GoneFishing70
New Member
My Navien CH-240 has a gas odor smell that I was able to narrow down to the manifold. You can smell gas (tested with a gas detector) when it first starts and then it goes away at high fire (stage 3) and then comes back when it backs down to stage 1. Any thoughts on where to start? The unit is 10 years old and wondering if it might be time for a replacement?