Water pump pulses no leak but why

[5150mike]

I filled my fresh water tank for the first time this year, the hot water tank bypass valve was shut, so no water going to hot water tank, and my pump was pulsing on off like a leak, so I looked all day for the leak no luck, took the pump off put a gage on the outlet pumped it up it held for days at 40 psi, reinstalled the pump same thing, now this is where I am confused, I opened the by pass on the hot water tank and let it fill the tank, pulsing was GONE someone please explain why, let me apologize for the poor grammar and punctuation just to get that out of the way

[kscherzi]

The check valve built into the pump preventing water from flowing backwards into the tank may have some debris causing a slow leak.

[5150mike]

I did take all that apart and clean it , but if it did why when I opened the hot water bypass valve did it just stop

[5150mike]

Originally Posted by kscherzi

The check valve built into the pump preventing water from flowing backwards into the tank may have some debris causing a slow leak.

I did take all that apart and clean it , but if it did why when I opened the hot water bypass valve did it just stop

[pcskier]

Perhaps the water heater bypass was open just a little or not fully sealing, and letting a tiny trickle of water through. If the pulsing stopped after you opened the valve and filled the tank, that’s all I can think of.

[Silvr_Bullet]

Originally Posted by pcskier

Perhaps the water heater bypass was open just a little or not fully sealing, and letting a tiny trickle of water through. If the pulsing stopped after you opened the valve and filled the tank, that’s all I can think of.

Yes X2

[5150mike]

I put a new pump on but it’s doing the same thing until I plugged it into shore power then the pump is pulling 7.+amps but on battery it’s only doing 3.3amps I think this is my problem but why is it doing this? The battery shows 12.4v and it’s on the trickle charger all the time

[Boxite]

Your water heater has a “head” of air within it’s tank….which acts as an accumulator. The pressure within the heater-tank keeps the system pressurized above the minimum the pump seeks….so your pump does not (or is delayed) to sense a fall in pressure. With the heater by-passed….that feature is not present.

If there’s no actual water leak in the system… Don’t sweat the small stuff. (and, unrelated topic,….don’t leave your trailer at the campsite while you go visiting in town or fishing with the pump on or the city-water supply still turned on…. A blown seal or line may flood your trailer.)

[5150mike]

Originally Posted by Boxite

Your water heater has a “head” of air within it’s tank….which acts as an accumulator. The pressure within the heater-tank keeps the system pressurized above the minimum the pump seeks….so your pump does not (or is delayed) to sense a fall in pressure. With the heater by-passed….that feature is not present.

If there’s no actual water leak in the system… Don’t sweat the small stuff. (and, unrelated topic,….don’t leave your trailer at the campsite while you go visiting in town or fishing with the pump on or the city-water supply still turned on…. A blown seal or line may flood your trailer.)

100% sure there is no leak I have to sweat this because on battery only and the hot water heater bypassed the pump runs all the time that’s why I think now it’s the low amps not allowing the pump to fully pressurize the system

[5150mike]

It’s fixed I am posting this hope it helps the next person. It was the mixer valve anti-siphon, so even with the bypass closed the mixer still has a way to leak back into the tank if the anti-siphon valve is stuck, that’s why when I let the hot water tank fill it all worked as it should, I did not replace it he part I took the anti siphon part and fix the plunger, I did soak everything in CLR. After searching the net seems this anti siphon valve screen gets plugged with hard water deposits, and will have low, hot water pressure. I hope this helps somebody.Mike