Hi Gary
On (21 Jan 98) Gary Collier wrote to Mike Ross...
 GC> I don't know eneough about how those systems work, to really
 GC> respond...but I thought those were High pressure boiler systems.
Convection works OK regardless of pressure. The main requirement is to
exclude air from the water paths.
Most convection ["thermo siphon"] heating of buildings works on the principle
that hot water from the boiler [usually in the basement] rises, due to the
higher density of the cold water descending from the [eg upstairs] heaters.
But if a radiator had air in it, then the rising hot water would be resisted
by air pressure- and stall. Result, a cold radiator. You will see that the
radiators have bleed- off plugs, to release the air. Like bleeding the air 
from
auto hydraulic brakes.
If the system had a pump then water could be circulated in spite of the
trapped air. The air is still a problem though, because it allows accelerated
corrosion of the metalwork especially! in the boiler.
I do
 GC> not want to have that high of a pressure cooker next to my house.
In this tropical paradise, very few home are boiler heated. But I suspect 
hat
the legal, insurance and bureaucratic complications of using a pressure 
essel
in a home [regular Inspection and Certification] would result in these
"pressure cookers" being very rare indeed!
Cheers...........ALEC
... ........When I contemplate the moon, my head aches [Galileo]
--- PPoint 1.92
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