Just received my new water heater today....

[nedb]

The Atwood marine in my water bay looks a little dated (rust and wet spots tend to look that way to me). I'd guess it is original to my 1991 coach, so it is due for an update, 'tho it still works.

So I shopped around and compared features like tank material, location of motor-aided heat ports, wattage requirements for immersion heat.

And in a late-night decision, against a lot of advice about the dubious value of stainless steel, I ordered an Isotemp Basic 30. I think it is made in Italy (older Isotemp equipment used in Europe was Italian-made), a very sheik cask-shaped stainless casing with stainless tank inside. It stands in free air, oriented horizontally in the longest dimension, supported by feet. That's a good design, no moisture will be trapped under it.

I think this is going to be a project, working around the existing Primus heat exchanger, expansion tank, and pump. I expect to move some things around, as this water heater is significantly wider (but less deep) than the old Atwood. Today I'll begin removing the old equipment, followed by inspection of the carpet and water bay structure, followed by sealing and rust-proofing. Actual bay rust will not be a big thing, as the Wanderlodge bays are built of galvanized steel

[davidbrady]

Good deal Ned. I'm looking forward to pics. That's right, any framing less than 1/4" thickness or so is galvanized on Wanderlodges - lucky for us!

[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!

[ernie ekberg]

Bluebird used a unitary backed carpet, most likely manufactured by Ozite. Tough stuff. They adhered it with contact cement.

[nedb]

(06-08-2013 19:20)ernie ekberg Wrote:  Bluebird used a unitary backed carpet, most likely manufactured by Ozite. Tough stuff. They adhered it with contact cement.

I looked at Ozite carpets on their web site--non-woven, won't unravel, easy to clean, colorfast... That sure sounds like what lines my storage bays. They sell 6' X 8' rolls, might be just the thing for for ground cover under the awning. Thanks for the info, Ernie.

[nedb]

(06-08-2013 16:58)nedb Wrote:  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 pa

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!

So. I got the BSPP-to-NPT adapter and compared it to the factory-supplied outlet on the mixing valve. The BSPP threads on the mixing valve should look different from NPT. As I've learned more recently, BSPP fittings do not seal like NPT threads, they require a steel and rubber washer at the base to seal, whereas NPT are tapered to seal tightly against each other as the fitting is tightened. That bit of info makes interpreting the following pictures pretty simple--the stainless is the NPT end of the adapter, and the brass is the mixing valve outlet ("BSPP").




Obviously, these are both identical tapered threads, no BSPP here. So I installed it without the adapter, sealed the threads with the Locktite, and it is all good.

Some older stock in warehouses could still have BSPP threads, but this one arrived without thread issues. At some point, they were apparently shipping the water heaters with an adapter for BSPP-to-NPT, but nothing like that was included in the box I received.

I didn't have to make any special request, this is just what they sent.

IsoTherm (aka Indel) ought to pump this info onto the web so that shoppers can buy with more confidence. The prospect of added time and cost for getting an adapter would drive some customers away.