Water Pumps - freshwater

[DavidWS]

I have to replace the water pump on my narrowboat. The current one is a Jabsco and has been no problem but the capacity is inadequate and it will cut off the hot supply (gas heater) if the cold it turned on. A bathroom tap will not run if a kitchen one is on etc. 12V system. It is getting on a bit and I probably bought the only one on the shelf at the time.

 

I have been looking at both Jabsco and Shurflo pumps.

 

Jabsco seems to be the flavour of the month - why?

 

Is the higher operating pressure of the Shurflo a problem or an advantage?

 

Having a kitchen mixer tap, a washbasin pair, a shower and bath what capacity pump should I have.

 

Who does anyone recommend as a supplier?

 

I have seen Johnson pumps too but know nothing of them. Are they an option?

 

I would appreciate any feedback please as I just cannot decide at the moment and have no learned friend to ask.

 

I think the 45psi of the Shurflo raises questions for me much as I lean that way but then I am not sure how relevant pressure is.

 

The Jabsco I have now had an alternative spring to give a higher pressure than the one fitted as it was hopeless on the low pressure. I forget what it is operating at now but think it is something like 35psi but it just doesn't have the volume.

 

I tried a very old Shurflo pump that it replaced years ago just to see the difference. It was frost damged and glued with superglue so not one I would use but it certainly did the business and I had a decent water supply. But it was only suitable for a test to see how poor my Jabsco really is.

 

So any advice please, biased or otherwise.

 

Thanks

[dor]

It is not pressure that is important on a boat for the problems you describe but volume. You can have a very high pressure pump, but if it doesn't have the volume it will be useless (compare the 200psi air pumps sold to inflate car tyres - they work fine for that, but it will take an age to inflate an inflatable mattress which only needs a few psi but lots of volume).

 

The shurflo 11 lpm is a minimum the 16 (i think)is better. Best is probably the variable flow type now available, but expensive. 45 psi sounds too high - I thought most pumps should shut off at about 30 psi. This doesn't mean it supplies water at the tap at 30 psi, just that when you turn the tap off it will build up pressure to 30 pis then cut off the pump. Most pressure relief valves on the hot water side are set to 3 atmospheres, so 45 psi could just continue pumping out of the relief valve!

 

There is an earlier thread on here somewhere discussing water pumps.

[Richard Bustens]

On the subject of pumps, has anyone got a Whale Gulper fitted, as the one i have for pumping out the bath waste tank pumps in spurts not continuous, and I'm sure the one i saw demonstrated at last years national pumped continuously?

[Big COL]

On the subject of pumps, has anyone got a Whale Gulper fitted, as the one i have for pumping out the bath waste tank pumps in spurts not continuous, and I'm sure the one i saw demonstrated at last years national pumped continuously?

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Richard

 

The Whale Gulper is a diaphragm pump, all diaphragm pumps discharge in spurts, two factors control the timing between discharges, 1- speed of the pump motor, 2- the length of the stroke, which is determined by the no of pistons & size of the cam.

The advantage of this type of pump is they will run dry and pump air without causing any damage. Whale have just introduced a new model that has a faster discharge rate.

Edited August 27, 2005 by Big COL

[DavidWS]

I appreciate the quick response Dor (Looks as though you are a biker too?)

 

I understand that the pressure is not a constant thing but I was wondering if by having reached that pressure when taps are shut off it could cause leaks or joints to go or something. It seemed high to me.

 

I looked back with searches here on the names of the pumps and also just 'pump' but didn't locate anything on the forum so please keep any opinions coming folks as there is nothing like your own experience.

 

I guess I will probably go for an overspec. in terms of capacity to make sure I have enough flow although that gets quite expensive and the Amps go up accordingly so there is a balance I want to achieve.

 

It would be interesting to know if there is a common factor in terms of pump capacity in boat installations. But then maybe you don't know what size your pump is if you haven't fitted it yourself. Since I failed to look into the subject properly when I bought the one I use I have ended up with one where I don't know its capacity either.

[Big COL]

David

 

I don't think you will find a common factor for pumps on boats, there are too many variables, the number of people on board the number of outlets in the boat, and how many outlets are open at the same time. I have a 70' trad with macerator toilets, shower, 2 sinks, the water pump running this is a Jabsco delivering 3.5 gallons/ min at a 5amp draw on 12v supply. The current will be I suspect will be proportional to the delivery rate, across the range of pumps available. Meaning, you may find a pump that only draws 2 amps but only delivers 2 gallons /min, so you have to run it twice as long, if you are tight on battery capacity you need to look at the ratio between delivery rate/ amperage and find a happy medium that will cater for your needs.

[John Orentas]

I have said this before but the biggest improvement you can make to the water system is to replace the rather crude control system which is fitted to most pumps. A good quality adjustable pressure switch and a good accumulator will transform the system and everything will work perfectly at 20 psi.

[DavidWS]

Thanks Big Col and John.

 

I have an accumulator.

 

It is good to have some idea what others have even if there is no common factor.

 

It probably isn't a difficult choice but having only just realised that I underspecified on the pump by picking the only one off the shelf I want to get it right this time. But you mention an adjustable pressure switch? What is the reason for this and is this different from the pressure switch on the pump? Does this mean you have a pump and a pressure switch as separate items?

Edited August 27, 2005 by DavidWS

[Big COL]

Thanks Big Col and John. 

 

I have an accumulator. 

 

It is good to have some idea what others have even if there is no common factor.

 

It probably isn't a difficult choice but having only just realised that I underspecified on the pump by picking the only one off the shelf I want to get it right this time.  But you mention an adjustable pressure switch?  What is the reason for this and is this different from the pressure switch on the pump?  Does this mean you have a pump and a pressure switch as separate items?

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David

 

You say you are running a Jabsco pump and it is under sized, what model is it? I have a list of some of the jabsco pumps and could probably be able to give you the flow rates. The model no will be on the pump, come to that so should the flow rates.

[John Orentas]

The pressure switch which is fitted as a integral unit to the Sureflow and other types are rather crude, difficult to adjust and with 'differential' far too great, on top of that they are not very repeatable resulting in a need to set them at a pressure that is far to high.

 

There is an ideal one in the RS Cataloge, which of course must be mounted separately. I can give further info to anyone interested.

[DavidWS]

Thanks Colin. When I next go to the boat I'll have a look. Will be a couple of days. I found the invoice for it recently which is fatal as I took it out of the file and now don't know where it is.

 

What is the RS Catalogue John? And do you still leave the pressure switch on the pump or presumably just have a basic pump? When you say it is rather crude does it matter as long as it switches the pump off? Why is the pressure so important except to stuff water in the accumulator and pipes so that you get a quick burst when you open a tap.

Edited August 27, 2005 by DavidWS

[John Orentas]

RS Components, catalogue something of a bible for electronics and electrical designers but contains stacks of other stuff, there are now six one inch thick volumes of thin paper. I and others use it also as a reference manual.

 

You leave the existing switch and locate the new one connected to any convenient part of the pressurised system. The differential of a pressure switch is the pressure difference between switching on and off, it needs to large enough that the pump does cycle too rapidly but small enough that you can have a reasonably low 'off' pressure with the switch still detecting the lower 'on' pressure.

 

To function reliably and with reasonable repeatability the switch must have a fairly large diaphragm and a friction free movement, fitted prassure switch has a small diaphragm and is poor mechanically.

 

Fitting a pressure gauge in the system makes things easier and looks impressive, and driving the pump motor through a relay makes everything longer lasting and elegant.

[DavidWS]

Just to say it was a bit of 'duff gen.' to say I had a Jabsco pump now Colin. I have just looked and it is a Shurflo which replaced an ancient Jabsco rotary pump that I let get frostbitten. And it also gives the flow as 1 4 IMP which is obviously the problem. (I am not sure if it means 14 pints of 1.4 gallons /min.) But it is rated at 4 amps so it can't be very much of a flow.

 

I don't think I will go for the elegant solution of John's last post as I doubt I use the boat enough to do it justice and the pump and accumulator are all tucked away out of sight and out of mind. So I am thinking the Jabsco is better due to the lower pressure and it is just a question of deciding what flow rate to go for. Can't imagine why I didn't get to grips with it sooner.

Edited August 27, 2005 by DavidWS

[dor]

My Shureflo has done at least six years of use (4.5 with me) with regular weekend use and also longer trips - so probably above average for a non-liveaboard. Still works fine - but having said that it will probably go wrong tomorrow. I think they are generally reliable in use.

 

David do you ride a bike? there's a few bikers on this forum - guess it makes an exciting contrast to boating.

 

Richard: I've got a whale gulper - excellent bit of kit for its designed use - i.e. pumping out showers/baths. Yes it does "spurt" - as Col says this is due to it being a diapragm pump. But it doesn't block and can handle the wife's hair without complaining.

[Big COL]

Just to say it was a bit of 'duff gen.' to say I had a Jabsco pump now Colin.  I have just looked and it is a Shurflo which replaced an ancient Jabsco rotary pump that I let get frostbitten.  And it also gives the flow as 1 4 IMP which is obviously the problem.  (I am not sure if it means 14 pints of 1.4 gallons /min.)  But it is rated at 4 amps so it can't be very much of a flow. 

 

I don't think I will go for the elegant solution of John's last post as I doubt I use the boat enough to do it justice and the pump and accumulator are all tucked away out of sight and out of mind.  So I am thinking the Jabsco is better due to the lower pressure and it is just a question of deciding what flow rate to go for.  Can't imagine why I didn't get to grips with it sooner.

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David

 

You need to determine the flow/ pressure required to keep your hot water heater going. Then size up wards from that.

[DavidWS]

I think my boat has had two pumps in its nearly 30 year existence! I don't know what life they are supposed to have.

 

Yes I am a bit of a biker too. BMW R1100RS SE. I don't swop and change but tend to look after things and keep them for a long time so it is also out of date but still looks pretty immaculate. Had only three different bikes since 1982.

 

As for flow rate for the Paloma, I guess it will be around what this pump is delivering. It only mentions the minimum pressure but it is the heater that is the suffering as opening the cold tap robs it so it goes out.

Edited August 27, 2005 by DavidWS

[Richard Bustens]

Hi Big C

 

Well it seems a silly pump to use for pumping out the gray water then but it is the one that Whale recomend for there gray tank, but the water from one tap pumps in faster than it can remove it, let alone when the bath plug is pulled.

[Big COL]

Hi Big C

 

Well it seems a silly pump to use for pumping out the gray water then but it is the one that Whale recomend for there gray tank, but the water from one tap pumps in faster than it can remove it, let alone when the bath plug is pulled.

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Richard

 

You have a problem then, have you a filter on the pump if so is it blocked? Or your fresh water pump is delivering a greater volume of water than the whale is designed to discharge. The other possibility is that one or two of the valves in the whale have some crud in them and they are not seating properly, and you are getting a lesser discharge rate. I use diaphragm pumps for both fresh water and shower discharge, both have filters on them, the only one that needs any attention is the shower pump. This needs the filter cleaning about every 6 weeks to clear out hair. IMHO a diaphragm pump is less troublesome than a impeller type, and I have experience of all types of pumps in my business.The valid point I made earlier, your discharge pumps should be designed to handle a greater volume of water than the fresh water pump can deliver. Otherwise you run the risk of overflow problems, which sounds as if you could have. If there is nothing wrong with your whale pump. Check the delivery rate of your fresh water pump compared to the discharge rate of the whale.

Edited August 28, 2005 by Big COL

[Richard Bustens]

It cant overflow as it goes into a sealed tank and the tank is a Whale as well, both are new and just being fitted now and i have only tested it with a pipe in the top from the pipe that will be the tap pipe to the bath 15mm this puts more in than is being pumped out, the outlet from the bath and sinks are all 1 1/2 inch and they will obviously back up when plugs are pulled.

 

What attention do you have to do every 6-10 weeks, as although it is get able to it is not easily access. i may have to move it.

[dor]

I took the filter out of my shower outflow - it was needed when I had an impeller pump and was a pain to keep dehairing and defluffing it. Now the whale gulper, everything seems to disappear.

[John Orentas]

It cant overflow as it goes into a sealed tank and the tank is a Whale as well,

 

 

 

Richard, how can that work you can't pump out of a sealed tank, there will be times when you are pulling a vacuum

[Big COL]

It cant overflow as it goes into a sealed tank and the tank is a Whale as well,

Richard, how can that work you can't pump out of a sealed tank, there will be times when you are pulling a vacuum

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John

Good point, with the pump off, waste water on a gravity feed will not fill a sealed tank either, when the pressures of the air trapped in the tank equalises with the pressure of the incoming water, the water will stop flowing. This system must rely on the incoming waste pipes as breather pipes as long as there is an open end even if the pipe is full of water the pump will still be able to operate correctly.

If this is how it works I can see no advantage in this system over having the pump directly on the end of the waste pipe, for the small amount of water that you can store, unless its a huge tank.

[DavidWS]

I don't know what the normal arrangement is but my bath/shower drain leads to a tank which is lower than the base of the bath and higher than the top But it isn't sealed and has a lid on. Inside is a normal bilge pump and to empty the bath I simply switch on and it shoves it out in no time with never any problems.

[Richard Bustens]

This is the tank.

http://www.whalepumps.com/marine/product_list/13/128/

 

The three big ones are 1 1/2 inch diameter and i have coupled them to the sink wash basin and bath one of the small ones is connected to the tank overflow release valve and one on the bottom is connected to the pump. the float switch is in the tank..

 

Perhaps i should run one of the other top ones as a breather to a high point but it does not say to do that. and they recommend the pump i have.

[Big COL]

This is the tank.

http://www.whalepumps.com/marine/product_list/13/128/

 

The three big ones are 1 1/2 inch diameter and i have coupled them to the sink wash basin and bath one of the small ones is connected to the tank overflow release valve and one on the bottom is connected to the pump. the float switch is in the tank..

 

Perhaps i should run one of the other top ones as a breather to a high point but it does not say to do that. and they recommend the pump i have.

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Richard

 

I have had a look at the installation instructions the inlet pipes will act as breathers as well, the air will rise to the highest point passing through the water.

The filter that you wanted to know about is usually on the inlet of the pump it is a fine gauze filter that catches mainly hair, being a diaphragm pump it does not necessarily need one as these types of pump will handle hair as part of the normal discharge.

Apart from the advantage of only having to fit one skin fitting I fail to see any advantage gained from this system. The disadvantage is that if any thing goes wrong with the pump or switches you will be unable to empty any of the outlets connected to it which may leave you unable to get rid of any waste water. I much prefer the standard method at least with the exception of the bath/shower they will empty by gravity which only leaves the bath/shower to worry about.