Seaward W/H Leaks at PRV When Water Cold

[DennisL]

I've gone through leaking PRV post and found nothing that relates to my problem.

We moved the boat to a different marina which required steaming 7 hours, which got the water heater water good and hot from the engine. Once at the new marina I hooked up shore water and the pressure relief valve began spewing. The Seaward water heater is 5 years old so I ordered and installed a new PRV. Realizing that the dock water is high pressure I also installed a 40 psi pressure reducer.

Imagine my disappointment when unheated water began flowing from the newly installed PRV once I hooked up shore water. I also tried just running the fresh water pump but it wouldn't stop running and leaked at one of the fittings. Where can enough pressure to open the PRV be coming from? What am I overlooking? Thanks

 

[Ralph Johnstone]

Imagine my disappointment when unheated water began flowing from the newly installed PRV once I hooked up shore water.

First question, what is the pressure setting on the new PRV (pressure relief valve) on your water heater.

Realizing that the dock water is high pressure I also installed a 40 psi pressure reducer.

Where did you install the 40 PSI pressure reducer ? A photo would be helpful.

I also tried just running the fresh water pump but it wouldn't stop running and leaked at one of the fittings.

It is quite possible you've have over-pressurized your boat's entire water system during this production and weakened your tubing and one obvious joint. The dock water supply pressure is likely 100 PSI which is commonly supplied to residential services.

I also tried just running the fresh water pump but it wouldn't stop running

You likely damaged the pressure sensing diaphragm in the fresh water pump and now it will not shut off. The pressure relief valve is small and only able to handle thermal expansion of the water. It cannot deal with an added supply of high pressure water.

I would suggest you do not attach the shore water again until all aspects of this problem are solved.

 

[rgranger]

I would suggest you do not attach the shore water again until all aspects of this problem are solved.

 

[DennisL]

Thanks for your reply Ralph.

The new PRV is a Watt XL set at 100 psi.

The pressure reducer (40 psi) is attached to the dock spigot, and then a hose runs to the fitting on the boat it attaches to. Until this problem gets resolved, neither shore nor tank water is available because of the leaking PRV.

It's possible both the PRV and the 40 psi pressure reducer are bad off the shelf. But if they aren't, why is cold water coming out of the PRV with water pressure of 40 psi. Seaward support was stumped as was my sailboat racing engineer son.

I'm going to the boat today and will look more at piping, but I feel like I'm working on a mystery without any clues.

 

[Ralph Johnstone]

It's possible both the PRV and the 40 psi pressure reducer are bad off the shelf.

If I were a betting man, I'd say one in a million or less. Much less.

You've described what you see but I always insisted on pictures when I was faced with unusual situations on the job. Too many thing we don't know yet.

What type of tubing are you using and more importantly, what type of joints are you using ? Your next step will be to install a pressure gauge immediately downstream of your pressure reducing valve to see what you're supplying to the system.

Once again .............. pictures, pictures, pictures. High res from a reasonable distance so we can enlarge them for detail.

 

[DennisL]

OK Ralph, pictures it is. I'll take one showing pressure before and after the pressure reducer. And I'll check the tubing and joints.

 

[DennisL]

So I checked the water pressure and to my surprise found 115 psi after the pressure reducer. I got another one with a gauge on the reducer so I'm hoping that will solve the problem.

 

[Ralph Johnstone]

to my surprise found 115 psi after the pressure reducer.

Would I be correct to say that all of your boat's potable water system has been subjected to 115 PSI ? OUCH !

Is the dock supply pressure the same 115 PSI ? I'd hate to think of it being more.

Do you want to tell me what your potable water tubing consists of ? What brand and a description of what the tube fittings are ? Let's see how it came out of the overpressure ordeal.

You will most likely need a new potable water pump as the diaphragm is shot as mentioned previously. Check out the pump under normal tank pumping and see if it shuts off. You had mentioned previously it didn't but best check it out once more before deep sixing it.

 

[DennisL]

Ralph, you are 100% correct that everything fresh water related inside the boat was subjected to 115 psi shore water pressure. And the 115 psi reading was just after the hose bib/spigot.

I'm attaching a picture of my access to the W/H and associated piping. I had to break it all down to replace the water heater and it is a huge pain in the ass. The access picture should help explain why I don't have good piping pictures. I could look in my log and at receipts for the compatible parts I bought when installing the new W/H, but I don't remember the brand and can't see from looking at it.

I do have a new spare water pump on the boat. Hopefully the PRV took the brunt of the high water pressure and I won't need to do a lot more once the pressure is actually regulated.

So I know everyone on here has ideas about how things should or shouldn't be done. I've been using shore water with this boat at different locations for 8 years. The logic is that it saves the pump which is used at anchor. It's unfortunate some marinas don't regulate water pressure. I also know my boat isn't a "sea" boat. It's very comfortable and it serves my needs well, but I spent my working life on ships at sea, so I know what the ocean can do.

 

[Ralph Johnstone]

Hopefully the PRV took the brunt of the high water pressure and I won't need to do a lot more once the pressure is actually regulated.

I don't know what you mean by the PRV taking "the brunt of the high water pressure". Every square inch, without exception, of the interior of your system suffered the same pressure.

As far as the remaining soundness of your piping system is concerned, maybe not too bad. You have Qest fittings which I believe are rated for 100 PSI but I can't find the manufacturer's literature on this. 115 PSI for a few hours would not hurt these.

You tubing is grey polybutylene and you can find its pressure rating along the edge of the tubing along with other specs.

I also suspect its maximum rating is around 100 PSI.

I also see you have an accumulator :

I would check its maximum allowable pressure on the label. It will look like this :

You should be OK to operate your potable water system with your new water pump set at 40 PSI.

Under no circumstances would I ever recommend attaching dock water to your boat again unless you replace your entire potable water system. The above is what we can see and it seems to be able to withstand 115 PSI for a short time. It's what you can't see that should concern you. Lots of fittings under the floor boards and you've already seen one leak. Polybutylene tubing does have a history of problems and it no longer used for that reason.

Without dock water attached, if the tubing fails while you're away from the boat, you put the water tank(s) in the bilge.
With dock water attached, if the tubing fails while you're away from the boat, you try to put the municipal water system in your bilge.

You've also seen that pressure reducing valves do fail and if the new one failed open, are you comfortable leaving it at 115 PSI for months on end through the winter ?

 

[DennisL]

I didn't know about the pressure rating on the tubing. But I guess I didn't garner the sympathy I had hoped for by showing the tight quarters of the W/H. I didn't do very well with picture taking before because of space but maybe I can turn the pipes enough to see the specs.

What I meant by PRV taking the brunt of the pressure was that once the shore water was turned on the PRV opened immediately--releasing pressure. So maybe less than 115 psi on the system. And once I realized the PRV had opened, the water was turned off in maybe 2 or 3 minutes.

I wouldn't leave the shore water on while the boat is unattended either. Turning off the hose bib is the last thing on my departure checklist. And winters here are a wee bit different. The boat doesn't shut down for our winter.

Tomorrow the Harbor does it's new tenant boat inspection. I'll hook up the new pressure regulator then and hopefully be able to report positive results.

 

[Ralph Johnstone]

But I guess I didn't garner the sympathy I had hoped for by showing the tight quarters of the W/H.

The picture you show of the water heater is almost a dead ringer for what I live with. All you need are skinny little fingers with the strength of a mega robot and you're set to change anything in there.

What I meant by PRV taking the brunt of the pressure was that once the shore water was turned on the PRV opened immediately--releasing pressure.

As previously mentioned the pressure relief valve did not reduce the pressure as it's just too small. It is meant to only deal with thermal expansion of the water and not an external input of high pressure water. Either way, we've determined that it's unlikely anything other than the pressure pump was damaged.

I wouldn't leave the shore water on while the boat is unattended either.

As long as you're confident you'll never forget, everything should be ready to go after you install the new water pressure pump.

 

[DennisL]

First off I want to thank you again for being willing to listen and trying to help. I'm not the most patient person, so trouble shooting is not my forte'.

As you suspected, everything works fine with pressure regulated (45 psi) shore water hooked up, and the fresh water pump wants to see if I can get my 72 year old gnarled hands in there to change it out. I've done it before so I'm hopeful. I couldn't find leaks anywhere else. I also couldn't twist any of the piping to allow reading what is printed on them, but they aren't leaking now. (Next post.)

Thanks Ralph.

 

[Ralph Johnstone]

I want to thank you again for being willing to listen and trying to help.

Let me tell you, it was an absolute pleasure working with you. I don't find you to be impatient in the least. And trust me when I say "I'm not just being nice."

You wouldn't believe some of the the characters who write in with a simple question and when you give them a simple answer, they don't believe you and stumble off in another direction. They are unwilling to test anything you say and won't tell you the whole story of the problem unless you back them into a corner. These are the ones I have no patience with.

Guess I'm just the product of spending a few too many years in lecture theatres where, if I yelled loud enough, I often got through to most of the students.