Sureflo pulsating pump (again) (1 Viewer)

Apr 7, 2014
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Sorry I know there’s umpteen threads on this but I’ve recently had the pump replaced and it pulses when water isn’t at full flow. I know this has been answered and there’s an adjusting screw somewhere but I can’t find it! Can anyone help please. Ta.
 

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R

Robert Clark

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On ours it’s a teeny Allen screw
It’ll be on the bottom of your pump on the pressure switch - look for where the cables connect
 
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Barryh
Apr 7, 2014
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Thanks very much for that. I’ll have a brew then go and check again.

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Barryh
Apr 7, 2014
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On ours it’s a teeny Allen screw
It’ll be on the bottom of your pump on the pressure switch - look for where the cables connect
Thanks but I can’t find any Allen screw.
Screw is here propably a Philips head on your pump.
View attachment 535629
Thanks but this just appears to be part of the moulding, there’s no screw visible.

I don’t know if I’m just being thick with this. Maybe I’ll just leave it as it is. On the positive side I have fixed a new blind catch today.

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Jan 19, 2014
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Thanks but I can’t find any Allen screw.

Thanks but this just appears to be part of the moulding, there’s no screw visible.

I don’t know if I’m just being thick with this. Maybe I’ll just leave it as it is. On the positive side I have fixed a new blind catch today.
It's on the end if it's like ours. N°2 pozidrive tip. The adjustment isn't very good and the instructions for ours are backwards ie winding in makes the pump cycle less 🙄 but in fact when I tried it the pump cycled more so I left it wound out 👍
 
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Aug 6, 2013
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The pump will cycle on reduced flow because the restriction (tap not fully open) allows the pump to reach switch-off pressure so it switches off. Then on again because the pressure drops. If it doesn't cycle at full flow it's fine. If it does you need to back off the pressure as described until it doesn't. You can reduce cycling when the tap isn't fully open by fitting an accumulator like this:

 
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Barryh
Apr 7, 2014
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The pump will cycle on reduced flow because the restriction (tap not fully open) allows the pump to reach switch-off pressure so it switches off. Then on again because the pressure drops. If it doesn't cycle at full flow it's fine. If it does you need to back off the pressure as described until it doesn't. You can reduce cycling when the tap isn't fully open by fitting an accumulator like this:

Ah ok. Thanks for that. I’ll probably leave well alone then.

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Barryh
Apr 7, 2014
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It's on the end if it's like ours. N°2 pozidrive tip. The adjustment isn't very good and the instructions for ours are backwards ie winding in makes the pump cycle less 🙄 but in fact when I tried it the pump cycled more so I left it wound out 👍
I must have something different, or I’m thick. I’m going to leave it alone I think. Thanks for trying to help.
 
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Dec 2, 2019
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Mine cycles even at full open tap flow. That’s because the water usage by volume is less than the pump capability. I do have a fiamma accumulator that helps with less starts when use a little water. About 1L tops. If you turn the screw in it’s just going to increase pressure. If you unscrew it will lower the pressure. The cycle is directly related to the volume of water usage, and will be delivered at a low or higher pressure. The screw on mine is set at 22psi measured with a monument tools analog pressure gauge. I’m happy with that.

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andy63

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Jan 19, 2014
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This may be splitting hairs a bit... but the adjusting screw on the sureflo pumps is not a pressure regulation device though ill accept its use may marginally alter the pressure..
The pressure these pumps run at is governed by the spring thats fitted..the adjusting screw alters the stroke or amount of movement and therefore the time required to operate the switch via a diaphragm..
Just nit picking but that's how I've understood the screws function..
Andy
 
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Aug 6, 2013
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The screw, via spring, adjusts the pressure at which the cut-off switch operates. Appropriate adjustment will prevent pulsing with the tap fully open.
 
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andy63

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The screw, via spring, adjusts the pressure at which the cut-off switch operates. Appropriate adjustment will prevent pulsing with the tap fully open.
As I said thats not quite my understanding.. the screw adjusts the stroke of the switch ..
I did strip one down and I'm fairly sure that was borne out by what I saw.. and sureflows own explanation in their instructions supplied with the pump..
Andy

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Jan 19, 2014
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This came with our new 30psi sureflow pump, but it's wrong 🙄

20210602_100155.jpg

20210602_100247.jpg
as I said above, winding the screw In made it cycle fast. So I wound it out and now the pump cycles less fast, about ¾ second.

Edit: got a whale accumulator too.
 
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Aug 6, 2013
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As I said thats not quite my understanding.. the screw adjusts the stroke of the switch ..
I did strip one down and I'm fairly sure that was borne out by what I saw.. and sureflows own explanation in their instructions supplied with the pump..
Andy
I think we're looking at the same effect from different angles. The switch is a standard microswitch with a fixed operating stroke. A spring loads the pressure sensing in 0diaphragm so that it contacts the switch earlier or later and in doing so adjusts the pressure at which the microswitch operates. The pump itself will achieve whatever pressure it is specified for unless its operation is cut short by operation of the microswitch. Adjustment (IMO) is most easily done with the best flowing tap wide open. Then adjust the microswitch until it cuts off then back until it doesn't. That's the best pressure / flow that can be achieved. As soon as there's any restriction caused by a partially closed tap the pump will pulse. If the pulsing is outside the limits described in the pump literature then an accumulator is needed. IMO an accumulator should always be installed to ease wear on the microswitch and to prevent the annoyance of fast cycling.
 
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andy63

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I think we're looking at the same effect from different angles.
quite possibly Tony.. I think you know from previous discussions I struggle to grasp some things..:rolleyes::LOL:and my memory is crap..
I just remember reading everyone talking about adjusting the pressure with the adjusting screw and that been a bit at odds with the instructions I got with my pump which I think was a 20psi rated model.... I eventually got round to opening one up and having a look and thinking I sort of get what they are saying..and im pretty sure that that adjusting screw altered the length of travel between the switch contacts in the casing and therefore the time it took the switch to operate.. again if I remember correctly it had minimal effect for me and I tried an accumulator..which still wasn't totally satisfactory :(
if I remember ill be having another look when I get home (y):LOL:
Andy

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Aug 6, 2013
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quite possibly Tony.. I think you know from previous discussions I struggle to grasp some things..:rolleyes::LOL:and my memory is crap..
I just remember reading everyone talking about adjusting the pressure with the adjusting screw and that been a bit at odds with the instructions I got with my pump which I think was a 20psi rated model.... I eventually got round to opening one up and having a look and thinking I sort of get what they are saying..and im pretty sure that that adjusting screw altered the length of travel between the switch contacts in the casing and therefore the time it took the switch to operate.. again if I remember correctly it had minimal effect for me and I tried an accumulator..which still wasn't totally satisfactory :(
if I remember ill be having another look when I get home (y):LOL:
Andy

I completely agree that pressure cannot be adjusted by the screw but the pressure at which the microswitch operates can. The reading when looking at a gauge with pump stopped and switch operated will be the pressure the pump has been allowed to build up before the switch operated. With a tap opened and assuming no restriction there will be close to zero pressure and (hopefully) a decent flow rate.

And my memory is worse than yours 😁
 
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Jan 19, 2014
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Just had a thought this morning, I don't think the whale accumulator is working, possibly because the new pump is a higher pressure. The pump is cutting back in before the diaphragm in the accumulator starts to move 🤔
Or maybe it's stuck/faulty I'm sure the old pump was 30psi same as the new one...
 
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Jan 19, 2014
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It's a surge damper not an accumulator 🤔 definitely isn't working like the old pump anyway, they're both 30psi pumps.

Old pump: Whale watermaster 2GPM 30psi
New pump: Surflo trial King 10.6L/minute 30psi

Any thoughts?

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Jan 19, 2014
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On further reading the whale anti-surge damper seems to be just an air bubble, an empty cylinder where the air expands and contracts. I'll check tomorrow to make sure it's not full of water as it could have flopped over before I screwed it up 🙄
 
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Dec 2, 2019
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On further reading the whale anti-surge damper seems to be just an air bubble, an empty cylinder where the air expands and contracts. I'll check tomorrow to make sure it's not full of water as it could have flopped over before I screwed it up 🙄
Not quite, a proper accumulator has a bladder that is pressurised/ pumped air at the pressure that the pump cuts in. The air and water are not in contact. That way, you get to use the water from it as it’s pushed out by the bladder, and after then the pump cuts in.

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Jan 19, 2014
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Not quite, a proper accumulator has a bladder that is pressurised/ pumped air at the pressure that the pump cuts in. The air and water are not in contact. That way, you get to use the water from it as it’s pushed out by the bladder, and after then the pump cuts in.
Yes the more expensive ones are like that (so I've read) but the whale one is empty. Some people have made them with a T piece in the pump outlet and a 2 foot piece of pipe off it vertically. I've also read the water board use big ones. There's a big thread on it on Caravan Talk forum.
 
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Aug 6, 2013
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It's a surge damper not an accumulator 🤔 definitely isn't working like the old pump anyway, they're both 30psi pumps.

Old pump: Whale watermaster 2GPM 30psi
New pump: Surflo trial King 10.6L/minute 30psi

Any thoughts?
It's an accumulator used as a surge damper. It has a diaphragm with air on one side and water on the other. The air pressure can be set to equal the pump cut-off pressure (approximately) .

Edit: Sorry you are correct - no idea what that thing does. The ones I've used have been accumulators with a Schrader valve on top.
 
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Dec 2, 2019
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Yes the more expensive ones are like that (so I've read) but the whale one is empty. Some people have made them with a T piece in the pump outlet and a 2 foot piece of pipe off it vertically. I've also read the water board use big ones. There's a big thread on it on Caravan Talk forum.
I know what you mean. Eventually that air space gets filled up. And you need to periodically half empty. A guy on you tube documented it pretty well. Search for it, not worth it. Go for a fiamma accumulator, blank one end, and T onto the other if only one connection is possible.

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Jan 19, 2014
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Yes full of water 😑👌

20210915_111811.jpg


That's noticeably better when the tap's open slightly but I think I'll fit a better one when we get home.
 
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Aug 6, 2013
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Yes full of water 😑👌

View attachment 536969

That's noticeably better when the tap's open slightly but I think I'll fit a better one when we get home.

Here's the one I use:

https://www.google.com/aclk?sa=l&ai=DChcSEwjQ2o3h14DzAhUWndUKHSMpDyQYABAHGgJ3cw&ae=2&sig=AOD64_0lGFnnsCGH0BhJy6pqLoY9Q4rokQ&adurl&ctype=5&ved=2ahUKEwjXsYHh14DzAhUQNxoKHS1ED4UQwg96BAgBECY
 
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Jan 19, 2014
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Update: It must have filled up again the pump switches on and off like mad 😡

The damper is the highest point though 🤔 air does dissolve into water of course otherwise fish couldn't breathe 🤔 so it must have been carried through to the taps molecule by molecule 🙄
 
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