Hurricane heat exchanger fitting

[Carl Boger]

Can anyone tell me what size the fitting is that goes to the heat exchanger above the seaward hot water heater.  It seems to be a 3/4 inch union that takes a 90 degree turn and downsizes to 1/2 inch copper.  My only problem is the thread size.  It doesn't appear to be NPT. 

I just repaired this and it is not currently leaking, but I would like to have some spare parts available or better change to fitting to pex fittings to make it easier to repair in the future.

Does anyone know the size and thread pitch of the top union?  It seems to be a little finer thread than NPT.

Thanks Carl 

[Richard Davis]

Carl
You are correct.  Those are not NPT threads.  NPT threads are tapered. Those threads will be parallel threads.  Probably either NPSM or NPSC.  Those components rely on pressuring the two tapered seated pieces together.  Those are commonly used to connect gas lines.
Richard

[Carl Boger]

Just to follow up,

I just got off of the phone with ITR, the new company who acquired/merged from  Hurricane heating and they stated that they could not ID the Heat exchanger and do not have any support for that type of fitting. 

If I have a problem in the future I will likely simply change out the heat exchanger for a different one that does use regular NPT fittings.  ITR said they could get the newer heat exchangers for me and it could be plumbed in with PEX for ease of maintenance. 

Thanks for any help, but unless someone has a few in stock I don't think I will be spending any more time trying to run them down