What are the symptoms of an oversized/undersized expansion tank?

[ballsonwalls]

For a chilled or hot water system?

Thanks

 

[GMcD]

Severe spiking pressure fluctuations on changes in system temperature. For example, if the hydronic system uses temperature reset as the seasons change, and the heating system supply water temperature is raised by 20-30F, and the system pressure spikes up to the point where any system pressure relief valves start popping, then you've likely got a flooded expansion tank.

 

[ChrisConley]

No symptoms for an oversized tank. Other than you spent too much money on the tank.

For that reason many designers work with a large safety factor and big rules of thumb on expansion tank sizing.

 

[willard3]

I just got done with a projet with lots of expansion tanks and the analytical solution is sooooooo easy I wonder why one would use a rule-of-thumb.

 

[ChrisConley]

Because you have to add up the lenghts of all that pipe willard3.... and adding stuff is like... hard. Plus you have to know diameters...

I use a homemade excel sheet, which simplifies the experience.