What is Water Flow Rate of Fogatti InstaShower 9 Pro RV Tankless Water Heater

Published 09/24/2025

Question:

What is the operation flow rate on the Fogatti Instashower 9 tankless water heater? That is, what flow rate is required to activate the burners?

asked by: Steven N

Expert Reply:

Hey Steven, the water flow rate of the Fogatti tankless water heater part # FG33FR that you referenced is 3.6 gallons per minute. Are you wanting to make sure your water pump can keep up?

expert reply by: Jameson C

Steven N.

9/24/2025

Well, that’s part of my concern. I want to know the minimum rate of flow necessary to trigger the burners. My worry is that if I’m hooked to city water with very low pressure, the flow rate may be insufficient to start the burners, resulting in cold water from “hot” water side of faucet. I’m less concerned about the water pump providing sufficient pressure.

Jameson C.

9/24/2025

@StevenN The minimum flow rate of city water is usually around 6 gallons per minute so I don't think you'd have any issue at all.

Steven N.

9/24/2025

@JamesonC I’d still like to know the minimum required flow rate, if that info is available. That will give me some idea how far open the faucet must be to continue to receive hot water. At some point restricting the flow at the faucet must result in only cold water coming through. Just curious. I’m trying to compare this heater with one made by Furrion. That one has a minimum flow rate of .32 gpm.