Open/closed system

fatalbert1

I have a outdoor wood boiler which is an open system going to a new shop with infloor heat. It will be separated by a water to water heat exchanger because of elevation difference. There is a pump on the load side to move the water around but wasn't sure if I would need an expansion tank as well?

hot_rod

On the closed loop, pressurized side you will

fatalbert1

If an expansion tank isn't connected would the water temp and pressure build up from the pump cause a leak?

Jamie Hall

If you are speaking of the closed side -- the side with the infloor heat, I presume, it's not the pump that's your problem. In a closed system, the water will try to expand as it warms up. Unless that expansion has someplace to go -- an expansion tank, perhaps, or in an open system a vented tank -- the pressures resulting from the expansion can be amazingly high. If you have a pressure relief valve, hopefully it will open before you have a problem. Otherwise, the system will fail -- catastrophically -- at the weakest point in the pipe or fittings.

Steamhead

hot_rod said:

On the closed loop, pressurized side you will

This.