2 pipe chilled water/hot water fan coil zoned


Old 01-21-14, 11:35 AM
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2 pipe chilled water/hot water fan coil zoned

in a system with zoned fan coil units, should the hot water or cold water run in the same direction on the 2 pipe hydronic system or should there be 2 circulator pumps and 3 way zone valves to have the water go in a different direction. for instance since heat rises it would come in at the top of the fan coil while chilled water cold goes downward so it would go opposite flow direction and come in at bottom of the fan coil radiator but what about the air blowing it towards the top? since its a forced convection with fan does this really matter? I am in the planning stage for a turbonics fan coil system.
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Old 01-21-14, 01:09 PM
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What fan coil / air handler are you using?

In ANY chiller / heater setup, one must be very careful to keep the flows separate. You know that under no circumstances must the chiller water flow through the boiler, right?

Many boiler installation manuals will show the piping for this.

What is the boiler make/model?
Old 01-21-14, 04:22 PM
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what really matters is that the most extreme temperature water is the last that the air flows through.
So, if the air flows left to right then you coil will have a pipe on the left side and one on the right side of the coil slab. If the air flows up then there is a pipe at the bottom and one at the top of the coil slab. In any event you want the return water to be closest to the fan, this gives you the best rise (or drop) across the coil.
In both instances the supply and the return are the same pipes. Now with storage / bufffer / mass tanks there is something to be said about how you plumb those.

Hope this makes sense

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