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  1. #1
    Join Date
    Feb 2008

    Default oldest known steel pipe radiant slab system? (stil operating!)

    Hello forum. Currently debating about whether to replace the BOILER on my radiant slab system from the mid 1950s. First of all, this is nothing like pictures I've seen of the cheap Levittown systems, with the copper pipes lain willy-nilly over bare ground. It's a beautifully engineered 3 zone system with the original circulators and pumps (!) still working fine after over 50 years. The supply pipes are huge, thick black iron. The return pipes curve out of the slab into some kind of collectors. The heating is remarkably even and in the one slab opening I can find, under the bathtub, there is a good layer of gravel under the slab, but, of course, it's not as well insulated as a modern PEX system would be. The house has a very high R value. This weekend I felt a little cold and clicked the thermometer way up and forgot about it for a little over an hour. The house built up so much warmth it stayed at a very warm 70 for over 36 hours with no additional firings! (I usually keep it at 65f because oil is so insanely expensive) The boiler was replaced in the late 70s, only once presumably. I have put a gauge on it, and all last summer, with the supply value closed, it did not drop in pressure. So there is currently no gross leakage from the system.

    I read somewhere a while ago of a system from the 30s known to still be working, more recently, I met someone ****** with a steel system in the DC suburbs from the 40s that is still working...and that in a 2 story house with a poured slab 2nd story...it's amazing settling hadn't busted one of the pipes by now. Anybody else have an old system like this that is still working? I love this form of heat and would like to keep it, even tho the operating costs are high.

    Oil dude gave a ballpark estimate of 3800 for a new boiler. For that price there's no way I'm sticking with archaic oil (sorry oil fans). Yeah, I know it has more btus per unit fuel but it's a mess for me because my clay flue liner is flaking from the oil acids and a stainless steel liner is something like 2500 installed. (even more ridiculous than the boiler) So I'd want to get a condensing gas boiler or possibly a tankless gas heater to be vented out a window. (will install a propane tank) It's just insane to have a non-condensing system that you have to keep running just to keep itself warm when the system only has to fire once a day under normal circumstances. The house holds heat so well...165K BTU is WAY overkill. This winter to keep 65F it runs about 40-45 minutes a day max, no matter the weather. (I do not heat one zone though, because it is over the cellar and stays warm anyhow)

    FWIW, Oil guy, who seems honest, says I'd be crazy not to just switch to heat pump (from central AC that is totally in the attic, not trivial because I'd at least have to drop some returns) because there's no guarantee the pipes won't fail 2 weeks after buying the new boiler.
    Last edited by DTorrance; 11-16-2009 at 05:57 PM. Reason: edited

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