Can somebody explain boiler water connections to me. The one I have (Grant)
has a low level inlet (the return) and a high level heated outlet.

I would have thought it more efficient to run the cooler water into the
higher level of the boiler near the flue to remove as much heat from the
flue gas before continuing to the much hotter air near the burner at the
bottom.

Not proposing to change the connections - just wondering why.

"G&M" wrote in message
...
Can somebody explain boiler water connections to me. The one I have (Grant)
has a low level inlet (the return) and a high level heated outlet.

I would have thought it more efficient to run the cooler water into the
higher level of the boiler near the flue to remove as much heat from the
flue gas before continuing to the much hotter air near the burner at the
bottom.

Not proposing to change the connections - just wondering why.

When water is heated it expands, and therefore has a lower density/specific
gravity, and so rises.

In a gravity/ natural circulation system this factor alone is used to circulate
water round the system.

i.e. hot water from the top of the boiler is piped to the top of the H/W tank
coil (or radiators) were it cools, contracts and circulates back from the bottom
of the H/W tank to the bottom of the boiler.

If you connect the boiler the wrong way round you would likely be using a pump
to overcome the natural force of nature.


Michael Chare

"Michael Chare" wrote in message
...
"G&M" wrote in message
...
When water is heated it expands, and therefore has a lower
density/specific
gravity, and so rises.


i.e. hot water from the top of the boiler is piped to the top of the H/W
tank
coil (or radiators) were it cools, contracts and circulates back from the
bottom
of the H/W tank to the bottom of the boiler.

If you connect the boiler the wrong way round you would likely be using a
pump
to overcome the natural force of nature.

True - but pumps are quite effective. Just thought it would be possible to
extract more energy from the flue gas.

"G&M" wrote in message
...

"Michael Chare" wrote in message
...
"G&M" wrote in message
...
When water is heated it expands, and therefore has a lower
density/specific
gravity, and so rises.


i.e. hot water from the top of the boiler is piped to the top of the H/W
tank
coil (or radiators) were it cools, contracts and circulates back from
the
bottom
of the H/W tank to the bottom of the boiler.

If you connect the boiler the wrong way round you would likely be using
a
pump
to overcome the natural force of nature.

True - but pumps are quite effective. Just thought it would be possible
to
extract more energy from the flue gas.

Extracting more energy from the flue gas isn't the issue in conventional
(non-condensing) boilers: _not_ extracting too much (and causing
condensation with resultant acid rain inside the boiler) is the trick.
Modern boilers tend to have connections at the same level anyway: only the
real dinosaurs intended to be able to work with gravity circulation (even if
they'd be used with pumps in some installations) had top and bottom
connections.