I was wondering, after reading the thread about hot water systems, what pressure those systems supposed to work at?
The foot pump is very low pressure - obviously - not sufficient to run a shower.
Are all the pressurized systems similar in pressure (?25-50psi?), or they vary wildly? 
Isn't the pressure set by the company that makes the pump?. I know you can get different volumes in GPH. I would think the pressure
settings would be very similar.
Water pressure is related to elevation. Higher flow pumps are lack of decent pressure.
read the spec for particular pump.
example of domestic standart in qld
pressure and flow standards in QLD
Our standard of pressure is a minimum of 210kPa (kilopascals) at the boundary of your property. This means that in the event of a pipe burst, water would shoot up about 21 meters. In trickle feed areas and services with private pressure booster pumps the minimum pressure is 100kPa.Our standard of flow is a minimum flow rate of 25 litres per minute in urban areas and 3.2 litres per minute in trickle feed areas. In urban areas, you can test the flow rate by using a 5 litre bucket and a stop watch at an outside tap on the front of your property; the bucket should fill in 12 seconds.
Ok, l meant yachts, and l was wondering about the systems on yachts.
This particular one has a 1/2 inch hard-hose system, (black non bendable half inch hose fitted to the yacht while from the tank to the pump 1/2 inch soft hose) galley, bathroom, shower, non electric hot water system. Run engine for hot water or it is all cold.
Could one fit a 9 litre/min pump with 50psi pressure instead of 25psi? The new pump comes with two possible pressure switches.
Having a 25psi pump removed, would the new one with a 50 psi pressure switch blow the system to kingdom come or not. According to my limited physics knowledge - l might be totally wrong - the pressure at the tap or shower head would quadruple.
Would a system handle this pressure or not?
The foot pump - on the picture - has been disconnected. The water runs from the soft hose into the hard black hose without any apparent problem.
Could l run higher pressure - up from 25 to 50 psi - without damage?
I am sure if you have plumbed up correctly and securely clamped the hoses, the hose you have there will handle the pressure.
The thing to think about with pressurised water systems is that if it is left on and a joint develops a leak or blows off, the pump will dump all your fresh water to bilge.
I adhere to the KISS principle and do not have a pressurised water system. The right foot pumps will do the job just as well and leave both hands free.
If you have a hot water system that runs off waste heat from the engine, consider that the water can be up to 80 degrees in temperature. That means you need to look at the operating temperature ranges of the pumps and hoses you are using.
With the right ingredients you can have your cake and eat it.
Low pressure plumbing, boats or caravans don't like anything over 30psi. My guess is you pushing your luck going
as high as 50, if your system is standard low pressure, better stick with that.
Select to expand quoteCharriot said..
Low pressure plumbing, boats or caravans don't like anything over 30psi. My guess is you pushing your luck going
as high as 50, if your system is standard low pressure, better stick with that.
I'm with Charriot. I have a 15psi or thereabouts pump which does tend to blow the hose off the hot water heat exchanger when it is hot and the hose a bit soft. It happened last year and Havefun was cleaning the bilge out while I was trying to tell him to turn the pump off first.
I have a switch for my pump at the galley, it gets turned off when before the tap so there is no pressure left in the hose. I have 3 tanks (2 105litre and one 80 litre) so will only ever lose the tanks worth. That is unlikely because the pump is loud enough to hear and the auto bilge pump comes on at about the 20 litre mark telling you you have a problem.
............and here i was thinking water pressure on yachts hase something to do with their displacement. Doh!
Select to expand quotecisco said..
I am sure if you have plumbed up correctly and securely clamped the hoses, the hose you have there will handle the pressure.
The thing to think about with pressurised water systems is that if it is left on and a joint develops a leak or blows off, the pump will dump all your fresh water to bilge.
I adhere to the KISS principle and do not have a pressurised water system. The right foot pumps will do the job just as well and leave both hands free.
If you have a hot water system that runs off waste heat from the engine, consider that the water can be up to 80 degrees in temperature. That means you need to look at the operating temperature ranges of the pumps and hoses you are using.
With the right ingredients you can have your cake and eat it.
I work on the ktwh (keep the wife happy) principal and have a pressurised, hot water system. The system heats of the engine, and yes it can run very hot. You need to be careful as the water is hot enough to burn.
Cisco, out of interest, what are you doing in the shower that needs both hands kept free.................
50 psi...that should be the shut off head? (shutoff head is the maximum pressure a pump can deliver which occurs when the discharge is shut off).
as long as the pump doesn't run while all valves are closed i don't think you would ever get 50 psi in your system. it would depend on how the pump was controlled as to how long it would run after you close taps / valves. However if the pump runs at shutoff head for a long time you might not wreck your pipework but you will wreck you pump.
If your running a higher pressure pump than you need your are wasting a lot of energy though. I dont think you need 50 psi/35m head in a yacht where the elevation difference might only be 2-3 m at absolute maximum.
Perhaps try looking for a higher flow rate pump it sounds like you dont need more pressure but higher flow rate
It is not a wife thing, l solved that problem years ago ('libera nos a malo'!), this system came with the yacht.
The old pump chucked it in, it got replaced with the one on the pic, same pressure 25 psi. l think it is what you call head pressure.
It works fine - though, it blew the foot pump, which l disconnected. The foot pump needs a direct connection to the tank, instead of running the pressure thorough it. l seldom leave the system pressurized.
I was just wondering what pressure those systems working at.
Larger flow rate would empty my small tanks too soon but l could do with a bit more flow at the shower head.
The hot water gets pretty hot after running the engine for hours.
Thanks for your inputs!
Select to expand quoteLMY said..
Cisco, out of interest, what are you doing in the shower that needs both hands kept free.................
Cupping cute bum cheeks. 
