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Best DHW for my situation

We just purchased a small, single-level ranch with electric baseboard & wood stove for heat. The hot water is currently a propane 50 gallon tank in the laundry room, which is about 10'x5'. With the dryer going, the worst-case depressurization fails and potentially back-drafts the atmospheric draft hot water heater. The current water heater cannot stay, and there is no where else to locate it. The crawl has no inefficient source of household heat, and is only 4' tall, less the joists.

The house is tight - about 1,300 CFM 50 for an 8,250 cu ft house. .44 ACHn. ( I know many of you don't like that calculation. Let's NOT have that discussion here, now!)

I have considered & eliminated the following:
Atmospheric Draft Propane Tank - see above
Sealed Combustion Propane On-Demand: too pricey to install & very slow payback, per several blog postings on this site.
Hybrid Electric Tank: Noisy & could chill the laundry room in the winter. The noise is my biggest concern. I was seriously thinking the wood heat would throw off enough excess to support this but the noise factor is important.

That leaves:
Electric standard tank - not very efficient
Electric On-Demand - expensive to install.

We do have 200A service & could disable a few of the electric baseboard circuits to suppor the On-Demand.

Thoughts & recommendations would be appreciated!


Asked by Bob Rueter
Posted Aug 25, 2014 3:26 PM ET


2 Answers

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The difference in efficiency between on-demand tankless and standard electric tanks isn't worth paying the upcharge on, if you're using at least 20 gallons/day.

If you want to buy back some space in the laundry area, here are plenty of low-boy ~40-50 gallon electric tanks less than 36" tall that would fit in your crawlspace, provided you have an access hatch big enough to get it in there. eg: http://www.bradfordwhite.com/sites/default/files/product_literature/203-...

The upcharge for a lowboy vs a standard height unit isn't usually very much.

I'm not quite sure what means " The crawl has no inefficient source of household heat..." in your vernacular. Ideally the crawl space would be insulated & sealed, but even if it isn't that wouldn't necessarily be a deal-killer.

Answered by Dana Dorsett
Posted Aug 25, 2014 5:12 PM ET


Regarding the lack of inefficient source of heat on the crawl, I mean there is no boiler or furnace that casts off waste heat.

Yes, we'll insulate the rim joist and walls properly. Right now there is fiberglass in the crawl ceiling between the joists.

Answered by Bob Rueter
Posted Aug 25, 2014 5:21 PM ET

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