• Mobile App For Android Now Online!

    Download it here. The app is searchable in the Google Play Store under Sailboat Owners.

    Sorry iPhone/iPad users, we are still waiting on Apple. :(

    Click the X in the upper right corner to make this go away

hot water heater thermostat woes, twice?

MitchM

.
Jan 20, 2005
824
Nauticat 321 pilothouse 32 Erie PA
so the old boat had a raritan made in NJ that lasted 25 years. the new - to - us boat (an 05, 2007 purchase ) came with a claimed 'top of the line ' indel marine 'basic' hot water heater with stainless steel tank, 'double overheat' thermostat protection, adjustable temp, replaceable gaskets. (very $$$ but it was OEM.) in 2016 i started getting inexplicable leaks into the bilge from the h w heater-- not from the hoses, but from the tank gasket.(diagnosed with a cheap water sensor from lowe's.) Rx: bought new gasket ($1$ of rubber for 52$.) Pulled the cover plate to fit a new gasket, found the cover plate had warped so much from high heat the tank was unusable.. bought a new tank summer 2017 , same model $550 . At yesterday's pressurizing of hot water tank --o NO ! another leaky gasket. I have yet to pull the new tank (to see if it warped its cover plate too. ) Did another 2 thermostats fail? what's the electric test to diagnose a failed thermostat? this unit has TWO thermostats-- how could both fail simultaneously so as to heat the tank so much the stainless cover plate warped again??? ideas??
 
May 20, 2016
2,911
Catalina 36 MK1 94 Everett, WA
Are you sure it’s the electrical element getting it to hot? Could it be your engine is running hot??
 
Nov 6, 2006
8,620
Hunter 34 Mandeville Louisiana
or an air bubble on the heating element (tank not fully purged of air)
 
May 17, 2004
2,423
Beneteau Oceanis 37 LE Havre de Grace
What are your winterization procedures? Could it be that water is left in the tank over the winter, freezing and causing the distortion?
 

NYSail

.
Jan 6, 2006
2,411
Beneteau 423 Mt. Sinai, NY
First thought I would agree with the air in the tank and need for big purge. I found my Seaward hw heater needs a real good burping.
Greg
 

MitchM

.
Jan 20, 2005
824
Nauticat 321 pilothouse 32 Erie PA
1. this is a counterflow ht excahger design where stainlesss tubes carry engine antifreeze heat into h w h. if there is h 2o in tank the engine waste heat heats water in h w h. engine was not running when h w h was being filled and even if it were the h w h is deisgned to take residual engine heat when empty w / o a problem. (it would be a very stupid design other wise. ) 2. folowed mfgr winterization to the letter using antifreeze.ther was a f in h w h . this is how i have winterized for 35 years. 3. filled water tank, ran out pink stuff thru both hot snd cold taps and put another 40galfresh water thru . 4. water tank was full of fresh water. hwh power was off. turned water pump on and per mfgr instructions waited till h 2 o came out air bleed valve of hwh tank which shows all air space at tank top was now m full of h 2 o not air. once water comes out air bleed the air in tank was displaced by h 2 o. so h w h per mfgr instruction is ready to start. closed air bleed valve per mfgr instructions. turned on h w h . got h w running properly thru both sink taps. 1 st day .. . shut off system h w was working fine thru both taps w no leaks. we do not leave h w tank on while we are away from the boat so turned it off . next day came in and turned h w h on. after a few minutes water came pouring out . . i suspect the overheat thermostat malfunctioned . if h w temp exceeds allowable, the o h thermostat should c.ut off power . if it does nt the h w t could get so hot the rubber gaskets could fry deform and let h 2 o escape. i will post a pic of the warped stainless cover plate and total loss of tank resulting from failure of last indel isotemp overhea t thermostat soon..