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Boiler protection with P/S piping

Student_3 Member Posts: 1
Hi All,

Replaced boiler and water heater last year. New one is conventional boiler and indirect fired water heater. Several questions.
a) What is acceptable time for return temperature rise to 130 F after night setback (there are visible signs of condensation during cold start up)?
b) Right now there is primary/secondary piping in the system. Is it a good idea to provide additional ‘by-pass’ piping to boost boiler temperature? Some sources (e.g. John Siegenthaler) recommend three way thermostatic valve for this purpose, but what brand? As far as I understand Cv of the valve has to be at least 10 in my case. Is it possible just to bypass close spaced Tees in primary loop and use Taco I-series two-way thermostatic valve as an “intelligent” bypass? I think it also might increase system's efficiency, because usually average boiler temperature during heating cycle is about 150 F

System data:
Boiler: AGA input : 75,000 Btu/hr
Heating Capacity : 63,000 Btu/hr
Primary pump: Taco 007
Secondary Pumps: Grundfos UPS15-58
Indirect water heater: Peerless PP-60 (57 gal)
It is one-pipe diverter T system with baseboards (a couple of cast iron radiators too).

You help is highly appreciated.


  • ALH_4
    ALH_4 Member Posts: 1,790
    Thermic Valve

    There are many ways to achieve boiler protection. Danfoss sells the ESBE Thermic Valve specifically for this purpose.
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