Boiler protection with P/S piping

Student_3

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

Thermic Valve

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