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Old 11-12-15, 08:14 AM   #12
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Originally Posted by Ice View Post
Hi All,

My first post.

I wonder what UNCSoc is using for a tankless water if his electric element backup is inefficient? If it is gas, the best you could expect is 80% efficient whereas electric element would give 100% efficiency. Now cost may be a different story but efficiency is a different story.

Here's what we can tell about the site and OP:

Two sources of energy exist, not including solar: electricity, propane. This suggests a location outside a municipality, due to no natural gas availability. Usually, this is a favorable condition for solar, no HOA problems, less stringent building codes, etc.

OP is using all available sources of energy. He is trying to improve the overall efficiency of the system. Serious consideration must be made before chopping up a working rig. Otherwise, the expenses add up in a hurry. Cobbling things together doesn't usually turn out well. Resistive electric tank is burning a hole in the bank account.

Future solar plans: wish-I-coulda-hadda. Not going to happen this cycle.

For today, a possible upgrade could be a new split heat pump (minisplit or whole home) with a desuperheater plumbed into the existing water heater tank. Another could be a retrofit HPWH such as the Airtap unit Xringer has chronicled. In tandem with a gas-powered tankless WH (as steve just mentioned), lots of electricity would be saved over resistive heating normal DHW during modest usage events. When a high-usage event comes along, the tankless unit could serve as a backup source.

A PV module could be added now or later to directly improve energy savings. This would not affect operation of the rest of the system whether the sun was shining or not.

Last edited by jeff5may; 11-12-15 at 08:47 AM..
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