T&T: A Water Heater Question

[Albin43SDtr]

Kevin and All,

>All of the water heater installation manuals I've seen have recommended a
>check valve on the input, and an expansion tank in the system. However, I've
>yet to see a boat with an expansion tank, and my current boat does not have
>one.

When I built the interior of our old sailboat, I did not put in 
either a check valve or expansion tank in the hot water system. The 
water heater had a heat exchanger as well as 120V element. The first 
time I ran the engine long enough to thoroughly heat the water from 
"cold", I blew a hose off of a fitting. "Must have been loose"... so 
I reinstalled and retightened the clamp. All of the hoses were nylon 
reinforced vinyl so the expansion was limited. I had several 
failures. I then put in both a check valve and an expansion tank and 
had no further problems.

On the Celestial, I never had any hose/connection failures, but when 
heating the water up to engine operating temperatures of 180-185 
degrees, then opening the faucet, it blasted water super hot water 
until the pressure was relieved. I installed an expansion tank (Sears 
1 gallon tank), and have no further chance of scalding someone. I 
installed the tank under the sink in the forward head so as to place 
it as far away from the super hot water, just in case the lining 
diaphragm could not withstand the temperature.

The Sears tank had no mounting lugs, so I used Liquid Nails to attach 
two 2x2 boards that I had cut matching curves on. The mounting boards 
extended out past the sides of the tank a little so that I could put 
4 screws in to mount it with. I had to reduce the air pressure on the 
diaphragm to accommodate the lower pressure delivered by the pump - a 
simple procedure.

Just my experience and solutions to experienced problems. The 
Celestial went many years without the expansion tank before we owned 
her. The previous owners apparently did not perceive the pressure 
build-up as warranting correction. One work around is to open the hot 
water faucets as the water heats up to periodically relieve the pressure.


Take care and be safe.

Wayne
Celestial
Albin 43 Sundeck
Near Panama City, FL