Hot water is TOO hot.

[By Invitation]

I have a question,

I have a perkins 4-108 which is running great and at the correct temperature. We have Raritan hot water tank which also works great. The problem is that our hot water is really too hot and I would like a simple way to install a thermostat in the heating line from the engine to keep the water temp at around 120 to 140 max. Has anyone done this? If so what thermostat should I use?

Thanks.

[EngNate]

Never heard of it done; Put a valve off the engine port on the return side and reduce the flow or close it when not in use. It is true that normal engine temp is way (about 40 deg F) over normal domestic hot water temp. Such a thermostat would have to be integrated into the water heater design.

[Auspicious]

Some boats have a thermostatic mixing valve on the output of the water heater to mix in some cold water and temper the output temperature. This serves to "stretch" your hot water supply and reduce the risk of burns from water that is too hot at the faucet. I expect that the mixing valves are available somewhere ...

[btrayfors]

They sure are. Lots of models. Here's one that looks like it might be appropriate for a boat: Watts Series MMV-US M1 Thermostatic Mixing Valve 1/2" (0206000) - PlumberSurplus.com

Bill

[never monday]

Scott,
Force 10 does this standard on the newer units. look at what they do and buy the parts or copy it.

[knottybuoyz]

Originally Posted by never monday

Scott,
Force 10 does this standard on the newer units. look at what they do and buy the parts or copy it.

We just put in a new Seward 6 gal this spring. I think I read in the phamplet that it's a USCG or ABYC req't to have the mixing valve (tempering valve) installed. I'll dig out the instructions tomorrow for a reference.

[AnchorageGuy]

OK< There is no such thing as ABYC required. ABYC is a set of standards written as a guide and not to be confused with any type of requirements or as standards for the Coast Guard. Certain equipment can be made to AYBC standards but if it is not that does not necessarily mean you can't or shouldn't use it. Most older vessels were not built to AYBC standards but they are still safe and seaworthy.


ABYC – American Boat & Yacht Council – is a not-for-profit membership organization that has been developing and updating the safety standards for boat building and repair for over 50 years. ABYC is actively involved with the International Organization for Standardization (ISO) and is a leader in education for the marine industry, as well as certification programs for marine technicians.

[knottybuoyz]

Originally Posted by Chuck Baier

ABYC is a set of standards

Yup. Got a set sittin' not 3 feet from me right now. Just too damn tired to look at them right now. I was only thinking I had read it somewhere wasn't sure exactly where though. I'll do the research tomorrow.

[GordMay]

About Tempering Water Valves:
http://www.watts.com/pdf/PG-MXV.pdf

Installation Instructions:
http://www.watts.com/pdf/1915906.pdf
&
http://www.watts.com/pdf/1915905.pdf

“Fail-safe”
in case of hot or cold water failure, most thermostatic tempering valves fail to “off”.
“Bypass”
Some valves have a built-in cold water bypass - in case of hot water failure the valve fails to “cold”.

[knottybuoyz]

A Temperature Control Valve on a Force 10 h/w heater. The TCV on the Force 10's acts a little differently than a mixing valve. It restricts flow of engine coolant through the heat exchanger loop as coolant temperature rises. Factory preset to 140 degs F. It does this to protect the h/w heater from excessive temps from an incorrectly thermostated engine or one that has overheating problems.

I found a reference in the documention to ABYC standard 23.7.4.2 but that wasn't specifically to do with the TCV but the Pressure Release Valve (PRV) and the req't for an overflow hose to be installed on the PRV. I knew I saw some sort of standard reference in the documentation. All ABYC says about temperature relief and h/w heaters is that the maximum relief shall be set at no more than 210 degs F. Section 23.8.12.1.2

[Boko~maru]

We Had the same set up, except the engine was a Westerbeke, with the same result. I recommend using a "single Lever" faucet, allowing you to mix in cold water as required. The metal casing rusted out on our Raritan, and has since been replaced with an Isotemp, which has mixing built in.