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Old 09-09-2012, 10:13   #16
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Re: High Fresh Water Pressure When Running Motor

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Originally Posted by Oliver L. View Post
Phantomracer,

if you don't have a pressure relief valve you are simply operating a dangerous system. Most likely there is a port for one on your water heater, and someone removed it because it was leaking. This is simply an accident waiting to happen - a second component failure, for example of the high limit thermostat, could create a nice little bomb inside your boat.

I would not worry about the hose clamps - screw type clamps are at least good for 150 psi if installed right. As far as your expansion tank is concerned, it has primarily nothing to do with this problem - it is supposed to be a pressure storage, and if large enough, it can hide the absence of the pressure relief valve. To test it: When you open a tap and it takes a while for the pump to come on, the tank is working. If the pump comes on immediately every time, the tank is not working. If it's not working you can try to pressurize it with a bicycle pump, although to do it properly it should be filled with Nitrogen. If the diaphragm is still intact, it will start working again. If the diaphragm is defective, you will be back to square one the next morning and then you need to replace the tank.

Oliver
Yes I know..aware of the danger. That is the reason for this post. As far as I know the pump and tank work as designed. It pressurizes, an I can use the faucets without the pump coming on all the time. I know it is not designed for a pressure relief valve.

The tank is new (previous owner installed it). He had it custom made (or bough it and it fit in the locker). unsure if it was designed to be a water tank or not). Either way there is no pressure relief on it that I can see...

I know what the problem is. I just don't know what the solution is. A part #, or at least what to search for or ask for would be helpful.

Paul
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Old 09-09-2012, 10:15   #17
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Re: High Fresh Water Pressure When Running Motor

I tried posting that video and it went to moderation.

The problem seems to be a malfunctioning thermostat. Someone said it best earlier, T&P valves are the last resort to keep bad things from getting much worse.
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Old 09-09-2012, 10:16   #18
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Re: High Fresh Water Pressure When Running Motor

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Originally Posted by HopCar View Post
Hi Sailorchick, you're right of course about the tank not exploding as long as the water doesn't boil. I guess the danger is that thermostats can fail and electric elements can boil the water. Did you ever see the Myth Busters blow up a water heater. Wow!
in my case there is no element or tstat, as it is a passive heat exchanging tank. I can't see how the water would get to boil as the engine only gets to 180 degrees or so.

having a hose blow out and water spewing out is not a good thing either! At least 2 of the 3 times it happened the pump was switched off. so only expanding water escaped. THe first time, the pump was on, and it was like a firehose! Thank goodness I was right there when it happened.
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Old 09-09-2012, 10:18   #19
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Re: High Fresh Water Pressure When Running Motor

Right, there are several different manufactures of the same small accumulator. I had one like it too. Replaced it with a new one just like it, which lasted 3 months before the diaphragm failed and let water to the back side. (from thermal expansion). I have a 2 gallon metal one from the box store that has been fine for 3 years now.

The quart models should give you about a pint of water before the pump kicks in, the larger ones will give a half gallon.

If your water heater does not have a relief valve, well at the least you should mount one. From granger, link below, The calibrated relief allows you to set it to any pressure, say oh 80 psig.. Its not a T&P relief, but the temp probe of a T&P relief will not fit in a tee and will not provide any safety if not immersed in the tank

WATTS Relief Valve, 1/2 In, Brass, M x FNPT - Relief Valves - 1X624|530-1/2 - Grainger Industrial Supply
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Old 09-09-2012, 10:23   #20
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Re: High Fresh Water Pressure When Running Motor

From reading your posts it appears the water system's pressure is just set too high. Personally I would not worry about the hot water tank having or not having an over pressure regulator which I know are needed with boilers.

Further, I presume you have this problem only when using tank water and not dock water.

I had trouble with my Jabasco water pump ever since it was new. That sucker intermittently just would not shut off forcing me to shut the circuit breaker off. I put up with it for a couple of years and finally purchased pressure switch from a plumbing supply store. The switch is one designed for home water well pumps. Now although my problem was different than yours, my solution worked because it by-passed the pump's pressure regulator by turning off the power after the system pressure reached what I had the switch set for which was about 15 psi. Heck, I don't need high pressure on my boat and this helps to prevent internal hose connections from popping off in places that I just cannot get to.

The regulator switch cost about $28 if I remember correctly.
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Old 09-09-2012, 10:26   #21
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Re: High Fresh Water Pressure When Running Motor

Hi Hopcar...Well no TV on my boat. but YES an exploding water heater would sink a boat or make a nice hole in a house. A whole lota death and destruction there when things go wrong..

Yes if he has in electric element then he has a problem for sure. If that is the case then replace that puppy tomorrow with one like you posted From the looks of the tank, I assumed it was a simple shell and tube exchanger someone fabrication..
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Old 09-09-2012, 10:32   #22
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Re: High Fresh Water Pressure When Running Motor

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Originally Posted by sailorchic34 View Post
Right, there are several different manufactures of the same small accumulator. I had one like it too. Replaced it with a new one just like it, which lasted 3 months before the diaphragm failed and let water to the back side. (from thermal expansion). I have a 2 gallon metal one from the box store that has been fine for 3 years now.



WATTS Relief Valve, 1/2 In, Brass, M x FNPT - Relief Valves - 1X624|530-1/2 - Grainger Industrial Supply
Chic---

That pressure relief valve has a low setting of 50psi which I believe is just too high of most older boat plumbing systems--i.e. before PEX tubing & fittings.

But a question about your expansion tank. I installed one similar to what you described into my old sailboat. I often thought "heck, why not just use a boiler expansion tank?" Is what you installed designed for potable water or one for a heating system....which will work the same way?

Foggy
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Old 09-09-2012, 10:36   #23
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Re: High Fresh Water Pressure When Running Motor

PR: So I would install the larger thermal expansion tank AND the calibrated relief valve. As you don't have an electric element, the one relief will give you peace of mind. The larger accumulator will prevent the relief valve from popping off.

In case you have not guessed yet, besides being a bimbo, I'm also an engineer with 33+ years designing plumbing, piping, hydraulics, and a whole bunch of other stuff.. If you need a Bio-pharma or 40 story high rise or semiconductor fab designed, I'm your girl. I also sail...
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Old 09-09-2012, 10:40   #24
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Quote:
Originally Posted by foggysail
From reading your posts it appears the water system's pressure is just set too high. Personally I would not worry about the hot water tank having or not having an over pressure regulator which I know are needed with boilers.

Further, I presume you have this problem only when using tank water and not dock water.

I had trouble with my Jabasco water pump ever since it was new. That sucker intermittently just would not shut off forcing me to shut the circuit breaker off. I put up with it for a couple of years and finally purchased pressure switch from a plumbing supply store. The switch is one designed for home water well pumps. Now although my problem was different than yours, my solution worked because it by-passed the pump's pressure regulator by turning off the power after the system pressure reached what I had the switch set for which was about 15 psi. Heck, I don't need high pressure on my boat and this helps to prevent internal hose connections from popping off in places that I just cannot get to.

The regulator switch cost about $28 if I remember correctly.
There is no pressure when the pump is off and I bleed the pressure from a faucet.

Always happens when the motor is run for a few hours and the pump power is ofd
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Old 09-09-2012, 10:48   #25
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Re: High Fresh Water Pressure When Running Motor

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Originally Posted by foggysail View Post
Chic---

That pressure relief valve has a low setting of 50psi which I believe is just too high of most older boat plumbing systems--i.e. before PEX tubing & fittings.

But a question about your expansion tank. I installed one similar to what you described into my old sailboat. I often thought "heck, why not just use a boiler expansion tank?" Is what you installed designed for potable water or one for a heating system....which will work the same way?

Foggy
Great question on the tank Foggy!!!, Yes a Boiler expansion tank and a thermal expansion tank look the same. But the listings are different. Sometimes its the same item with a new listing but sometimes the rubber diaphragm (if it has one) is a different rubber compound. There are thermal expansion tanks listed for potable water.

You can pick one up at the big box stores in the plumbing department. Oddly enough the thermal expansion tank also works as an accumulator and the price is half the marine plastic jobbies.

On the pressure setting, I think 50 to 80 psig should be fine for most boat fresh water systems. In general, plumbing bits and pieces are designed for a maximum pressure of 80 psig.

BTW: Plastic DWV fittings are NOT rated for pressure. There is a different in the wall thickness of fittings used for sanitary and water systems. Just fyi

http://www.freshwatersystems.com/p-5...-2-gallon.aspx
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Old 09-09-2012, 10:52   #26
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Quote:
Originally Posted by sailorchic34
PR: So I would install the larger thermal expansion tank AND the calibrated relief valve. As you don't have an electric element, the one relief will give you peace of mind. The larger accumulator will prevent the relief valve from popping off.

In case you have not guessed yet, besides being a bimbo, I'm also an engineer with 33+ years designing plumbing, piping, hydraulics, and a whole bunch of other stuff.. If you need a Bio-pharma or 40 story high rise or semiconductor fab designed, I'm your girl. I also sail...
Any particular model tank you like?
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Old 09-09-2012, 11:05   #27
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Re: High Fresh Water Pressure When Running Motor

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Any particular model tank you like?
Yes I psychic too. Though some might say Psycho

Check the post above yours for a link. to a tank :-)
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Old 09-09-2012, 11:13   #28
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Re: High Fresh Water Pressure When Running Motor

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Originally Posted by sailorchic34 View Post
Great question on the tank Foggy!!!, Yes a Boiler expansion tank and a thermal expansion tank look the same. But the listings are different. Sometimes its the same item with a new listing but sometimes the rubber diaphragm (if it has one) is a different rubber compound. There are thermal expansion tanks listed for potable water.

You can pick one up at the big box stores in the plumbing department. Oddly enough the thermal expansion tank also works as an accumulator and the price is half the marine plastic jobbies.

On the pressure setting, I thing 50 to 80 psig should be fine for most boat fresh water systems. In general, plumbing bits and pieces are designed for a maximum pressure of 80 psig.

BTW: Plastic DWV fittings are NOT rated for pressure. There is a different in the wall thickness of fittings used for sanitary and water systems. Just fyi

ProFlo Thermal Expansion Tank 2 Gallon - FreshWaterSystems.com

Chick!

Geez, it sure helps to have a technical background!!! I share your thoughts but just never got around to look for potable tanks. Heck, I just Googled between posts and found there is a bunch of potable tanks out there for almost peanuts! By that I mean for less than $50.

Darn it though, they are just not stamped "marine use "

I have been putting off adding a tank to my current boat, after reading this thread I will look into installing one.

Plastic fittings--- We traveled this road before and of course you were correct then so ... I don't know what fittings are used in my boat other than they are plastic which hopefully I will change later to PEX.

Getting back to the OP, i still believe his best solution is simply to wire a pump pressure switch in series with his pump's 12vdc power. Of course it also requires plumbing it in series with his water line. I also don't see a need for high water pressure in my boat, I keep mine below 20psi.

Foggy
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Old 09-09-2012, 11:14   #29
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Yup saw that

Got to see where I can put that puppy.
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Old 09-09-2012, 11:32   #30
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Re: High Fresh Water Pressure When Running Motor

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Chick!

Darn it though, they are just not stamped "marine use "

Foggy
If you like, I'll be happy to sell you one with a marine stamp on it for four times the price. Those stamps cost money to make you know.. :-)
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