Hydronic Heating System Bypass

[floobydust]

Cold return less than 130°F would cause condensation at the burner and corrosion, so they are trying to control (increase) that with the valves - but doesn't flow vary with demand? Your system I don't think has a constant flow rate, as demand varies.

[jpanhalt]

It wa s the mixing valve.  I followed the service bulletin and system is working as expected.  Main problem was I couldn't get the plug removed, so I had to do a fair bit of disassembly and reassembly. 

Of course, I started that disassembly on Friday.  Not a good choice of days, except it was warm and today is likewise.

Merry Christmas to those who celebrate it.

John

[jmelson]

It wa s the mixing valve.  I followed the service bulletin and system is working as expected.  Main problem was I couldn't get the plug removed, so I had to do a fair bit of disassembly and reassembly. 

Great!  Well, it had to be the valve, as that was the only thing you had not replaced!  Glad to hear you now have heat in the house!
Jon

[kbrill]

Suggest you go to the Caleffi  website they have the best and most comprehensive literature in the industry

[jpanhalt]

Thanks for that additional information.  SteveyG's electrical impedance explanation also helped put me to thinking right about it.

EDIT:  We had an exceptionally dry and warm Fall.  Shortly after getting the bypass valve removed, weather got more typically cold. In fact, two recent storms not only made up for the snow deficit, but we are now above average.  A slow storm (Wednesday afternoon until Friday noon) left more than 12" of heavy wet new snow plus sleet and freezing rain.  Low temperatures in low single digits °F and highs <20°F.  What a mess that is to dig out of, particularly when you live on a hill.  Nevertheless, the boiler and heating system have worked like champs.  Zone temperatures are at their settings and stable.