Shurflo water pump replacment

[Barry38]

I am considering replacing the surface mounted Shurflo diaphragm pump (7 litres per min. at 20 psi) on my motorhome with a submersible type suspended or mounted in the fresh water tank. I am aware that it will be necessary to alter the pipework, filter, non-return valve and pressure switch arrangement which will not be a problem to me.

Has anyone successfully achieved this set-up as a retro-fit and if so any recommendations or pitfalls to be aware of?

Which type of pump to use?

I do not like the existing Shurflo which can be highly susceptible to the slightest air leak which can be a pain to find and permanently resolve.

 

Any help or thoughts would be helpful

[Derek Uzzell]

I believe you own a 2009 Autocruise Rhythm. Is your motorhome’s fresh-water tank located inside the vehicle or external?

 

If the latter, the task will be more challenging and (despite your reservations regarding pressure-sensitive water-pumps) a submersible pump in an exterior tank has potential drawbacks that should be fairly obvious (eg. if the pump clogs/cavitates/fails access to the pump may prove difficult).

 

However, as you are confident that you can carry out the work, I can’t see why it can’t be done - one submersible pump is much like another and it will just be a matter of choosing the make and a suitable pressure/flow-rate specification. Similarly with the in-line pressure switch - the Whale product is probably the most commonly used, but there are a few alternatives.

 

Must you do this? I accept that a motorhome water system that includes a pressure-sensitive pump (be it a SHURflo one or any other make) will be susceptible to any loss of pressure (normally a water leak rather than an air leak) ‘downstream' of the pump, but you are contemplating a lot of work to guard against that and, when you’ve done the work, any air or water leak (be it ever so minor) ‘downstream’ of the submersible pump can still occur and cause problems.

 

 

[Robbo]

I assume you have a Truma boiler. If so, check the water inlet elbow connection. This incorporates a non-return valve (NRV) with clear plastic tube exiting through the floor.

 

My Shurflo pump kept triggering for no apparent reason. Eventually found that water was leaking from the boiler connection via the clear plastic tube. This lowered the pressure in the system and triggered the pump.

 

I removed the elbow and tested the NRV by blowing through it. Sure enough, it passed air in both directions, indicating it was faulty. Replaced it with a new elbow and now pump working normally.

 

So, before you consider changing the system.....carry out this basic check.

[Barry38]

Thanks for the info. Derek.

In my working experience if a serviceable submersible pump's suction point is 'flooded', it will generally attempt to pump whatever is on it's delivery side to a controlled outlet point where any air within that section of pipework can be purged and any leak can readily be identified.

A diaphragm pump fitted above it's supply point cannot 'lift' water effectively if the minutest amount of air enters the suction side of the pump and equally any leakage within the said pump will allow water back into the supply tank and therefore ANY leakage either before or after the pump will have a detrimental effect.

I accept that as my supply tank is mounted under the floor, access to a submersible would be more difficult and time consuming but my wife likes me to be kept busy during the winter months !

It's 'horses for courses' I think but any faults in submersible pumps are generally much simpler to source and resolve in my experience.

The jury is still out on this one!