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Old 04-28-2009, 10:54 AM   #21
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Originally Posted by Unclebob
Thanks. I assumed the city water would fill the tank first, and the 12V pump would still be used for the water pressure.

Maybe they do run in parallel but are seperate. I do not know if the city water connection could fill the tank since it would need to go backwards through the diaphram pump first. There's also a valve whith what appears to be a vent tube on it, between the pump and tank. I guess that could be used to prime the pump.

I was just afraid to have the hot-water heater on if I wasn't 100% sure water was getting to it via city water, you know? The city water line tees off from the tank and has a line that goes directly to the water heater, so I guess I have no need to worry?
Hi again UncleBob

Unless you have a real special one, the city water connection does not refill the on board fresh tank. Just like Mack said. OR if yours actually does then you could have a real problem. The water pump has a built in check valve to stop the down stream water pressure from blowing back in the tank. When the water pump runs it pumps up the pressure in the camper then when it turns off, the check valve sets and holds the pressure. If you have blow by by the check, it will drain back in the tank and you loose pressure.

That check has to work good too as when you hook up to city water it has to stop the water from going backwards thru the pump or else eventually your fresh tank will start overflowing out the side of the camper.

The HW heater, yes it does take some time to fill it. Either on the water pump or the city supply. It could be 2 minutes to fill which seems like forever when it is happening.

Now that vent line you are talking about near the pump. Again “normally” something that looks like a vent line right at the pump is actually a winterizing kit. You stick that clear hose (it is generally clear but not always) into a gallon of the pink RV water system anti freeze and pump it thru the camper to freeze protection. Verses filling up the fresh tank with anti freeze to get it thru the camper. That hose is not for priming the pump.

The pump self primes. You need to fill the tank at least ½ full sometimes but then open a faucet, turn on the pump and she will prime all on her own. The faucet being open does help as it allows the air to escape and help not air lock the pump. If it will not self prime, sooner or later you will have issues getting water to flow when you want it even after the 1st time it is primed.

There is a vent line to the actual fresh tank. It is again normally a small tube that starts outside by your tank inlet fill hose and runs to the tank. That vents the tanks as it fills and prevents the pump from trying to suck the tank inwards. There is generally a small screen over the end of that vent tube to keep things out.

The hot water heater, I’ll have to look up that model and report back.. If your HW heater is the older all gas ones (meaning no electric element either,) can’t figure out what the red rocker switch is doing? I may be going back to old in all gas and it is part of the safety circuit. Will look it up and report back.



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Old 04-28-2009, 11:01 AM   #22
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Wow, thanks for all the great info guys.

It appears my water system is fine, I just didn't understand it correctly. Water does not fill the tank when city water is hooked up, and I assumed it did.

I dunno all about that winterization stuff, it rarely freezes here. But that's good to know. :P

'98 Sunline Advancer 2553
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