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Water Pipe Sizes?


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I've now got a 22mm stop tap exiting my main water tank...would it make any difference to continue around the boat with a 22mm main circuit, and then tee off from that to taps, etc., in 15mm? Or would it be best to get the stop-tap down to 15mm and go from there?

Any thoughts/rationales for or against either option?

Many thanks for your help,

Stuart

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22mm will give less resistance to water flow, so pump will be able to produce more water faster at the taps.

 

From calorifier to hot taps, 15mm might be better, as it holds less than half the water volumne of 22mm, so less hot water is wasted.

 

22mm costs more.

 

(As a quick smiley_offtopic.gif diversion, our current abode once had a Baxi fire with back boiler, which heated a tank in the roof space. Snag was the distance from tank to the taps, To overcome the lack of flow, the pipe size was 11/4". Problem with that was that by the time hot water came out of the tap, most of the tank contents seemed to be in the pipes, so we had to run off all the hot water we needed in one go. No matter how little or much we used, we'd apparently used the entire tank full.

 

Iain

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I've now got a 22mm stop tap exiting my main water tank...would it make any difference to continue around the boat with a 22mm main circuit, and then tee off from that to taps, etc., in 15mm? Or would it be best to get the stop-tap down to 15mm and go from there?

Any thoughts/rationales for or against either option?

Many thanks for your help,

Stuart

Where does the water pump fit in this set up?

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Where does the water pump fit in this set up?

My first choice is under the galley sink so, basically, a 25ft run down the portside from our bow-tank to 1 cold tap, then on a further 19ft to 1 cold tap and a shower. After this the cold supply will cross the boat under the engine room floor to then track down the starboard side 12ft (inc 6ft crossing over) to a washing machine, before travelling a further 3ft to the calorifier! Of course, the hot water then makes the return journey to the final hot tap in the galley, a total 34ft of hot water piping!

59ft cold pipe (4 outlets, plus calorifier feed)

34ft hot pipe (3 outlets [maybe 4...still haven't thought the washing machine through properly, yet?])

I was thinking/hoping a 24v Jabsco Par Max 4 would cope?

I know the run's not pretty, there was just no other place to put a calorifier, given we'll eventually be installing a Heritage Stove for a hot water feed!

 

Anyone know what 34ft of 15mm pipe holds? I was wondering how much cold water I'd have to pull off at the galley sink before the hot arrives?

 

Would the Jabsco handle my set-up, I know the litres per minute is phenomenal?

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Ours is all 15mm with a pump in the galley probably 15ft from the water tank with a full flow ball valve on the tank outlet. From the pump one line goes under the floor to the other side of the boat to the sink, another carries on back to the calorifier, loo, shower, wash basin, engine room sink. Hot water from the calorifier also goes to all these outlets except the loo. All 15mm Hep2O pipe.

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Just found an online calculator for pipe volume! I am surprised to learn that 34ft of 15mm pipe only holds 1.8 ltrs...I thought it would be much more than that!

Ours is all 15mm with a pump in the galley probably 15ft from the water tank with a full flow ball valve on the tank outlet. From the pump one line goes under the floor to the other side of the boat to the sink, another carries on back to the calorifier, loo, shower, wash basin, engine room sink. Hot water from the calorifier also goes to all these outlets except the loo. All 15mm Hep2O pipe.

Many thanks, DC, I'll likely go with 15mm myself now!
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There will be bugger all improvement in performance from using 22mm pipe.

 

The only advantage I can think of is 22mm pipe will freeze solid slower than 15mm. A LOT slower.

 

Not that this helps much as the frost will still kill your water pump and shower mixer as quickly as ever... :-/

 

 

MtB


P.S. although the Morco (if you have one) will be the first to burst!

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There will be bugger all improvement in performance from using 22mm pipe.

 

The only advantage I can think of is 22mm pipe will freeze solid slower than 15mm. A LOT slower.

 

Not that this helps much as the frost will still kill your water pump and shower mixer as quickly as ever... :-/

 

 

MtB

 

P.S. although the Morco (if you have one) will be the first to burst!

Thanks, MtB...that's a done deal, then, definitely the cheaper 15mm!
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Just found an online calculator for pipe volume! I am surprised to learn that 34ft of 15mm pipe only holds 1.8 ltrs...I thought it would be much more than that!

Many thanks, DC, I'll likely go with 15mm myself now!

Was that for copper, Hep2O has a thicker wall so less volume

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I cheated a bit and just used a 15mm calculation! If the internal diameter is considerably less than 15mm on Hep2o, then it's going to be hardly anything, surprisingly! Have you got an old piece for a measurement?

From the web the wall thickness is 1.85 so that would give a bore of 11.3 mm

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Our boat is plumbed with very early polypipe so its 1/2inch OD 3/8ths internal. Its great except its almost impossible to get fittings for. You can get 12mm OD from specialists but I've not managed to find 1/2inch. Does anyone know of a manufacturer or supplier?

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  • 1 year later...

Just to revisit this as I am about to plumb in the water system. I have used 22mm for central heating main pipes (15mm reducing T's to rads) and was planning on 15mm for domestic water hot and cold. The calorifier am looking at appears to have 22mm feed for the hot water. So back to the original part of this thread should I use 22m or 15mm for cold down the boat (40ft length of pipe) and ?same for hot water?

 

thanks

keith

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I'm going to watch this one with interest......when I was laying out the barge I spent weeks humming and harring over it.......in the end I cheated and put a hot tank at each end and used 22mm for the cold feed, 15mm for the hot feeds as they were then only 3 or 4 feet. It's worked fine unsure.png but I have often wondered what the correct decision would have been cheers.gif

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The current boat has a lot of stuff - including plumbing - rammed into really awkward spaces, copper was just too awkward, plastic not much easier so I used some sort of blue hose from ASAP supplies that was supposed to be ok for plumbing both hot and cold systems (not heating or rads) and it has been absolutely fine, also if it were to freeze I doubt if it would split, did the lot in a couple of days and not touched it since.

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