Pump Cycling
- Thread starter BugOutBoat
- Start date
No. Do you have an accumulator tank? The pump should pressurize this tank and it should remain full until a faucet is opened. If there is a small leak, the tank will call the pump to pump more water in to the tank. That causes the cycling. If this is happening, there is probably a small leak some where. It could be a leaking faucet, a bad hose connection, or a leak in the accumulator tank.
An accumulator helps to even out the surges of water pressure when the pump starts and stops by holding some pressure in reserve.
The pump switches on whenever low pressure is sensed on the outlet side. The accumulator is an air filled reservoir that provides a cushion of air on the outlet side and serves to smooth out the pressure on the downstream side of the pump.
If the pump only comes on briefly with an hour or more between then there may be no leak, just water seeping back through the pump valves from the high pressure (downstream) to the low pressure (suction) side. This is insignificant.
If the pump only comes on briefly with an hour or more between then there may be no leak, just water seeping back through the pump valves from the high pressure (downstream) to the low pressure (suction) side. This is insignificant.
Like JohnB says it might just be the valves in the pump allowing some pressure to escape, or it could be a small leak in the plumbing or a faucet. In any case you can add an accumulator tank to mask the symptoms; then the pump will go much longer between cycling and run longer when it does.
I wrote a analysis and needs for an Accumulator on this link...
https://forums.sailboatowners.com/i...ter-accumulator-analysis.180421/#post-1311270
Probably more than most want to know, but most SBO experts agreed with my post.
Jim...
https://forums.sailboatowners.com/i...ter-accumulator-analysis.180421/#post-1311270
Probably more than most want to know, but most SBO experts agreed with my post.
Jim...
Some boats have a check valve or pressure valves near the pump discharge. Most pumps today are built into the pump. Maybe starting to go bad.
Thermal expansion/contraction is another potential cause of the pump cycling on. If your water heater is up to temperature (typically 140F or hotter) and that heat is removed (engine shut down or power turned off to water heater or hydronic furnace turn off) the water in the tank will contract reducing system pressure to a point where the fresh water pump may cycle on.
I have water pressure in my heads. My main shower lost pressure and now seems to have gained pressure. My Galley sink is low pressure. So some weird stuff going on. I'm going to pull the sink water filter, check the water pressure at the filter then just replace the filter. if the water pressure is good there, then I'm at the faucet.
All of the faucets have strainers or aerator screens. I am guessing that your supply pump has a suction strainer too.
I am not sure if your water source is Soft or Hard, but Hard Water could be a contributor to "weird" stuff.
Jim...
Mine too!
I traced it to a "Drip" on my Accumulator Shroder inflation valve stem. Mine cycles every 6 hours or so for about 2 seconds.
Jim...
PS: The "Drip" was barely detectable. thus the link in my Post#9.
It could be hard water. I pulled the water filter and ran the water to test the inlet to the water filter and it filled a 2 gallon bucket fairly fast. When I replaced the filter there was some reasonable pressure through the sink. I did clean the faucet strainer on the sprayer and also checked the flow coming out of the sprayer hose. Our sink faucet has a detachable spray head that doubles as the sink faucet. When I replaced the Cullagan water filter (charcoal type) that services the cold water into the sink the pressure at the sink dropped to a dribble. Both hot and cold seem to dribble so I believe it may be the faucet. It's hard to tell if the problem is the cullagan water filtration system or the faucet. Likely both. I'd bypass the water filter if it allowed me to but it's a single inline water filter and the attachment on the inlet side is the blue water line, and the outlet is a braided and the attachments don't connect. If I replace it I'll make sure it has a bypass valve in it to allow for quick water system fault isolation. Hind sight is twenty-twenty 
Some household faucets will limit the hot water flow if there is no cold water pressure as an anti-scald feature. I don't know if any marine faucets do that but it may be worth considering.
My faucet is acutely a marine faucet. I think everything inside the faucet and filter needs to be rung out completely.
I have a 2003 H466 and the fresh water pump started burping recently. Performed all the "leak" checks and found none. Given the age of the pump it was possible that it had deteriorated some and there was internal leak by through the diaphragm. A quick trip to the local West Marine for a replacement and about 40 minutes to remove and install new. Voila, no more burping or cycling. The old pump was a 2.8 gpm 40 psi. Could not find the exact replacement so I bought a 2.9 gpm 50 psi pump that fit perfectly. Snap in ports were really nice. Also, I could discern no difference in faucet pressure. Really happy with the fix.
I found a leak this morning. While I was laying in bed I heard the tank under my bed gurgalling. So I got up and started removing deck plates. I found water trickling from under my port water tank. My tanks are plastic. I checked the fittings and they were not leaking. I drained over 100 gallons over night. So Houston I have a problem!