On 07/05/2019 20:26, John Rumm wrote:
On 07/05/2019 20:14, charles wrote:
In article ,
Â*Â*Â* John Rumm wrote:
On 07/05/2019 17:11, charles wrote:
In article , ss
wrote:
On 07/05/2019 16:06, John Rumm wrote:
Remember that if its an upstairs rad, then the pressure at the RAD
could easily be half a bar (i.e. 15' of head) lower than that seen at
the boiler. Many boilers will work down to 0.5 bar, which could
equate
to no nett pressure at all on the first floor.

That could be it, the rad in question was on 1st floor.

surely on a sealed system, the pressure will be the same throughout the
system.

If the pressure gauge is low down in the system it will "see" the weight
of all the water in the system above it added to whatever pressure you
have as a result of the compression of the gas in the expansion vessel.

1 bar is ~30' of water.

32ft when I was at university, but so much has changed in the intervening
57 years, that has probably, too.

:-)

Yup that's inflation for you, I think the accurate conversion is 33.46'
now, but I was allowing for some wiggle room with my "~"



Although this is a bit academic, it might be of general interest to
someone. The International Standard Atmosphere defines sea level
pressure as 1013.25 hPa; in the bottom part of the atmosphere, this
decreases by approximately 1 hPa every 30 feet. The real-world sea-level
pressure varies daily between (very roughly) min and max of 980 and 1040
hPa, so that's between about 32.8 and 34.8 feet of water.
Here endeth the lesson ;-)