water pump runs short burst every 30 mins or so...

[Donna D.]

I'm going to guess... pressure release valve on the water heater. Not that it's bad, just that it needs to be "seated" IF you've opened it to allow air to escape. I know mine will occasionally drip... just a few times a minute, if I don't "get it just right" after I've futzed with it. That may be just enough to cause the pump to quickly turn on, then off.

[Ian G]

Once every 30 minutes your water system is working great!!! The pump will cycle when the pressure in the system drops, the valves in the pump are very light rubber "flaps" that cannot be expected to seal perfectly. Over time some pressure will bleed and trigger the pump to re-pressurize the system. you cannot expect it to hold pressure forever, it will cycle occasionally.

[sclifrickson]

The Suburban SW6DE manual states that presence of an air pocket in the tank will *reduce* weeping at the overpressure valve, and that the tank is designed to create such a pocket when filled, but that over time it can dissipate. The manual then provides instructions on how to re-establish the air pocket.

[Jim Bennett]

During the day we leave the pump on, usually trying to remember to shut it off when leaving the trailer. In the 19 it was under the bed which was a bother in the night if it cycled, but in the 5.0TA with it far away under the dinette we find we just leave it on most of the time. They are designed to be left on, so we mostly do.

I too think the OPs problem is air in the lines or a faulty valve in the pump.

[cpaharley2008]

Originally Posted by AllanEdie

Perhaps not applicable to your situation since you seem to have narrowed it down to your hot water tank, plus you mention a new anti-backflow valve - but as most of these pumps age, their internal valves can allow a slight seep back through the pump head, which will cause this kind of pump behaviour. Solution in that case is rebuild the pump, or turn it off.

Good luck with the chase, let us know what you find.

That happens to a lot of us, as we age also.......

[C&G in FL]

Originally Posted by Ian G

Once every 30 minutes your water system is working great!!! The pump will cycle when the pressure in the system drops, the valves in the pump are very light rubber "flaps" that cannot be expected to seal perfectly. Over time some pressure will bleed and trigger the pump to re-pressurize the system. you cannot expect it to hold pressure forever, it will cycle occasionally.

I would tend to agree with this. And if a slight burp every 30 minutes or so bothers you, do as Karen suggested, turn the pump off when not needed which, in reality, is most of the time.

The bigger problem is when the check valve “flap” hardens or wears to the point that it allows water to deep backward through the pump it will, if connected to a city water supply, eventually fill and cause the fresh water tank to overflow. While this will not cause any damage to the trailer, it can be a real PITA. While this situation MAY be temporarily corrected by 1) shutting off the city water supply, 2) turning on pump to pressure system, then turning off the pump, 3) releasing the pressure by opening a faucet, 4) turning city water supply back on. This procedure can dislodge debris in the pump’s check valve assembly and/or “force” the check valve to close. However, when “backfilling” starts occurring repeatedly, it is time to buy a check valve kit and rebuild the pump. All it takes is proficiency with a screwdriver and 10 or 15 minutes.

[elongest]

If there was air trapped in the system I would think it would act as an accumulator and help the situation. If there are no leaks then I would think the pump differential is set to close. It seems there is no differential setting on the sure flow but there is a pressure setting screw in the front of the pressure switch on the front of he pump. (You Tube) People seem to be adjusting the pressure screw to get a better steady flow.
After looking a several videos I appears slightly adjusting the screw (CCW) may make decrease the system pressure and make the pump stay off longer. Looks like the backing off of the screw will make the pump switch less sensitive by allowing more movement of the pressure diaphragm.
I'm not a pump expert but it look's like all the other causes have been covered I would take a look at the switch, switch diaphragm or pressure adjustment next.
Eddie
Edit: If the water heater is on, the cycling of the WH will change the pressure in a closed system. A properly functioning WH cold water input check valve should keep the pressure changes out of the cold water side of your system which could effect the pump sensed pressure .

[wetzk]

Originally Posted by elongest

If there was air trapped in the system I would think it would act as an accumulator and help the situation. If there are no leaks then I would think the pump differential is set to close. It seems there is no differential setting on the sure flow but there is a pressure setting screw in the front of the pressure switch on the front of he pump. (You Tube) People seem to be adjusting the pressure screw to get a better steady flow.
After looking a several videos I appears slightly adjusting the screw (CCW) may make decrease the system pressure and make the pump stay off longer. Looks like the backing off of the screw will make the pump switch less sensitive by allowing more movement of the pressure diaphragm.
I'm not a pump expert but it look's like all the other causes have been covered I would take a look at the switch, switch diaphragm or pressure adjustment next.
Eddie
Edit: If the water heater is on, the cycling of the WH will change the pressure in a closed system. A properly functioning WH cold water input check valve should keep the pressure changes out of the cold water side of your system which could effect the pump sensed pressure .

Over time the air gets adsorbed into the water. That is why it was so nice when they came out with bladders in pressure tanks for water. No more having to shut the system down and bleed the water tank Now just once a year or so I shut it down, bleed off the water pressure and check the air pressure in the tank. Much nicer.