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JGL

Frozen/Thawed... maybe a leak?

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I'm new to this.. but made the school boy error of letting the pipework freeze up with water in. No major catastrophes from what I can tell - no big pools of water, although things are a bit moister in bits of the engine room than I remember them.

 

Once I realised I opened up the taps and warmed the boat up to thaw everything, trying the pump every so often. Took quite a while of heating/stove on for things to properly thaw.

 

Now things have thawed out everything works... but there's a clear change - it used to take maybe 1 second from turning the tap on to the pump kicking in. Now it takes way longer, 5+ seconds. This is effecting both the hot and cold systems. I assume it means there's a slight leak somewhere, hence it takes longer for the pressure drop (when I open the tap) to register with the pump.

 

Does that sound like a sensible hypothesis? If so, any tips on how to find the leak? 

 

Thanks!

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That doesn't seem likely to me. If there was a leak the pump would run, somewhere between continuously and very infrequently (depending on leak size) when all the taps were closed.

 

I think what's more likely is that the water in the pressure switch which is part of the pump froze and damaged it. They're made out of fairly small and delicate plastic parts and bending and distorting those parts can mess things up. 

 

If I was you I'd adopt a strategy of watchful waiting, but expect that I might have to replace the pump at some point fairly soon.

 

MP.

 

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Possibly the pressure switch froze and has adjusted itself so now cuts off at a higher pressure.  If it were a leak big enough to take significantly longer to achieve pressure then the pump would run several times every night when no water was being used.

 

added - same as above ?

Edited by Chewbacka

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If the pump turns out to be undamaged other than the internal pressure switch then buying a Square D external switch would be a good move. 

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3 minutes ago, MoominPapa said:
2 minutes ago, Chewbacka said:

Possibly the pressure switch froze and has adjusted itself so now cuts off at a higher pressure.  If it were a leak big enough to take significantly longer to achieve pressure then the pump would run several times every night when no water was being used.

 

added - same as above ?

 

I think what's more likely is that the water in the pressure switch which is part of the pump froze and damaged it. They're made out of fairly small and delicate plastic parts and bending and distorting those parts can mess things up. 

 

 

 

Ah okay, this makes sense - thanks @MoominPapa & @Chewbacka .. I'm not sure what current pump is and not on the boat right now, but do you have any particular recommendations? (I may get a replacement in now so I've got one ready when/if it fails).

Cheers again

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10 minutes ago, WotEver said:

If the pump turns out to be undamaged other than the internal pressure switch then buying a Square D external switch would be a good move. 

Great... I shall get to googling and figure out how that works ?

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The pressure switch is often the failure point on any pump, so an external one is a good move in any case. 

  • Happy 1

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I am very surprised that you have had frozen pipes already unless you are a Scottish boater where the last week has indeed been parky.

It usually takes several days of sub zero temps, with daytime zeros for a boats pipework below waterline to freeze.

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18 minutes ago, JGL said:

Ah okay, this makes sense - thanks @MoominPapa & @Chewbacka .. I'm not sure what current pump is and not on the boat right now, but do you have any particular recommendations? (I may get a replacement in now so I've got one ready when/if it fails).

Cheers again

Try to get one that is a direct replacement so you don't have to bugger about with plumbing mods

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4 minutes ago, matty40s said:

I am very surprised that you have had frozen pipes already unless you are a Scottish boater where the last week has indeed been parky.

It usually takes several days of sub zero temps, with daytime zeros for a boats pipework below waterline to freeze.

Was on hard standing when it happened  ?

3 minutes ago, ditchcrawler said:

Try to get one that is a direct replacement so you don't have to bugger about with plumbing mods

Makes sense. Thanks! 

Edited by JGL

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2 hours ago, JGL said:

Great... I shall get to googling and figure out how that works ?

I'd like to know that too, have seen it advised before.

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Not sure about the "direct replacement" advice.

Most are pretty similar, and generally if instructions have been followed, (which of course they may not have been!), the final connections to the pump should be in flexible hose rather than solid pipe.  If they are then slight differences in geometry shouldn't matter.

Personally I would say "not Sureflo".  Sureflo used to be reliable - more modern ones seem not to last many years, and wheras you used to be able to buy bits and repair them, it now often seems to be a mistake to try that.  ParMax seem OK.

 

 

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I agree with Alan. Buy a decent pump. Why would you buy the same pump if the original wasn't very good? If it is a good pump then fine, buy a direct replacement but make sure it's connected properly with a strainer and flexible hose. Any boat owner should be able to do that much plumbing.

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11 hours ago, JGL said:

Great... I shall get to googling and figure out how that works ?

 

9 hours ago, Timx said:

I'd like to know that too, have seen it advised before.

 

Its a separate switch that you screw into a T in the tap side of the pump's pipe work. Then you cut the two leads  going into the pump's end cap (pressure switch). These two leads are then fitted to the pressure switch using extra cable as required. While messing about there I would also fit a pressure gauge.

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1 hour ago, Tony Brooks said:

 

 

Its a separate switch that you screw into a T in the tap side of the pump's pipe work. Then you cut the two leads  going into the pump's end cap (pressure switch). These two leads are then fitted to the pressure switch using extra cable as required. While messing about there I would also fit a pressure gauge.

I found a suitably ranged gauge from a Hot Tub supplier

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53 minutes ago, Narrowboat Nimrod said:

Have you bled the calorifier? Air trapped here or in any part of the system will Cause the pump to run longer. Might be worth checking.

Nope. Will try, I assume that's simple- i.e. find a valve on it and relieve any pressure (as I would a radiator?)

2 hours ago, Tony Brooks said:

 

 

Its a separate switch that you screw into a T in the tap side of the pump's pipe work. Then you cut the two leads  going into the pump's end cap (pressure switch). These two leads are then fitted to the pressure switch using extra cable as required. While messing about there I would also fit a pressure gauge.

Okay, sounds simple... I'll investigate tonight when I'm back at the boat and see if this is looks as simple as it sounds :)

11 hours ago, alan_fincher said:

Not sure about the "direct replacement" advice.

Most are pretty similar, and generally if instructions have been followed, (which of course they may not have been!), the final connections to the pump should be in flexible hose rather than solid pipe.  If they are then slight differences in geometry shouldn't matter.

Personally I would say "not Sureflo".  Sureflo used to be reliable - more modern ones seem not to last many years, and wheras you used to be able to buy bits and repair them, it now often seems to be a mistake to try that.  ParMax seem OK.

 

 

Right-o, thanks for the tips. I'm sure it's a decent pump in there now, but I'll check the brand.

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The symptoms point to a faulty pressure switch, rather than the pump itself.  On the various pumps I've had apart, there is usually a plastic disc with a (very) small hole on the wet side of the pressure switch. If this hole gets partially blocked, it leads to the symptoms described, with the pump being very slow to react to changes in system pressure. I have opened the hole out to 3 or 4mm diameter with a drill, which didn't cause any problems, although I guess it might lead to the pump cycling more if there wasn't an accumulator fitted. Not worth changing a pump for a faulty pressure switch, IMO. Better to repair, or fit a Square D.

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3 hours ago, nbfiresprite said:

These D switches last for years 

water presure switch.jpg

Looks very nice and technical, but I don’t see a switch. What is it and what does it do please.

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10 minutes ago, Iain_S said:

The symptoms point to a faulty pressure switch, rather than the pump itself.  On the various pumps I've had apart, there is usually a plastic disc with a (very) small hole on the wet side of the pressure switch. If this hole gets partially blocked, it leads to the symptoms described, with the pump being very slow to react to changes in system pressure. I have opened the hole out to 3 or 4mm diameter with a drill, which didn't cause any problems, although I guess it might lead to the pump cycling more if there wasn't an accumulator fitted. Not worth changing a pump for a faulty pressure switch, IMO. Better to repair, or fit a Square D.

I think there's no accumulator...

Okay this is useful, I'll have a thorough investigation when I get back to the boat.. was rather clueless before, but now got plenty to go on.

Updates to come...

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52 minutes ago, Nightwatch said:

Looks very nice and technical, but I don’t see a switch. What is it and what does it do please.

It is a double pole switch so you get a spare pole when used for boat's water pumps. The actual contacts are under the screw terminals mounted on the black plastic "block". If you look carefully you can just see the edge of the diaphragm chamber underneath bottom right.

 

The big nut and large spring adjusts the cut out pressure while the much smaller ones to the diagonal down right adjust the cut in differential pressure. You cant see the hollow fitting thread that is sticking out below it.

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9 minutes ago, Tony Brooks said:

It is a double pole switch so you get a spare pole when used for boat's water pumps. The actual contacts are under the screw terminals mounted on the black plastic "block". If you look carefully you can just see the edge of the diaphragm chamber underneath bottom right.

 

The big nut and large spring adjusts the cut out pressure while the much smaller ones to the diagonal down right adjust the cut in differential pressure. You cant see the hollow fitting thread that is sticking out below it.

Thanks Tony. This is for another day perhaps.

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5 hours ago, Nightwatch said:

Thanks Tony. This is for another day perhaps.

I've never found the need for one but my understanding is that you bypass the pump's internal pressure switch and use one of those square D switches instead. As far as I'm concerned a decent pump should have a decent pressure switch already, but if it doesn't then I'm sure these square D switches are a good idea. Looking at the video I suppose the other advantage is that the dedicated switch is far more adjustable - should one have the need for that feature. I don't.

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