Water Pressure

[Bob_Vaughn]

You hook your water hose to the pedestal and lay the hose in the sun. As the sun heats up the hose and the water inside doesn't the pressure inside increase also ? So at the pedestal you have say 100 PSI wonder what it would be at the RV on a hot summer day?

[down_home]

Lost a few of the wally word/camping world white hoses due to pressure. Don't know how much but suspect 85psi or more.
I have an adjustable regualtor but when I use it is after the filters, and inside the bay.
Went to a much heavier hose with black lining with silver particles.
It makes sense to fill tank and disconnect until tank is low again but we don't always do it. A piece of heavy plastic pipe over hose would shield from the sun.
We've seen several that do that.

[myredracer]

wa8yxm wrote:
First: If you have 100 PSI at the park pedestal DO NOT HOOK UP Your RV is likely rated for no more than 50 PSI..

RV plumbing systems must follow the requirements of NFPA 1192 and section 7.7.2 for testing of water piping systems. Section 7.7.2 states in part "The entire piping system shall be filled with water and pressure tested with air or water at 80 psi to 100 psi" and must hold for a period of at least 10 min. The RVIA requires testing of the water piping system (as per NFPA) to a pressure of 80-100 psi according to this RVIA RVIA Plumbing Systems manual and pressure for testing should be 80 psi for CPVC pipe.

Most (all??) RV water piping systems nowadays use PEX pipe. PEX pipe is rated for 100 psi at 180 degrees F. The ASTM standard to which PEX is manufactured requires pressure testing at 1.5 times the working pressure for a min. of 30 min. In an RV, it's the fittings, valves and fixtures that could be more of a concern than the pipe. Without doing more investigation, I would say it's safe to say that RVs that have PEX piping should have no problem being able withstanding up to 100 psi. I have had our regulator set to 60 psi for several years now. When I built our house I had to demonstrate to the plumbing inspector that the PEX piping would hold 100 psi for 24 hours.

Bottom line is, CG water pressure can be all over the map and if you don't use a regulator you are playing with fire.

[wa8yxm]

First: If you have 100 PSI at the park pedestal DO NOT HOOK UP Your RV is likely rated for no more than 50 PSI.. Instead use a Good Pressure Regulator, I recommend any of the following

Watts 1/2 inch or larger with hose adapters
Zurin 1/2 inch or larger with hose adapters
and though I've not PERSONALLY tested: Valterra adjustable

NOTE: My Watts and Zurin are both 3/4 inch

When new.. I set these to 50 PSI and open a Shower.. The needle does not move on the pressure gauge.. as they age,, it starts to move, but you can rebuild them. (I need to get a Watts Kit).

Now to your question:

Does the pressure increase due to the sun.. the answer is both yes and no.. YEs but by a very tiny fraction of a PSI you will never notice.... The park's pressure tank or the city pressure tank, will absorb any increase.

NOTE: one park I visit is 120 PSI by measurement... They blow hoses apart there often.. That's why I have the ZURIN, it holds at a solid 50 PSI and I mean SOLID.

[4x4van]

If your regulator is at the pedestal, the increase in pressure in the hose due to temp is not going to be enough to cause an issue, since you're starting off at only about 40psi. If your regulator is instead at your RV, any pressure increases in the hose would be buffered by the rest of the municipal system, so again, no issue. What COULD cause an issue is the fact that the hose material will soften with the heat, and given enough pressure, could then fail. Which suggests that the best location for the regulator is at the pedestal rather than the RV.

[Sport45]

Bob Vaughn wrote:
You hook your water hose to the pedestal and lay the hose in the sun. As the sun heats up the hose and the water inside doesn't the pressure inside increase also ? So at the pedestal you have say 100 PSI wonder what it would be at the RV on a hot summer day?

I doubt the pressure would change much even if the hose was sealed on both ends. As things heat up the water will expand. But the hose will expand due to thermal growth too. The hose will also soften some at the higher temperature.

[ScottG]

I came back to the site one time to see a geyser next door. Though comical looking, it was big waste of water and was causing a muddy mess. If he'd had a regulator it wouldn't have happened.
So yea, it happens - probably even more often with "off-shore" junk hoses we have to get now.

[CavemanCharlie]

Lynnmor wrote:

2oldman wrote:

myredracer wrote:
Psi inside your camper would remain the same as the incoming CG pressure. If you are thinking your hot hose could drive the pressure up from the CG faucet connection all the way through the municipal distribution system back to the water system source (dam, well, lake), not possible. If you had the CG faucet off, any pressure increase in the hose and RV piping would be insignificant.t.

Good points.

Gil beat me to it again, he saves me a lot of typing.

Not quite all the way back to the source. Every water system is going to have built in Back Flow Preventers at points in the system.

Many of the camp ground I frequent use no-freeze water hydrants. In those cases there is a Back Flow Preventer screwed right on the hydrant. In this application the OP question would still be relevant.

I don't think the little bit of extra pressure is going to do much in any case.

[Lynnmor]

2oldman wrote:

myredracer wrote:
Psi inside your camper would remain the same as the incoming CG pressure. If you are thinking your hot hose could drive the pressure up from the CG faucet connection all the way through the municipal distribution system back to the water system source (dam, well, lake), not possible. If you had the CG faucet off, any pressure increase in the hose and RV piping would be insignificant.t.

Good points.

Gil beat me to it again, he saves me a lot of typing.

[azdryheat]

Perhaps why our water hoses are white, to keep the water temps down. We camped for many years at our Arizona lakes and endured the triple digit summer temps. Heat related water pressure was never an issue.

[jplante4]

The flexible rubber hose expands to equalize the pressure.

[Old-Biscuit]

I don't leave my hose lying out .............

Fill fresh water tank and then put hose away until needed to fill fresh water tank.

No hot hose!

[2oldman]

myredracer wrote:
Psi inside your camper would remain the same as the incoming CG pressure. If you are thinking your hot hose could drive the pressure up from the CG faucet connection all the way through the municipal distribution system back to the water system source (dam, well, lake), not possible. If you had the CG faucet off, any pressure increase in the hose and RV piping would be insignificant.t.

Good points.

[myredracer]

Psi inside your camper would remain the same as the incoming CG pressure. If you are thinking your hot hose could drive the pressure up from the CG faucet connection all the way through the municipal distribution system back to the water system source (dam, well, lake), not possible. If you had the CG faucet off, any pressure increase in the hose and RV piping would be insignificant.

RV hoses have different max. psi ratings. The pressure at which a hose will burst is affected by temp. and dia. of the hose. A smaller dia. 1/2" hose can withstand more pressure than 5/8". As a hose would heat up in the sun, the hose material would soften and expand, have it's pressure rating go down and at some psi would burst. The concern about high water pressure is what the CG system psi is. We've seen it as high as 140 psi so far and it has been reported by some as high as around 200 psi. RVs are supposed to be tested for at least 100 psi.

Cheapie hoses can have a rating as low as 40 psi like this standard Camco hose. RV drinking water hoses are available with a rating as high as 375 psi like this Valterra hose. We have a regulator inside our TT and use a heavy duty, high pressure 5/8" hose rated for 200 psi.

At the very least, you want a basic inline regulator at the pedestal faucet end of the hose. There are other better regulators available. If you put your regulator at the city water inlet, it would be wise to get a hose with high pressure rating. Always a good idea to have a spare drinking water hose, even if just for the times you need 50' or more to reach the faucet.

[DutchmenSport]

A few years ago we had a garden hose hooked up to the campground water spigot laying in the, almost, 100 degree sunlight. Didn't think anything about what was going on, until a neighbor camper walked up and suggested we look at our hose. So we did.

Um, a section of about 3 feet blew up like a hot-air balloon. It had to be at least 12 inches in diameter! Before I could make it to the spigot to turn the water off .... she blew! Split long ways, about 6 inches and what a wonderful shower flow of HOT water! I'm glad I witnessed the event, I would have never believed it otherwise.

That was one of many events that ultimately led me to never leaving the water hose connected to the trailer and spigot and left on. That, and unknown pressure coming out of that spigot at every campground we go to, we now fill our fresh water tank, pump from the on-board water pump, and keep the campground spigot turned off, except to fill the fresh water tank.

So yea, sitting in the sun can cause pressure to build, but the risk of busting your garden hose is greater the hotter it gets.