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-   -   Tankless Water Heater, CNG? (http://www.sailnet.com/forums/living-aboard/100075-tankless-water-heater-cng.html)

Dr.Why 06-02-2013 12:48 PM

Tankless Water Heater, CNG?
 
Anyone tried any of the less expensive tankless water heaters? Has anyone installed one to CNG? My old 110 tank is dying. I don't have a heat exchanger on my S2 9.1 either, so hot water away from dock and less weight (we also race) would be good. I have CNG for cooking and like it.
I'm looking at installing one of the small tankless water heaters out there and running it off my CNG. Has an ignition system that runs off of 2 D cells and is only on when water runs through it. I mostly use the hot water for dish washing and the odd twice a decade shower.
Any thoughts on installation? Anyone done this before?

deniseO30 06-02-2013 01:14 PM

Re: Tankless Water Heater, CNG?
 
why don't you use the engine to heat HW? it's not that difficult to do. Then even if you had a sea water cooled engine, to convert it to a RW cooled heat exchanger is also not that difficult.
I used to do tankless systems in my land based business they don't work well on boats because they need venting,

Dr.Why 06-02-2013 01:21 PM

Re: Tankless Water Heater, CNG?
 
My Yanmar 2 GM runs quite cool with our Puget Sound water. Not much heat with a raw water system. Looked at conversion a while ago--fairly expensive plus weight.
Why is venting a problem? I was considering mounting it on a custom bracket where my existing water heater is now and running the venting aft and out of the boat.

deniseO30 06-02-2013 01:54 PM

Re: Tankless Water Heater, CNG?
 
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?

Capt Len 06-02-2013 02:18 PM

Re: Tankless Water Heater, CNG?
 
Since hot rises on its own ,I'd bet it wouldn't breath well out the transom. CO could be an issue. Any way the pressure inside has to be greater than outside or it inhales to your peril.One way to a bi annual shower is a black solar water bag with a small connection thru deck head into washing area. control valve inside. Unless you run some pipe either shower at the galley sink or pile the dishes in the head.

Dr.Why 06-02-2013 02:51 PM

Re: Tankless Water Heater, CNG?
 
Quote:

Originally Posted by deniseO30 (Post 1038583)
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?

Depending on unit requirements and dimensions I was planning on venting it through the stern. What units are you talking about?

Waltthesalt 06-02-2013 05:12 PM

Re: Tankless Water Heater, CNG?
 
I've got an old Wolter. The installation venting issue was that you needed at least a foot of flue pipe before the mushroom vent. The vent needed a foot of clearance from other stuff like dorade vents hatches etc. that could cause a downdraft. This ensures that the flow goes out the pipe and not back into the boat. For the unit itself you needed about four inches of clearance on the side and eight above. There needed to be an air supply about 20 sq inches. While tankless units are lots better now the same principles probably apply

elspru 06-12-2013 05:48 PM

Re: Tankless Water Heater, CNG?
 
what about electric water heaters? I remember when I was in thailand they didn't have central hot water, but these boxes that could turn on and they would heat up the water.

something like this:
http://www.northcoastpets.com/pics/p...ccotemp_l5.jpg

mitiempo 06-12-2013 06:17 PM

Re: Tankless Water Heater, CNG?
 
Quote:

Originally Posted by elspru (Post 1043275)
what about electric water heaters? I remember when I was in thailand they didn't have central hot water, but these boxes that could turn on and they would heat up the water.

something like this:
http://www.northcoastpets.com/pics/p...ccotemp_l5.jpg

They would only be workable when on shore power due to power consumption - at 120 volts.

Capt Len 06-12-2013 08:11 PM

Re: Tankless Water Heater, CNG?
 
Those electric water heater are great. would work well on a boat if you had a goodly supply of 220 volt power; the wattage required would be more than most shore cords can handle;; or use the designated generator when you want to wash hands


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