All,

Two years ago we purchased a house that was originally built in 1740.  The house has an old steam system with a new burner that worked well last winter and continues to keep the house warm albeit with a higher oil bill.  Last fall we had the house repainted but did not change the color.  The house is yellow.  For the last few weeks we have had rusty colored moisture leaking through the clapboards on the outside of the house.  The moisture is concentrated in two areas but both are fairly large.  One section encompasses an entire wall on the outside of the house. 

My first thought was that the steam system was leaking inside the walls and the steam was finding its way through the outside of the house but I continue to be perplexed.  There are no signs of moisture on the inside of the house.  Common sense tells me that if the pipes were leaking inside the walls it would be much easier for moisture to come through old plaster walls than find its way through clapboards and a new coat of primer and paint.  But the moisture looks like the rusty colored water from our steam system.  Another confusing aspect of this is that the rust colored stains appear in areas above where any heating pipes travel.  For example, the stains are seen on the outside of the house on the wall both above and below where a radiator is located. 

Could steam be leaking through piping inside the walls, rising, condensing, and then finding its way through the walls and then dripping down the outside the house without causing any visible signs on the inside of the house?  Has anyone ever heard of this happening before? 

It honestly looks like the house is bleeding.  One entire wall on the outside is just dripping with rust colored stains.  I had our heating company over to look at the situation and the technician said he had never seen anything like this.  He suggested we contact the painter to see if there could have been some reaction between the existing coat of paint and the new primer and paint.  Again, the house was originally yellow, the new primer was yellow and the new paint was yellow.  The only difference between the two paints was that the original was an oil base while the new paint is latex.  Could this somehow have an effect? 

Another point of interest is that I accidentally overfilled the system with water a few weeks ago.  However, the rusty colored water on the outside of the house had been occurring prior to my overfilling the system with water although it did seem to get worse after overfilling the system.  After overfilling the system, I immediately shut down the boiler and called the heating company over.  They only emptied three buckets of water out of the system and told me that the water never even made it to the first floor.  (There are 2.5-inch steam pipes in the basement.  And, no water came out of any of the radiators.) 

I would greatly appreciate any thoughts anyone might have? 

Thanks,

Henry