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Old 16-02-2012, 20:47   #31
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Re: Water Hose from Water Heater

Ditto on PEX for boats. Its very good for boat hot and cold water systems. Oh PEX is PEX, so the PE in the big box store is the same as the PEX in the marina store, just less expensive. I've used the slip on fittings, both plastic and the sharkbite brass ones. both work well and yes even a blonde can install it

Back in the 70's and 80's PEX and PB got a bad rap for the chrimp connections. Seems back then they used brass fittings and aluminum crimp rings. Being dissimilar metals they had different coefficients of expansion and had a whole boatload of leaks and lawsuits.

Now a days crimp systems use the same material for the fitting and chrimp rings or should be anyway. Though I really like the easy push on connections.

Another nice think is PEX is tubing so 1/2" pex (which is 1/2" Outside diameter) will slide inside 1/2" PVC pipe (which is 1/2" inside diameter) for example. Makes it easy to run the new tubing when your boat had PVC installed.
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Old 17-02-2012, 05:34   #32
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Re: Water Hose from Water Heater

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Originally Posted by sailorchic34 View Post
Ditto on PEX for boats. Its very good for boat hot and cold water systems. Oh PEX is PEX, so the PE in the big box store is the same as the PEX in the marina store, just less expensive. I've used the slip on fittings, both plastic and the sharkbite brass ones. both work well and yes even a blonde can install it

Back in the 70's and 80's PEX and PB got a bad rap for the chrimp connections. Seems back then they used brass fittings and aluminum crimp rings. Being dissimilar metals they had different coefficients of expansion and had a whole boatload of leaks and lawsuits.

Now a days crimp systems use the same material for the fitting and chrimp rings or should be anyway. Though I really like the easy push on connections.

Another nice think is PEX is tubing so 1/2" pex (which is 1/2" Outside diameter) will slide inside 1/2" PVC pipe (which is 1/2" inside diameter) for example. Makes it easy to run the new tubing when your boat had PVC installed.
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Old 17-02-2012, 06:02   #33
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Re: Water Hose from Water Heater

A couple of years ago, I replaced all of my potable plumbing. I was very much on the side of using PEX but I went with High quality hose from Trident. My reasoning was quite simple: If my old system (hose) lasted for 30+ years, then replacing it with similar will last longer than I will likely own the boat. Another reason was the ease of repairs to the hose with no special tools required plus the added benefit of ease of disassembly. The hosing, as a system, is a lot cheaper than the special fittings that the PEX requires when you add it all up.
The downside to using hosing is the possibility of algae, but I usually sterilize my lines at least once a year and I also keep a touch of bleach in my water, so I really haven't noticed any build up.
Oh, this may or may not be an issue: the hosing is easier to snake through the boat.

Just my view and my reasoning
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Old 17-02-2012, 06:09   #34
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Re: Water Hose from Water Heater

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I have a one year old Beneteau First 36.7 and have been surprised to find ruptures in the hot water hose coming off the water heater. Happens after every long use of the diseal when motoring for several hours. Taking heat from the engine, the water gets pretty hot and the hose leading from the tank to the sinks gets little ruptures in the first 3 to 5 feet of the tank...
Pacific,

Looks like you have received lots of advice on lots of subjects which is very typical in this forum. Our previous boat was a Beneteau.

I believe that I read every posting, and have a suggestion for you that has not been published. Beneteau will normally build a boat without a pressure accumulator on the hot water side. Most people believe that an accumulator is only used for reducing the fresh water pump cycles...BUT, an accumulator on the hot water side will also "absorb" the increase in pressure caused by the water expanding in your hot water heater and hot water lines as it is heated by your engine. It is really important in vessels with less plumbing lines and smaller vessels because there is not much area for the pressure dissipate. Some yacht builders believe that the pop-off pressure relief valve on the water heater is sufficient for this...I do not.

I think if you were to add an accumulator to the hot water side of your fresh water system, you will solve your problem...AND/OR...replace the hot water heater's pop-off valve which possibly could solve your hose bursting problem.

Bill
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Old 17-02-2012, 15:17   #35
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Re: Water Hose from Water Heater

The accumulator can be on the cold side too, Btw even though the new vsd pumps don't need it, its really good to have to keep the pressures in the water lines under control when the water heater goes from cold to hot. Its actually a pretty big problem on boats. By building code its required on all new building construction, Least wise in the UPC, think BOCA too. (building codes)-ish

I use a bigger 2 gallon residential thermal expansion tank available at the big box stores rather then the little jabsco tanks at the marine stores. It just works better as a accumulator, on a boat. I found that the jabsco bladder tanks will rip the bladder after a while from hot water expansion.
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Old 21-02-2012, 00:47   #36
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Re: Water Hose from Water Heater

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Originally Posted by sailorchic34 View Post
The accumulator can be on the cold side too, Btw even though the new vsd pumps don't need it, its really good to have to keep the pressures in the water lines under control when the water heater goes from cold to hot. Its actually a pretty big problem on boats. By building code its required on all new building construction, Least wise in the UPC, think BOCA too. (building codes)-ish

I use a bigger 2 gallon residential thermal expansion tank available at the big box stores rather then the little jabsco tanks at the marine stores.
VSD pumps don't need it for maintaining pressure, but water systems need accumulator tanks for compensating for water expansion as the water heats.

I agree...when we replaced our 4 liter accumulator (expansion) tank which was located near the hot water heater, we bought the new tank from a "well water shop," and increased it to a 9 liter...much better. It is important to properly adjust the pressure on the air side of the accumulator tank. If you are not sure what to adjust it for, 40psi should work for most boats.

The reason I like to suggest placement on the hot water side, is it is best to place the accumulator as close to the source of increased pressure as possible...that way, you are not exposing more feet of hose to the source of the pressure increase. I find that most accumulator tanks used to assist the water pump in maintaining constant pressure are placed near the pump. For a typical yacht of less than 18m, I recommend one 4 liter accumulator near the pump and one 9 liter near the hot water heater.

Oh, one more thing, I suspect the root cause of commonly experienced leaks near/around the heating element seal are caused by increased pressure in the hot water heater.

Bill
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