Hot water circulation no longer working effectively

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Pktaske

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Hey guys. When we bought our current house, we used to run the water for minutes before we'd get any hot water ( I have a long ranch and the bathrooms and HWH are on opposite ends of the house). I installed a small industrial circulation pump in my attic about 13 years ago to pull hot water through my pipes and recirculate back into the hot water heater. Just flick a switch in the BR and we have warm water in about 15 seconds. Well, that used to be the case. My HWH recently went and I put in a new one. It now takes about 10 minutes of the pump running before the water gets warm at the tap and its still not super hot in the shower until you're about halfway through (ie- until you need to start turning up the cold water).

I am perplexed. The only thing I did was replace the water heater. It's a little more offset than the last one by about 5" but I dont think this has much to do with it. I replaced the flexible SS inlet and outlet hoses that I used with this new installation with 3/4" copper thinking it would help (the old one had 3/4" too) but little change.

Important to know is that when I turn the pump on, I can feel the outlet pipe coming out of the HWH get hot all the way to the point where it goes into the floor (we're on a slab) yet the return pipe coming out of the attic remains cold. (Note that I also have a 1-way valve on this return line so that cold water should not be able to run backwards).

Could the new water heater have some kind of restriction on it preventing water from flowing back into it unless hot water is being actually drawn somewher in the house? I'm at a real loss here.

Thanks...
 
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LLigetfa

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A couple of things... first off, the old water heater probably lacked any sort of anti-percolation so there may have been a trickle flow going through the pump/return line with the pump being off. Second, the temperature settings on the new WH is probably lower so the water is not as hot to start with.

Did your recirc pump return line go to the cold side of the WH?
 

hj

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Your line goes up into the attic, so that is where ALL the air would accumulate and the pump CANNOT pump air. Purge the line and it will work properly, assuming the check valve and pump are working properly.
 

Jadnashua

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A pump that ran dry, might be shot...they use the water flow for both cooling and lubrication on most models. Often, people will run the return line into the WH drain. WHere is yours connected? The new WH might have heat traps in it, which might restrict the flow if you tried to run it backwards through them, thus, the drain line (which should be unobstructed), may solve that.
 

hj

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No matter HOW the pump is connected, it would have to be a completely botched job if they were trying to run the water "backwards through the heat traps", and if that were the case it would NEVER work even without heat traps.
 
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