Air elimination in potable hot water recirculation loop

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Old 10-08-18, 09:09 PM
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Question Air elimination in potable hot water recirculation loop

I have a running loop where I hear noise from the pump as a result of air in the system. I am setting up a new system and want to include air elimination in the loop. There are many options to choose from as long as one is using a closed heating system but I have yet to find a single product for air elimination that uses lead free construction.

Two questions: -
  1. Does anyone know of an air elimination product approved for potable water?
  2. WIll a lead free strainer installed upside down with a vent connected to the drain plug serve as an air scoop? Will it do a reasonable job? Can I improve its function by putting some stainless steel shavings inside the mesh strainer to encourage the air to come out of the water?
 
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Old 10-19-18, 08:43 AM
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Add a tee and a foot long at least 3/4 inch diameter seemingly useless pipe sticking up somewhere in the loop, preferably above where a vertical section turns horizontal at the top. This is the same thing as a water hammer arrestor except you put a valve at the top end. Air will accumulate in the upright length of pipe and can be let out when needed.
 
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Old 10-21-18, 10:16 PM
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Maybe one of these would work:

https://www.supplyhouse.com/Air-Eliminators-310000
 
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Old 10-22-18, 05:28 AM
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Those are the ones I was hoping to use but learned that none are leadfree.
 
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Old 10-22-18, 05:43 AM
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My physical situation does not permit installing a high spot in the system as the highest spots in the system are the PEX loops inside a concrete slab and the pump and distribution manifolds are all below the slab. I have decided to go ahead and use an upside down strainer with an air vent in the drain plug. This will be installed in a straight run of pipe just before the pump. I have a feeling that putting something inside the screen to help entrained air come out of the water will be a good idea but since the lead free brass brass strainer is not transparent it will be difficult to find out what works the best.
 
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Old 10-22-18, 12:46 PM
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Is this for a domestic hot water recirculation loop, or for heat? If the former, I think that most, if not all, of the air will eventually find it's way out of a faucet. If the latter, it's not considered potable and should be kept separate with a backflow preventer like an RPZ.
 
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Old 10-25-18, 06:36 AM
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The current system assumed that the air will find its was out at faucets - but I still hear noises at the pump. That is why I want to do the new system differently.
 
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Old 10-25-18, 11:43 PM
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How big is the pump? Only a small pump is needed for recirculation. Some systems will recirculate w/o a pump by convection -- that' s how my own house is set up.
 
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Old 10-29-18, 05:37 AM
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I plan to use a Grundfos Alpha 2 which has much more capability than needed but seems to be the one to use if one want to limit energy consumption. My system will not circulate by convection - all loops are horizontal and the height difference is less than 6 inches.
 
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Old 10-30-18, 01:46 AM
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Mine is more than that, but not by much. You'll also have the height of the water heater if you pipe the return into the drain at the bottom. I'm often surprised at what will recirculate by convection. I'll usually try it and install two convenient valves in case I do need to add a pump. Insulate everything except for the last 6' at the water heater.

I asked about the pump because if it's over-sized, it could conceivably cavitate and add to the noise.
 
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