Seems simple! (PAH)

hot_rod

This seems like such a simple thing to figure out, yet the coil companies I've contacted are scratching their heads. Here's what I'm asking for:

Hydronic inlet temps of 140 F

CFM of 1,400

Btu delivery of 128,000 Btu's

Seems nobody sizes their coils to 140 F incoming water temps with such low CFM's! Yet, if I'm to use a condensing boiler with a hydro air unit - I need to maintain lower water temps to stay in the condensing range to maintain the high efficiencies. Can't go bonkers with CFM's cause it's existing ductwork sized for 3.5 tons of A/C.

Help!

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RB_2

Have you tried Heatcraft or First Co.?

Any of these folks doing combo systems should be able to help you out Dave.

Also, that 140 F ewt changes the flow/output performance characteristics on the coil. So if you plan on using a two or three way modualting control valve select something preferably with split characteristics. Linear would be your second choice and make sure the pressure loss through the valve is roughly the same as the loss through the coil and related piping.

If you 'can't get no satisfaction'...let me know...somewhere in the archives I've got some coil sizing software.

RB

David Sutton

frist co. hydros...

i be live that frist co. hydro coils rate theres with 140 degree water not 100% sure but take a look. i use them all the time only set back you need to add a 6006c to reg the running time of the coil. tha aquastat will help get more use of the remianing heat after zone shut down and stop cold air on start up till coil is hot hope this helps .. David Sutton

jim f

maybe

the largest first co. air handler will do 94,000 btu @ 140*
entering water temp @ 9 gpm. this is a 5 ton coil. why not put in a variable speed air handler and a seperate hot water coil in the duct work sized for the application.

hot_rod

coil sizing software

Robert,

I'd be willing to bet a lot of Wetheads could benefit from having access to software for coil sizing. My low CFM's have evidently tossed a monkey wrench into traditional sizing software!

You have my pics from the Dover farm house & our chilled water system. There again, I found myself in unchartered waters - although not quite as badly.

The information needed for these systems seems difficult to obtain & I'd bet there's going to be an increasing number of folks who could use this info in the near future.

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