View Full Version : Honeywell Programmable Thermostat Wiring B wire

Dec 6, 2009, 05:24 PM
I am (trying to) install a Honeywell prog. Thermostat. My old stat was an Automag (fairly old) and had three wires attached to it. A Red wire labeled (R), White (Y) and Blue (B). So, I don't have spot for the blue. Called Honeywell and they told me to put Red to R, Blue to W and White to Y. This didn't solve the problem (the heat doesn't ever turn on). So, it was getting cold so I reattached the old stat, but now that one doesn't work either. Now I don't know what to do :confused:
I looked on the furnace, and it has an electrical box that has two gold plates, one labeled B one labeled R and two rows of screws that have the white wires attached to them. At one point the breaker for the rooms I was working on was in fact tripped, but I've reset it to no avail.
Please help, my baby is cold in there! TIA for any info!

Dec 6, 2009, 06:14 PM
Mmmm... Did you change the stat with the power off? Bet you didn't.

First, Turn off power and put the old stat back.

Second, Look for an automotive style fuse on the circuit board about 3 Amps or so. It's probably popped.

What kind of heating system do you have (oil, electric etc)?

Model of furnace and thermostat if known?

Model of new stat (link to install manual would be really cool)?

Dec 6, 2009, 07:38 PM
Of course not! I just told my wife to come in with a wooden pole if she smelled anything funny ;)
The old stat doesn't seem to have any kind of fuse. If you wouldn't mind, here's a bunch of pics of my setup and old stat Picasa Web Albums - EKing - Furnace (http://tinyurl.com/ybf7wyv).
The install manual for the new stat is here: http://tinyurl.com/yzhk64x
Thanks so much for your help!

Dec 6, 2009, 10:16 PM
The furnace board has the fuse. See the purple component on this board for example: Carrier Gas Furnace Circuit Control Board HH84AA023 [furnace board HH84AA023] - $92.68 : Appliance Parts from Midwest Appliance Parts, Appliance Part Service, Chicago, Water Filters, Appliance Parts Chicago (http://midwestapplianceparts.com/index.php?main_page=product_info&products_id=6112&cPath=999&utm_source=googlebase&utm_medium=cse&utm_campaign=export_feed#googlebase)

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Dec 6, 2009, 10:21 PM
The black thing on this pic contains a fuse. Picasa Web Albums - EKing - Furnace (http://picasaweb.google.com/eastonking/Furnace?authkey=Gv1sRgCIr7sqTI88aLCA&feat=directlink#5412315331253244258)

Turn off power before opening. It should twist open and expose a glass fuse about 1-1/4" long.

I gather this is a "boiler" with a zone valve or something. Do you have a model #.

Dec 6, 2009, 10:26 PM
I did find this: http://www.icca.invensys.com/UNILINE/a/a13.pdf CM-64W?

So, it is a 3 wire zone stat. SPDT

Is your system heating only or heat/cool?

Dec 6, 2009, 11:39 PM
You may need a thermostat that can operate a 3 wire zone valve. Take a look here: http://www.white-rodgers.com/wrdhom/pdfs/instruction_sheets/0037-6895.pdf

I know you can make a regular tstat work if you add an extra relay. Let me think about it for a bit.

Dec 7, 2009, 12:13 AM
It seems at times we talk to ourselves.

Dec 7, 2009, 05:58 AM
OK, so I checked the fuse, it doesn't appear to be blown. Closed that back up. It should be noted that the other zones seem to be working fine. It's just this one zone that I tried changing that I'm having a problem with.
The boiler does have 3 zones. It is a Remco LA1256E built in 1983. I tried searching for this model on the web but can't find any results.
The comment about a 3 wire zone tstat seems to make sense. It does have both zones and 3 wires. Is this an unusual setup? I guess you're saying it would it require a special type of tstat, right?
System is heat only, there's a separate tstat for the a/c.
Since the fuse is OK, isn't it strange the reattaching the original tstat to the leads did not allow me to operate the zone anymore?
Thanks again for assistance, it is much appreciated. Please let me know if you need any more info.

Dec 7, 2009, 06:39 AM
So further researching this (now that I know what it is), it seems that a 3 wire zone system is not an easy tstat to replace with off the shelf options... Do you know of any way to make a regular tstat work with 3 wires?

Dec 7, 2009, 07:46 AM
Here is at leat one zone valve stat that will work: Buy Honeywell TL8100 Programmable Hydronic Thermostat - Heat-Only | Honeywell TL8100A1008 (http://www.iaqsource.com/product.php?p=honeywell_tl8100a1008&product=173744)

I did a search for zone valve thermostat. A bunch of other stuff came uo, but I didn't look at them closely.

A 24 VAC SPDT relay such as this should work. ALTRONIX RELAY AND BASE MODULES - Altronix, RAC24, Relay & Base - 24VAC operation, 45mA current draw, DPDT contacts rated @ 10 amp/220VAC or 28VDC, DIN Rail Mount, UL Recognized. (http://www.surveillance-video.com/rac24.html?productid=rac24&channelid=FROOG) It looks DIN rail mountable. Usually screws are an available option too. See Altronix: a leading manufacturer of electronics and high technology components (http://www.altronix.com) for better specs.

You could use (C), R and W from the thermostat. (C) is optional, but avoids batteries.

The 24 V transformer would go to the terminals (C) and (R).
The coil of the additional relay would go to (C) and (W)

You would then have a (Common), a NC and a NO contact that would attach to where the tstat wires went.

Dec 7, 2009, 07:52 AM
(R) would probably be common of the added relay. (B) would be (NO) and (Y) NC. If heat/cool were backwards, reverse the (NO)/(NC) connections.

Dec 7, 2009, 08:26 AM
You have a old Automag zone control system. See the Automag company below.

You can add there relay or similar to make your 3 wire zone valve work.

CNV84 Relay
Relay to adapt existing 3-wire thermostat system to 2-wire thermostats. (One relay required for each thermostat.)

OR you can just replace the valve head (I recommend this instead of a relay)

Call them. They have been around a long time and are very knowledgeable. Many years ago I installed a bunch of there stuff on contract jobs for the US Government.

Automag division of KCI Industries, Inc.
Manufacturer of "Fail-Safe" normally open Zone Valves

1111 Hill Street, Jessup, PA 18434
(800) 451-2002
(570) 383-2428
FAX: (570) 383-9820

Web site loaded with info.

AUTOMAG (http://www.automagzonevalve.net/index.php)

Dec 7, 2009, 08:26 AM
OK, besides the link to Honeywell, you've kind of lost me on those last two posts. Not sure if you are saying that this would work with the tstat I have now, or if you are saying that's how it would work if I added a relay. Anyway, I will try a search for zone valve and look through what's there. I had been searching for 3 wire thermostat with limited luck...
Is this piece a relay? http://picasaweb.google.com/lh/photo/0OKiBt8-vcA5Vhz7OZPYtA?authkey=Gv1sRgCIr7sqTI88aLCA&feat=directlink I would guess that this is the electronic part that controls the valve?? Not really sure what a relay actually does in this situation.
One more question that will put me at ease here... Is it possible to blow out the actual original tstat? Is that why it is no longer working once it is reattached? If so, I'll move the one from another room into this room (AFTER turning off the power) and re-test to see if it is now controlling the valve. Then I'll replace with a proper 3 wire tstat, assuming you are saying the one I have now is not capable of controlling it.

Dec 7, 2009, 08:29 AM
See my post. Call Automag to save yourself a bunch of trouble.

Dec 7, 2009, 09:24 AM
Did you check the fuse I mentioned in your picture.

Your old thermostat is mercury based, so I has to be mounted level.

You need to use the word valve in your search. i.e. 3 wire valve thermostat

Your valve, requires power to open and power to close, so when there is a call for heat the thermostat opens the valve. When there is a call for cool it closes it. The valve is noting but a bidirectional motor with two limit switches. One common terminal to the valve and a winding to open and a winding to close.

Another technique is Spring to close, power to open. This is in esscence what's needed for a conventional thermostat to work.

The additional relay, takes the "Call for heat", W terminal and creates a complement signal. Not call for heat. The Not call for heat closes the valve.

A mercury switch stat is difficult to blow up. The fuse I pointed out is a good possibility. A transformer burning out is another.

Do what hvac100 has to say.

The new stat you have is not capable of controlling the system without a relay.

Dec 7, 2009, 09:33 AM
Here is another thread. Thermostat upgrade on 3 wire hydronic system - DIY Chatroom - DIY Home Improvement Forum (http://www.diychatroom.com/f17/thermostat-upgrade-3-wire-hydronic-system-13735/)

Some of the Hneywell Vision Pro thermostats work too from the same source I gave you. http://www.ntsupply.com/files/products/69-1896EF.pdf Note the stuff on Series 20 in the document. The setup may be too intimidating for you. It's a complex thermostat.

Remember I gave you a link to an $80 zone valve thermostat.