Tankless for long run to bonus room above garage?

[Suey Vee.]

I apologize if this has been posted, I looked but did not see a similar situation.

I am finishing a bonus room above an attached garage. No gas/ lp available, electric only.

The tank water heater is approximately 80' away from the garage. In the bonus room there will be a bathroom shower on one end and kitchen sink on the far end - so it would be a long run from the water heater. We are in Northern Michigan, and the main garage level will only be heated to 45 or so. Should I install a second / smaller tank type heater or go with a tankless inline with the existing tank, just in the garage for faster hot water? The space is mostly for guests and hot water won't be needed that often, I don't want to heat water that won't be used (especially a tank in the 45 degree space). Garage electric has not been completed yet, there will be a full panel so I can plan for either. Thank you.

 

[Stuff]

Have you considered an on-demand recirculation pump?

 

[Sponsor]

 

[Suey Vee.]

Have you considered an on-demand recirculation pump?

I looked into them, but with the room not getting used much up there, the units with the timers did not apply, and I saw one with a push-button - but having to explain to guests and teen-agers how it works seemed somewhat not likely to be used. Any advice is appreciated, thank you.

 

[Dana]

Electric tankless heaters are an abomination, abusive to the grid infrastructure, and totally inadequate for you wintertime incoming water temperatures.

An 80' run of 3/4" plumbing has about 2 gallons of water in it, an 80' run of half-inch about 1 gallon. With a demand circulation pump it would still take several seconds for hot water to arrive, but running a low flow shower could seem endless.

With an 8-10 gallon water heater in the bonus room space that takes the output of the main water heater into it's cold-side there is sufficient dilution factor that the 1-2 gallons of tepid water between the tanks never affects the output temperature, and hot water arrives to the kitchen or shower in a "normal" amount of time. Keep the storage temperature of the local water heater at 130-140F, and temper it down to 115F or so with a thermostatic mixing valve for distribution to the local kitchen & bath. With the extra bath the additional capacity of the small tank matters too.

If it isn't already, insulate all of the hot water distribution plumbing to at least a code-minimum R3 with pipe insulation ( R5 would be even better.) An 80' run has a lot of surface area to lose heat from, so intermittent short draws of less than a few gallons can waste a fair amount of heat if uninsulated, but with insulation it will have retained most of the residual heat even after an hour.

 

[Suey Vee.]

Excellent, thank you Dana.

 

[Stuff]

I looked into them, but with the room not getting used much up there, the units with the timers did not apply, and I saw one with a push-button - but having to explain to guests and teen-agers how it works seemed somewhat not likely to be used. Any advice is appreciated, thank you.

That is a drawback. They now offer occupancy sensors to get rid of the button. OK in the bathroom but kitchenette might be a challenge.