Trane Intellipak DWU Help

[b-man]

I have a site that has several Intellipaks (Vintage 1994). They are VAV units with gas heat. They still have an older Tracer 100 BMS on the system. My question is about the gas heat. The units run 24/7, so MWU is not an issue, but I thought gas heat was enabled when DWU initiate stpt was reached. There are several units reacting different, but none ever bring on gas heat.
They all appear to be to stop economizing and start to warm up the space just on recirculation. Some actually show mode as DWU, others still show mode as cool, but close off OA and start recirculating.
Am I missing some setting in the unit or Tracer that is holding out the gas heat?
Any suggestions would be appreciated.
b-man

[FREDIEFREON]

It has been a number of years, but I had the same problem there is a setting in the HI that has to be enabled, don't remember what section, (menu)...Hope this helps...FRED

[b-man]

FREDIEFREON
Have DWU and MWU enabled. Don't know if this is what you are refering to.
Thanks for th reply
b-man

[FREDIEFREON]

I will look to see if i still have the manual, I think I left it in truck when changed job. But can remember doing same thing you have done and there was another setting..FRED

[jayguy]

Daytime Warm Up description:
If the unit is in the Occupied Mode and the zone temperature as measured at the Daytime Warmup sensor is lower than the Daytime Warmup Initiate Temperature then the unit will switch from Occupied to Unoccupied Mode. fter the Occupied/Unoccupied relay has been energized, the economizer goes to minimum position and the inlet guide vanes go to 100% open (the supply fan remains on during this transition). After the inlet guide vanes are full open, the heat is staged to maintain the Occupied Heating Setpoint. The unit will operate in the Daytime Warmup mode until the temperature in the space reaches the Daytime Warmup Terminate Temperature. After this temperature has been reached, all heat outputs are disabled, inlet guide vanes go closed, and unit will switch back to the Occupied Mode and control to Occupied Setpoints.

you also have to enable Daytime Warm Up and you have to give it Setpoints of Initiate and Terminate. You also need to designate a sensor for the unit to look at.

trane is constantly changing the baords and programming so some of the above may or may not apply to you. the menus where these items are located also changes.

good luck.

[supertek65]

ofcourse Jay is correct!


I have a few setup that way

you do need to have a sensor telling you what return air or space temp is!

the problem I had was that the unit has to communicate with all of the vavs to tell them to open so the vfd/igv can go to 100% before the heat would come on!

I think the system or the engineering idea needs a little work?:stinks:







Daytime Warm Up description:
If the unit is in the Occupied Mode and the zone temperature as measured at the Daytime Warmup sensor is lower than the Daytime Warmup Initiate Temperature then the unit will switch from Occupied to Unoccupied Mode. fter the Occupied/Unoccupied relay has been energized, the economizer goes to minimum position and the inlet guide vanes go to 100% open (the supply fan remains on during this transition). After the inlet guide vanes are full open, the heat is staged to maintain the Occupied Heating Setpoint. The unit will operate in the Daytime Warmup mode until the temperature in the space reaches the Daytime Warmup Terminate Temperature. After this temperature has been reached, all heat outputs are disabled, inlet guide vanes go closed, and unit will switch back to the Occupied Mode and control to Occupied Setpoints.

you also have to enable Daytime Warm Up and you have to give it Setpoints of Initiate and Terminate. You also need to designate a sensor for the unit to look at.

trane is constantly changing the baords and programming so some of the above may or may not apply to you. the menus where these items are located also changes.

good luck.

[b-man]

jayguy
I think these are setup like you described. DWU initiate/terminate set at 68/72, DWU/MWU enabled, space sensor wired to Heat Module.
Like I said earlier, units are acting differently. One will actually display HEAT/DWU OCCUPY, others never show DWU mode, still show COOL. None ever show a transition from Occupied to Unoccupied. All of them will close economizer to minimum and eventually you see Modualtion (IGV) 100%, but never try to bring on gas heat. I am trying to test this sequence by raising the setpoints 74/78. So it appears the units are reacting to setpoints, just not fully following the DWU sequence.
The customer wants to prove the gas heat works as described.
I feel I am still missing something in the setup of unit or Tracer.
Thanks
b-man

[Phisher]

Your units run 24/7 so like you said MWU is a nonissue. DWU is initiated when the coor building temperature drops below the DWU setpoint. Have you checked the HI to see what sensor the DWU is looking at and what the DWU setpoint is? Is the temperature falling below setpoint and the heat doesn't come on or is it possible that the VAV's are keeping the temperature above setpoint and the heat isn't calling?

[b-man]

Phisher
DWU is looking at same sensor as MWU uses, wired diectly to the Heat Module. This sensor is not associated with any VAV, it is there just to monitor space temp. I am raising the setpoints above this space sensor reading, to try to test sequence.
b-man

[jayguy]

a couple of things...

1. before the gas heat comes on...the space temperature may rise naturally and so the heat does not need to come on

2. perhaps there is a problem with the gas train (tripped safety, etc)

3. run the unit in TEST mode and prove that the gas heat works

[Phisher]

Phisher
DWU is looking at same sensor as MWU uses, wired diectly to the Heat Module. This sensor is not associated with any VAV, it is there just to monitor space temp. I am raising the setpoints above this space sensor reading, to try to test sequence.
b-man

It's true that the sensor isn't directly associated with any VAV. The DWU is only in play when the average building temperature drops below setpopint. If the temperature drops below setpoint the HI will switch the unit from VAV mode of operation to CV mode of operation to reheat the space. If the VAV's are doing there job and heating the space then DWU should never be initiated.

[b-man]

jayguy
Already did a heating checkout of burners in test mode of all units. Left 2 units with raised DWU setpoints for 3 hrs and space never reached terminate setpoint, economizer at minimum, 100% IGV and no call for gas heating, and again only 1 actually displayed it was in DWU.
Guys, I appreciate the input! It at least makes me feel like am not overlooking something obvious.
b-man

[jayguy]

is there a problem with the space temp? or is this just a note while you were inpsecting the units?

[b-man]

jayguy
The building is an office building, but it is a steel frame and shell that is not the best insulated. When the OA really drops, the building starts to lose ground temp wise, especially at night. Have shot the walls with an infared when OA temps are 0-10 deg, and on the north side showed 50 deg on the inside. Like I said, they run the building on a 24/7 schedule, but some of the floors are now not completely occupied. Even with VAV's in full heat, it takes until about midday for the building to be back under control. If you manually start the heat in "Test", it will definitely heat back up, which is essetially what I thought DWU should do.
b-man

[Phisher]

Tracer can control the DMU set point. Change the setpoint from the HI won't help if Tracer is controlling the setpoint. Look at Tracer and see if there is a DMU setpoint. I think factory default is 67*.

[nytrane]

If the units are saying there in DWU and not heating you need to raise the occupied heating setpoint. The burner will shut down if the space temp reaches the Occ heat setpoint and the unit will stay in DWU but not heat. Good luck.

[redfive]

We had this problem, but it was the configuration of the stats. It was set up on an averaging system (voting). All stats would open and shut the VAVs, but it took at least 2-3 stats calling for heat to actualy do a changeover. But only certian stats had a vote. Sort of like masters and slaves. To make it worse most of the stats were out of calabration. Our tracer is about 1995-96 ventage. Trane wasnt much help. Just had to muttle through it.
Redfive