Originally Posted by tk03
I believe you are confused. The amount of head has nothing to do with height. It is resistance to flow. Everything the water passes througth has a resistance to flow. See the resistance of the panels. It will be listed as ft head or psi drop.
Than add the piping and fittings and radiator.
By the way. If you are talking about a standard cast iron radiator and you are piping the same side you may loose about 20% output. If it is cast iron baseboard depending on the length you may lose upto 40% output.
As flow drops btu output drops unless as stated above you are way too fast. The rule within the limits of pipe size and amount of radiation is speed water up get more heat slow water down get less heat.
The rule for heat producers speed flow up get less heat and slow flow get more heat......Confused yet?
Head and resistance to flow (friction loss) are two different things.
Head is the vertical distance from opening to opening and is a constant when at rest with consideration to the medium, altitude, barometric pressure and temperature. Head does not change with configuration of the system. There is pressure head (at rest) and hydraulic head (in motion).
Friction loss is the increased resistance to a pressurized medium in motion due to non laminar flow within a system. A smaller vessel will have much more resistance than a larger vessel at the same operating pressure. There is no friction loss when the medium is at rest but there is still head pressure.
Friction loss is increased by things that cause non laminar flow like 90's, curve pipe, the diameter of the pipe, the surface of the interior of the pipe or anything else that disrupts flow.
More pressure will increase resistance and less pressure will decrease flow.
For years my life depended on friction loss. Not enough flow if water and I died. I appreciated the increase of water going from a a 1 1/2" attack line to a 1 3/4" attack line. Lots more water for little extra weight. The extra flow saved my life more times that I care to think about.
When a pump is rated for so many gpm's at a set height that is the ability to pump against gravity (or head).
My solar setup is over kill for anything that will put out more than a few GPM. It is all level. The highest point is 6 feet above the lowest level. It is all connected in a closed system.
This allows water that it going downward to decrease pressure on the upward side. Since my water is flowing at a very slow rate since it has to stay in the solar panels to heat up (I have them set up in a combination of series and parallel) I don't need speed in they system. Then when it is in the heat exchanger it has to move slowly to give off as much heat as it can. I have the differential set at 15 degrees since there is a declining heat transfer rate below that.
So moving heat in a fluid is different for different situations.
I don't think I am confused.