long piping after water tank before pump

[DanMax&Belle]

Hi All,

 

Any reason why I shouldn't have the fresh water pump (most probably a variable speed Jabsco or Johnson in my boat a good 18 meters from the fresh water tank?

 

The intention is to house it along with main Webasto unit, calorifier, expansion tank, fresh water piping through bulkhead and a tiny water heater plumbed into the main circuit away in the engine room where it can be well insulated from sound and cold in an insulted boxed off area of the engine room (the rest of the engine room is totally uninsulated).

 

I'm hoping to bring down noise and chance of frost damage to a minimum with this set-up but it requires that the pipes are run the length of the boat as my fresh water tank is under the bow deck. I've been advised that mounting the pump level with the top of the tank or higher and using a dip pipe to suck the water up with act as a "failsafe" meaning a leak on the inlet side would cause less of a problem.

 

Also FYI I'm using 22mm polly pipe.

 

Cheers

 

Dan

 

 

[bottle]

Pumps, pump, they do not suck very well.

 

I doubt your proposed set-up would work, it may work if the pump is below or level with the bottom of the tank and the take off is also at the bottom of the tank.

[Flyboy]

Most pumps have a limit to how much they can suck but are good at blowing.. .This could be the reason why this idea is not used?

[DanMax&Belle]

Pumps, pump, they do not suck very well.

 

I doubt your proposed set-up would work, it may work if the pump is below or level with the bottom of the tank and the take off is also at the bottom of the tank.

thanks - makes sense. My pump is not and the take off is also not....

Most pumps have a limit to how much they can suck but are good at blowing.. .This could be the reason why this idea is not used

Thanks FB glad I asked

 

Anyone think of anything that might help with this set-up, preposting I was very pleased with this idea!!

[Chalky]

Our pump is about 14' away from the tank. Works OK and has done for the last 8 years.

[system 4-50]

Mine sucks. Well within the pump's spec. Have the sucking pump close to the tank. My pump is close to the gunnel well above the tank. Did it to avoid the leak risk as you describe. Still have to wary of a leak causing siphoning in the design of your pipework,.

Edited February 11, 2015 by system 4-50

[bottle]

Our pump is about 14' away from the tank. Works OK and has done for the last 8 years.

 

but where is the tank take off

 

Mine sucks. Well within the pump's spec. Have the sucking pump close to the tank. My pump is close to the gunnel well above the tank.

 

All pumps will 'suck' within their specification but sucking up and along 18 metres I would suggest would not be possible.

 

The 18 metres would count as hight as well as the actual hight from the bottom of the tank.

[Detling]

A pump at gunnel level will freeze in winter and even if it is only a few drops left after draining can wreck the impeller if power is applied. A pump near the base plate at the bottom of the boat is far less likely to freeze as the base plate is unlikely to go below 5-6 degrees C, this is why most people have the pump low down and the pipe from tank to pump also low down. Boxing the pump in with insulation from the air but not the steel bottom has been good for me over several winters, I do drain down though but you will never get every drop out.

[blackrose]

Hi All,

 

Any reason why I shouldn't have the fresh water pump (most probably a variable speed Jabsco or Johnson in my boat a good 18 meters from the fresh water tank?

 

The intention is to house it along with main Webasto unit, calorifier, expansion tank, fresh water piping through bulkhead and a tiny water heater plumbed into the main circuit away in the engine room where it can be well insulated from sound and cold in an insulted boxed off area of the engine room (the rest of the engine room is totally uninsulated).

 

I'm hoping to bring down noise and chance of frost damage to a minimum with this set-up...

 

 

Firstly, insulation by itself (without a heat source) will not stop pipes, pumps, etc, from freezing. Thinking that it will is a common misconception. Everything tends towards equilibrium, including thermal energy gradients, so without a heat source eventually the temperature will be the same on both sides of the insulation. The same principal applies when people leave a small heat source on their boats when they're not onboard in winter to stop pipes from freezing, despite the boat being well insulated. The insulation won't keep the boat warm by itself.

 

The other thing is that the sound of the freshwater pump is something that most boaters use to check for leaks. If you can hear your pump cycling for no apparent reason you will investigate, but if you can't hear it you won't.

 

When they're not onboard (and unable to hear their freshwater pump), sensible boaters switch the pump off.

Edited February 11, 2015 by blackrose

[GUMPY]

So long as the pump is below the outlet it should work.

Pump on last boat was 14m from the tank and about 200mm below tank outlet.

Pump on this boat is 10m from the tank and about 100mm below tank outlet.

Both outlets are at the bottom of the tank so no lifting.

I tend to put calorifier and pump as close to the shower as I can saves running off water to get the shower hot, and somewhere I can hear the pump when its running.

[blackrose]

I tend to put calorifier and pump as close to the shower as I can saves running off water to get the shower hot...

 

Trouble is, unless all your freshwater outlets including the kitchen sink are in a similar location, then you will have to run off water to get it hot somewhere.

[GUMPY]

 

Trouble is, unless all your freshwater outlets including the kitchen sink are in a similar location, then you will have to run off water to get it hot somewhere.

Yes but shower needs to be hot when you use it, kitchen sink can have cold and hot mixed in the basin before you use it so much less waste.

[blackrose]

Yes but shower needs to be hot when you use it, kitchen sink can have cold and hot mixed in the basin before you use it so much less waste.

 

Yes that's true, but I don't always fill the kitchen sink with water. Sometimes I just want to quickly wash a few things or I just need a bit of hot water for something from the kitchen taps and then I have to wait, so either way water is wasted.

Edited February 11, 2015 by blackrose

[smileypete]

Can't guarantee 100.000%, but 22mm pipe and pump at baseplate level sounds reasonable, given the 18m distance and a pump of around 20lpm.

 

cheers, Pete.

~smpt~

[Richard T]

On our boat the water pump is under the double bed adjacent to the calorifier. The feed is by gravity from a tank under the front cockpit sole. The feed pipe is about 12m long. There is a stop cock at the tank outlet and another one near the pump. We have noe problems with this set up.

[Speedwell]

On our boat the water pump is under the double bed adjacent to the calorifier. The feed is by gravity from a tank under the front cockpit sole. The feed pipe is about 12m long. There is a stop cock at the tank outlet and another one near the pump. We have noe problems with this set up.

Ours is the same layout as this (apart from the bed location), also no trouble.

[Scholar Gypsy]

Given most boats slope downhill (ie with the bows higher than the stern) I don't think you will have a problem with the pipe run.

 

You may want to think about adding a drain point to the pipe between the stop cock (which should be as near to the tank as possible) and the pump, as close to the pump as is convenient.

 

Mine drains into a plastic pot in the bilges, which I then lift out and empty. Once I have run the pump for a few seconds with the stop cock closed, there is very little water left behind anyway....

 

[DanMax&Belle]

 

but where is the tank take off

 

 

All pumps will 'suck' within their specification but sucking up and along 18 metres I would suggest would not be possible.

 

The 18 metres would count as hight as well as the actual hight from the bottom of the tank.

The Pump I am planning on using is the Johnson Pump Flow Master 5.0 GPH Variable Flow Demand Pump 12V - http://www.sailsmarine.com/ItemDetail.aspx?c=81981&l=g&cc=GB#.VNyklOasWSo

 

Not sure what sucking ability it would have, i searched the specs and don't see any reference to it.

 

Dan

[DanMax&Belle]

Mine sucks. Well within the pump's spec. Have the sucking pump close to the tank. My pump is close to the gunnel well above the tank. Did it to avoid the leak risk as you describe. Still have to wary of a leak causing siphoning in the design of your pipework,.

I'm planning on getting the Johnson Pump Flow Master 5.0 GPH Variable Flow Demand Pump 12V

 

http://www.sailsmarine.com/ItemDetail.aspx?c=81981&l=g&cc=GB#.VNyklOasWSo

 

Any idea of what I am looking for spec-wise to tell me if it can suck? terminology etc?

[bottle]

Found it: PDF document page 10

 

Max.
Suction lift: 2.5 m/8.2 FT.

 

but also found this

Turn off
pressure: 3.45 bar/50 PSI

 

That is way to high for a 'standard' calorifier with a PRV of 3 bar (45 psi)

[DanMax&Belle]

A pump at gunnel level will freeze in winter and even if it is only a few drops left after draining can wreck the impeller if power is applied. A pump near the base plate at the bottom of the boat is far less likely to freeze as the base plate is unlikely to go below 5-6 degrees C, this is why most people have the pump low down and the pipe from tank to pump also low down. Boxing the pump in with insulation from the air but not the steel bottom has been good for me over several winters, I do drain down though but you will never get every drop out.

great does this include on the swim in the engine room?

 

The insulation will box in the Webasto, the Webasto piping, the hospital silencer, the calorifier all of which sit on the swim or bilge next to the engine mounting and emit heat. I live on the boat all year round so in the winter will be regularly turning on the engine for power or to warm the calorifier and the webasto will come on at least twice a day. This insulated housing should therefore hold onto the heat and hopefully prevent the piping, pump and expansion tank freezing. I will have a stat in here to monitor performance and the whole of the side of the insulation comes off for the summer.

 

Firstly, insulation by itself (without a heat source) will not stop pipes, pumps, etc, from freezing. Thinking that it will is a common misconception. Everything tends towards equilibrium, including thermal energy gradients, so without a heat source eventually the temperature will be the same on both sides of the insulation. The same principal applies when people leave a small heat source on their boats when they're not onboard in winter to stop pipes from freezing, despite the boat being well insulated. The insulation won't keep the boat warm by itself.

 

The other thing is that the sound of the freshwater pump is something that most boaters use to check for leaks. If you can hear your pump cycling for no apparent reason you will investigate, but if you can't hear it you won't.

 

When they're not onboard (and unable to hear their freshwater pump), sensible boaters switch the pump off.

thanks Blackrose.

 

I'm planning on plumbing in as small a heater as i can into the central heating system and this will sit within the insulation housing. Equally given the heat sources of hospital silencer, webasto and webasto piping are within and i am a liveaboard running all systems fairly regularly in the winter then i was thinking the insulation should hold heat (or let out cold slower) in this area as opposed to the zero insulated engine room.

 

Feedback on pump sound duly noted.

[DanMax&Belle]

So long as the pump is below the outlet it should work.

Pump on last boat was 14m from the tank and about 200mm below tank outlet.

Pump on this boat is 10m from the tank and about 100mm below tank outlet.

Both outlets are at the bottom of the tank so no lifting.

I tend to put calorifier and pump as close to the shower as I can saves running off water to get the shower hot, and somewhere I can hear the pump when its running.

Thanks Loddon,

 

Given Scholar Gypsy's genius insight after your comment, I have remembered that there is a serious slope in my boat running from bow to stern. I don't know what it is but I'd estimate at least 80 cm (difference in height between bow doors to floor and height between stern doors to floor).

 

However the outlet is definitely at the top and uses a dip stick style outlet - do you think this is a show stopper?

Can't guarantee 100.000%, but 22mm pipe and pump at baseplate level sounds reasonable, given the 18m distance and a pump of around 20lpm.

 

cheers, Pete.

~smpt~

thanks Pete,

 

as per Scholar Gypsy's comment I think something like a 80cm drop in the gradient from bow to stern may help my case even more. Pump specs above.

Given most boats slope downhill (ie with the bows higher than the stern) I don't think you will have a problem with the pipe run.

 

You may want to think about adding a drain point to the pipe between the stop cock (which should be as near to the tank as possible) and the pump, as close to the pump as is convenient.

 

Mine drains into a plastic pot in the bilges, which I then lift out and empty. Once I have run the pump for a few seconds with the stop cock closed, there is very little water left behind anyway....

 

I don't know what to Say Scholar Gypsy apart from i think my idea is still alive because of your thinking. I'm fairly sure I've a substantial gradient from bow to stern, i can easily put the pump at bilge level (although not what i initially intended).

[system 4-50]

Found it: PDF document page 10

 

Max.

Suction lift: 2.5 m/8.2 FT.

 

but also found this

Turn off

pressure: 3.45 bar/50 PSI

 

That is way to high for a 'standard' calorifier with a PRV of 3 bar (45 psi)

Yes. I have a pressure reduction valve thingy to protect my cauliflower (as advised by Jabsco). Note that this is a different beastie from a pressure relief valve.

[bottle]

Well that's OK then but there is still the problem of the 'suction lift'

 

From the bottom of the tank to the tack off may well only be a metre or so in hight but the additional 18 metres in length is to far.

 

Note that all those that have said that their pumps are a long way from the take off point say the take off's are at the bottom.

[smileypete]

However the outlet is definitely at the top and uses a dip stick style outlet - do you think this is a show stopper?

 

Far far better to have the output at the bottom, just about every other boat does that.

 

Any reason why it can't be that way?

 

cheers, Pete.

~smpt~

Edited February 12, 2015 by smileypete