Go Back  DoItYourself.com Community Forums > Heating, Cooling, Air Conditioning, Ventilation and T-Stat Controls > Thermostatic Controls
Reload this Page >

Replacing old Honeywell T6069D Fan Coil Thermostat with Honeywell TB6575A1000

Replacing old Honeywell T6069D Fan Coil Thermostat with Honeywell TB6575A1000

Reply

  #1  
Old 04-16-19, 08:28 AM
Member
Thread Starter
Join Date: Apr 2019
Location: Canada
Posts: 8
Received 0 Votes on 0 Posts
Question Replacing old Honeywell T6069D Fan Coil Thermostat with Honeywell TB6575A1000

Hi everyone

I've searched for an answer to this on many different forums with no luck, and I'm hoping for some success from this community.

I have a 2-pipe fan coil unit with a VT3343 Schneider Valve, and an Aquastat in my condo apartment.

The old T6069 has 7 wires: Blue, Red, Brown for 3 fan speeds; Black - live; Yellow - cooling; Orange - heating; and Violet - Aquastat. The Orange and Yellow wires connect directly to the Aquastat, and the Violet is connected to both the valve and the Aquastat. The T6069 has only two switches that toggle: 1) POWER On, Off, and Auto; and 2) FAN SPEED Low, Medium, High.

The new TB6575 has corresponding terminals for the Blue, Red, Brown, Black, Yellow and Orange (but not the Violet). It has additional terminals for Neutral, Ground, Pipe Sensor, Remote Setback, and Remote Sensor.
From what I've read, and from the TB6575 manual, I can connect the Blue, Red, Brown, Black and Orange (Yellow is not used for the 2-pipe system).

I am guessing that the Violet should connect to the Pipe Sensor terminal, in which case I have to run a ground wire to the Ground terminal.
I have also run a neutral from the junction box to the N terminal on the TB6575.

I think I am getting close, but the problem is that the thermostat will turn on the heat, and start the blower for only a few seconds, and then reboot.

What have I got wrong? Any help would be appreciated.
 
Sponsored Links
  #2  
Old 04-16-19, 11:33 AM
Member
Join Date: Jun 2012
Location: USA
Posts: 1,412
Received 12 Votes on 11 Posts
Try without the pipe sensor terminal connected and see if it is stable. The pipe sensor is designed to be switched from the Sc (sensor common) and you are connecting it to line voltage when the valve is called to open.
Currently wired as figure 9 of http://lit.stromquist.com/docs/HONEY.../95C-10678.PDF
You need to wire as figure 10 of https://customer.honeywell.com/resou...0s/62-0278.pdf
 
crabbylegs voted this post useful.
  #3  
Old 04-16-19, 04:42 PM
Member
Thread Starter
Join Date: Apr 2019
Location: Canada
Posts: 8
Received 0 Votes on 0 Posts
Thanks for the quick response and also referring to the installation manual which confirmed my own guesses about my system and wiring. What you wrote has helped me understand what the wires are doing.

I'll give it a try and report back.
 
  #4  
Old 04-22-19, 04:44 AM
Member
Thread Starter
Join Date: Apr 2019
Location: Canada
Posts: 8
Received 0 Votes on 0 Posts
Replying in case this is helpful to others.

Thank you Astuff for the helpful hints - when you said "Sc" stands for Sensor Common, that helped me to make sense of why the pipe sensor (Aquastat) is hooked up the way it is. I then saw a paragraph in the TB6575 manual that cleared everything up:

Remote Pipe Sensor Wiring
The remote pipe sensor is used for 2 pipes auto and 2 pipes heat and cool with auxiliary heat changeover. The pipe sensor will sense the temperature in the pipes to tell the thermostat when the system is set to Heat or Cool.
1. Check Installer Setup number (IS) 5 to ensure it is set to the desired value. (See Table 4 on
page 12).
2. Wire pipe sensor to Sc and Ps terminals.
3. Attach pipe sensor to bottom side of the pipe
with the leads pointing down.
4. Insulate pipe sensor, as necessary.
etc...

I did #2 above, removed the separate ground wire I had connected to the Sc terminal, and voila!

Thank you once again!
 
  #5  
Old 06-29-19, 09:17 AM
Member
Thread Starter
Join Date: Apr 2019
Location: Canada
Posts: 8
Received 0 Votes on 0 Posts
Cooling function not working

Hi everyone

Follow up problem here. The thermostat worked great to heat our place, but now that the building has switched over to cold water in the pipes, the unit is just blowing warm air.

Could it be my wiring? I think it's got something to do with the valve not opening to let cold water run through the coils. Strangely though, my pipe sensor is reading 52 degrees Celsius in the pipes (about 125 Fahrenheit), which doesn't make sense if the building has switched to cold water.

I'm stumped. Please help!!!
 
  #6  
Old 06-29-19, 10:15 AM
Member
Join Date: Jun 2012
Location: USA
Posts: 1,412
Received 12 Votes on 11 Posts
May need a purge which opens the valve to let the thermostat know what mode to be in. Try turning the thermostat off for a bit - should then do a 5 minute purge when powered up.
 
crabbylegs voted this post useful.
  #7  
Old 06-29-19, 12:04 PM
Member
Thread Starter
Join Date: Apr 2019
Location: Canada
Posts: 8
Received 0 Votes on 0 Posts
Thank you for the quick response! I tried the purge - no difference! I have also been trying different thermostat settings - changing the cooling threshold, etc. After exiting Settings mode it always does a 5-minute purge. So still no luck after many purges.

Should there be an audible noise when the valve opens? I haven't heard anything.
 
  #8  
Old 06-29-19, 12:26 PM
Member
Thread Starter
Join Date: Apr 2019
Location: Canada
Posts: 8
Received 0 Votes on 0 Posts
It also just occurred to me that the new TB6575 thermostat doesn't use the Yellow (Y) lead for cooling, whereas the old T6069D did use it. I have simply capped it off. Could this be the issue? Do I need to bridge the W and Y terminals on the thermostat?
 
  #9  
Old 06-29-19, 08:02 PM
Member
Join Date: Jun 2012
Location: USA
Posts: 1,412
Received 12 Votes on 11 Posts
That thermostat doesn't use the Y/A terminal if set to 2 pipe.

1- Are you sure there is cold water in the pipes now?
2- Can you document what terminals of the thermostat connect to what device?
3- Most valves are fairly silent. Feel pipe near valve to verify it is warm. Most valves are normally closed but could be normally open. First try disconnecting leads to valve and see if it gets cold. If not try jumping live and valve wire to open.
 
  #10  
Old 07-02-19, 03:57 AM
Member
Thread Starter
Join Date: Apr 2019
Location: Canada
Posts: 8
Received 0 Votes on 0 Posts
I will go over there and take a picture and verify the wiring today! Thanks for your patience.
 
  #11  
Old 07-03-19, 01:04 PM
Member
Thread Starter
Join Date: Apr 2019
Location: Canada
Posts: 8
Received 0 Votes on 0 Posts
So I caved in and called in a technician to help me. He said that the problem was I had an Aquastat, which didn't function like a pipe sensor in the way I thought it did. I had it wired like Fig. 10 here: https://customer.honeywell.com/resou...0s/62-0278.pdf, and he disconnected what I thought was the pipe sensor, and wired it like Fig. 11 (in the same document I just linked). So even though I don't have a 4-pipe system, he said it needed to be wired like that. He then set the thermostat to 4-pipe.

Now it works, but it's left me confused! Does this make sense to anyone (Astuff)?
 
  #12  
Old 07-03-19, 01:28 PM
Member
Join Date: Jun 2012
Location: USA
Posts: 1,412
Received 12 Votes on 11 Posts
Doesn't make sense. There are different types of pipe sensors. Code 5 (page 12) should cover the aquastat.
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
Display Modes
 
Ask a Question
Question Title:
Description:
Your question will be posted in: