No problem --
If you want a simple check - put a gallon of water with a squirt or three of dishsoap in the exchanger, then start the engine and check your exhaust flow for bubbles.
Works every time.
That's also a good way to check if a raw water impeller is working for folks where the exhaust is under water and they can't see the flow - put a squirt of soap in the impeller chamber
Helps to slide it in too.