Radiant Floor Heating Pump Always On


Old 05-14-13, 05:31 PM
Thread Starter
Join Date: May 2013
Location: USA
Posts: 2
Received 0 Votes on 0 Posts
Radiant Floor Heating Pump Always On

Hi, I have a 3 story home with radiant floor heating. It works fine, except that even when no heat is required the water pump remains on.

The electrical components of the system consist of:
A) 3 Honeywell TH1100 Thermostats (one for each story of the home, R and W terminals have wires, C unused)
B) 3 Honeywell V8043E Zone Valves (one for each story of the home, each has 4 wires: 2 yellow (motor) and 2 red (end))
C) 1 Honeywell R8239A Fan Center
D) 1 Water Pump (input is hot water, output flows to the 3 Zone Valves)

Here are the connections from the thermostats (T1-3) to the Zone Valves (ZV1-3) that control the motors of the valves and correctly open and close them:

T3.W ---------- yellow-ZV3-yellow----\
T2.W ---------- yellow-ZV2-yellow----+--- 'C' R8239A
T1.W ---------- yellow-ZV1-yellow----/

T3-1.R ---------------------------------- 'R' R8239A

The problem area would appear to be the 'End' connections (red leads) from the Zone Valves to turn the pump on/off. If none of the valves are open, then it would be sensible for the pump to be off. If any of the valves is open, then the pump should be on. One red lead from each zone valve is connected to the 'R' terminal of the R8239A fan center. The rest of the wiring is:

ZV3.R -----------\
ZV2.R -----------+--- 'Y' R8239A
ZV1.R -----------/

'C' R8239A ------ (blue) pump power?

'G' R8239A ------ (blue) pump power?

I would guess that the intent is that 'Y' input should be controlling whether the 'G' connection is activated to provide power to the pump or not. Is that correct?

Jeff Kelley
Sponsored Links
Old 05-23-13, 07:08 PM
Thread Starter
Join Date: May 2013
Location: USA
Posts: 2
Received 0 Votes on 0 Posts
To answer my own question:

Unscrew the wire from the 'Y' connector and screw it onto the 'G' connector. The pump then shuts off when all 3 valves are closed, and turns on when any valve is open.
Old 05-23-13, 07:29 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 58,568
Received 1,041 Votes on 965 Posts
Welcome to the forums.

Are you hearing voices Jeff
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
Ask a Question
Question Title:
Your question will be posted in: