Electric Water Heater for Occasional-Use Space
I’m looking at finishing a mother-in-law apartment over a detached garage. It will be used for an actual mother-in-law and occasional guests, probably max 30 days / year.
I’m (newly) all electric on this property and not interested in reintroducing fossil fuels to the mix, so I’m limited to electric options for hot water.
I’ve read a lot of helpful stuff on the forum indicating that natural gas tankless heaters don’t make sense in retrofit situations when used in a regularly-occupied space, but my situation is more suitable, I believe, in that the standby cost differential between a tankless system and a tank would be more significant due to the 9/10 unoccupied days in this space.
So my question is, does (electric) tankless make sense in this context, serving a shower and sink for ~1/10 days of the year for 1-2 people? Or should I get a well-insulated (eg Rheem Marathon) small (eg ~20 gal) tank heater and put a controller on it (eg Aquanta, which I already use in my main house and don’t love but would do the job) to disable the heater remotely when it’s not in use?
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