Define Twinning

[chriskmb5150]

Originally posted by mayguy
Wouldn't it be cheaper to just just an air handler in rather the furnace that will not be used for heating???

I'd think that's a waste??

one of the main criteria of twinning is that you use identical units...identical airflow etc..

not really a waste if you think about the when/if one of the operational furnaces needs a heat exchanger, inducer motor, gas valve etc

[onesidedcoin]

Inventive idea for a job.I have done serveral twins over the years and I am interested how you set up the controls.Normaly the boards communicate by running feed to each board thus the fan speed is the same for the mode the system is in.Can you run the jumper to more than two boards?Also did you add hi temp limits on the blowers?

[selfemployed]

Looks good. Try and get pic of old equip. next time. Makes the new stuff look even better.

[mss control]

Question: Can I assume there is staged capacity control for heating and cooling? If so, what would be the sequence of operation ...say 50 capacity ...assuming some fans on and some
fans off...would this let supply air into and back flow through the "turned off" furnances. Assuming they are connected to the same connected supply ductwork? Does this allow the "turned off" fan motors to free wheel when not in operation?

[Edited by mss control on 12-20-2005 at 02:14 PM]

[chriskmb5150]

all fans run simultaneously in heating and cooling. furnaces have belt drive, single speed fan motors. each triplet of furnaces have a master and 2 slaves...

system sequence of operation in heating mode is:

2 master furnaces against back wall start then all 6 fans start.....
2nd stage heat is 2 furnaces in foreground gas valves, inducer etc..

system sequence of operation in cooling mode is:

all 6 blowers fire off simultaneously.

stage 1 - both 20 ton condensers (with electric unloaders) start unloaded with 4 solenoid valves energized.

stage 2 - remaining 2 solenoid valves energize and load remaining cylinder(s)



[Edited by chriskmb5150 on 12-20-2005 at 09:14 PM]

[chriskmb5150]

Originally posted by onesidedcoin
Inventive idea for a job.I have done serveral twins over the years and I am interested how you set up the controls.Normaly the boards communicate by running feed to each board thus the fan speed is the same for the mode the system is in.Can you run the jumper to more than two boards?Also did you add hi temp limits on the blowers?

the stat has its own transformer that controls the units thru relays mounted in the box on the back wall.
master furnaces are controlled in parallel off of said relays.

all furnaces have high temp limits on the blowers wired in series to heating control relay coil and freeze stats on all coils wired in series to cooling control relay coil.

if you have autocad email me at: ductmaster2112@yahoo.com for details if you like.

[troyorr]

Get a qualified person in there to replace that illeagle gas line installation.

[chriskmb5150]

Originally posted by troyorr
Get a qualified person in there to replace that illeagle gas line installation.

get a qualified person to post for you that can spell illegal



gas lines were subbed out to plumbing co. and yes there were legal when this job was done (3 years ago). the only code requirement that Has changed is that you have to run hard line from the gas valve to a minimum of 2" out of the cabinet then you can run flex.

i dont know where youre from but around here (central TX) they're all done this way.

[troyorr]

Bite me. Running flexible lines that penetrate the cabinet is wrong. So you subbed the work out and the sub did it wrong. You are responsible.