Sold our old trailer to my wife's brother. His wife called one night wanting help to get the hot water going. She could hear the burner so thought all was good.
The husband called a few nights later and asked the same. We went over it several times. He said he was good. Next day when taking a shower, I thought of them not changing the valves when they dewinterized it. Texted him info, he did face plant... he knew he was forgetting something under the sink but could not remember what it was... he never said if they got hot water or not.