I'm thinking of putting a temperature gauge on my return line, after the three-way mix valve, to be sure that the return temps are not contributing to creosote accumulation. Does this make sense or is there a better place to put the gauge. On that topic, what other gauges are considered important for troubleshooting & verifying efficiency? I want to get this right the first time and really don't want to go crazy with unnecessary gadgets (no matter how cool they seem to be). I'm very close to completion and can't wait to post the final photos.