Gravity fed radiator

[ditchcrawler]

2 hours ago, Tracy D'arth said:

Likewise, now just wiser. I predate mechanised pipe machines, used to thread 2" conduit by hand on a pipe vise. Can't even pick it up now.

 

I have been seen walking the streets of Gt Yarmouth with a bundle on my shoulder.

[ditchcrawler]

2 hours ago, Ronaldo47 said:

  home-made bending block of the type that that old books described as being used by builders for bending pipes in the days when proper pipe benders were expensive. Just a hole somewhat  bigger than the pipe, drilled  through a piece of fairly thick  timber. You secure the wood to something immovable,  thread the pipe through the hole, leaving enough out to get a good leverage, and press down firmly. The pipe will bend slightly where it emerges. Pull out the pipe a bit more and repeat. Or perhaps it was push the bent bit through the hole and repeat, it was a long time ago when I last did it. I managed to make enough gentle  step-wise bends with some slight crippling of the pipes  that was sufficient for my needs and I did use a blow lamp first to soften the pipe at the bend location. The pipes were at the back of a built-in cupboard so appearance was unimportant.  

 

 

 

Use to use them for steel conduit as well, not fixed but stood on end, hole at the top leaning straight away from you and bearing down on the pipe. If it was a big job we took the benders and vice

 

[John Lewis]

5 hours ago, Tracy D'arth said:

How far from boiler to rad? If its less than 4m to 5m then 15mm will be fine if it is installed well. If not, then 22mm for the straight run on the flow and return with 15mm on the verticals to the boiler. If 15mm try to avoid any soldered bends, its easy to bend with a spring.

Can you guarantee that the flow from the boiler is rising all the way to the highest point even when the trim of the boat changes? And the return rises all the way back to the boiler so it vents

Can you join the header tank feed to the absolute highest point? 15mm will be fine for the feed/vent.

Use a bending spring wherever possible. Slow copper bends otherwise.

Plastic pipe is out unless you fasten it on top of a continuous batten to avoid sags and crests which will make venting air impossible.

Flow into top of rad, return opposite bottom is best for flow and heat output.

 

Anything else, just ask.

Nice one Tracy, 

I was looking at left over 15mm and was tempted to use that, as going to get more 22mm is an ordeal.

So if I could get away with 15mm that would be ideal - as I say it is for just a sole radiator..

 

I actually have a spring already.

 

Its about 4m down the boat to where Im gonna place the rad - 1M wide by 330mm high.

 

So the rad should be mounted up a bit you're saying.. so the return flows back down is that right?

 

running it along the floor won't do?

Edited October 27, 2021 by John Lewis

[Quattrodave]

5 hours ago, BEngo said:

You only need to get it very hot with a big gas blowlamp.  You can cool it in water if you are in a rush, or just wait.

 

The process of annealing alters the material molecular structure, when you heat the metal the molecules rapidly vibrate and the structure becomes more random.  This randomness is what you want to 'fix' into the metal to make it more maluable.  You 'fix' it by cooling quickly / quenching...

 

At least that's how it was explained to me many years ago... 

Edited October 27, 2021 by Quattrodave

[Tracy D'arth]

28 minutes ago, John Lewis said:

Nice one Tracy, 

I was looking at left over 15mm and was tempted to use that, as going to get more 22mm is an ordeal.

So if I could get away with 15mm that would be ideal - as I say it is for just a sole radiator..

 

I actually have a spring already.

 

Its about 4m down the boat to where Im gonna place the rad - 1M wide by 330mm high.

 

So the rad should be mounted up a bit you're saying.. so the return flows back down is that right?

 

running it along the floor won't do?

The return will be fine on the floor   providing   you can be sure that it will vent at one end or the other. Rising up again to the boiler is OK. Rads too near to the floor will not circulate the hot air properly, allow some space up from the floor.

[BEngo]

1 hour ago, Quattrodave said:

 

The process of annealing alters the material molecular structure, when you heat the metal the molecules rapidly vibrate and the structure becomes more random.  This randomness is what you want to 'fix' into the metal to make it more maluable.  You 'fix' it by cooling quickly / quenching...

 

At least that's how it was explained to me many years ago... 

Sort of true for hardening  steel where there are various solutions of carbon and iron in play.   Cooling hardenable steel rapidly from red heat fixes a particularly hard combination of iron and carbon.

 

Not the case for softening steel, where you heat it up and cool it as slowly as possible  so it gets chance to settle in the least hard configuration.  Nor for  copper, which work hardens because the grains get distorted when it is bent and dont want to move over and round  each other.  When you heat it up the grains reform in a shape  more amenable to movement, so you can bend it (and incidentally harden it up again).  Once they have grown out the internal stress the grains  don't care if they are cooled rapidly as no shape change happens.

 

N

[LEO]

Hi,

Interesting post, I think the problem will be the fire will produce too much hot water and one radiator will be insufficient to off load it it - I run a Kabola OD4 and this runs for days quite happily, it produces hot water for  the calorifier, One rad, and the large expansion tank acts a radiator in the engine room. All the water heats to about 80/85C, and the fire has a hot water, oil 'shut off' valve which operates at 90C, not sure if your Refleks has such as valve, so the water may just boil. It works mainly on a gravity circulation system, but has a pumped bypass circuit which operates automatically.

 

Sometimes the fire shuts down if the water gets too hot, this is running the fire on it's lowest setting and the circuit has swept bends.

 

Hope this helps

[Boatingbiker]

21 hours ago, Tony Brooks said:

 

Yes, pipe fittings, because I know that without a pipe bender it needs skill to bend 22 mm pipe through 90 degrees, let alone 28mm.

Ideally you would make the bends yourself so you cam make them even larger than fittings allow but for most  it is simply not practical.

 

 

 

 

Basically, the frictional losses of an elbow is greater than a 90 degree bend which in turn is greater than a pulled large radius bend. For gravity systems to work the resistance of all fittings and the pipework need to be the lowest possible. Pipes need to be installed with a good rise to highest point ideally the radiator to promote flow.

 

However, we had a boat with a reflect stove as shown, which used 15mm pipework and a circulation pump. Once the pump was stopped the stove would lockout on high temperature. The stove would then need to let cool down over a couple of hours before being relit.

 

[John Lewis]

20 minutes ago, Boatingbiker said:

Basically, the frictional losses of an elbow is greater than a 90 degree bend which in turn is greater than a pulled large radius bend. For gravity systems to work the resistance of all fittings and the pipework need to be the lowest possible. Pipes need to be installed with a good rise to highest point ideally the radiator to promote flow.

 

However, we had a boat with a reflect stove as shown, which used 15mm pipework and a circulation pump. Once the pump was stopped the stove would lockout on high temperature. The stove would then need to let cool down over a couple of hours before being relit.

 

I guess I'll just have to suck it and see.

 

I don't run the reflex's full whack, but medium, then turn it down, so hopefully won't boil..

 

How do you fill the system by the way?

[Tracy D'arth]

6 minutes ago, John Lewis said:

I guess I'll just have to suck it and see.

 

I don't run the reflex's full whack, but medium, then turn it down, so hopefully won't boil..

 

How do you fill the system by the way?

By the header tank and bleed all the air from the highest point bleed fitting if that is not the header tank.  Premix antifreeze and water before filling, never pour neat conc antifreeze in, it does not mix and stops circulation.

Edited October 28, 2021 by Tracy D'arth

[Ronaldo47]

51 minutes ago, Boatingbiker said:

Basically, the frictional losses of an elbow is greater than a 90 degree bend which in turn is greater than a pulled large radius bend. For gravity systems to work the resistance of all fittings and the pipework need to be the lowest possible. Pipes need to be installed with a good rise to highest point ideally the radiator to promote flow.

 

However, we had a boat with a reflect stove as shown, which used 15mm pipework and a circulation pump. Once the pump was stopped the stove would lockout on high temperature. The stove would then need to let cool down over a couple of hours before being relit.

 

Shouldn't 'greater' be 'less'? 

Edited October 28, 2021 by Ronaldo47

[John Lewis]

If its one rad, would it be best to enter from the top furthest away then cool, and return on the lower front side?

[Tracy D'arth]

16 minutes ago, John Lewis said:

If its one rad, would it be best to enter from the top furthest away then cool, and return on the lower front side?

If you wish, makes no difference to heat output.

[agg221]

You mention you have offcuts of 15mm copper pipe and a bender. I think I would be inclined to try and bend up the whole section from the Refleks to the upper pipe in one by inserting the bender from each end in turn, so first make the swept bend from the stove to the cladding (a little less than 90degrees if you want to follow the profile) and then insert the bender from the other end to make the curve round to the upper pipe. You then have swept curves, less soldering, fewer opportunities for leaks and a better overall fit. If you have several pieces to play with then you can afford to get it wrong at least once. Between this section and the straight pipe is a sensible location for a compression fitting including a bleed screw, joining on to the long run of pipe. If you do increase diameter at this point then a suitable fitting can be used and the whole lot is visible rather than buried so you can keep an eye on it and be sure it isn't weeping.

 

Alec

 

p.s. you may already know this but if not, it is much easier to make the bends with the ends slightly over length and then cut them off to fit, rather than trying to put a bend close to the pipe end, It also allows you trim to actual fit, rather than hoping it works out!

Edited October 28, 2021 by agg221

[BEngo]

1 hour ago, John Lewis said:

If its one rad, would it be best to enter from the top furthest away then cool, and return on the lower front side?

As Tracy says, but  keep the entry and exit at opposite ends.  This gives the most even flow through the rad ( so it all gets hot) and the greatest heat output.

 

Your diagram shows the return rising to the Reflecks.  Try to avoid this, raising the rad if needed and practicable.

 

Don't forget the header tank needs a feed to the return pipe and a vent,   at the top of the header, connected to the flow pipe, or to the spare top tapping in the radiator.  Otherwise  if the system accidentally boils, the header tank will emit lots of boiling water and steam.

N