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Old 06-08-2011, 07:51 AM   #1
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No hot water from water heater unless the furnace is on

Ok here is the setup cold water goes into my elec hot water heater and comes out and goes into the inlet of the furnace then the outlet outlet of the furnace goes to the house. When I have the furnace on I get HOT HOT HOT water but when my furnace is off I only get water that is prob about 100 degrees. I do not want to run the furnace in the summer. What is the best way to set this up?



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Old 06-08-2011, 09:03 AM   #2
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Add some T's and valves so the hot water coming out of the electric heater can skip past the inlet to the furnace and rejoin the outlet from the furnace. One valve goes in the middle of this bypass, the other valve just before the inlet to the furnace. In summer you close off the inlet to the furnace and open the bypass. In winter you close the middle of the bypass and open the inlet to the furnace (and also turn off the power to the electric heater).

The way you have it now, the hot water loses much of its heat passing through the cold furnace in summertime.


The good conscientious technician or serviceperson will carry extra oils and lubricants in case the new pump did not come with oil or the oil was accidentally spilled, so the service call can be completed without an extra visit.

Last edited by AllanJ; 06-08-2011 at 09:10 AM.
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Old 06-08-2011, 09:20 AM   #3
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Thank you so much for a fast reply!! I will try that and post my results for others to see
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Old 06-08-2011, 02:28 PM   #4
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Also check the temperature setting on the electric water heater. It may be set relatively low to act as a pre-heater only with the furnace doing the final temperature rise.

I'd try that first before doing a bunch of replumbing. That said, the heat loss to the furnace may make it worthwhile to do so anyway.
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hot water

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