Dual water heaters?

[Ron20324]

Due to a problem in the 110 side of my 6 gallon water heater I have only the engine-heated hot water. While I may or may not be able to fix that, I had another idea of leaving that water heater in place, and add a second one of same model. In the lazz there is a shelf right above the WH. My thought is to put the new heater on that shelf, move the 110 electric line to the new one, and plumb the two in series to have 12 gallons heated.

Hot water in the tanks could last longer but it cools down quicker because the cold water (even colder in the fall) comes in to mix with the hot water in the tank. With two tanks, the original one would supply hot/warmed water to the second one. And 12 gallons of hot water would be nice to have. Yes, it would take more engine coolant. No, I don't weant to pay for a 12-gallon tank. I got a good price on this new one.

Has anyone tried this before? Thoughts?

 

[Stu Jackson]

Clever idea -- there are two loops

Ron, try running the engine fresh water loop through the two heaters in parallel, not series. This way you get the hottest engine coolant to both dhw's at the same time & temperature.

[revised] On the dhw side: You could valve them off from each other to avoid running hot through cold. That's probably be better because they're tank heaters, so there are the whole six gallons in each.

 

[RichH]

If you put two 6-7 gallon heaters in series ... the heater with the cooler water will extract heat from the hotter with the water is flowing .... will be less a problem if the first in the series is cooler as it will 'pre-heat' the water to the second in the series.
Putting two in 'parallel' will require a 'proportioning valve' or a thermostatically (12 vdc.) controlled valve to 'prioritize' the flow from the hotter of the two tanks.

Here's a link for the thermo-solenoid valving: http://www.yandina.com/hints.htm#Water ....(go to saving water, etc.)

 

[Franklin]

Speaking of hot water heaters...I've noticed that my heater will not only heat the water in the internal tank, but also the water in the hose leading up to the fauset. I like that, but if the water is going to pass the heat along through the pipes, how come it doesn't pass it back to the fresh water tank? Maybe a one way valve that seperates the water?

 

[Stu Jackson]

how come it doesn't pass it back to the fresh water tank?

'cuz you have that pesky little water pump in the way.

Heat rises, my dhw htr is right below our galley faucet, don't know where yours is.

 

[Stu Jackson]

Rich, you'reright, I revised

my post. Still the two loops though.

 

[Franklin]

how come it doesn't pass it back to the fresh water tank?

'cuz you have that pesky little water pump in the way.

Heat rises, my dhw htr is right below our galley faucet, don't know where yours is.

About 6 feet forward. It can't be the water pump, because then it would heat up the cold water between the pump and the fauset too and that's not happening.

 

[RichH]

...because the inlet to a hot water tank is on the bottom and outlet is on the top. The heat conducts 'upwards' in the water, the top of the tank is 'hotter'.

 

[Dan Johnson]

Ron...

since you are getting heat into the hot water tank from the engine not shore power, consider instead of a duplicate of the same tank, install one of the shore powered "instant" water heaters that heat on demand, in parallel with the installed marine one. Use a pair of Y-valves on the feed and output lines to switch the water flow from one to the other, depending whether you are in-port (instant heater) or under way/anchored out (existing water heater).

To cure the electrical heating problem, check out what heating thermostat the current tank is using and get a replacement from a home center store. It may save you all the above suggested work. Check out the heating element too--they too can be replaced at the same store.

 

[RAD]

Keep it simple and fix the old one

You can by pass the thermostat and see if that makes hot water,if not its probably the heating element and thats an easy fix, drain the tank and unscrew the element and match up a replacement

 

[Bob J.]

There's not much to go wrong w/ the electrical side of these heaters.
If you've got power coming into the thermostat, & on a call for heat, you got power going out to the element then the element is the problem.

Bob

 

[SamLust]

Do you really want an additional 60 pounds or so at the far end of the boat? The ends are not where you want added weight. Spend the hour and $15.00 and repair the heater.

 

[Ron20324]

Dan, using the 110 AC is of no concern since I'll no doubt be on shore power when visiting some other marina. I have a Honda 2000 if I need the heater working when I'm out "roughing" it. The instant heater was my first thought, but I don't know how well they would keep up when using the shower. Besides, in West they are 25 percent more expensive than the regular heating unit. The new unit is on a delivery truck somewhere. Once i get it and have the owner's manual, maybe I'll deal with the broken one. It's at the very bottom of the lazz, and under a shelf. Dealing with this heater will give me an chance to change the engine anit-freeze, also.

Sam, thanks to Boaters World going out of business, I just put 177 feet of chain in the bow (for now), so I need a little counter-balance to even up the waterline.

I am in a sailing club, and often have two or three ladies as weekend crew- some having never been on a boat, and some that never should be. I just had a blockage in the head plumbing I had to deal with. She won't be back. Telling anyone to not waste electricity, ice, or water is all too often forgotten, so I try to head off any forseeable missuse, and pre-emptively plan accordingly.

 

[Barnacle Bill]

Most likely the reason your water heater doesn't heat water electrically is because the heating element might be burned out. This happens most frequently when people flick the water heater switch to on when there is no water in the heater, which will burn out the element. Replacing it is very easy unless access is not so good. But, by finding out the water heater brand and model, you should be able to go to your favorite chandlery and buy it from them or have them order it for you. Often there is 4 hex bolts holding a plate that secures a rubber gasket to prevent leakage. After removing the bolts, it pulls right out and you will see that the element is attached. The electrical wire attaches to the exterior part. You will have to remove that and reattach to the new element. Sometimes the element is beneath an outer water heater cover, which has fiberglass insulation between it and the actual tank. You need to remove that outer cover to get at the element itself. Some other water heater elements actually screw into the end of the tank, which is the case on some European boats. All in all, it is an easy job and certainly a lot easier than installing a 2nd water heater and plumbing it.

 

[Ron20324]

All in all, it is an easy job and certainly a lot easier than installing a 2nd water heater and plumbing it.

If only you remembered that I want that 12 gallons of water.

 

[Dan Johnson]

Ron...

an "instant hot" water heater should have no trouble keeping up with the limited volume flow of water on a boat. If we used the shower on the boat, my 30 gallons would be gone in no-time before I got a crack at it--that's what marinas are for! Check out commercial versions as they may be as adequate (and safe) as a marine version as in WM.

I had to take apart my aft dinette furniture to replace my hot water heater two seasons ago. A ton of agravation (it evidently was #3) in just getting it to fit, much less hook up to existing connections. Can imagine what you need to go through.