I am writing about a Dettson HGRC-170 hot water boiler which is part of my
1) What is the proper operating water pressure for such a thing? Two
pressure relief valves on the system are 30 psi so I assume the proper
operating pressure should be somewhere lower...but not sure
where...Currently it around 8 psi but that doesn't seem right to me (the
upper floors are barely getting any water in the radiators furthest from the
2) What is the proper operating water temperature for such a thing? Mine
hovers around 100 degrees F. Does that sound right?
Theo. Assuming that the system you are describing is a forced hot water
heating system having a closed expansion tank (diaphragm or air), you will
want to have approximately 4 - 6 psi at the highest radiator. Easy way to
figure this out is to calculate the difference in elevation between the
pressure gauge on the boiler (measure in feet) and the highest radiator in
the system. Multiply this height difference by 0.434 and add 4-6 psi to this
number. For example, if your highest rad is 20 feet above the pressure
gauge, go 20 x 0.434 = 8.68 Add 4 psi to that, and your gauge should read
about 13 psi. The total length of pipe from the boiler to the furthest
radiator does not affect this calculation. This calculation only takes into
consideration the difference in height from the gauge to the highest rad. If
you still have circulation problems, it could then be with the piping
design, closed valves, etc. Of course, if your expansion tank is open to
atmospheric pressure, you would disregard all the above information and make
sure the tank has water in it :)
This information was very useful. I believe I have a faulty (or dirty)
Mueller valve (some people call it pressure reducing valve). I have already
made arrangements to get it replaced sometime today.
Lori & Dean Wigmore wrote in message ...
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