Water Pump

[TomJames]

I have a 2005 34 Foot Alpine with a Shurflo Extream 5.7 water pump. Just recently I am experiencing a problem. After partially filling the storage water tank (1/2 full) I switch back to City Water. When using City Water the pressure drops very low and it appears that water is pumped back into the Fresh Water storage water tank. About 25 gallons of water is pumped into the Fresh Water Tank in a 24 hour period of time. When City Water is turned off and the Fresh Water Tank is used there is normal water pressure and volume. However, when the fixtures are turned off the water pump also turns off but then it cycles for about 8 seconds at a high rate, dropping to a low rate for about 2 seconds and then turns off. (Like there is a external leak). No external water leaks can be found. Is there a one way check valve inside the water pump I should look at? Any ideas of what or where the problem is?
Tom James

[Jim A]

Tom,

I would look at the valve that is used to fill the tank. If it does not completely shut off, the city water will slowly fill the fresh water tank. (Eventually overfilling it.) When running on the pump it will slowly pump the water from the tank and return it to the tank, which causes the pump to cycle. How often is a matter of how much that valve leaks. (Not leaking to the outside, but leaking past the shutoff.)

There is no other check valve that I am aware of. This valve serves that purpose.

The fix is simple. If that valve is haywire, like mine was, it is easy to pull off the top of the valve and replace the stem and seal with a stem and seal from a new Flair-it valve. Much easier than pulling the valve off of the PEX tubing and replacing the whole valve.

[takepride]

Jim is exactly right. That is what happens when the three-way valve leaks back. And of course Jim is recommending the easy way to make the repair.... instead of my more difficult, complete valve replacement..... completed a few months ago...... before I read Jim's much better method......

[EngineerMike]

You can put in-line 1/2" Sea-Tech check valves in line heading each way from the offending 3-way valve (I had to cut in some tubing w/elbows & such to fit this on one place in my 08 because the place I needed to tap had too short a run of pipe to put the check valve in-line). The valve is maybe 3" long and takes ~5/8" of pex pipe pushed into each end for installation. I'll see if I can snap a pic & post it. Chk-valves are like $12 each, but the push-type of install makes it well worth it vs. labor of assembled fittings in the tight space you have to work.

[zinom]

There was a discussion about this problem at the GearHead session at the Balloon Festival. Several comments were made along the line that there are several check valves that should prevent this from happening. I just looked at my plumbing schematic and verified it on coach; that there are no check valves anywhere except at the city water hose connection connection. If the City/Fill vale is operating properly the only other place city water can enter the tank is via the water pump head. A call to SHURflo tec-support verfified that the pump head's valving arrangement acts as a check valve. HOWEVER, with age they have found that high pressure from the Hot Water Tank or city water can reduce the efficiency of the valving in the head and water has been known to bypass.The expensive fix is to replace the valve assembly or pumphead. If the pump seems to be working OK otherwise;the more common fix is to insert a check valve on the output side of the pump. SHURflow added that the check valve furthur protects the pump and will extend it's life...They wish coach builders would install one when the coach is built.. but tec-suport and marketing don't always agree. The check valve looks like any easy fix to me.

[Old Rv'er]

FWIW - Although not totally associated with this discussion, there should be a check valve on the water heater incoming line to prevent hot water from back feeding the aforementioned system. This would only occur on convential equiped coaches, Hydro/Aqua hot coaches are not affected from this malidy I don't believe, but since it's an Alpine, they might be.

Yes to EM's suggestion using the push on type connectors. But by replacing the complete valve assembly, you are getting all new parts instead of only half new parts, since I won't have this to deal with (APEX), I may not fully understand the issue. That being the case, forget what I say. Yes, I know it's tight in there, as I had to replace the solenoid valves which control the use of my water tank/fresh water system, you need three arms, four hands, and or 20 fingers each, and be no bigger than a elfe.

[bcbowers]

Monty, I wouldn't think that a check valve exists on the "incoming line" which is coming right out of the fresh water tank. I know mine has a check valve right on the output side of the pump which serves to keep water (hot or cold) from backing up into the pump.