Multiple pump water systems

[TandC]

Just wondering about the benefits of separate water pumps and the practicality of how it works...  I've seen a few posts of people remarking on having "we have two water pumps" - but not really grasped how this works in the system. 

 

Is it one pump for hot, one pump for cold?  How does it work with a calorifier?

 

Benefits?  

 

Does it gain increased shower pressure...?  That would be the main attraction and if it could make a significant benefit then that would perhaps be worth exploring.  But otherwise things like the impact of turning on the cold tap in the kitchen while someone is showering etc doesn't really merit the faff/expense.  

 

 What's people's set ups - and what are the benefits/considerations as to why you've got it in such a manner?  

[David Mack]

2 minutes ago, TandC said:

I've seen a few posts of people remarking on having "we have two water pumps" - but not really grasped how this works in the system. 

One in use and one spare which can be easily slotted in if the first fails.

[Tony Brooks]

1 minute ago, David Mack said:

One in use and one spare which can be easily slotted in if the first fails.

 

That was how two pumps on my ex hire boat were fitted, a not so obvious switch would allow the pumps to be swapped over by telephone instruction from the hire base.

 

I have heard of people use one pump for hot and one for cold, but I fear that could make shower water temperature control interesting. I can't see the point of the extra pipework etc.

[rusty69]

We have a two pump system on our sailboat, but one is electric the other manual. The reason is that before solar became available it gave a great way of obtaining water without draining the batteries. We still use the manual pump most of the time,but it obviously doesn't work for hot water via the water heater. 

 

I can't really see the point of a dual electric pump setup for redundancy reasons (unless it's a hire boat) if a spare pump is kept on the shelf. It's literally a ten minute job to change out certain pumps. 

Edited September 26, 2023 by rusty69

[Slim]

I used have two pumps on a yacht I had. Yes, I could have kept one in a locker as a spare but who has ever heard of a pump failing at a convenient time. Space constraints prevented me replicating the setup on my nb.

[magnetman]

My second narrow boat had separate pumps for hot and cold. 

 

The shower problem was solved by just having two taps which you balance manually to get the required temperature rather than a thermostatic bar thing.

 

Worked nicely. I was just shurflo pumps on the old Acorn push fit pipes. 

 

 

[Tony Brooks]

25 minutes ago, magnetman said:

My second narrow boat had separate pumps for hot and cold. 

 

The shower problem was solved by just having two taps which you balance manually to get the required temperature rather than a thermostatic bar thing.

 

Worked nicely. I was just shurflo pumps on the old Acorn push fit pipes. 

 

 

 

If the pumps and settings were well-matched and the shower output was greater than the pump delivery, so they did not cycle, then this would work well, BUT if they cycle you could easily get rising pressure and thus flow on one, and a falling pressure and less flow on the other. Not ideal for a steady shower temperature.

[magnetman]

It seemed to work well but I am not what one would call a fastidious utiliser of onboard ablution related mechanical equipment. 

 

I can go rather a long time between uses so may simply not have noticed but it seemed alright to me. 

 

 

[frahkn]

My Orion is a 70' tug with the water tank below the tug deck.

 

It has 2 water pumps which take cold water (via two pressure vessel thingys)  down each side of the boat. One pump runs when cold water taps are used, the other when hot is demanded. I haven't really thought about how the calorifier is involved.

[IanD]

4 minutes ago, frahkn said:

My Orion is a 70' tug with the water tank below the tug deck.

 

It has 2 water pumps which take cold water (via two pressure vessel thingys)  down each side of the boat. One pump runs when cold water taps are used, the other when hot is demanded. I haven't really thought about how the calorifier is involved.

 

Isn't it more normal to have the calorifier which supplies hot water also pressurised by the cold water pump (on the incoming cold feed)?

[frahkn]

50 minutes ago, IanD said:

 

Isn't it more normal to have the calorifier which supplies hot water also pressurised by the cold water pump (on the incoming cold feed)?

Don't know - I'm going to have to think about it.

 

Most long Orions and some Hudsons use this system though.

[magnetman]

Both pumps are cold water pumps in that arrangement. 

[blackrose]

4 hours ago, David Mack said:

One in use and one spare which can be easily slotted in if the first fails.

 

Same. I have a higher pressure pump for summer when I'm using the Morco instant gas water heater and a lower pressure pump for autumn/winter when using the Webasto/calorifier for hot water. The Morco doesn't work very well with the lower pressure pump, but the high pressure pump is noisy so I swap them around.

Edited September 26, 2023 by blackrose

[ditchcrawler]

1 hour ago, blackrose said:

 

Same. I have a higher pressure pump for summer when I'm using the Morco instant gas water heater and a lower pressure pump for autumn/winter when using the Webasto/calorifier for hot water. The Morco doesn't work very well with the lower pressure pump, but the high pressure pump is noisy so I swap them around.

Plumb in parallel with a change over (2 way light) switch 

[Tracy D'arth]

A light switch is normally rated at 5A AC, pump loads of 10A to 12A DC will ensure a short life.

[ditchcrawler]

46 minutes ago, Tracy D'arth said:

A light switch is normally rated at 5A AC, pump loads of 10A to 12A DC will ensure a short life.

Yes mine has only lasted 20  years, not sure what I will replace it with when it fails

[Tractor]

I have two pumps connected in parallel, selected by individual pressure switches. If high pressure is achieved, one pump runs, if high pressure is not achieved two pumps run. This is made by adjusting pressure switches.

[nb Innisfree]

Innisfree has, or had, two water tanks, a bow tank + one under rhe dining table, a pump for each was simpler and served a kitchen calorifier and a bathroom calorifier, worked out really well as they were cross connected and one pump could be switched off and the other would serve the kitchen and bathroom, handy when one tank was empty,  just switch pumps over. Sounds complex but in fact was quite straightforward.

[J R ALSOP]

I have a Jabsco 12/24v that increases speed as more demand is needed, pressure out of taps remain constant even with 6 taps on.

Will be at boat nest week so will get model no. off it.

[magnetman]

I think it is one of the Jabsco 'smart' pumps. They are now called VFlo but there was another name for them at one time. There seems to be a pwm speed controller built in which varies pump speed according to demand. 

 

 

 

 

[magnetman]

double post

Possibly a Jabsco Ultramax. 

Edited September 26, 2023 by magnetman

[TandC]

Okay aside from the off-topic replies about having a spare pump in a box somewhere, which wasn't really the question asked, although is good advice - in general, it sounds like an unnecessary consideration!    

[nbfiresprite]

I do have two ParMax4 pumps installed more than 20 years ago, set up so that should first pump fail, simple turning two valves and flicking a switch to bring in the backup pump. Allowing the failed pump to be replaced when you have time to do it. With a single pump and maybe a spare in a box. As according to Murphy's law, the pump will fail when your covered in soap while in the shower.

Edited September 26, 2023 by nbfiresprite

[MtB]

7 hours ago, frahkn said:

Most long Orions and some Hudsons use this system though.

 

My Orion tug has a properly bog standard single pump system pumping both hot and cold, even though Richard was a horror for doing things differently and unnecessarily complicatedly. 

 

Works perfectly well just like all single pump systems. He must have been in one of his sensible periods. 

 

 

 

[frahkn]

1 hour ago, TandC said:

Okay aside from the off-topic replies about having a spare pump in a box somewhere, which wasn't really the question asked, although is good advice - in general, it sounds like an unnecessary consideration!    

Yes, I have no idea why it was done this way and I cannot see the advantage of my system.