Domestic Water Pipework - what to use

sbrockman

sbrockman

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I'm going to fit a calorifier and a pressurised hot and cold water system to my Nic 32. I'm assuming I have 2 choices re pipework, flexible hose and jubilee clips or plastic pipe and hep20 fittings (or similar).

Are there any advantages/disadvantages of one system over the other?
 
I have just installed two wet heating & calorifier systems on my catamaran. I used 22mm JG plastic pipe and 22mm rubber hose with quick fasten circlips. I have clips, hose and heat exchangers (lightweight radiators) left over. I have PM'd you with my tel number, call if you can use any of these or just want advice. Dave
 
I've fitted a three complete systems over the years, the first mostly copper with flexible pipe where necessary, the second with wholly flexible (blue and red water pipe caravan type) and finally the current a combination of plastic flexible and Hep2O. The Hep2O is more troublesome to get the fittings to seal down properly on the calorifier (domestic side only) but otherwise no working difference. I've only used 15mm because frankly unless you've got a massive pump I doubt you'll need anything larger. The first calorifier had an expensive expansion chamber fitted, the last has a pressure relief valve, which is cheaper and just as effective.

With engine water heating pipes I use rubber heater hose with the advantage that you can put a loop in it to prevent the heat thermo-syphoning out and keeping the engine warm but allowing the calorifier temperature to drop off overnight.

Having a low point in the domestic side of the system with a drain cock to the bilge aids draining out in winter, although on the last boat I fitted a "Tee" via a "ball-o-fix" valve to a through hull fitting (tank connector actually) so I could turn on the ball-o-fix and let it drain overside.

The tank on that one was high up in the bows, on the present one it lies along the keel so I don't have that option. Do use stainless steel hoseclips though, the Halfords type corrode too easily.
 
Choice is down to personal preferences with lots of pros & antis for each that you suggest and indeed a mixture of both but, one piece of advice I will give is to make sure that any "quickfits" aren't so near to a bulkhead hole through which the pipe passes that they can be undone by movement under way triggering the release tabs. Keep all unions at least 75mm fom bulkheads.

My personal preference, after over 30 years experience on many boats is to use the red and blue Whale piping with the dedicated connectors.

Steve Cronin
 
EH?

This business about "heat syphoning back to the engine" is, with respect, a load of tosh. Look at the volumes involved. The heat contained in the contents of a few feet od 15mm pipe ins insignificant. AND, it's out in the relatively cool air outside the engine bay (probaby under a bunk). Much better to have a rectangular calorifier in the free space ABOVE the engine where the hot water will rise, when at rest and keep the calorifier hotter longer.

Steve Cronin
 
Re: EH? Steve Cronin

No it bl**dy well isn't a load of "tosh"! I had an Elysian 27 and it used to do just that, the engine was mildly warm next morning, the water was cold, we hadn't used hot water since switching off and spent ages wondering where the heat had gone to from an insulated calorifier. Guessing the problem finally, I looped the engine water hose which stopped it. BTW - I should have known better when installing, I was a heating engineer after all!!
 
Think thermal capacities

Which is more likely to keep warm a big lump of cast iron with a water jacket all around it or a scarcely insulated tube a few centimetres across and 80 or so wide.

I repeat, the best place for a calorifier in above the engine where it will have the 9marginally) hotter water rising into it as well as being served by the residual heat of the engine - the vastly more significant factor. If your calorifier needs to stay under a bunk, then I would suggest that filling the void around it with some insulation would have a major effect on heat conservation (of the vastly larger than the coil's capacity) in the body of the calorifier. To suggest that the thermo-syphon effect of only the cooler water at the bottom of the engine block through the coil after the engine has been stopped a while is absurd. For a long time after stopping, there is nothing other than hot water available from the block. That is why your engine still feels warm in the morning. The calorifier NEVER starts at the same temperature as the engine so it is small wonder that it gets cooler first.

Steve cronin
 
I fitted a hot water system to my Moody 27, albeit very much under the instructions of the Webesto agent who certainly knew what he was on about (Toby ?, based in Poole).

His requirement was that I buy the flexible plastic domestic water piping, which incidentally will take the full heat of domestic hot water. This is perfectly adequate for boats. The only thing I got a bit wrong was that the pipe is far more flexible than I realised and I used too may angle connections.

You can get all the bits from B&Q for very little when compared with the red and black marine piping. An added bonus is that it will come apart easily should you need to change pipe runs, or replace /add anything new.
 
If you use the modern "plastic plumbing pipe" (polythene) buy a quantiy of the stainless inserts, but use conventional brass 15mm compression fittings. When tightened, onto the end fitted with insert,the olive bites slightly into the plastic forming a 100% watertight joint. Have had problems in the past with Hep2o fittings which sometimes leak under low pressure
 
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