Baller DefectiveDave Posted November 11, 2014 Baller Share Posted November 11, 2014 So based on the recommendations in this forum I've decided to design and install my own hot water shower in the boat, saving a bit of money. I'm ready to get started, but I have one thing holding me up. What type of fittings do I use to tap into the hot water in the engine block? I have a 1992 nautique with the 351 PCM engine, which is a cast iron block. All fittings I have found including brass, copper, and stainless steel will galvanically corrode when in close proximity to cast iron in fresh water. That being said, I'm not sure what the corrosion rate is and I'm too lazy to go tracking down the literature. What types of fittings have others used for this purpose, or what do the factory installed options use? Have they held up well over the years? Any help is greatly appreciated! P.S. I'm hesitant to use plastic fittings due to vastly different thermal expansion coefficients, leading to potential mechanical cycling fatigue. Link to comment Share on other sites More sharing options...
Baller paul Posted November 11, 2014 Baller Share Posted November 11, 2014 heatercraft uses a standard brass/bronze npt to nipple foe connection to the block Link to comment Share on other sites More sharing options...
Baller DefectiveDave Posted November 11, 2014 Author Baller Share Posted November 11, 2014 @paul, Interesting, and there's been no corrosion over the years? It might be that the rate is so low that I don't even need to worry about it. Link to comment Share on other sites More sharing options...
Baller thager Posted November 11, 2014 Baller Share Posted November 11, 2014 5 years and no corrosion showing on mine. Link to comment Share on other sites More sharing options...
Baller DefectiveDave Posted November 11, 2014 Author Baller Share Posted November 11, 2014 That's exactly what I needed to know, thanks @thager! Link to comment Share on other sites More sharing options...
Baller colo_skier Posted November 11, 2014 Baller Share Posted November 11, 2014 Do you have a heater in the boat? If so just plumb into the hot water feed for it. I put my own shower in and didn't have to do anything with block connections. Don't worry about flow through the heater, the return feed restriction from the heater is about the size of a pencil lead. Link to comment Share on other sites More sharing options...
Baller_ Jody_Seal Posted November 12, 2014 Baller_ Share Posted November 12, 2014 Quit worrying about galvanic decomposition and install the Brass and move on. just another part in the system that needs addressing 5-6 years down the road, regular interval maintenance... That is if you still own the boat! you could also install a sacrificial anode! and patch ground it.. Link to comment Share on other sites More sharing options...
Baller rockdog Posted November 12, 2014 Baller Share Posted November 12, 2014 Agreed, forget about the corrosion! Just put the brass in and be done with it. Link to comment Share on other sites More sharing options...
Baller RAWSki Posted November 12, 2014 Baller Share Posted November 12, 2014 On a related subject how many of you with heaters have auxiliary circulation pumps in line to create better heat at idle/low speeds? If so any suggestions? Separately switched or tied in with the heater fan switches?? Thanks Link to comment Share on other sites More sharing options...
Baller JC McCavit Posted November 12, 2014 Baller Share Posted November 12, 2014 Hoses, fittings, demand pump, mixing valves, y-tube, etc. all need to be matched for proper consistent flow, pressure and heat. I found it was less expensive to order the complete kit and y-tube from skidim when they run one of their10% off sales than engineer it myself. Link to comment Share on other sites More sharing options...
Baller DefectiveDave Posted November 12, 2014 Author Baller Share Posted November 12, 2014 Thanks all. I've ordered the brass fitting and will be installing soon. Maybe in salt-water the corrosion issue would be more important. Better safe than sorry. @colo_skier, I don't have a heater in the boat unfortunately, maybe next year. @Jody_Seal, How did you know I was considering a zinc anode? Just kidding! Link to comment Share on other sites More sharing options...
Baller rockdog Posted November 12, 2014 Baller Share Posted November 12, 2014 @RAWSki all you need is the Y piece to fix the low idle heat. I put one in last year and it works perfectly, this is what they are designed to do. Heatercraft, Nautiqueparts, Skidim all sell them. http://www.heatercraft.com/low-idle-wye-1-25-hb-x-5-8-hb/ Link to comment Share on other sites More sharing options...
Baller RAWSki Posted November 13, 2014 Baller Share Posted November 13, 2014 Thanks @rockdog I looked at that Y piece. But somewhere I saw that it couldn't be used on my PCM 6L with closed cooling and heat exchanger? I may will call Heatercraft and confirm the best way to go. Link to comment Share on other sites More sharing options...
kstateskier Posted November 13, 2014 Share Posted November 13, 2014 Thread tape it and don't worry about it. My 90MC had a brass heater block tap in it for 6 years with no corrosion. Link to comment Share on other sites More sharing options...
Baller_ MISkier Posted November 13, 2014 Baller_ Share Posted November 13, 2014 +1 for the Teflon tape on the threads of the brass fittings. The worst slalom equipment I own is between my ears. Link to comment Share on other sites More sharing options...
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