Hot Water system, Pressure Gauge and Expansion Tank

[mech9238]

Hello,

Expansion Tank

Hot water system, starting at 70 degrees or domestic water temperature.

Testing a radiant heating panel system.

Start: 70 Temp, 40PSI
Finish. 120 Temp

Includes an expansion tank and pump. Pex piping.

Will the system of a hot water system, which increases in pressure due to temperature, will the expansion tank maintain system pressure?
Will the pressure gauge locaated on the return side with an expansion tank increase when the temperature increases? Will the system pressure gauges stay the same? Will the expansion tank take the pressure of the system and all pressure gauges remain constant?

Thank You

 

[mk3223]

Can you share a system sketch to show the hot water system and tank with the connecting pipes?

Normally, the water pressure goes up as the temperature goes up. Unless, there is a way to release the excessive pressure such as a relief valve or an open vent.

 

[itsmoked]

The pressure will go up with temperature. The amount it goes up is dependent on the size of the expansion tank and the amount of water trapped in the entire system. The point of an expansion tank is to keep the pressure rise to a couple of PSI and not usually more than 3 to 5psi. Without an expansion tank the pressure can go up many tens of psi. If an expansion tank is too small it will 'bottom out' and then the system pressure will sky-rocket.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[byrdj]

thought of this months ago to determine the air volume versus pressure/temperture relations ship for automotive coolant system.

simply;
use thermal expansion equation to determine the volume change of your non compressiable (water).
then use the ideal gas law for the water volume to determine the new pressure in your compressiable (air).
that gas pressure will set your fluid pressure