shurflo water pumpbypassing

[regis]

Have a 2013 210UDS. While walking around the trailer , I noticed the potable water tank overflowing from the service port. I opened the drain to let it empty. Couldnt figure out why this happened as I was hooked up to city water. Found out the water pump was bypassing and filling up the potable water tank. I was informed that I should shut the city water off. Can someone give me as to how this may have happened. The pump had a total of 1 hr usage since Sept 2012, and this happened in Jan 2013 and that usage was mainly during new trailer orientation and parked in the driveway for a week. After that the tank was drained. Pump is back to Shurflo for repair/replacement. But still baffles me. Other than that its a great trailer for wife and I .

[webslave]

Depending on the style/make of the pump, all RVs have either a pump that incorporates a built-in one way valve or there is a one way valve inserted into the output or inlet line of the pump, but, before the "T" where the shore water inlet's pipe joins the main plumbing of the RV. Since the pump and the shore water inlet both share the same water supply lines in the RV, there are usually two one way valves: one is on the backside of the shore water inlet to prevent pumped water from flowing back out the shore water connection and another valve (or an internal pump lock) that prevents just the problem you had...shore water flowing past the pump and into the tank. Your pump valve (either external or internal to the pump) failed. Since your pump is out for refitting, I'll assume that the one way valve for the pump line is internal to the pump.

Here's a "basic" diagram of how the various "plumbing" parts relate to each other in a typical RV:



In the image above you can see how the two water supply options (shore and on-board pump) are related and the valves that control the direction that the water may flow when delivered from each supply source. The above diagram does not show the water heater bypass lines of valves, but, you'll also have some of those, too. I have other diagrams for them, but, they aren't pertinent to your problem. As for the "why" of it happening? Probably just a defective, in your case, pump. Stuff happens!

[regis]

thats pretty much the story I got about the check valves. What I dont understand is what cused it. I was told by the Shurflo people that something as small as a rug fiber , or calcium build up could cause the problem. Utilized a filter for shore water and a pressure relief at the hose bib. Guess all bases werent covered.
We'll see how it goes when I reinstall the pump.

[webslave]

You don't mention how it was winterized, but, if it was winterized and the pump wasn't used to pump the antifreeze through the RV there was most likely some water left in the pump/valve. If you use a hand pump and the shore inlet to put antifreeze into the RV, you have to run the pump "dry" for a minute or so to get all the water out of the pump and valves. Pumping antifreeze through the system via the shore inlet is a frequently used method for winterizing, but, due to the valves, antifreeze introduced that way doesn't flow back to the pump and through it. That's the biggest advantage to the "Winterizing kit" that permanently installs into the pump's intake line (between the fresh water tank and the pump). It uses the pump to pickup the antifreeze and pumps it through the RV, but, a lot of the manufacturers aren't putting them in at the factory. If you used an RV dealer for the winterization, even with a "winterizing kit" installed, they most likely used an external pump and antifreeze reservoir to pump through the shore inlet it is more cost effective for them when they have a lot RVs to winterize...they may have forgotten to run the pump dry prior to doing it. Of course, the opposite is true...if you use a "winterizing kit" and that's all you use to get the antifreeze through the system, you'll most likely miss the water at the one way valve on the shore inlet and that will freeze and fail...then when you turn the pump on, it will run non-stop as it pumps your fresh water out of the tank through the shore inlet!

That's just one scenario in addition to the "piece of crud" causing the failure...it could have been a poorly constructed seal that was cracked to begin with and your "only using it for an hour" was enough to cause it to fail completely... There's a whole host of "might have beens" and more than likely you'll never know exactly what caused it. At least the "damage" was limited to that and didn't cause anything catastrophic My "bet" goes to a bad valve seal from the factory...

[regis]

If there was or should have been no water in the pottable water tank ; I can say it wasnt winterized. The water in the tank was from the dealer's orientation and was drained out within a few weeks of purchase. It was brought to my attention that sometimes there is a few gallons still in the tank supposedly even after draining. Would it be wise to sanitize the tank when I get a pump reinstalled? In reading the maintenance info on the pump, lack of not santizing can cause the problem I had. But if not using the tank/pump at all it seems I shouldnt have to santize,, especially after atotal of 1hr use since Sept 2012.
Thanks for the info .

[webslave]

If I'm reading your reply correctly; there was some water in the tank (freshwater) for orientation and demonstration purposes and that later the tank was drained, and thusly, considered "winterized".... While the water in the tank may have been drained, and there may, indeed and most probably, been water remaining in the tank (tanks don't drain "dry", there is always residual water, but, even 5 gallons, if frozen, won't destroy the tank as there is plenty of room for expansion) merely draining the tank does not remove the water in the line from the tank up to and an through the water pump. It is that small amount of water, caught in the line and pump that, when frozen, causes the damage. If the pump was not "run dry" when the RV was winterized, that most likely is the culprit, not lack of sanitizing.

To answer the sanitizing question, the system should always be "sanitized" in the spring at the beginning of the season along with any hoses that you carry for hooking up to water supplies at the campground. Any moisture in the lines and tanks, and there is always some present, just from condensation if nothing else, can cause bacteria to grow and when the weather starts to warm up, those bacterial colonies "bloom" and can cause illness. While it is possible that, if you only use "city water" (treated from a plant) you may get away with not sanitizing, it is relatively easy and economical to do it just to make sure you aren't in the beginning of a nice trip and the whole family comes down with Montezuma's Revenge IMHO, aways sanitize; at least once in the spring when you are getting ready for your first trip and I recommend re-sanitizing if the RV has sat idle (not being used) for more than six to eight weeks, more frequently if the last water run through the RV was from a questionable source (just the fresh water tank), the lines themselves tend to hold up better, longer. I also recommend that you use a KDF whole house filter on the water going into your RV and a point of use "drinking water safe" filter (Pur, for example) if you are drinking the water from the campground. The KDF filter will take the big stuff out and guard against a lot of contaminants and the Pur style filters will catch the rest. A lot of folks will drink nothing but bottled water, but, I find that to be a waste of resources (all those plastic bottles) and terribly expensive to both purchase and haul (water is heavy; takes energy to haul that weight). We've always done just fine with the KDF filter on the inlet hose either for shore water connection or when filling the tank and a "point of use" Pur filter on the faucet in the kitchen. We've never, knock on wood, gotten sick from any of the water we've used over the years, but, I still sanitize at the beginning of the season.

[regis]

your info on the potable water tank and santizing and winterizing are greatly appreciated. When I get the pump back from the manufactor , I'll do the sanitation on the system.
Thanks