Hot water from cold faucet

[vcrt]

I'm the OP and it doesn't bother me if someone"highjacks" my thread, I think it's good when others learn and inquire about a topic under discussion. We're all learning!
Rich

[JohnB]

Originally Posted by johnnybgood

Sorry if I kinda hijacked this thread. I didn’t search the forum before asking about my problem.

John

Hi John,

Your questions were on the same technical issue of pressure building in the water heater, so this is not really a hijack. And Rich is good with it, so no issues. And as Rich said, we are all learning. The more we talk on things, the more we learn. I had totally forgot the rear wall on your vintage Sunline were on an angle and your heater is mounted in that area. It can have some effect on the air pocket, just not sure if it is enough to be an issue. Sometime post the angle, I’m curious to know.


Thanks

John

[vcrt]

I had a chance to install the new bypass valve after removing the plunger from the back-flow valve and everything is working well!
Thanks again for the solution to this problem John!
Rich

[johnnybgood]

Originally Posted by JohnB

Hi John,



I had totally forgot the rear wall on your vintage Sunline were on an angle and your heater is mounted in that area. It can have some effect on the air pocket, just not sure if it is enough to be an issue. Sometime post the angle, I’m curious to know.


John

John, here’s a pic of the water heater. Best I can tell it’s about an 11 or 12 degree angle. The OSB platform board is 16” long and it’s 3” above the floor at the rear.......

IMG_4620.jpg

[JohnB]

Originally Posted by johnnybgood

John, here’s a pic of the water heater. Best I can tell it’s about an 11 or 12 degree angle. The OSB platform board is 16” long and it’s 3” above the floor at the rear.......

Attachment 6859

16" long with a 3" lift, the math comes out to 10.62 deg. OK, I'll have a look in the barn and report back. That pic and the board size/lift is perfect to show what you have.

[johnnybgood]

I installed a new P&T valve and have a question. Is it supposed to be seated tightly to the opening? I didn’t take notice before removing the old one. It feels awfully tight now and trying to avoid messing something up (it’s not cross threaded).......


IMG_4632.jpg


And here is the old one......

IMG_4634.jpg

[Tinstaafl]

If you mean the shoulder at the end of the threaded portion, no. Pipe threads are tapered, so they start off very loose and get progressively tighter as you screw the fitting together. You shouldn't be able to screw it in until the shoulder hits.

I can't give you a torque in foot-pounds, just that it should be tight enough not to allow leakage. For non-nerds, that's a matter of experience and "feel". Usually about 3/4 of a turn or so past the point at which you encounter noticeable resistance.

[JohnB]

John,

Tinstaafl is right on with the NPT tapered threads. The tank and the PT valve are both NPT. (National Pipe Thread which is a taper lockup thread)

You should not bottom out under normal conditions. Some of the newer water heaters have a foam donut shaped ring over the exposed threads to help insulate the exposed threads. It is good if you have the donut, but there are a lot of them without it. It just loses a little more heat without it.

Now, how tight it tight. I'll add one thing to Tin's quote here,

I can't give you a torque in foot-pounds, just that it should be tight enough not to allow leakage. For non-nerds, that's a matter of experience and "feel". Usually about 3/4 of a turn or so past the point at which you encounter noticeable resistance.

There is the "experience factor" at work here. After cracking enough 1/2" pipe fittings, especially on thin brass or aluminum, one learns, thats' too tight.

There are 2 main needs.

1. It is tight enough to not leak.
2. The discharge port is normally pointing towards the left over by the heat tube exhaust guard. That helps keep the PT weeping water off the gas burner at the igniter area or worse on the electronic control board.

By your one pic, it looks like yours it is not far enough tight just yet. Not for thread leaks, but weeping PT valve drips.

This pic shows what all the Atwood heaters I have seen come from the factory. Look at which way the valve discharge points.


There is not a "perfect" direction for it to point to, as even to the left water weeps down on the connections of the ECO and the T stat wires in the stock configuration. But, being to the left is better than the other options.

The ones I have installed, tightened up "tight enough" to not leak is in the general area when the discharge is pointing to the burner area. Which is where yours is now. You will feel the resistance is good. You then need to get it to the left some more. Do not go a full rev past, that tight enough spot, as that may create a crack in the tank fitting. Go slow when tightening.

If by chance, you cannot stop it leaking when you are to the left and feel you can't or don't want to try another full rev of rotation, take the PT valve out and build up more teflon tape on the threads and start over. That sometimes helps shift the tight enough point to something less in rotation.

This is really not that bad. But all we can do is use words to try to explain a simple, how tight is enough.

[johnnybgood]

Thank you all for the info!

John, I’ll tighten it a bit more to get the same orientation as the pic you posted.
Unfortunately it won’t be until spring before I can test it. [emoji3525]

[johnnybgood]

Well, nearly 4 months later and we’re finally out camping and happy to report that the new P&T valve has cured my problem. Been using the water heater going on six days with no weeping.

[JohnB]

Yeh on 2 fronts,

The new PT valve works!

Even better, you made it out camping!!

Thanks for reporting back.

John

[Torskdoc423]

John; reading thru this thread and it seems to me a "Water Hammer arrestor" (shaped like an CO2 cartridge on lots of Steroids) would do the same thing (keeping a damping bubble in the H.W. system). About 1-1/2' of 1" copper pipe with a cap, and a tee adapter, mount on bulkhead vertically next to the water heater. If you had enough room and a support for the top of it, then you could attach the top end to the support and "T" it off at the hot water outlet. Or am I thinking out my a** again???


Larry

[JohnB]

Originally Posted by Torskdoc423

John; reading thru this thread and it seems to me a "Water Hammer arrestor" (shaped like an CO2 cartridge on lots of Steroids) would do the same thing (keeping a damping bubble in the H.W. system). About 1-1/2' of 1" copper pipe with a cap, and a tee adapter, mount on bulkhead vertically next to the water heater. If you had enough room and a support for the top of it, then you could attach the top end to the support and "T" it off at the hot water outlet. Or am I thinking out my a** again???


Larry

H'mm, interesting idea. After thinking on this, I'll give the idea a "maybe" it might work. But it all depends on a few things.

1. Charge pressure in the water hammer arrestor.
2. Volume of capacity of the expansion chamber.

These little water hammer arrestors have a different need then thermal water expansion of a water heater. The average arrestor has a pre-charged pressure which works on a conventional home water supply. I looked quick and cannot find what that charge pressure is nor the volume of the chamber. The small ones on a washing machine hookup, my instinct is they may be too small. But one has to try it to be sure.

I did find one brand that has an adjustable pressure and is larger then the standard little cylinder ones on a washing machine hose attachment.

Watts make a LF150A water hammer arrestor you can change the charge pressure https://www.watts.com/products/plumb...restors/lf150a

A cut sheet on it and sketch of the internals. It looks like a mini bladder tank.
https://www.watts.com/dfsmedia/0533d.../es-lf150a-pdf

Now the unknown, is the volume capacity of these compared to what a 6 gallon water heater can create in thermal expansion above 50psi?

The water hammer arrestor just wants to absorb a fast blast of water flow stopping. The water heater builds pressure from 35psi when the camper pressure is low or from 45-50 psi when the pump cuts off, all the way to close to 150psi when the water heater safety relief valve starts weeping.

My gut instinct is, the Watts unit may help but it "might" not be large enough to stop the above 50psi pressure build. Just because the internal volume of the bladder is not big enough.

Then there is cost. A quick look and the Watts LF150?A cna cost $65 plus tax and shipping https://www.amazon.com/Water-Hammer-...-9&tag=mh0b-20

While the water hammer arrestor is small and easier to fit in a camper, the water accumulators have more volume and adjustable pressure on the bladder. Just they get bigger in size to do it and mounting one depends or room available in the particualr camper.

A Shurflo camper water pump accumulator can be $60 plus tax and shipping but it is much larger volumne. https://www.amazon.com/SHURFLO-181-2...1801144&sr=8-5

Another brand camper accumulator, Seaflow is around $35 plus tax and shipping https://www.amazon.com/Seaflo-Accumu...1801144&sr=8-7

And if you can find and fit a 1 gallon home water heater accumulator tank in your space, it will solve a bunch of issues and may a boondocking setup even more efficient.

Good thoughts though on the idea.

Thanks

John