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Most efficient way to heat hot water in our situation?
Due to a pile o' stuff happening at once, we had to do many high dollar projects and had to skimp on the furnace install (furnace, septic, well, sick cat, etc - all needed repair/replacement this year). We ended up with another tankless coil system (oil) which is working fine and appears to run less and use less oil than our almost 40 year old leaky vaillant.
It's coming up on winter and it's Upstate NY, so it will be on most of the day for both heat and hot water no matter what. The plumber suggested we add (DIY) an electric hot water heater for the summer, enabling us to shut the boiler off. I've seen others suggest this will cause rust or other issues with the boiler - and we do have a rather damp basement. Any truth to this?
Another suggestion I saw was to keep it as the source of hot water, but shut it off if you won't be home using it for long stretches. We'd probably be able to shut it off completely from 8AM to the next morning around 4AM during the week - would starting it up each morning cause any problems?
Adding an indirect oil tank is probably not an option at this time - just curious if anyone had any thoughts/suggestions.