What tube to use on under berth heating?

[FullCircle]

I am going to fit under berth heating fed from the engine, on its way to the calorifier. I think a good flexible hose rather than a rigid copper pipe system, as I think copper would give me a bad back.
Could you siggest the right bore and material?
Will I need to insulate the locker tops?
The engine is a Yanmar 3YM30 and is very efficient.

If its a success, I will route it to the aft cabin double berth too.

 

[Cliveshep]

Can I suggest Hep2O? You would probably want to use the 22mm size to get any useful heating area and minimise friction pressure losses as your pipework will inevitably be a whole lot longer than the short runs to a calorifier and you've only got the engine's circulating pump to push it around. Being plastic it's easily cut with a hacksaw, uses push-fit fittings, and has fittings available to connect to hose or BSP standard threads. You can buy it pretty much anywhere, Plumber's merchants, Wickes, B & Q etc. It's a plastic that will bend with a bender to avoid elbows which cause friction losses and it is rated for CH systems.

However, are you absolutely sure you really have enough waste heat to spare for heating without your diesel engine running too cold? I suggest you do some sums to check out your required heating area for the volume of the space you want to heat first. I haven't dabbled in heating for years but I seem to remember that the volume of the space in cu feet x a factor of (probably 4.5 for a boat) gives you the required btu/hr to heat the space. That probably represents quite a large heating area, so either miles of pipe or use caravan type fin rads. I still question if you have enough circulating pump output and spare heat energy to do the job. Why not fit an Eberspacher instead, they are super efficient? Sorry about imperial units - I'm an Ol' Fa$t they say!

 

[pvb]

Actually, copper would be the best choice if you have a bad back - copper is a proven remedy for sufferers of arthritis. It's also good for alzheimers, although sufferers often don't remember the improvements.

 

[Spuddy]

I'm a right bore....at least, I was teaching fractions this pm and was told it was boring. OFSTED want to get rid of boring teachers but there's the textbook I'm supposed to use - what should I do ? Role play, put it on ice ? It's blinkin fractions ; they're boring and no use to anyone unless you want a complicated way of dividing up a pizza. Back to your tubes : I went to see the Lost and Found Orchestra - I reckon they would fit a mouthpiece to one end, a traffic cone to the other so you could get a tune out of it. The blowing would warm you up.

 

[Csail]

Google Nu-heat for ideas.

 

[Graham_Wright]

Flexible hot water tube from ECS (red)?

No fiddly joints and if you want more area/less friction, run two or more in parallel. It's very cheap.

 

[steve28]

I dont know if anyone else has found this but my yanmar 2gm20 does such a good job in the heat exchanger that the water never gets really hot enough to heat the calorifier unless the engine is used for at least an hour.
because of this i added a hydronic i had which obviously gave the water in mins.
The point is, are you going to get any heat to allow it all to make any diffrence.

steve

 

[winfarthing]

I haven't given too much thought to this idea so it may get knocked down in flames. I would also worry about the effect on the engine cooling circuit and pump. How about taking water from the calorifier instead? A suitable sized circulating pump could deliver it around your proposed heating circuit and back the calorifier. This way, the engine is not affected and you can even switch the pump off when you don't want it.

 

[saltwater_gypsy]

If you are only going to use it when the engine is running( which is implied by putting the tubes in the calorifier feed) you might as well get an electric blanket and run it off an inverter. Electric blankets are typically 60 to 100Watts so its not a big deal.

 

[cormorant]

I don't think you will get much benefit from this really. I have a big diesel heater and rads, copper pipe above and speedfit below the bunks, cupboards, etc. I do get some heat in the lockers from the speedfit pipes but not a fantastic amount.
I have found that a duvet under as well as over works the best.

 

[Graham_Wright]

Naively;- are not engine cooling systems fitted with thermostats?

A car engine certainly generates sufficient heat to make the interior uncomfortably hot.

 

[Refueler]

I believe you can get 12v blankets ? But that was my thought - a low wattage 240v job on an inverter ? I think the single I have is about 60w.
(tip - double electric blankets - budget ones are too small and also poor for each side setting. So better buy 2 single budget jobs and put side by side !)