bypass hot water heater

[Lazy Daze]

I've heard/read about not blowing through the fresh water pump, but I've honestly never researched it any more than that. However, the diaphram inside the pump (the "pumping" part) is just a thin piece of rubber, so it sounds like this is solid advice.

 

[kilroy]

I did it for years in my travel trailer (in fact the TT came pre-plumbed to blow out lines) and now I do the same on the boat. Not sure if it's doing any damage but I do set the compressor to a lower pressure. I guess time will tell.

 

[TimTech]

In order to bypass the HWH, I made the connection to join the water lines, but then it got me thinking about the other two hoses from the motor water system into the HWH. Based on your info above, if I drain the MOTOR water lines (blocks, HWH hoses), remove the thermostat, reassemble and run -100F antifreeze through the motor system, I should be all good with both MOTOR water systems and FAUCET water systems correct?

The antifreeze I used last year was the marine grade -100F protection from West Marine. Like you, better safe than sorry.

I drained the water from both my 7.4L blue water engine blocks/manifolds after heating them up to operating temperature. I then ran -100° AF through the engines via a hose adapter I made for the strainers until I saw AF exiting the exhaust. Afterwards, I pulled the two lines that ran from each of my engines to my hot water heater (port engine) and cockpit heater (starboard engine). When I blew compressed air through these lines, clear water came out. So, for those of you that pull AF through your engines, I would not assume those heater lines get winterized.

 

[Brian 59]

I blew through the shore water connection and I pumped the tank empty with no problem. I added a few gallons of pink to run through and cant seem to build much pressure to get a steady stream. I have been doing this since day 1. The mystery continues, possibly time for a new pump?