Our hot water is too hot !?!

[SVEnchantress]

Sailed our new to us 303 up from Melbourne to Titusville this past weekend. Due to the winds, it was an 8 hour motor (couldn't even motor sail) -- at one point in the afternoon my wife went to use some hot water and it was HOT HOT HOT and she nearly scalded herself. There was a plastic spoon in the sink and it actually melted the plastic. Even water from the cold tap was hot.

My question is this: I know that the water is heated by re-circulating engine coolant, but should it be scalding hot ? And what could possibly be making the cold tap hot as well ?

I meant to check the cold tap before leaving the boat to make sure the PO didn't do something odd, but alas I forgot.

 

[Maine Sail]

Sailed our new to us 303 up from Melbourne to Titusville this past weekend. Due to the winds, it was an 8 hour motor (couldn't even motor sail) -- at one point in the afternoon my wife went to use some hot water and it was HOT HOT HOT and she nearly scalded herself. There was a plastic spoon in the sink and it actually melted the plastic. Even water from the cold tap was hot.

My question is this: I know that the water is heated by re-circulating engine coolant, but should it be scalding hot ? And what could possibly be making the cold tap hot as well ?

I meant to check the cold tap before leaving the boat to make sure the PO didn't do something odd, but alas I forgot.

You need to add a thermostatic mixing valve...

 

[NYSail]

The cold water may only be hot for a few moments due to plumbing exposed to engine heat. Let water run for a moment then check.

 

[Maine Sail]

The cold water may only be hot for a few moments due to plumbing exposed to engine heat. Let water run for a moment then check.

Nope.... Sadly it has been legal in the US for boat builders to connect the water heaters HX to a source with 180 degree plus water in it for years. That is FINALLY changing in the next revision of the ABYC standards.

This sort of nonsense is NOT allowed on shore and should have NEVER been allowed on boats, but it has been. Feed a 6 gallon water heater 180F engine coolant for long enough and guess what, eventually the water inside the water heater gets to pretty much 180F.....:cussing:That temperature would instantly spell lawsuits on land but on boats folks just seem to accept it.....:cussing: It is simply flat out dangerous to not have a means of tempering the hot water coming out of the water heater...

All boats with a heat exchanger water heater should have a thermostatic mixing valve whether required to or not.

Some of my customers have massive diesels that run at 200F not 180F......

 

[SVEnchantress]

Is there a thermostatic mixing valve specifically made for boat use or do I just get a normal one from plumber's supply place ?

 

[Maine Sail]

Is there a thermostatic mixing valve specifically made for boat use or do I just get a normal one from plumber's supply place ?

Any domestic hot water heater thermostatic mixing valve will work... I usually use the Watts 1170-M2 1/2" tempering valves...

 

[StargazerP303]

Here is a "Point of USE" mixer valve that requires 0.5 psi to operate properly. However, the costs are still high $ 250. and up! I think ill use the old-method of touchy-feely..lol

Capt. Rob

 

[JamesG161]

For info: 180°F is sanitary temperatures for dish ware in public restaurants. 150°F to rapidly touch without burn. 120°F is safe to mix or "brush" wash dishes. ~105° is hot shower.

Building codes require "anti-scald" for showers which adjusts temperatures when water demand pressures change (this "ouch" shower when you SO flushes the toilet) and maximum 140°F water heaters.

I found this link for Marine stuff but if you check all popular brands like Delta, Kohler, Moen etc. they have many anti-scald fixtures.
http://safeshower.com/faucets.htm

In a pinch, post a "Extremely HOT Water" sign.
http://safeshower.com/faucets.htm

Jim...