Shurflo Revolution 4008 severe hammering

[pickjare]

Severe water hammering. Installed the water pump last summer and has worked flawlessly. If a water faucet is fully open, the pump works flawlessly. But there’s a problem when a faucet is turned on a small amount such as to wash hands. Instead of the water pump cycling on/off every 3 seconds or so to maintain pressure, it makes a low tone pulsing/click noise repeatedly very fast and sounds like it’s running on a low low voltage, and shakes side to side incredibly far. Very loud knock knock sound. Hard to explain. But, imagine we needed 25% water flow. Instead of pump simply cycling on and off to provide the flow, it seems to try to turn itself constantly on (never cycling)BUT only at 25% of it ability.
We have 12.8 volts going to it, it’s screwed to floor the same way it’s always been and same the last pump was.
Seems to have started after I drained old water from heater, so I have opened water heater relief, opened hot faucet closest to heater, then tried again, no change. So I re-opened heater relief valve and opened ever faucet and toilet, the closed relief valve at water heater and tried with no noticed difference. So I tried taking air pocket away by leaving water pump switch on and cracking relief valve open at water heater to push air out. No change.
We have no accumulator but have never needed one. Shouldn’t just suddenly need an accumulator, to me something else has changed, cannot figure it out.
Thanks for any suggestions.

[pickjare]

Thank you both for the advice. I truly appreciate the time you each took to help, and you both helped, thanks. I’ll consider a accumulator but I am not trying to make the pump silent. I was wondering why it was shaking like an out of balance washing machine, running real low and sputtering instead of cycling on and off like it is supposed to. Old-Biscuit, the pump pressure adjuster needed tightened 1/2 turn. As soon as I cracked the screw 1/8 turn, the pump shut off, waited, then turned on, then off waited, then on. That’s what it’s supposed to do. This was with faucet cracked open around 20%. It still shook though so I tightened it further. End result was 1/2 tighter on the pressure screw and it cycles on and off as it needs to with a faucet cracked open, shuts off when faucet is closed, runs smooth the whole time without shaking and works good with faucet fully open. It seems fixed and ready to go. I wouldn’t have changed a factory setting without your advice. Thanks to you both. Really appreciate your time.

[LouLawrence]

Required/not required is always an interesting statement. I never said it was required but I have/had the 4008 (2 actually) in both coaches and the accumulator is a very nice addition. Without an accumulator, the pump must run if you want water be it noisy or not.

[Old-Biscuit]

Shurflo 4008 is a Bypass Pump....uses an internal bypass diaphragm that is designed to control low demand cycling
No accumulator tank required

A few suggestions:
*Check the pump inlet strainer ...clean and doesn't suck air (bad o-ring)
*Check the pump head screws....tight/not fallen out
*Water Heater Air Pocket.....there to minimize pressure increases due to water swelling in volume when heated
(turn water source off....open faucet/relieve system pressure....HOLD open T&P Relief Valve until water stops flowing out---let it SNAP closed....turn on water source/close faucet---Air Pocket established in top of WH Tank)

Now as to that hard hammering....
Try the Down/Dirty Adjustments on pump Pressure Switch AND Bypass setting
Shurflo 4008 Down/Dirty Adjustments

[LouLawrence]

While you might not need one, adding an accumulator makes what's pretty good really good. We didn't have one in our last coach our new one does. It's like night and day! Sorry I can't answer your question related to the pump as my solution to annoying problems is to replace the thing making me crazy!