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post #11 of Old 06-12-2013
Maine Sail
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Re: Tankless Water Heater, CNG?

Originally Posted by deniseO30 View Post
Well I did a bit of looking up. It seems there are a number of tankless units that meet ABYC guidelines. CNG and LPG are very differen't but the safety guides are not very differen't.
where will you make "another hole in your boat" ? for the vent?
There are a lot of sleazy companies that lie and say they are made for use on boats when in-fact they do not meet the minimum ABYC safety requirements..

I don't know of a tankless propane or CNG heater that actually meets the ABYC standard. Unfortunately there are plenty of companies willing to market these tanks to boaters knowing darn well they don't meet the minimum safety requirements..

Please be aware that some companies like Ex--l are purposely misleading customers. No "vent free" water heater meets the minimum safety standards for installation on boats in the USA under ABYC, NFPA 302 or NMMA. No exhaust vent only heater meets the minimum safety standards.


26.5.10 Unattended appliances shall incorporate a room sealed combustion system.

ABYC Definitions:


Unattended Appliance - appliances intended to function without frequent attention by an operator, and that may cycle on and off automatically, such as refrigerators, thermostatically controlled cabin heaters, and water heaters.

Room Sealed Combustion System - a combustion system in which incoming air, the combustion chamber, and the outgoing products of combustion are sealed from the boat interior.

26.5.10 Unattended appliances shall incorporate a room sealed combustion system.

This means that the unit must be vented and also must take combustion air from outside the boat in a sealed combustion manner, meaning exhaust vents out side the vessel and intake air also comes from out side the vessel. Usually a dual wall vent pipe is used with make up air coming in around the out side of the inner vent pipe to also help keep it cool though some appliances use a two vent system..

A water heater meets the ABYC definition of an "unattended appliance" a galley stove is an "attended appliance".

Just because a manufacturer makes lofty "claims" it does not mean they are legitimate claims or in the slightest bit true if you want to do things to current and accepted safety standards or to have a vessel that could pass an insurance survey.

The Ex--l or any other "vent free" water heaters do not meet these requirements.. Use at your own risk and please check with your insurer before installing one..

I have had to remove a "vent free" water heater that failed to pass an insurance survey.

If a surveyor in the USA passes a boat with a "vent free water heater" they are simply a poor surveyor and simply not doing their job.

One owner who called me with a fairly new vent free water heater was extremely PISSED OFF that they bought a product that purposely mislead them because their surveyor flagged it is an unsafe heater.....

When shopping for a LPG tankless water heater it is buyer beware and please be careful...

-Maine Sail / CS-36T

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Last edited by Maine Sail; 06-12-2013 at 09:19 PM.
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