Slow water flow

[fishead209]

Experiencing very slow water flow when running the sink it starts off with good pressure then drains down to a trickle even though the pump is running. Same in the shower. Is this a sign of a bad pump or just need the filters changed? Note, the water tanks are full.

[Zanshin]

I had calcification in the filters a while back, which reduced certain faucets to delivering mere trickles. When you turn off the water how long does it take for the pump to also switch off? If the pump runs, after the water has been turned off, it might be that your pressure equalizer is broken or needs to be pumped up. Do you get good pressure and flow out of any outlet? If not, then perhaps it is the pump. Do you have more than one water tank? If so, check another tank to ensure that it isn't a restriction on the input side.

[fishead209]

Thanks for the feedback, after shutting the faucet off the pump runs for some time maybe half a minute to pump back up then shuts off. Same for the bathroom and shower. All start off strong then drain down to a trickle. SO379, not sure if there is more than one tank.

[jy51]

I would tend to agree with Zanshin.  It sounds like the accumulator tank probably needs re-pressurising, a very simple job to do, you will normally find what looks like a bicycle tire type valve on the top, this should be pumped with a normal bicycle pump.  The pressurised diagram in the tank is designed to maintain a regular pressure rather than the surging with a pump alone.

[fishead209]

Great advice thank you both.

[allegria]

Hi Fishhead,

Another thing to look for is your faucet tap nozzles. Unscrew them and clear any debris/gunk... it is common to find them clogged up...

Cheers,
Allegria

[Mistroma]

Oct 17, 2022 14:44:47 GMT jy51 said:

I would tend to agree with Zanshin.  It sounds like the accumulator tank probably needs re-pressurising, a very simple job to do, you will normally find what looks like a bicycle tire type valve on the top, this should be pumped with a normal bicycle pump.  The pressurised diagram in the tank is designed to maintain a regular pressure rather than the surging with a pump alone.

I don't think the symptoms really match an accumulator with no pressure. I'd expect rapid cycling in use with no pressure in the accumulator. I tend to pump ours up every so often when I get that behaviour, probably only once every 1-2 years. I pop a car tyre gauge on to check and then top up with a bicycle pump as already suggested.

I didn't see a reference to rapid cycling in the original post. However, the description did indicate pulsing in the flow and I picked it up wrongly. The flow doesn't simply drop off to a trickle in my system, it pulses up and down as the pump runs and stops.

Starting off with strong flow and then dropping to a low rate (not pulsing up and down) would indicate something moving to block the flow and falling back once the tap is off again.

It's easy to check the galley tap on our boat at the filter cap can be unscrewed by hand. The shower and other basins need a spanner to remove the filter part. It's worth a look as they do clog up but it doesn't sound like a tap problem.


Following might be useful:
1) Do you get the same effect with every tap?
At least that would let you know if it is a particular pipe or tap. The problem is probably further back if they all behave in the same manner.

2) Check the strainer
You might find a lump of something floating around. Don't overtighten the cap or it will split.

3) Check the tank
The symptoms would match a problem with the inlet. I did once see a piece of plastic in a tank and it was being sucked across the pipe taking water to the pump. However, it is not likely to happen every single time the tap is opened and I'd be surprised if you see anything.

The only other thing I can think of is some problem with valves inside the pump. Perhaps they work briefly and then stick open. The pump would run with little effect and the valves could drop back into position again over time.

It's difficult to point to a specific area without details of the exact symptoms (timing, problem frequency, speed it happens, noise of pump, etc.)

[buddyseattle]

Following up on what Mistroma suggested, I would add that we had the same issue as fishead209

After checking all the obvious issues as suggested, the issue was that a tiny bit of air was getting into the system before the pump. I could see this when I turned on the water, the clear pre filter would fill with about 40% air. This caused an air gap and would cause the pump to run, with little pressure. Once the tap was shut off, the pump would run for 15 seconds or so while it filled the system and the accumulator tank. Then once the tap was turned on there would be a burst of pressure as the water in the accumulator was used, but then the pressure dropped to a trickle. I found that when I bypassed the pre filter and the tank manifold by running a section of pipe from the pump to a bucket of water, everything worked great. working through each conenction, the backflow valve was the issue (copper colored fitting in photo). Elimilating this small piece solved all the problems.

Others with older pumps from Johnson report that there was a known issue with the clear cover on the prefilter getting small cracks near the seal that would allow air in. Replacing the gap solved the problem and was diagnosed by sealing the cap with plastic wrap to see if that solved the air leak. But you could also bypass the prefilter for testing purposes if you have the parts.

[rxc]

I just (today) dealt with a similar problem. My boat came with a FLojet Quiet Quad pump, which has worked well for 20 years, but has been making some troubling sounds for 2 weeks. I bought the Flojet diaphram kit and the check valve kit, took the pump apart, replaced both, and the pump now works as expected. I have had a spare pump for 15 years which never needed to be installed, but it seems to need the same sort of treatment - evidently the elastomer parts die whether they are in active service or not. Much less expensive than a replacement pump.