Low hot water pressure only on city water

[michelle_tim]

we have 2022 Momentum 399. We recently took it out for a first trip. We hooked up to the RV park water regulated through a pressure regulator to 45 psi. Cold water was good everywhere in the rig. Hot water had virtually no pressure but hot water. However, when I switched to dry camp we had equal pressure on the hot and cold side. I have read several posts about the check valves being bad. Would this behave this way? We hate to replace a valve only to find out that’s not the real problem. Also a bit of urgency to this fix as we are about to live in it for an extended period on one months time.

[ThePowells]

This may be of help.. https://gdrvowners.com/forum/operati...water-pressure

[Country Campers]

michelle_tim

Do you have a tankless water heater? If so there is a flow control on the front of the heater, outside, that will control how much water flows thru the water heater. If you have water heater with a tank the hot water flow should be the same from city water and the pump. Having better water flow from the pump may mean a pinched line between the city water inlet and the water heater.

Brian

[howson]

Cold water was good everywhere in the rig. Hot water had virtually no pressure but hot water. However, when I switched to dry camp we had equal pressure on the hot and cold side. I have read several posts about the check valves being bad. Would this behave this way?

I doubt it's the valve. Water source doesn't matter.

Does your Momentum have a Nautilus panel (with all the colored knobs)? If yes, is there a red one? If there is a red knob and you're willing to try a test...

1) Turn off the hot water heater.
2) With the red knob on the Nautilus panel facing straight up (12 oclock position) and city water pressure feeding the camper, the hot water flow from any faucet in the camper is still low, right?
3) Turn off city water source at the pedestal and reopen a cold and hot water faucet in the camper until there's no more water flow. Then close the faucets.
4) Move the red knob on the Nautilus to the 9 o'clock position (heater bypass).
5) Turn the city water source back on at the pedestal.
6) Check flow from a hot water faucet--any change?

Remember to turn off city water at the pedestal, relieve pressure by turning on both hot and cold water faucets, and then return the red knob on the Nautilus back to the enabled position (pointing straight up) before turning the water heater back on.

For more information with drawings (if curious) on how the Nautilus P1 version panel works is documented here: https://gdrvowners.com/forum/operati...abled-disabled and here: https://gdrvowners.com/forum/operati...el-information

Howard

[michelle_tim]

Thanks all for the great advice and links. This forum is invaluable to a first time owner.

Update:

We have a tanked hot water heater and the nautilus system.

We get back home and hooked the trailer to our home water supply. We have have low pressure in our house so the pressure regulator says we are only delivering 30 psi to the trailer. The hot and cold water have equal pressure. Both have a higher pressure for a brief second after turning on a faucet (equal throughout all the faucets) but then drop down to a steady water pressure that is equal on the hot and cold side. Turned on water heater and let it get hot and it still has equal (but not great given our home water pressure, we live on top
of a hill). The rv park had higher pressure that our regulator (set to 45 psi) was limiting. However the water pressure of the hot water at our home is significantly higher than we had at the RV park, while the cold water pressure is slightly lower than it was at the RV park.

Out of curiosity I did follow Howard’s instructions above both before and after the hot water was heated in the tank, just to be sure and saw no difference.

I am glad it’s “fixed”, but would love to know what was wrong so I don’t get stuck when I leave in a month to spend three months in the rig.

any thoughts?

and thanks again for all the help

Tim

[howson]

michelle_tim -- I'm going to defer to Cate&Rob or others who may have more insight on the issue. Before RV ownership (and learning from Rob and others) I knew very little about plumbing. I've learned a bunch (and have done a fair bit at this point) but still have my limits...

Howard

[Cate&Rob]

michelle_tim
Hi Tim,

The observation of high initial pressure that then drops off, is indicative of a flow restriction. I would suspect your pressure regulator. Remove the pressure regulator (since you have low pressure anyway) to see if this evens things out. As supply pressure increases, the pressure regulator becomes more restrictive . . . this could also explain what you were encountering at the RV park.

As I have described many times on different threads, a system water pressure gauge T'd into any cold water line is the best $15 that you can spend on understanding what is going on with your water system. The gauge on your pressure regulator cannot measure what is going on past the inlet check valve, within your RV water distribution system.

Rob

[michelle_tim]

Rob

Thank you, that seems to have fixed the problem for the most part. The hot water is still about 80-90% of the hot water. If it ever stops raining I think I may open the basement and see if there is anything linked anywhere. Would there be utility in changing that check valve at that time? I read about it failing so much.

[Cate&Rob]

Hi Tim,

The plastic check valve on the water heater outlet is a frequent source of problems and could quite likely be the cause of a restriction in hot water flow. Replacing this check valve with a better quality brass version would be good “preventative maintenance”.

Rob