Water pump issues

[Tasemu]

Hi me again! I have another question on my long journey of new boat ownership and things going wrong.

 

I have recently replaced my immersion heater and i made the mistake of running the water pump with the tank isolated when I had finished. Ever since this I have noticed that the water pump takes a very long time to kick in when running a tap, and then runs for a very long time before stopping. I imagine I have damaged the pump but was hoping to get confirmation before replacing, i thought maybe I could have also screwed up the accumulator tank but unsure how.

 

Also not sure if related to the issue, but since this has started happening, I have also noticed that I occasionally have warm water running from my cold tap until the pump turns on.

 

As always, thanks for any and all advice! I'm slowly getting there.

[Guest]

14 minutes ago, Tasemu said:

Hi me again! I have another question on my long journey of new boat ownership and things going wrong.

 

I have recently replaced my immersion heater and i made the mistake of running the water pump with the tank isolated when I had finished. Ever since this I have noticed that the water pump takes a very long time to kick in when running a tap, and then runs for a very long time before stopping. I imagine I have damaged the pump but was hoping to get confirmation before replacing, i thought maybe I could have also screwed up the accumulator tank but unsure how.

 

Also not sure if related to the issue, but since this has started happening, I have also noticed that I occasionally have warm water running from my cold tap until the pump turns on.

 

As always, thanks for any and all advice! I'm slowly getting there.

The warm water running could be simply due to the procimity of the pipes. Once the pump operates it expels the warm water from the cold tap.

 

It sounds like you have created an air lock and you need to re prime your accumulator.

Edited August 23, 2020 by The Happy Nomad

[Tracy D'arth]

16 minutes ago, Tasemu said:

 

 

I have recently replaced my immersion heater and i made the mistake of running the water pump with the tank isolated when I had finished. Ever since this I have noticed that the water pump takes a very long time to kick in when running a tap, and then runs for a very long time before stopping. I imagine I have damaged the pump but was hoping to get confirmation before replacing, i thought maybe I could have also screwed up the accumulator tank but unsure how.

That is describing normal operation with an accumulator on the system.

What make is the pump? Very few would be damaged by running dry for a short time.

[Tasemu]

Just now, Tracy D'arth said:

That is describing normal operation with an accumulator on the system.

What make is the pump? Very few would be damaged by running dry for a short time.

It is a jabsco pump. Before I ran the pump dry the pump would kick in after a few seconds and turn off after a few seconds, now it will non kick in for 20+ seconds and the water pressure drops significantly before it kicks in. Maybe this is intended, but it definitely worked vastly different beforehand.

[Guest]

Have a skeggy at this old thread.

 

 

[Tracy D'arth]

Check any filter on the pump.

It could be an air lock but its odd.

Check accumulator pressure, that thread should help.

[Tony Brooks]

There may be air trapped in the top of the calorifier acting as an extra accumulator but the fact the pressure falls further than it once did before cutting in suggests this is more likely to be a reluctant pressure switch or switch diaphragm/diaphragm drilling problem than anything else. By all means check the inlet strainer but that will often cause a low flow and noise. I don't see how you can link low air pressure in the accumulator to a low pump cut in pressure but no harm in chceking. I suspect its time to fit an external pressure switch (Square D)

Edited August 24, 2020 by Tony Brooks

[Bee]

Does it do this with all taps? this happens to our kitchen tap from time to time, I unscrew the end of the thing and inside there is a gauze filter which gets clogged with sand or scale. You turn the tap on, two drips emerge, wait another 10 secs, a third drip comes out and then the pump senses a pressure drop and it starts. Stupid thing.

[system 4-50]

Guessing: You created a partial vacuum that lifted some crud which has fouled the pump? Clean everything and try again?

[Higgs]

17 hours ago, Tasemu said:

Hi me again! I have another question on my long journey of new boat ownership and things going wrong.

 

I have recently replaced my immersion heater and i made the mistake of running the water pump with the tank isolated when I had finished. Ever since this I have noticed that the water pump takes a very long time to kick in when running a tap, and then runs for a very long time before stopping. I imagine I have damaged the pump but was hoping to get confirmation before replacing, i thought maybe I could have also screwed up the accumulator tank but unsure how.

 

Also not sure if related to the issue, but since this has started happening, I have also noticed that I occasionally have warm water running from my cold tap until the pump turns on.

 

As always, thanks for any and all advice! I'm slowly getting there.

 

Start checking the cheap options first. Make sure your system is fully filled and bled. Open the taps to check the supply. If the immersion is still isolated, there could be air in the pipe. This will lower the effectiveness of the accumulator, resulting in a longer run time for the pump. Providing the filter on the input side of the pump is clean, only run the cold side into the galley sink, for instance. Close off the tap and wait for the pump to shut off. If it is taking too long, check the pressure in the accumulator. If that is good, you probably have at least an air lock somewhere. Take the time to fully bleed the system before checking the rest. 

 

I've run my pump dryish on many occasions. It tells me the tank's empty. It takes a while after putting some water in the tank for the pump to fully prime itself. I doubt yours would have been bone dry. 

 

 

 

 

Edited August 24, 2020 by Higgs

[Tony Brooks]

Exactly how do the last few replies account for the water pressure dropping lower than it once did before the pump comes on? @system 4-50 could be correct in that crud just might have managed to block the diaphragm chamber drilling or filled the diaphragm chamber so the diaphragm has difficulty moving.

 

If it were an accumulator or air lock issue then the pressure drop before the pump runs would be similar to before but just take a different amount of time for the pump to turn on and off.

 

If its an airlock in the inlet pipe then the motor would turn on and off as before but with reduced flow. If the inlet is blocked (strainer?) then the same would apply. Its the combination of the longer tome it takes to come on AND the lower pressure that needs considering in my view. Not either in isolation.

[Higgs]

8 minutes ago, Tony Brooks said:

Exactly how do the last few replies account for the water pressure dropping lower than it once did before the pump comes on? @system 4-50 could be correct in that crud just might have managed to block the diaphragm chamber drilling or filled the diaphragm chamber so the diaphragm has difficulty moving.

 

If it were an accumulator or air lock issue then the pressure drop before the pump runs would be similar to before but just take a different amount of time for the pump to turn on and off.

 

If its an airlock in the inlet pipe then the motor would turn on and off as before but with reduced flow. If the inlet is blocked (strainer?) then the same would apply. Its the combination of the longer tome it takes to come on AND the lower pressure that needs considering in my view. Not either in isolation.

 

The pump will come on sooner and take longer to switch off (with an air lock somewhere). It's a factor. There will be some hysteresis in the pressure switch. 

 

 

Edited August 24, 2020 by Higgs

[Tony Brooks]

6 minutes ago, Higgs said:

 

The pump will come on sooner and take longer to switch off (with an air lock somewhere). It's a factor. There will be some hysteresis in the pressure switch. 

 

 

I agree but that ignores the new symptom of lower water pressure once it does come on.

 

Anyway we will await the outcome.

[Higgs]

58 minutes ago, Tony Brooks said:

I agree but that ignores the new symptom of lower water pressure once it does come on.

 

Anyway we will await the outcome.

 

Yes. Well, I've got water problems of my own. I know I definitely do have a leak in the input side, because I pumped 14 buckets of water out of the bilge - clear water. Mike Heywood, who built the boat, built a drain valve into the bulkhead, by the floor in the engine room. I bought the boat in 2003 and never ventured to open it until five days ago. The boats been keeping me busy this last week. I suppose this is what retirement was for. 

 

 

[Tracy D'arth]

10 minutes ago, Higgs said:

 

Yes. Well, I've got water problems of my own. I know I definitely do have a leak in the input side, because I pumped 14 buckets of water out of the bilge - clear water. Mike Heywood, who built the boat, built a drain valve into the bulkhead, by the floor in the engine room. I bought the boat in 2003 and never ventured to open it until five days ago. The boats been keeping me busy this last week. I suppose this is what retirement was for. 

 

 

Sounds crazy but this could be drips and condensation over the last 17 years. It won't show rust unless you stir it up. I think Mike used to weld a 1/2" coupling into the tank as the outlet, these rust through on the exposed threads.

[Higgs]

49 minutes ago, Tracy D'arth said:

Sounds crazy but this could be drips and condensation over the last 17 years. It won't show rust unless you stir it up. I think Mike used to weld a 1/2" coupling into the tank as the outlet, these rust through on the exposed threads.

 

That was my first thought, when I had to tackle a collection of water halfway down the boat, a few weeks back. It meets what was a wet room and can't make it down the boat. That was partly due to the boat having a slight list to port that favoured the water collecting up against the wet room. I eventually got that to a drying level and forgot about it, until now. I have specifically caused the list to list to the starboard side now. There is a free run for water on that side, all the way to the stern drain valve. 

 

The coincidence I couldn't ignore happened when I'd finished draining through the stern valve - my domestic water supply ran dry. Not convinced, I started to fill the tank up the following day, if any proof was needed;  I emptied quite a few more buckets out, where the previous night I'd drained the bilge. 

 

It's ongoing. And as you can imagine, some drying out is happening and I don't have room to empty below the front deck, to check the tank or the pipe work thoroughly. The water tank is integral and is in the bow section. The boat is without it's domestic water supply until I can fix the problem. Other than that, the boat is very dry. 

 

  

Edited August 24, 2020 by Higgs

[Iain_S]

My money goes on partial blockage in the pressure switch. When the pump runs on for longer than normal, is the water pressure higher than before, if a tap is opened immediately after the pump stops?

[Tasemu]

Sorry for the late reply, I have just checked the strainer going into the pump and its clean, also checked the accumulator tank which was at 40psi, i dropped it to just below the cut-off value of the pump (24psi) but the issue persists. My next throught is to loosen the immersion heater with the pump on to see if I can get any air out of the top of the calorifier. Otherwise maybe I've buggered the pump.

[Tony Brooks]

43 minutes ago, Tasemu said:

Sorry for the late reply, I have just checked the strainer going into the pump and its clean, also checked the accumulator tank which was at 40psi, i dropped it to just below the cut-off value of the pump (24psi) but the issue persists. My next throught is to loosen the immersion heater with the pump on to see if I can get any air out of the top of the calorifier. Otherwise maybe I've buggered the pump.

An accumulator (as opposed to an expansion vessel) needs setting to the CUT IN pressure or about half the cut out pressure. You seem to have set your accumulator as if its an expansion vessel so it won't be doing anything much accumulator wise.

 

By all means try loosening the immersion heater but two of us have now pointed to a likely pressure switch problem rather than an actual pump problem. If its a blocked diaphragm drilling as @Iain_S suggest then stripping the end of the pump and clearing it might work as it would if the diaphragm chamber is full of muck but the pressure switches are no that reliable in the long term so rather than spend £80 on anew pump spend maybe £30 on a decent external pressure switch and solve pressure switch problems for 40 or 50 years.

[Tony Brooks]

A further thought - do you know the difference between an accumulator and expansion vessel because they are both the same physical thing but with different air pressures and different tasks.

 

Just to be sure:

where is this "accumulator" in the system, in a cold or hot pipe?

If in a cold pipe is there a non-return valve between it and the calorifier?

If in a hot pipe is there a NRV at the cold calorifier inlet. If there is no NRV in that position then air in the top of the calorifier may well act as an accumulator and force hot water back down a cold pipe and out of a cold pipe.

 

 

[Sea Dog]

What Tony said at post #19 ^^^^ about the accumulator pressure - iirc I set mine at 12 psi. YMMV.  You'll soon get used to how long the tap flows before the pump kicks in and how long the pump runs after you turn the tap off, and this will help you to keep an eye on things fresh water system wise.  The pump kicking in unexpectedly may indicate an otherwise unnoticeable leak, for instance.  Folk often try to silence their pump, but too quiet is potentially a bigger problem than too loud in my opinion.

 

In the case of a potential water pump problem, my course of action would be to buy a replacement to ensure you have a known good pump and pressure switch in the system.  My thinking is based upon the benefit of carrying a spare pump anyway, since either a leaky or a duff pump needs replacing straight away and there no managing without one. The old pump will become your hot spare if it turns out to be OK or is fixable (as mine was).

[Guest]

1 hour ago, Sea Dog said:

What Tony said at post #19 ^^^^ about the accumulator pressure - iirc I set mine at 12 psi. YMMV.  You'll soon get used to how long the tap flows before the pump kicks in and how long the pump runs after you turn the tap off, and this will help you to keep an eye on things fresh water system wise.  The pump kicking in unexpectedly may indicate an otherwise unnoticeable leak, for instance.  Folk often try to silence their pump, but too quiet is potentially a bigger problem than too loud in my opinion.

 

In the case of a potential water pump problem, my course of action would be to buy a replacement to ensure you have a known good pump and pressure switch in the system.  My thinking is based upon the benefit of carrying a spare pump anyway, since either a leaky or a duff pump needs replacing straight away and there no managing without one. The old pump will become your hot spare if it turns out to be OK or is fixable (as mine was).

Carrying a spare pump is indeed not a bad idea.

 

I have been caught out and it was a couple of days before I could source one. Living without running water is no joke.

[Tony Brooks]

1 hour ago, The Happy Nomad said:

Carrying a spare pump is indeed not a bad idea.

 

I have been caught out and it was a couple of days before I could source one. Living without running water is no joke.

I agree but carrying a spare pump with a duff pressure switch is hardly carrying a spare pump. Converting to a decent  external pressure switch allows you to water both the cut in and cut out pressures independently to suit you use. You are then permanent free from unreliable internal switches and they are so unreliable I think I can promise that the switch will fail before the pump in probably 75% of cases apart from if you let the pump freeze.

[Guest]

9 minutes ago, Tony Brooks said:

I agree but carrying a spare pump with a duff pressure switch is hardly carrying a spare pump. Converting to a decent  external pressure switch allows you to water both the cut in and cut out pressures independently to suit you use. You are then permanent free from unreliable internal switches and they are so unreliable I think I can promise that the switch will fail before the pump in probably 75% of cases apart from if you let the pump freeze.

To be clear Tony I was only suggesting carrying it as a spare if it proved not to be defective or was repaired as suggested in the post I was responding to. It goes without saying really that carrying a defective pump to use in place of a defective pump is .......well pretty pointless.

[bizzard]

A foot operated water pump at foot level beneath the sink, looped into the water supply. I have mine on the cold water tube to the cold tap. I find I use it a lot for filling the kettle ect rather than the electric pump, saves a lot of 12v elec, my left leg has bulging muscles.

Edited August 25, 2020 by bizzard