Cannot say enough great things about Francesco. Prompt, friendly, smart, knowledgeable, professional, fair, honest, and reasonable. What more can you ask? I wish I could give him more stars in this review. (Also even though he's listed in here for Vallejo, I know he does work also in East Bay (Oakland, Berkeley, etc.) and San Francisco. I hired him to fix a mess left by another plumbing company when they tried and failed to properly install tankless water heater at my home. After this first company screwed up, I talked with 5-8 other vendors to make sure not to repeat that mistake. Was very impressed when Francesco came out to give an estimate. He was very patient and frank/honest with me about realistic options (repairing the first plumber's mistake or starting over). Very knowledgeable and great problem solver. I was not disappointed when I hired him. Francesco has a really impressive work ethic. He has the technical knowledge and experience (unlike some of the other vendors who send out technicians who don't actually understand the mechanics / technology of tankless water heaters). Francesco takes pride in doing the work well, solving problems elegantly, and making sure his work looks good as well, even if it takes more effort. He was very conscientious of the budget/estimate and scheduling, and did an amazing quality work at a reasonable price. I know I will be calling him first for any plumbing job that I might need in the future.