance: some are better than larger units by emitting far less gases and particles. UL has checked that out. As in everything, there are cheaper (unapproved) units on the market mostly from overseas, but that's the "buy cheap" mentality you have nowadays...

Look at their application: they heat one room at a time where occasional heating is needed...now we're not talking Alaska or Montana, but look where they are popular: in the South.

Look at their cost: a propane tank for supply and about $100 for the unit. Pretty cheap investment to me.

Look at the demographics: down south, perhaps rural applications, drafty dwellings (so the dangers are minimal), warmer climate conditions, cost effective, easy installation...does that scream "Manhattan" to you? Nope. Probably used by millions of people...

Unless they start legislating against stupidity of the users, to prevent the millions from the odd accident, like they do sometimes, they're here to stay.


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## mhpruitt727 (Dec 22, 2009)

We live in the South - Eastern Shore of Virginia - where it hardly ever goes below freezing for more than a day or two.....

The past few days we have decreased the humidity in the room and the walls are doing much better....it was a quick and fairly inexpensive solution to the problem. 

I realize that some people think that using unvented propane heaters *because they are cheaper* is not a good reason, but I would ask them to try to live on my income as a secretary (husband is disabled) with all the usual expenses, and then add a $800 monthly heating bill to the equation - as it is we spend at least $400 a month, which is a struggle for us, but manageable.....but, we all know what they say about opinions, right? 

Thanks for everything.


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## ccarlisle (Jul 2, 2008)

Glad to hear you've solved the problem...may I ask how you decreased the humidity?

As I said earlier, I think your type of propane heater makes sense...OK maybe not in _every_ sense but IMO they have their place in the "occasional heating" areas of your country - so no need to convince me. I read somewhere that some 12 million people use that type of heater...wow!

If you the precautions necessary, for $100 they're a steal for the usage! :thumbsup:


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## mhpruitt727 (Dec 22, 2009)

decreased the humidity by turning the heat up and using a dehumidifier in the room.


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