Flow jet pump

Mel

Moderator
Mar 17, 2007
5,525
1,446
25,935
Visit site
On another forum there has been some discussion about how noisy pumps are on Swift Caravans. Our pump is certainly noisy.
The consensus seems to be that it is not the pump that is the problem, but the way it is mounted, causing vibration. Folks suggest using mounting screws with a sort of rubber bung in the middle ( they have a name, someone will know it) as a way of reducing the noise. May be worth considering as much cheaper than a new pump.
Mel
 
Nov 11, 2009
21,185
6,709
50,935
Visit site
I replaced re my Flojet pump and I mounted it on a piece of board which used soft rubber mounts screwed into it. The Flojet itself was then mounted on the board using its supplied mounting piece. But I took care not to over tighten the mounts so as not to stiffen them. Inlet and outlet pipes pipes I also fixed using resilient mounts. It improved it quite noticeably. But generally I would question why the caravan maker locates what is acknowledged to be a noisy vibrating pump right under where you sleep without any cognisance of noise reduction measures.
 
Mar 14, 2005
17,937
3,302
50,935
Visit site
The reason inboard pumps are much noisier than external pumps is the need for the internal pump to be able to produce enough suction to lift water from an lower external water container. The only pumps that can achieve this and still be a practical size and power for caravans are "positive displacement"or diaphragm pumps. This type of pump has to have reciprocating parts , which inevitably makes the pump body vibrate. Caravans need to built with thin wall and floor panels and just like fine musical instruments they can easily amplify the volume of anything that vibrates in contact with it.

There are vibration absorption pads which can mount the pump on to reduce the transmitted vibrations but they will never be completely suppressed with this type of pump.

The alternative approach as used by many caravan manufacturers is to use an external submersible pump which is dropped into the external tank and becasue it is in the water it does not have to create an air vacuum to suck the water into it. You may need to prime the pump after refilling an external tank, but that is usually simply achieved by disconnecting the pump from the side of the caravan when you are about to refill the water tank, and then dropping the pump into the fresh tank before reconnecting it to the caravan.

The submersible pumps are quieter for two reasons, firstly they use a rotating impeller rather than a reciprocation motion, so the pump tends to be much smoother and quieter than the inboard pump, but becasue it is external to the caravan it is almost silent inside the caravan.

It is important not to allow submersible pumps to run dry as that will dramatically reduce their working life, so you need to be vigilant and make sure the tank is kept full enough to prevent this.

If you decide to change to an external pump, you would need to make some changes to the pipework where the old pump was, you would need to fit a water pump inlet fitting to allow the power to get to the pump, and you would almost certainly need a pressure switch. All these items are readily available from caravan dealers.
 
Jan 3, 2012
9,861
2,130
30,935
Visit site
When we had our Abbey caravan our pump was very noisy but it was working if it wasn"t we would get our caravan engineer to sort it for me
 
Jun 20, 2005
17,814
3,861
50,935
Visit site
The main reason for the on board pump is filling and using the on board water tank in addition to an external source eg aquaroll
 
Jul 15, 2008
3,676
718
20,935
Visit site
.....I have a Swift with an onboard diaphragm pump. Swift basically mounted it directly to what amounts to a sound board that amplifies it's noise.
I changed the mountings to flexible rubber blocks glued to the board and bolted to the pump.(similar to Otherclive)
I then wrapped the whole pump in several layers of bubble wrap held in place with a plastic tie.
I can still hear if it is working but its no longer annoying.
My pump never works unless a tap is opened and this should be the case if the pump and pipework have no leaks or faulty non return valves.
 
May 7, 2012
8,598
1,816
30,935
Visit site
I did discuss this with a caravan engineer who was repairing out caravan. He was not aware of a complete answer and the best he could suggest was using a piece of thick carpet under it. The pump runs for so little time though we lived with it and at least it cannot be stolen easily when om site. Unless you are having a shower it is at best a very minor distraction.
I did wonder if moving it over an under floor support brace might help but never tried it.
 
Nov 11, 2009
21,185
6,709
50,935
Visit site
I did discuss this with a caravan engineer who was repairing out caravan. He was not aware of a complete answer and the best he could suggest was using a piece of thick carpet under it. The pump runs for so little time though we lived with it and at least it cannot be stolen easily when om site. Unless you are having a shower it is at best a very minor distraction.
I did wonder if moving it over an under floor support brace might help but never tried it.
It’s the nighttime din right under the front beds.
 
  • Like
Reactions: Barry C
Sep 16, 2018
297
190
10,735
Visit site
We have an onboard pump for the on board tank, as well as a submersible in the barrel. Last thing at night we always switch over to the submersible to avoid the noisy pump under the bed disturbing us at night.
 
Jan 19, 2002
1,571
454
19,935
Visit site
Not sure about the exact mounting of the pump but did find ‘mechanical vibration damping mounts’ in various formats on Amazon amongst others, so maybe a possible cheap solution.
 
Nov 11, 2009
21,185
6,709
50,935
Visit site
Not sure about the exact mounting of the pump but did find ‘mechanical vibration damping mounts’ in various formats on Amazon amongst others, so maybe a possible cheap solution.
Here’s a typical Flojet similar to the one I fitted to my caravan. As I posted above I double mounted mine and flexibly mounted the adjacent inlet and outlet pipes. Intersting that the price is now on a par with what I paid, but in summer 2020 as lockdown eased they were as rare as hens teeth and traditional caravan suppliers were asking £115, many though just putting you on an open ended waiting list. I bought mine from a specialist pump supplier.

 
Last edited:
Jun 15, 2024
7
4
15
Visit site
In case this helps, we have had a similar problem with our brand new Swift Sprite Alpine 2 2024 caravan, and have managed to solve it. The pump still makes a little bit of noise, but much much less than it was doing.

This is our first caravan with an internal water pump, so feared it was normal, especially as some folk say they are a bit noisy anyway. But this was way beyond "a bit noisy". Like a road drill under the bed at night - really! Hammering through the caravan's bodywork.

Swift's persistent advise was to alter the pressure switch setting on the pump, which was completely inappropriate. Changing the pressure at which the pump turns off is no use at all when the noise only occurs while the pump is running. Like taking your car to the garage because it is makes a horrible noise whenever the car is moving, and being told to stop the car sooner!

The problem was that the water inlet pipe feeds into a hard plastic elbow fitting, before it goes into the pump, and this elbow fitting was up against the wooden bulkhead the pump is mounted to. As the pump moved on its flexible mountings (as it is meant to) it was hammering this plastic elbow fitting onto the bulkhead, which was very loud. I could reproduce the same noise by just gently wiggling the pump on its mountings by hand. The bulkhead acts as a soundboard and amplifies the noise. So I fixed that by re-routing the inlet pipe so the elbow is now positioned away from the bulkhead. No more road drill noise.

But I also then realised there was a really annoying whine/hum, and so I ran the pump detached from the bulkhead, just held in my hand, and the noise stopped. The noise reappeared when positioned onto the bulkhead, even before its rubber mountings made contact. Turned out to be due to how Swift have routed the wiring for the pump, between the pump body and the bulkhead. The pump's flexible rubber mountings can only damp out the noise so long a there is no other acoustic connection between pump and bulkhead, but with the cables jammed in between, the motor noise was transmitting directly to the bulkhead! I fixed this by using 1/2" rubber tap washers (which are about 4mm thick) between the rubber mounting feet and the bulkhead, with longer screws, so none of the wiring then jammed between.

Really disappointed with Swift on this. People have been complaining about this for 10 years or more it seems, and it is really just a simple bit of production engineering and/or quality control to sort it for people. Either Swift's production drawings are wrong and they need to sort, or they are correct but not being followed correctly by their production staff.

And as for the stock response of telling people to adjust the pressure switch - that just demonstrates a total lack of comprehension of the issue.
 
Last edited:
  • Like
Reactions: otherclive and Mel
Oct 19, 2023
321
239
435
Visit site
Is there a reason for having your pump switched on overnight? I have an external pump but always switch it off before I retire for the night.
 
Mar 14, 2005
17,937
3,302
50,935
Visit site
Is there a reason for having your pump switched on overnight? I have an external pump but always switch it off before I retire for the night.
There are arguments both ways, Occasionally with a pressure switch controlled system, the pressure in the pipework may reduce overnight due to particularly the hot system cooling down. or if there is a leak, this may be sufficient to cause the pump to run to regain the pressure. If the pump is noisy like an internal diaphragm pump its momentary action might be disturbing.

Alternatively with an external submersible pump, if for any reason the tank empties and the pump gets an airlock it would continue running. If its left running it will burn out. At one camp site there was am incident where someone stole a water container and left the pump dangled on the ground. It was found burnt out the next morning.

these are two arguments for turning the pump off

But if there are multiple users in the caravan such as children who might use water at night, that would be a reason to leave it turnrd on.
 
  • Like
Reactions: Barry C
Jun 15, 2024
7
4
15
Visit site
Is there a reason for having your pump switched on overnight? I have an external pump but always switch it off before I retire for the night.
The pump only runs when a tap is running. The problem is that at my age I need to pay a visit during the night, and then use the tap to wash my hands. The pump has to run in order to get water out of the tap. The pump is under the bed my wife is still asleep on.
 
Last edited:
Nov 11, 2009
21,185
6,709
50,935
Visit site
Is there a reason for having your pump switched on overnight? I have an external pump but always switch it off before I retire for the night.
Ours was left on overnight, mainly for hand washing for hygiene reasons. When out during the day it was turned off.
 
Oct 19, 2023
321
239
435
Visit site
Ours was left on overnight, mainly for hand washing for hygiene reasons. When out during the day it was turned off.
I find there's enough pressure in the system to push a couple of litres of water out for that purpose, guess it depends how many people there are in the van and how many get up in the night. Like you I also turn the pump off when we leave the caravan (I normally turn the control panel off so everything is off - might be OTT but it's above the door so no inconvenience).

I did wonder if it was something to do with maintaining water pressure for the boiler, but I turn that off as well.
 
  • Like
Reactions: Barry C

Mel

Moderator
Mar 17, 2007
5,525
1,446
25,935
Visit site
We also have an Alpine 2. Pumps on Sprite vans are well known for being really noisy and “ Jack hammer” is not much of an exaggeration. Well done to Barry C for quieting the beast and in the experience of most of us, it is absolutely nothing to do with the pressure switch. IMHO I would go straight to my AWS techie and never ask a dealer anything.
Mel
 
  • Like
Reactions: Barry C
Nov 11, 2009
21,185
6,709
50,935
Visit site
The pump only runs when a tap is running. The problem is that at my age I need to pay a visit during the night, and then use the tap to wash my hands. The pump has to run in order to get water out of the tap. The pump is under the bed my wife is still asleep on.

Edit: I made this comment in the context of an earlier comment I made in this thread about now I solved our "machine gun noise", not realising that the earlier post is still awaiting moderation. So this comment may be a bit out of context. I've changed it to "road drill noise" in case that was the problem.
I remounted mine on a new baseplate and used rubber grommets as mounts to the baseplate. I also rerouted the pipes so I could also mount them on flexible mounts and not hard fixed to the van. It made a discernible improvement.


 
Last edited:
  • Like
Reactions: Barry C

Sam Vimes

Moderator
Sep 7, 2020
1,819
1,359
5,935
Visit site
Somewhat of an old thread but never mind.

I had a 2006 Swift Motorhome with the same noisey pump. On one tour it packed up on site and I managed to get a replacement sent directly. When I replaced it, I made some improvements. Swift weren't interested.

They're not alone in the Fit and Forget attitude.
 
Jun 15, 2024
7
4
15
Visit site
......wrapping the pump in several layers of bubble wrap dampens the noise considerably.
See post #8 of this thread.
The only thing that would worry me there is if the pump motor started overheating, especially if on for a little while, such as when showering for instance, or maybe when priming the system. But it's an interesting thought.
 

TRENDING THREADS

Latest posts