Standard vs. tankless hot-water heater

[sneuman]

I like the elegance of tankless hot-water heaters, but I gather the marine versions don't work as well as those use in homes.

Also, is there any reason to use a "marine" version (of either tankless or standard) instead of the smallest one I can find in Home Depot?

[SkiprJohn]

I just installed a Bosch tankless propane water heater at the house. What a dream. Instant hot water and doesn't require any electric hookups. I can't say what the difference would be for marine version or installation but I really do like the one I just got hooked up yesterday.
JohnL

[Alan Wheeler]

I don't think there is a difference (performance wise) than one for a house. I think the only major difference would be the way the gas is ignited. Marine ones are either battery or 12V. House ones will be mains operated. Apart from that, there are several sizes of califonts. I think the smallest is 5 or 6ltrs/mon and then there is a 10ltr and I have a 12ltr. They are rated at supposedly increasing the water temp by 25degC from the ambient temp at the rated flow. With 12ltr, I can turn the water flow down and have the water temp increase dramaticly. Danw can wash dishes (and she loves really hot water to do so) with water straight from the tap. WIth the smaller 5ltr unit, she could never get the water hot enough for her likeing. Of course, the bigger the unit, the more gas it will consume as well.

[hellosailor]

The "marine" version might be built with different venting provisions, different CO protection and flame cut-off, different metals to resist salt air...or might just have a bigger price sticker and lower capacity per hour.

You'd have to compare units.

[Pblais]

We have a Bosch on Demand propane heater aboard. It's been with the boat since 1991. It works great. This is a ventless unit that has an Oxygen Depletion Sensor so it needs no outside vent or chimney. Most other units do need one so it is a nice feature if you can install it without a vent. That said I always open the port when using it as the heat is significant. This aids in drying out the shower / head since the unit is literally in the shower stall.

The unit has an inline shutoff for the propane so you can take it apart if need be. It seems to make enough hot water that you could drain the tank and still have warm water. That's probably the bad news as you really could take a very long shower until you ran out of water or propane. You can adjust the flow rate through the unit. On our water system at full force the water comes out pretty hot in the summer when the water temp in the tank is quite high but needs to be shut down in the late fall early spring when the water temperature is colder. On any boat water system it should work fine as you pressure is not as high as on land.

It turns the burner on and off as you open and close the valve so it is very economic on the propane.

The ignition is with a a push button pizeo button like you see an many house gas hot water heaters. You slide the button into light position, press the button and hold it then a thermocouple sets up so you can let go and slide into on position. the pilot light then remains on until you slide the button back to off. So you may light it for a period when all might use hot water then turn it totally off and shut the shutoff so no propane is on or can be turned on.

[sneuman]

Originally Posted by Pblais

We have a Bosch on Demand propane heater aboard. It's been with the boat since 1991. It works great. This is a ventless unit that has an Oxygen Depletion Sensor so it needs no outside vent or chimney. Most other units do need one so it is a nice feature if you can install it without a vent. That said I always open the port when using it as the heat is significant. This aids in drying out the shower / head since the unit is literally in the shower stall.

The unit has an inline shutoff for the propane so you can take it apart if need be. It seems to make enough hot water that you could drain the tank and still have warm water. That's probably the bad news as you really could take a very long shower until you ran out of water or propane. You can adjust the flow rate through the unit. On our water system at full force the water comes out pretty hot in the summer when the water temp in the tank is quite high but needs to be shut down in the late fall early spring when the water temperature is colder. On any boat water system it should work fine as you pressure is not as high as on land.

It turns the burner on and off as you open and close the valve so it is very economic on the propane.

The ignition is with a a push button pizeo button like you see an many house gas hot water heaters. You slide the button into light position, press the button and hold it then a thermocouple sets up so you can let go and slide into on position. the pilot light then remains on until you slide the button back to off. So you may light it for a period when all might use hot water then turn it totally off and shut the shutoff so no propane is on or can be turned on.

paul,
which model do you own?