Just received my new water heater today....

[nedb]

This project is going to turn out all right. The bay (and even the carpet) have really responded to a thorough cleaning with carpet shampoo. No rust. Blue-bird lined the SP36 bays with flannel-gray outdoor carpet, which was pretty frowsy looking but intact.

I was prepared to replace the carpet. Wouldn't a "sanitary white tile" water bay, with stainless steel gauges, controls, manifold, and fixtures, be great? ALAS, it doesn't need extensive re-work at all. I will save the white tile design for a bay that really wants a major overhaul. This one is in fine shape.

I did run into a snag with the new IsoTherm. I ordered the heater with a mixing valve on it, so now the mixing valve becomes the warm water outlet that I connect plumbing to. Oddly, the mixing valve connector is threaded BSPP--it is 1/2" British Standard Parallel threads. You know, Whitworth threads--they're the ones that bolts and nuts from the hardware store never seem to fit even though they're the same nominal size.

It is the same 1/2" pipe with 14 threads per inch as OUR standard NPT 1/2" 14 tpi, but the shape of thread is different. NPT threads are pyramidial, BSP threads are flat on top. The two threads are also cut at different angles.

Blimey. IsoTherm's recommended solution is to convert the "male" BSP fitting to "female" with a $15 bronze adapter from McMaster-Carr, then attach my plumbing with an NPT male + Loctite 577 thread sealer paste ($25 for 50 ml tube).

Oh well, no point in getting steamed. If I remove the mixing valve, there's a nice 1/2" NPT pipe on the tank that I can connect to without further adieu.

But I wonder, why put a BSP outlet on the mixing valve? Is there a standards war looming? Is Britain to be the new hegemonic power in plumbing??

IsoTherm really does make nice looking water heaters. I'll order the adapter and thread sealer, and reinstall the mixer once I get the plumbing sorted out. Hot Diggity!