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Heating coil questions

Heating coil questions

Heating coil questions

(OP)
This is the first time I will design heating coil since most of the project I design don't need heating.

When I do cooling coil selection - I used psychrometric chart to select the coil in/out condition (computing mix air, use 55f supply air, 7c 12c chilled water entering & leaving, etc). I guess this how you do in selecting heating coil selection except the supply air is roughly at 100f...is there any special computation I need to know for mix Air (or its the same computation as with cooling coil)?....what's the normal or recommended hot water in/out temp?

Also are you guys using psychrometric too when you do heating? In cooling I used psych chart a lot.

RE: Heating coil questions

There are some simplified equations since it's a sensible only process.

However since you have mixed metric and imperial units I'm not going to attempt to work them out.

If you're comfortable working with a psychrometric chart for cooling go right ahead and use it for heating too.  Everything works the same.  

RE: Heating coil questions

If your heating is from overhead, I don't recommend exceeding 85F, due to buoyancy.  ASHRAE 62 will penalize if you exceed 85F, with overhead heating.  Hot water traditionally uses 180F supply temperatures with delta T of 20/30/40.  With Condensing boilers, you may want to use as low of a return temperature as possible, in that case, your coil approach temperature could be anywhere between 8F and 80F.  It may be a tradeoff between approach temperature/boiler efficiency and coil air pressure drop.

RE: Heating coil questions

Is you post for comfort heating or process heating?

RE: Heating coil questions

How to get the steam data (inlet pressure & lbs/hr) for heating coil?
Thanks  

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