Air Conditioning - Two thermostats on one AH

I had a central AC system installed and now it's my turn to wire it. The line power is completed and now the controls.

I have a Trane split system cooling only with TWE variable speed airhandler in attic and XL 14i condensor out back. The house was ducted for two zones, 1st and 2nd floors. The HVAC contractor installed zone dampers for each floor.

My question is how do I wire both thermostats to a single airhandler with zone dampers? The typical diagrams don't show my setup. Will I need to have an ice cube relay for each damper and have them pick from the fan control from each thermostat?

Am I over thinking this??

Thanks!

Its hard to say here . Dont know what all you have.
I had a central AC system installed and now it's my turn to wire it. The line power is completed and now the controls. First if they put it in they should wire it for sure.If it dont work they can say you did it. Dont wire it have them.Dont you have a control box with the dampers.Schermatic should be there. Do you also have the bypass damper in the ducts? Most time the tstat opens the damper and the damper will turn on the units. "This is why we put a unit for up and a unit for down in a two story home."

ED :wall:

I am not sure how much you saved by doing this yourself? You should of let them do it.. LIke Ed said, If something is done wrong, it'll go back to you..

They should do it, and also make sure all the dip switches are set up for your set up, and system for best results.

I was not happy with the installation of the equipment and ductwork so I sent this guy on his way as soon as the (6 month!) job was completed. I certainly wasn't going to let his company do the wiring too. SO I deducted the electrical portion of the bill and told him I would take care of it myself.

I am an electrician by trade and have wired basic systems but none like what I have here...Basically the supply duct off the AH is split into the upstairs and downstairs zones. Approximetely 4 feet from the AH there are the two 24V normally open, power closed damper motors by Honeywell. Should these dampers have end switches to start the unit when fully open?

He did not leave a control box with the dampers should there be one?

Not sure what you have there :confused:

Can you go on line to honeywell the company that made the damper motors. Like you said the tstat should open them and they should then start everthing.
Is there a by pass damper in the duct?
If you wire it how do you know if they pumped it down and opened the freon valves??? what is the charge in it???
Ill go along that you can wire it in but dont fire it off if they are not there

I sent this guy on his way as soon as the (6 month!) job was completed.
Is this for real for the AC in the home. :eek:

ED :thinker:

Yeah, the AH was set in August, tin started shortly thereafter, 4 supply drops to the first floor and seven to the second floor all old work. The installer didn't coordinate the runs very well in the attic and backed himself into a corner as well as very limited access to the unit itself. I made it clear from the beginning that I wanted all steel duct work, as things got tighter he tried to sneak in flex but I made him rip it out. They took forever.

So he was very discouraged and it was a battle to get him back a few times to finish up but finally finished in January.

As far as the controls, I finished up yesterday, I used RIB's (relay in a box) for zone control and tested fan with the zones and they worked well. Thanks for the tip, I had the T-Stats pick the RIB and had the contacts pick the zone damper and fan.

I will have tech do start up next week.

Thanks for your help!

Up n running
I wish that I seen this before you did the wiring hope it is not to late.
There needs to be some protective controls in the works.
There needs to be some freeze protection.
With a time delay and the bit about the by pass damper is there one in the circuit.
Maybe the guy that does the start up will give it a good look over.

Thanks for the help so far guys.

Update - I finished the controls and got the fan circulating air in the house. I left the condensor power off.The zoning worked out good. Now I am ready for start up.

The installer told me he charged the system last year, could you give me an idea what I should expect to be done at start up.? Is their programming to be done at the AH. Generally how long does it usually take to complete?

It's a Trane Variable speed system I was curious as to how the unit determines what speed to run or is it basically a soft start and stop motor control.

Scott - I will inquire about the freeze stat, the only other protective controls I see would be internal to the equipment ( I hope). There is a small pump with a trap in the bottom of the AH with a poly drain run out to the pad powered up.

Thanks!

Not knowning what model air hander/size of a system you have. but here are the tips to set the dip switches at on the board.

Dip switches 1 to 4, is used to set the CFM per ton Also, find out how many tons is your outdoor unit is.

I'd suggest the "normal" 400cfm/ton. Low (350cfm/ton) can be used for very humid air, and high for hot dry area (450cfm/ton)


Dip switched 7 to 8 is your Aux heat speed.Id' suggest med-low or Med high

I don't see it on my end if you can set up fan control for comfort-r or not? I am guessing it's already set up?? Look on the back side of the blower door, there should be a chart that you can look at for the dip switch set up.

W/ Comfort R on, the blower will do a soft start and slowly speed up as time passes.. and slow down after there is no call for cooling.

Jay - Thanks for the hints. Start up tech is scheduled for monday morning, I'll let him do his thing, I'm just curious what has to be done to fire it up.

The AH is a Trane TWE049E13FB, no reheat, and the outdoor condensing unit is a XL14i 4 ton.

Thanks.