Steam generator 3/4" threaded mystery

[joeyjoejoe]

Hello,

I have a residential steam generator made by Saunacore. Unlike other brands, for some reason it is using straight pipe fittings.

The water supply and drain are both 1/2" straight, and I used appropriate fittings.

I'm scratching my head on the 3/4" steam. It's 3/4 flat thread, 14 threads per inch (measured it with a thread gauge). Stainless steel. I need to keep the entire length in brass/copper to avoid corrosion - no cast iron. It is not under pressure - the line is 3/4" throughout until the steam outlet in the shower. No valves are to be installed and no reduction in sizes. Steam condensation can drip back to the unit.

Any part in this line needs to handle 100 Celsius for obvious reasons

I am in Canada, but a helpful person on Reddit suggesting it might be BSPP and I might need a 3/4" BSPP Female to 3/4" NPT Male adapter, then I could screw on a 3/4" FNPT to sweat adapter and off I go. Only place I've found that is McMaster Carr in the USA which would take a few days to get.

Would there be any chains in Canada that would sell to homeowners or is there something else I could do?

Here is a picture :

 

[Fitter30]

Copper and steam have problem with cyclical heating and cooling making the copper brittle and solder joints failing. Brass threaded pipe and fittings or stainless tubing with swagloc or another brand of double compression fittings. Stainless threaded pipe needs special dies.

 

[Sponsor]

 

[Marlinman]

A 3/4" stainless water heater flex line in a male x female should work fine. They accept straight and tapered threads.

 

[joeyjoejoe]

Fitter30 - I'm not sure I can afford to work with brass, and cutting to length would be tough. The previous install was 20 years old with no issues. I'm not saying you're in-correct, I'm just thinking I might not be able to control that

Marlinman - would a 3/4" stainless heater flex line be OK for steam though?

 

[Reach4]

Fitter30 - I'm not sure I can afford to work with brass, and cutting to length would be tough. The previous install was 20 years old with no issues. I'm not saying you're in-correct, I'm just thinking I might not be able to control that

Marlinman - would a 3/4" stainless heater flex line be OK for steam though?

Careful-- there are at least two kinds of stainless WH flex lines... braided, which you don't want bcause those are usually braided covering rubber hose, and good ones are corrugated.

 

[joeyjoejoe]

Yeah I see some corrugated copper/stainless that look better than the hose ones. 12" is the shortest, and they have 3/4" FIP to sweat.

https://www.amazon.ca/gp/product/B0006946F0

https://www.amazon.ca/gp/product/B00AO76G6Q

But it still says FIP so I'm concerned...

 

[wwhitney]

My understanding is that a stainless corrugated flex connection depends on a rubber washer, and the female ends have straight threads. As such they would thread onto either straight or tapered threads, and the washers seals against the end of the male pipe. The question is what the temperature limits of the washer are.

Cheers, Wayne

 

[joeyjoejoe]

So I just had a crazy thought and screwed on a garden hose thread fitting and it seemed to be great.

:|

Can't say I'm super impressed with the manufacturer.

I guess an option is garden hose thread to NPT adapter with a suitable high-temp washer?

 

[wwhitney]

Maybe a silicone garden hose washer? I have no particular expertise in this matter, just seems like it would fit the bill.

https://www.amazon.com/Backyard-Dudes®-Garden-Silicone-Washers-10-pack/dp/B00ZJBVV8U

If you need a flexible connection between the steam generator and the outlet, it makes sense to me to have it directly at the steam generator, rather than converting to 3/4" NPT first.

Cheers, Wayne

 

[Fitter30]

Stainless corrugated would have condensate setting in the corrugations. Plumbing supply houses will have all the fitting you should need.

 

[wwhitney]

PS. Garden hose threads (GHT) are apparently 11.5 threads per inch (tpi). While 3/4" NPT/NPS/BSPP are all 14 tpi. So you should be able to distinguish by counting threads. The fact the garden hose attachment works suggests it must be 11.5 tpi.

Cheers, Wayne

 

[joeyjoejoe]

Good call on the thread pitch. I'll go grab the gauge again to make sure.

I'm using unions near the generator to make servicing easier - I think I did a great job in this aspect, because as some like to say.. the next guy who has to work on this thing is probably gonna be me.

 

[joeyjoejoe]

Ugh, yup - it is 14TPI for sure. So I guess garden host is out. It did seem to thread OK by hand, but the pitch gauge doesn't lie...

 

[joeyjoejoe]

:O

This might work..

https://www.amazon.ca/gp/product/B086JQXZ1Z

 

[Marlinman]

Look at the specs for Fluidmaster water heater supplies. The braiding is over EPDM rated at 250 F degrees

https://www.fluidmaster.com/wp-content/uploads/2017/01/Spec-Sheet-Connectors_2015-1.pdf

 

[Fitter30]

Blue monster tape or anaerobic pipe dope for the strait threads.

 

[joeyjoejoe]

Wow, so that G-thread adapter fits!

I'll use teflon tape likely as a means against mechanical vibration to ensure a tight fit if needed, and a silicon gasket for the actual seal.