Will this manifold work?

Mark J Strawcutter

I think in the situation you describe you would have 2 GPM back into the primary at the return and 1 GPM flowing "backwards" from the return T to the supply T.

Mark

SM

I have attached a picture of a manifold I have built for one zone of a three-zone system I am going to install. I will tie the manifolds to a primary loop and this will connect them as a crossover (I believe I am using the correct terminology). My question is will the manifold that I have put together work? What have I forgot? Do I need the air vent if there is one in the primary? I did not put a balancing valve in the crossover because all three zones are close in design heat loss (19500, 18,300 & 17400) or should I? The primary will have a mixing valve to control the temperature of the water. The primary pump will turn on when any one of the zones call for heat along with respective zone pump. Also on the primary loop should I use a reverse return? The primary will be less than 20 ft of pipe and the crossovers will be about 15" apart? Thanks for the help.

Steve Ebels

Couple things

1. Ditch the air vent. If you've piped your primary loop correctly you won't need it and I have seen them admit air when installed in that proximity to the pump.

2. Make sure you have more flow through that "rung" of the crossover than what that blue (007?) will move. If the secondary flow is greater than the rung flow you will mix the rung return back into the rung supply. (Did that make any sense?) In other words if flow going into your first tee is 2 GPM and the secondary pump is moving 3 for instance, the additional gallon will be provided by the return tee with only 1 gallon going back out to the primary loop. You may want to install a balance valve on the return side of the secondary to throttle it back if needed.

3. For purging the secondary, it works well to install a couple tees with boiler drains in them so you can isolate that loop and then purge it directly. You already have one on the return side. Put another one on the supply at the same location.

heatboy

Bridged P/S

Doing P/S the way you have pictured is the only way to assure the same primary water temperature to all secondary loops. Set your primary loop in a reverse return fasion and you will eliminate any short cyclying of the water that you would experience with direct return.

Warm Regards,

heatboy

"Expert in Silent Warmth"™

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