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Posted: Wed Mar 28, 2007 9:49 am
The Weltzheimer House gravity heat failure may be due to the decision by the Weltzhemers and the apprentice (Ted Bower) not to raise the floor the three steps (9-10") from the flat land here. Because of this the dry stone foundation was seldom dry and like most of the USA east of the Mississippi we've had many years of acid rain. I keep hoping that the 2" spaces left by the iron pipe could be coated or threaded with a flexible and sealable material to reestablish the gravity heat and there are companies that claim to be able to do it but none so far that we are confident enough to go along with (or that we are able to afford).
Posted: Thu Mar 29, 2007 8:29 am
thanks DRN. I was about to offer about the same clarification about protection of rebar in concrete as you did. the "problem" is not in the basic technique but in the improperly installed or deformed installations of rebar in concrete. it had nothing to do with the basic design as RJH implies.
so, has RJH suddenly given up on his electrolysis theory? I would still be curious to hear how the electrical current enters the water-filled steel pipes in the concrete...
and what does graduating from penn have anything to do with this topic? most penn architectural graduates I have encountered have too much academia snobbery, marginal real world knowledge, and need serious field training to become more than self-appointed experts. that's not a denigration of the entire institution; just a stereotyping from personal experience.
Posted: Thu Mar 29, 2007 8:51 am
In some cases, they laid electrical wires in metal conduit over the steel heating pipes before they poured the concrete.
Posted: Thu Mar 29, 2007 8:54 am
And, steel heating pipes were often laid touching the bottom of the concrete on top of a bed of large gravel not encased in the concrete.
Posted: Thu Mar 29, 2007 9:11 am
Richard wrote:In some cases, they laid electrical wires in metal conduit over the steel heating pipes before they poured the concrete.
whoa! now that does raise some serious questions. thanks for adding that info.
even if not a given that the situation would cause problems, it is inherently a potentially bad scenario. (though I am still not sure it qualifies as electrolysis.. where's the electrolyte?) either way, it's not a good practice.
Posted: Thu Mar 29, 2007 2:50 pm
Could the conduits cause a dissimilar metals issue? The heating pipes I would guess would be steel or maybe cast iron. Most conduit of the period and since is galvanized steel: hard conduit or armorflex.
The lack of encasement of the pipes in the slab and the potential for condensation cycling seems to be a factor. I believe the amount of moisture trapped under the slab is a variable in the equation: drainage characteristics of the underlying soil, profile of grade away from the building, and even the weather conditions of the site just prior to slab or crushed stone placement. If the stone (or sand as the case may be)was wet when placed there could be a lot of moisture under the slab.
I'm not sure of the ability for the moisture to escape.
Posted: Thu Mar 29, 2007 7:53 pm
I think that the discussion has not addressed the real problem - its called corrosion, or oxidation. When hot water is pumped through steel AND copper piping, the piping gradually corrodes to the point that it will fail (case in point, the 3 mechanical companies that do nothing but repair Eichler Homes in Palo Alto, all equipped with Copper Piping). Pex tubing will also fail in time. Anyone with a radiant system SHOULD NOT flush the system unless they must, as the old, brown, stinky water has less oxygen than new - AND they should buy de-oxidizing agents that can be added to the system. Finally, yes, it is possible to thread new 1/2 pex tubing through the old steel piping, provided it has large radii corners (not sharp elbows) that allow for this. The Weltzheimer House would be a perfect house for this fix, as would many other Usonians w/ 2-3 inch steel piping. That way the slab would not have to be removed, and more original fabric could be preserved at a greatly reduced cost.
radiant heat in Weltzheimer House
Posted: Fri Mar 30, 2007 12:28 pm
MHolubar had forgotten that the Weltzheimer House (1948) plans actually present the option of 2" wrought iron pipe or seamless copper tubing for the radiant heat lines. The Weltzheimers chose wrought iron. The House is an L plan and the living/dining workspace wing failed sometime in the late before 1980s, during Prof. Johnson's residency. The bedroom wing continued to function for a period. Now, however, we will need a full restoration at some future date.
Oberlin terrain is flat and has a high water table and the Weltzheimers began construction before Ted Bower arrived to supervise the work in July of 1948. He wrote about difficulties during the foundation period, complaining to Taliesin "Nobody ever uses an instrument to lay out a house here and I think what happened is partly our fault because the plans we sent had no specifications concern layout. They think it is their fault and I let them think so..." Yet somehow the construction overlooked the 3 (front) terrace steps and 4 (rear) carport steps that would have raised the House foundation significantly. Consequently, the iron pipes were doomed to fail.
Posted: Sat Mar 31, 2007 11:10 am
outside in: Thanks for that great information about corrosion of steel and copper pipes, including the retrofit with small dia. pex. I think you have hit all the salient points.
And nowhere did I hear a word about electrolysis-- Thank you.