Water pump starts and stops every second

[vanboosh]

I've searched and found posts regarding pumps coming on every few minutes, but ours is starting and stopping every second. Just started happening after the water tank was running low/nearly empty. I think I can hear a sort of bubbling as it comes on, so maybe air in the pump? If so, how do you 'vent' it?

Thanks!

[Tony Brooks]

4 minutes ago, vanboosh said:

I've searched and found posts regarding pumps coming on every few minutes, but ours is starting and stopping every second. Just started happening after the water tank was running low/nearly empty. I think I can hear a sort of bubbling as it comes on, so maybe air in the pump? If so, how do you 'vent' it?

Thanks!

 

You don't because they should be self venting unless it is a very old design of pump. I assume that you have filled the tank up, if not do so ASAP and all will probably be well. Check the strainer near the pump inlet for clogging. You may haev jamed the pump valves open with muck from the tank so the pressure leaks back into the tank.

[Tracy D'arth]

Fill tank, open all taps at the same time and run off several gallons. Close all taps. If that doesn't fix it clean filter and pump of grot.

Edited December 14, 2021 by Tracy D'arth

[vanboosh]

I filled up the tank straight away but that didn’t stop it. Tried running the water for a while but it’s still doing it, so I guess maybe some grot in there?

do I just disconnect the water pipes (shutting off the supply from the tank and emptying the taps first) and clear it out? 

[Tony Brooks]

It seems that you may not have an inlet strainer so any muck in the tank will get sucked into the pump.

 

I fear you may have to strip the pump.

[vanboosh]

I think you might be right. I’ll strip it in the morning and report back. Fingers crossed it’s just some debris or something in there!

[Tony Brooks]

You will probably find 3 small diaphragm pumps each with a flimsy plastic inlet and outlet valve, look for dirt trapped under some valve seats.

[MtB]

3 hours ago, vanboosh said:

but ours is starting and stopping every second.

 

Sounds to me as though the non-return valve (usually built into the pump) has stopped working and is allowing the water to flow backwards back into the tank. Thus causing the pressure past of the pump to fall back to zero when the pump shuts off and the pumps starts again to raise it back to normal. Then it leaks back and the process starts all over again, once a second. 

 

Find the NRV and clean it. Or fit another one between the tank and the pump.

 

 

Edited December 14, 2021 by MtB
Edit to fiddle with it,

[vanboosh]

3 hours ago, Tony Brooks said:

You will probably find 3 small diaphragm pumps each with a flimsy plastic inlet and outlet valve, look for dirt trapped under some valve seats.

Will do! Thank you!

57 minutes ago, MtB said:

 

Sounds to me as though the non-return valve (usually built into the pump) has stopped working and is allowing the water to flow backwards back into the tank. Thus causing the pressure past of the pump to fall back to zero when the pump shuts off and the pumps starts again to raise it back to normal. Then it leaks back and the process starts all over again, once a second. 

 

Find the NRV and clean it. Or fit another one between the tank and the pump.

 

 

NRV being a Non Return Valve?

[Tony Brooks]

Except I think you have two non-return valves per pumping diaphragm - an inlet and outlet valve. By all means try fitting a NRV in the pump inlet pipework, That may work if it is just one pumping chamber valves i trouble. most plumbers merchants have them, I would use a flap type to make it easier for the pump to rime itself. maybe easier than stripping the pump.

[David Schweizer]

13 hours ago, Tony Brooks said:

It seems that you may not have an inlet strainer so any muck in the tank will get sucked into the pump.

 

I fear you may have to strip the pump.

 

Admittedly this is a Jabasco, but I never fitted the strainer to the Shurflo pump on our boat, as they always seemed to leak (or break!), and I never found any muck in the pump when I serviced it. Perhaps some people don't have very clean water tanks.

 

But back to the OP's question. I always found that limescale build up in the pressure switch caused pump cycling, It always cleaned off eaily with a soft toothbrush.

 

 

Edited December 15, 2021 by David Schweizer

[Tony Brooks]

48 minutes ago, David Schweizer said:

 

But back to the OP's question. I always found that limescale build up in the pressure switch caused pump cycling, It always cleaned off eaily with a soft toothbrush.

 

 

 

That is a possibility but the frequency suggest a leak and then we have the gurgling sound. Those two together, in my view, makes back leakage into the tank more likely but we will have to wait until the OP reports back to know for sure.

[vanboosh]

Reporting back! I stripped it back as far as I thought I safely could without breaking anything, and It really wasn't terribly mucky at all. There was maybe 2 or 3 teeny bits of debris in the 'holes', which I removed hoping this would fix it, but no luck. It looks like there could be some limescale build up behind the plastic 'seal thing' but I don't think I can get to it without breaking it and leaving me with no water. A new pump is £79, so we might just go for that for now and then I'll have a bit more confidence tearing the current one down further, and we'll have a spare!

[vanboosh]

Photo of the 'oles and possible limescale for clarification. 

 

Edited December 15, 2021 by vanboosh
Edited image size

[booke23]

You could try soaking those parts in a solution of de-scaler. That will completely remove the limescale in an hour or two, and will only cost you a few quid. Worth a go before you fork out for a pump.

I buy 1kg bags of citric acid in granular form from amazon for this purpose.....it works out much cheaper than supermarket de-scaler. A couple of table spoons in a pint of warm water will descale anything!!

Edited December 15, 2021 by booke23

[vanboosh]

4 minutes ago, booke23 said:

You could try soaking those parts in a solution of de-scaler. That will completely remove the limescale in an hour or two, and will only cost you a few quid. Worth a go before you fork out for a pump.

I buy 1kg bags of citric acid in granular form from amazon for this purpose.....it works out much cheaper than supermarket de-scaler. A couple of table spoons in a pint of warm water will descale anything!!

Great idea! I'll give it a go tonight!

[Tony Brooks]

2 hours ago, vanboosh said:

Photo of the 'oles and possible limescale for clarification. 

 

 

The white thing with all the holes is one of the valves and I think the black disk to the right is a pumping diaphragm. Can you get to the back of the valve and gently flex the ribber disk down so you can ensure nothing s stopping it sealing onto the hole.

[ditchcrawler]

Another way to prove it as as son as the pump stops close the tank isolation valve so the water cant get back and see if it cuts in again. Out of interest do you have an accumulator on the system?

 

[vanboosh]

22 hours ago, ditchcrawler said:

Another way to prove it as as son as the pump stops close the tank isolation valve so the water cant get back and see if it cuts in again. Out of interest do you have an accumulator on the system?

 

The pump doesn't stop for long enough to close the tap (quite literally on and off every second), but I can try and give it a go. We have a heating issue as well, so decided to run away to the parents place for a warm Christmas and deal with it all when we get back. I will update on our return!!

Edited December 16, 2021 by vanboosh

[Tracy D'arth]

22 hours ago, ditchcrawler said:

Another way to prove it as as son as the pump stops close the tank isolation valve so the water cant get back and see if it cuts in again. Out of interest do you have an accumulator on the system?

 

If the pump valves are leaking chamber to chamber this will show nothing. Its not a single non return valve.

[Tony Brooks]

I would urge the OP to make absolutely sure any PRV, usually near the calorifier, is not leaking and that the bilges are not filling up. It sounds like pump valves to me and it would need to be a very bad leak to cycle that frequently but you never know.

[phantom_iv]

I happened across this video the other day while taking apart one of these pumps - https://www.youtube.com/watch?v=ZM4F7jbFh-I

 

Apparently there's a dampener in the pump which you can change which may improve this if this is what you're seeing -  https://www.youtube.com/watch?v=jd5aePEB-4g&t=34s

 

[ditchcrawler]

1 hour ago, Tracy D'arth said:

If the pump valves are leaking chamber to chamber this will show nothing. Its not a single non return valve.

If the valve on the inlet is shut where is the pressure going to go if its not an external leak, My bet is the pressure switch bouncing at the moment. I wonder what happens if you run a tap?

 

[Tony Brooks]

1 hour ago, phantom_iv said:

I happened across this video the other day while taking apart one of these pumps - https://www.youtube.com/watch?v=ZM4F7jbFh-I

 

Apparently there's a dampener in the pump which you can change which may improve this if this is what you're seeing -  https://www.youtube.com/watch?v=jd5aePEB-4g&t=34s

 

 

Thanks, very good find.

[vanboosh]

Update: I’ve replaced the pump! It’s all working perfectly now. I also added the filter thingy that the previous one didn’t have so that will hopefully help in the future. Thank you everyone for the help!
 

For those interested, this is the pump I got:

 

https://www.foxschandlery.com/jabsco-par-max-2-9-pressure-controlled-pump-12v-40psi?gclid=EAIaIQobChMItauigMSV9QIVzN_tCh1IsQCiEAQYAiABEgKg0_D_BwE