Expansion / Accumulator Tanks

[Bikertov]

Am I right in thinking that marine plumbing is not connected with copper pipework and fittings like domestic plumbing is ?

[Regulo]

Normal practice is blue and red flexible, or proprietary push fit plastic. Not sure what the correct name is. Copper fittings can be used, but it's not generally used for pipe runs. 

[BroadAmbition]

Sort of, some yes, some no.  I know you wanted a straight forward answer but at least I'm being honest.

Plastic speedfit plumbing is the way to go, no need for soldering therefore blow torches. Also much easier to go round curves / bends and the like.  Plastic is also more robust at resisting freezing.  However onboard 'B.A' I used copper from the calorifier and around the first metre or so away from the pump and engine area then switched over to plastic for the rest of the system.  Plumbing on boats really is simple

Hope this helps

Griff

[Vaughan]

Most older boats are plumbed in copper pipe, usually 15mm with compression fittings, not soldered joints.  They are easy for maintenance and access but do have the problem of starting to leak at the joints with engine vibration.  Nowadays I guess pretty well all boats are in plastic pipe, with simple screw fittings.  This has the tremendous advantage that it doesn't burst when it freezes, although severe icing can sometimes pop the joints off.

Just a point about the drawings of a water system : the Jabsco pump shown is of a diaphragm type with inlet and outlet valves, so it is also a non-return valve in itself.   Other types of rotary impulsion pump would need a non-return valve fitted, between the fresh water tank supply, and the pump.

[JanetAnne]

Mine are in soldered copper. It's flow rate is far superior to plastic giving the pump an easier and longer life. It stays exactly where I fix it with no sagging or rattling and is just a much neater job. Long runs and a pipe bender mean very few joints to worry about.

With a Webasto / Mikuni wet heating system all those plastic elbows slow the flow rate down considerably which can mean pulsing of the boiler. Look down the inside of a 15mm push fit 90 deg elbow and you'll see it's reduced to about 10mm. Imagine a dozen or more of them on a run.

Interestingly Webasto recommend a minimum ID of 22mm throughout the main loop. In plastic the fittings mean that my desired 22mm is closer to 16!

 

[Smoggy]

I used well lagged copper (with plastic pushfit elbows) for the longer straight runs on mine purely because it keeps water nicer if it's standing in it, copper is a natural bactericide, once into the twisty bits of the cabin/bog it's the regular red/blue plastic flexi stuff.

[Bikertov]

10 hours ago, BroadAmbition said:

Sort of, some yes, some no.  I know you wanted a straight forward answer but at least I'm being honest.

Plastic speedfit plumbing is the way to go ...

 

 

2 hours ago, JanetAnne said:

Mine are in soldered copper. It's flow rate is far superior to plastic ...

 

 

1 hour ago, Smoggy said:

I used well lagged copper (with plastic pushfit elbows) for the longer straight runs ...

Of course, ask simple a question, and get 3 different answers 

Thank you all for your differing views, and the reasoning behind them.

Being that I am still at the very start of my boating journey, it is all helping to understand "beneath the decks" as it were, so that when I am looking at a boat I can better judge it's condition and any benefits or potential issues - it is not just a case of whether it looks nice from the outside !

[Smoggy]

The best option pretty much boils down to the available space and how many twists and turns, there is rarely a single answer to fit all boats (probably never), everything on a boat is a compromise somewhere and no boat will do everything well.

[annv]

Hi Biker I use Hep2o plastic pipe sheathed in Armorflex this will stop any chafing where it touches the hull, and keep the heat or cold in, the advantage with plastic is that you can push it through in one length as it is flexible and will always rest against any bearers or where it touches you then dont get any rattles, it is easy to cut to length, i use the demountable twist fittings,  they are a little dearer then the push fit ones but if at a later date you need to disconnect them they can be undone by hand  rather then use the disconnect tool, i find if you wrap a piece of tape round the pipe at the distance that the pipe needs to enter into the fitting to make the correct fit you then will have a correct push fit,  they can be a little difficult to get right if not a plumber. John