Any Old Port in a Storm - S3-E2
Plot hole: Carsini has a wine vault (with very expensive wine in it) with an integrated air conditioner. There are indeed wine vaults like that. But mostly active cooling wine vault are used by "amateur" wine lovers (who can't afford an underground cellar) but not by wine connoisseurs like Carsini. Active coolings are not very reliable. A power failure or a simple malfunction and Carsini would lose all of his expansive wines he collected for many years (like we saw in the episode). So why shouldn't a huge wine connoisseur build a cellar, surrounded by cooling soil where temperatures never rise that high? He is rich, he as a big estate, a villa, and he knows better to store the jewels of his passion adequately. Why store wines in a potential oven where high temperatures (without air conditioning) can even kill a man (his brother) in the first place? It is a far fetched and an unnecessary gambling just to have a murder-plot.
Answer: In the show, he was already a Lieutenant. A promotion would put him in the next rank up, which for the L.A.P.D. would be Captain. However, some of a Captain's duties would be overseeing other officers and ensuring they're compliant with policies, regulations, and standards. It would also most likely take him out of the field. This is something Columbo has no desire for as he rarely goes to police HQ's. Nor does he show interest in compliance and standards (for example, not going to his semi-annual evaluation at the firing range). However, he could still be assigned to a higher pay grade based on expertise, which is a form of promotion that does not include rank advancement. This would be going from Lieutenant I to Lieutenant II. I don't believe in the show it's ever started what his pay grade is. Although, in s02e01 (I believe) he mentions making $11K a year. Whether or not this was a true statement on his part, if you could find pay scale information for an LAPD Lieutenant in the 70's, it could give you an idea of his pay grade.
Bishop73