New Indirect Hot Water Tank Air


  #1  
Old 04-10-20, 10:42 PM
A
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New Indirect Hot Water Tank Air

Not sure if this post belongs here, so please direct me if this has been visited in another thread.

I have a new 40 gallon Laars indirect fired water heater serviced from a gas fired boiler on its own circulation zone. City water comes into the house (100PSI town pressure - crazy!) and is immediately reduced to 50 PSI with a PRV (which is rececntly been installed too), then goes to a T where it splits off to 1) serve the rest of the houses faucets 2)goes into supply for the Larrs water heater. There are no extra valves or backflow preventers before city water goes into the Laars tank. The hot water out of the tank then splits off and goes to 1st floor kitchen, bathroom and laundry, and 2nd floor bathroom.

My issue is that everytime I turn on HOT water in my faucet or shower upstairs, I get pulsing and sputtering. I believe its air in the lines. I've gotten a clear glass and filled it during this event and there are bubbles, not milky white though. If I run the hot water upstairs and wait maybe a half hour, it will happen again.

I have ran all my hot water taps and showers in the house for about 10 minutes to try and purge any air collected in the tank, but it has not solved the problem.

Lastly, after my boiler runs to heat the tank, I get a small overpressurization in all taps in my house, cold or hot. It's not extreme, but is a noticeably pulse when I turn on the faucet.

I think the air in the lines has to do something with the pipes cooling and sucking in air from random shut off valves in the system? Would this cause what I am experiencing? Do I need to install an expansion tank on the city water supply side before my hot water tank?

Thanks for the help!

A

 
  #2  
Old 04-11-20, 05:13 AM
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In retarding tank rusting and corrosion, the anode rod may give off some gas. How much ytou see blasted out depends somewhat on how long it was since the previous shower or other usage.

Does it seem like a lot of "air" or just one short not so powerful blast or two feeble blasts?

2. You need an expansion tank regardless. If you did not have the "air blast" problem, the normal expansion of each new tankful as it is heated may have forced open the water heater relief valve from time to time and gotten water on the floor. The spurious "air" compressed to at least partially accommodate the expansion of the water (and gave you a small overpressurization) but water does not compress.

While some models of pressure regulators might allow water heater water expansion to relieve pressure in the house system back into the water main, in your case you would have to get past 100 PSI (external, main, pressure) before this relief happens.
 
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  #3  
Old 04-11-20, 06:27 AM
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I can confirm the relief valve on the tank has never popped. Remember the tank and pressure relief valve is brand new, so without any chances of the unit being defective, everything should be in new working condition.

The water out of the tap sputters more than one time. It will sputter, and then you can hear the next wave coming through the pipes (almost like the Doppler effect) and a a few seconds later it will happen again. Sometimes more than twice even.
 
 

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