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Posted: Tue Aug 26, 2008 3:51 pm
peterm: A Buderus rep was just in our office, and we looked up prices for the boiler and oil burner at my house:
Buderus G215/4 boiler $2068.00
Beckett AFG oil burner $ 811.00
Please note: these are trade prices and not list prices, but they give an idea of dealer cost when speaking with sellers.
Posted: Tue Aug 26, 2008 4:45 pm
SDR: To answer your question, yes, casting PEX in concrete is very common in addition to the "dry" system. Pex can be cast in a regular concrete slab or in lightweight concrete over wood framing for upper storeys of wood framed buildings. You just have to be very careful to not place the tubing where walls will be fastened (the nails!) and renovating after-the-fact can be tricky for the same reason.
Posted: Wed Aug 27, 2008 8:44 am
Don't get me wrong, radiant heat is wonderful - it works well with Passive Solar too, as the floor can be heated by the sun and then supplement heat provided by the radiant coils.
I would only advise that the tubing be installed in such a manner that it is accessible, i.e., beneath the sheathing (staple up) OR within the sleeve of wrought iron, using the W.I. piping like conduit, so that the pex can be removed and replaced in the future. The latter is very expensive, but should be considered for retrofitting an existing (leaky) system.
Posted: Wed Aug 27, 2008 9:40 am
I suppose that it would be theoretically possible, on a good day, to fish the PEX into an existing W.I. or copper embedded heat coil system -- unless there were right-angle fittings ? Maybe those would be near the boiler only, and could be excavated, without ripping up the whole slab. . .
Posted: Wed Aug 27, 2008 10:21 am
The "fishing" technique has been used in refrigeration coils - and would probably NOT work in a cast-iron system - it would be ideal for a 2 inch diameter wrought-iron system with curved piping, however. A "mouse" is first sent through the piping with pull chords attached. The piping is lubricated and then pulled through the pipe. A fairly simple fix, and far less costly than pulling up the entire concrete slab.
Posted: Wed Aug 27, 2008 2:10 pm
Posted: Wed Aug 27, 2008 2:30 pm
In looking at construction photographs, it appears that the piping was set upon gravel and the concrete poured over the top, which is different from the method used today. We can only speculate, but it appears Wright thought that the steel/cast iron/ copper piping would double as the concrete reinforcing, which is best off placed near the bottom of the slab. Today most PEX piping is applied to the top of the steel mesh and imbedded in the slab. In either case, replacement involves removing the slab, installing new piping (as well some insulation to thermally isolate the slab) and repour the slab.