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valhalla360

No paticular place.

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Posted: 06/06/22 11:47am

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I seriously doubt the diaphragms are simply vibrating it to 100psi.
- Hot water tank overheating and building pressure could be an issue. I don't recall the pressure when the hot water pressure relief valve will release but might be around 100psi.
- Unlikely but the water pump has a spring loaded pressure switch. If the spring is weak, it could be turning on intermittently while bouncing down the road...but as mentioned, the odds of getting two unit with this problem is highly unlikely.
- A bad pressure gauge may be the problem.

Personally, we usually turn off the pump and water heater while traveling. If we stop for lunch, it takes just a second to turn on the pump and the hot water heater will stay hot for several hours, so no real burden. This avoids the potential for a leak to spray the entire contents of the fresh water tank before we find out and/or burning out the water pump.

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Grit dog

Black Diamond, WA

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Posted: 06/06/22 04:44pm

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dougrainer wrote:

One thing that MAY cause a problem even if the water heater is OFF. Does the OP have a Motoraid water heater (It would be an Atwood). Motoraid Water heaters when OFF will still have 180 plus engine coolant flowing thru the heat exchanger pipe on the back of the water heater. That may cause a rise in pressure(it will heat the water up to the 180), even with the air gap. To the OP, NOT DRIVING, you don't have the problem? Doug

If there's any reason why the OP's issue might actually be possible, this could be it.
But yes, otherwise, you dont have 100psi pumps so you aint getting 100 psi out of them. It's not the pump(s).

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JimK-NY

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Posted: 06/06/22 05:14pm

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We have still not heard from the OP about the use of the water heater. If you heat cold water, the pressure will increase greatly. In fact, when I do this, I turn off the pump and open a faucet, so the pressure does not build as the water heats.

Dutch_12078

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Posted: 06/06/22 06:13pm

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JimK-NY wrote:

The water heater maintains an air pocket that compresses as the water expands. There's no reason to turn off the pump or open a faucet. RV's that are equipped with an accumulator tank have even more capacity for expansion.

Oh, and water heated from 70 deg.F to 212 deg.F only expands 4% or about 2/3 of an ounce per gallon before it vaporizes.

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dougrainer

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Posted: 06/06/22 07:38pm

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Dutch_12078 wrote:

JimK-NY wrote:

It is very common for people to LOSE that air pocket. You must restore the air pocket. Also, the usual product of no air pocket is increased pressure and the Pop Off valve starts leaking. Doug

joshuajim

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Posted: 06/06/22 08:12pm

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LouLawrence wrote:

When it's at 100 pounds and you open a faucet, is there a huge burst of water under extreme pressure? Most plumbing systems are not even designed to handle that much pressure so you would also likely have leaking connections somewhere if the pressure is truly that high.

The P&T valve on your water heater does not release until 150 PSI. Modern piping is designed to exceed that pressure. Otherwise the pipes would burst and spray hot water everywhere

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wguss

So. California

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Posted: 06/06/22 08:25pm

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We usually turn on the water heater when we're a few minutes from stopping for the night. It does have the feature of using the engine's hot water to also pre-heat the water in the water heater.
It could certainly be a bad pressure gauge but when I attach the hose for city water or turn on the pump it shows 45 pounds each time. I can turn a valve to add water to the tank and it snaps back to 45 pounds when static pressure returns. I often cycle the water from the pump through the tank to get all the air out of the lines and once again the pressure gauge always reads 45 pounds.

wguss

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Posted: 06/06/22 08:29pm

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A reply to Doug's question about the problem when not driving. No, there is no over-pressure when parked. There are places we stay that have electric only, no city water and when disconnecting the next morning the water pressure from the pump only is always 45 psi.