If the By-Pass Valve is closed in a Gas Heater, what is the most probable effect?

When the bypass valve in a gas heater is closed, it causes changes in the flow of gas and water within the system. In this situation, water can begin to condense due to reduced flow or changes in temperature. Gas heaters typically operate at certain temperatures; if the bypass is closed, the water being heated may not be circulating effectively, leading to lower temperatures at certain points and increasing the likelihood of condensation forming.

Condensation can harm the efficiency of the system and potentially lead to water damage or the need for repairs. Thus, the closure of the bypass valve does not normally enhance efficiency or increase water flow; instead, it primarily creates conditions conducive to condensation within the system, making this the most probable effect when the bypass valve is closed.