Boiler with Honeywell RTH2300B1038

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  #1  
Old 11-14-13, 06:19 PM
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Boiler with Honeywell RTH2300B1038

Hello everyone,

I attempted to upgrade the old mercury thermostat to the honeywell programmable one. When I disconnected the previous thermostat is had three wire connections red, yellow, and white with an additional green wire in the wall unconnected. I read through the manual and tagged what color wires were connected to which terminal (since the wire colors didn't match the connection) and proceeded to make the connections to the honeywell thermostat. I verified all the connections and turned on the controller. The programs seemed to work the first few days (or I wasn't pay attention too close) but not it seems like the thermostat temperature is reading high. It is set at 65 most of the time. When we looked at the temperature today it said that the room was 79. It felt a little warm but I didn't think that warm. So we are wondering if there is a compatibility issue or maybe something is wrong.
  • The thermostat is on a wall with no radiant vent on it so it shouldn't be getting heated more then the room would be
  • We read up that for heat only systems that you may need a relay. is this true?
  • Should the green wire be connected since it wasn't connected previously?
  • Can a boiler be controlled with a simple honeywell programmable thermostat?
  • How would you test the thermostat or boiler?

Thanks in advance
 
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  #2  
Old 11-14-13, 08:09 PM
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We read up that for heat only systems that you may need a relay. is this true?
Did you read that in the thermostat manual? If not, where?

Should the green wire be connected since it wasn't connected previously?
No.

Can a boiler be controlled with a simple honeywell programmable thermostat?
Of course.

How would you test the thermostat or boiler?
Before getting to this, you should tell us what terminals the three wires were connected to on the old thermostat, and what terminals you connected them to on the new thermostat.
 
  #3  
Old 11-15-13, 06:38 AM
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Did you read that in the thermostat manual? If not, where?
It was not in the manual. We read it on a site online for boiler heating.

I tried the connection without the green wire and it still seems like it is always on. We left the thermostat at the off position all night and it stayed at 75 all night at the off setting.


Before getting to this, you should tell us what terminals the three wires were connected to on the old thermostat, and what terminals you connected them to on the new thermostat.
I always take a picture on my phone for reference for this.
There was the following connections on the old circle thermostat.
Thermostat terminal letter -> Wire color
R -> Black
W -> Red
Y -> Yellow
And there was no green used but there was one disconnected in the wall. I tagged all the wires with the provided tags from the new thermostat to what they were connected to. I made all the connections to the new thermostat based on these tags. I left the switch to gas/oil type furnace that was on the back on the thermostat. There is a jumped from R to RC that I left in place. I have tried the green wire as both connected and not connected. The batteries are brand new so is the thermostat.

The thermostat has all the settings required for a gas/oil type furnace both hardware and software wise. The other rooms are still analog and work correctly.

So at this point I am still thinking its a wire issue, temperature reading issue, or a furnace issue.
 
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Old 11-15-13, 07:05 AM
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It was not in the manual. We read it on a site online for boiler heating.
In SOME cases an 'isolation relay' is needed, but I see no reason why your system would need one.

Thermostat terminal letter -> Wire color
R -> Black
W -> Red
Y -> Yellow
What are these wires connected to at that BOILER end of the thermostat wire?

I'm not sure why the yellow wire was needed... what was the make/model of the old thermostat?

Do you own and know how to use a multimeter?
 
  #5  
Old 11-15-13, 12:07 PM
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What are these wires connected to at that BOILER end of the thermostat wire?
Ill have to look when I get home.

I'm not sure why the yellow wire was needed... what was the make/model of the old thermostat?
I will also have to look when I get home. I believe it was an old round honeywell but I need to look up the part number.

Do you own and know how to use a multimeter?
Multiple meters and scopes. Electrical Engineer by day....not a very good HVAC/Electrician by night.
 
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Old 11-15-13, 01:13 PM
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No spectrum analyzer? I'll need to know the 3db points of the thermostat filter.

I probably should have asked this earlier...

Are there multiple zones? If so, what make/model are the zone valves. Probably should know the make/model of the boiler and the aquastat installed on it also.
 
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Old 11-15-13, 06:09 PM
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So i thought I would post on here what I have done and discovered.

So I have 3 zone valves with my boiler. They are White Rodgers 1311. So I did the following to diagnose my system.
  1. Checked to make the 24V transformer. All three zones had this
  2. Verified the wiring from the zone valve to the thermostat. It did and the green wire wasn't used
  3. Checked the open voltage when the signal was on. It worked fine and read as 24 volts as it should have.
  4. Check the closed voltage when the signal should be off. This is where the issue was. The close voltage would be 24V but the open voltage would still be roughly 12V. This would make the valve always be somewhat open and cased the valve to heat because of the motor voltage for open and close
  5. Switched the old thermostat back in and everything went back to normal

So after all that work and possibly looking into having someone come out ($99 for the visit, $150 for diag, $300-$500 to change out the zone valve) it just turned out to be a thermostat incompatibility. So I am glad I saved money but now I am on to the next step.

I either need to find a thermostat that is compatible (which how do I determine this?) or I need to possibly add a relay or some other circuit to control this bad boy. Any final ideas or something I could have missed?
 
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Old 11-15-13, 07:25 PM
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They are White Rodgers 1311
I don't have to read any further than this.

Wish you had told us that first, could have saved some time.

The 1311 is a THREE WIRE ZONE VALVE and the thermostat you have will NOT work with those zone valves, but I guess that's what you've learned tonight.

The 1311 is 'power open, power closed' while almost all other zone valves are 'power open, spring return to close'.

The Honeywell FocusPro 6000 series will work with 3 wire as long as it's configured properly.

There are others, but you need to look specifically for one that works with 3 wire.

You COULD wire up a SPDT relay if you wanted to use 2 wire thermostat.
 
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Old 11-17-13, 05:47 AM
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Thank you for all of the assistance!

I am investigating both options to see what I can find.

I am also trying to understand the 2 wire system. I see that my system has 3 wires (red, white, and yellow) so I guess what do you mean by 2 wires? I know one is hot and the other two determines what to click on but I think this is the assumption that one does heat and one does air which wouldn't be the case. So that just leaves me with just red and white for heating. So based on that this diagram should be the right. Control a 3-wire zone valve with a 2-wire thermostat | [Observations of a geek.]

Do that seem right and am I making the right assumptions?
 
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Old 11-17-13, 07:58 AM
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I know one is hot and the other two determines what to click on but I think this is the assumption that one does heat and one does air which wouldn't be the case. So that just leaves me with just red and white for heating.
No...

The 1311 is 'power open, power closed' while almost all other zone valves are 'power open, spring return to close'.
MOST zone valves used today use 2 wires and they supply 24VAC to the valve open mechanism, whether it's a standard 'synchronous motor' or what is called a 'heat motor'. Either way, when 24VAC is applied to the motor, the valve is opened.

When 24VAC is REMOVED from the motor, the valve closes under spring return.

The W-R 1311 and a couple other zone valves require 24VAC to OPEN, but ALSO require 24VAC to CLOSE. Upon removal of the 24VAC from the valve it will REMAIN OPEN. There must be power applied to the correct terminal to close the valve.

Yes, a three wire thermostat is more expensive, probably due mostly to demand.

The diagram's terminal designations may not correspond to the 1311 terminals, so you can't wire exactly from that... give me some time and I'll take a look to let you know what terminals to connect to.
 
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Old 11-17-13, 08:51 AM
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Try this Greg..................

 
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Old 11-18-13, 06:29 AM
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Greg, I think my drawing may have the NO and NC connections reversed.

I'll double check and fix it later and repost if necessary.


Scratch this... it IS correct as drawn.
 

Last edited by NJT; 11-18-13 at 06:37 PM.
  #13  
Old 11-24-13, 06:31 PM
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Ok, sorry for the delay. Took a week off because of painting and some smaller projects. Thanks for clarifying everything.

One last question, looking at ordering the relay. Is there a recommended pole and throw configuration (single pole, double throw, etc...)?
 
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Old 11-24-13, 07:07 PM
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You only NEED a SPDT (Single Pole Double Throw) but you can use a DPDT and simply not wire the second pole. You NEED DOUBLE THROW though.

This one from White Rodgers will work:

90-293Q - White Rodgers 90-293Q - Fan Relay, Type 84, 24 VAC Coil, SPDT. Coil Data: 90 Ohms DC Resistance, 125 mA (Nominal), 3 VA (Nominal), 4 VA (Inrush)

But ANY relay with 24VAC coil and SPDT contacts will also work.
 
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Old 01-11-14, 11:16 AM
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Revival Question

Hello Everyone,

Finally after 2 months and the Christmas season we were able to get a relay. I have one last question that I am not sure of...what do I do with the yellow wire? It is currently connected to 5 on the zone valve (where the NC connects from the relay)? Do i leave this disconnected since this is a boiler system or what is the purpose of it? From reading I am under the impression that the yellow wire is for cooling so would this be left unconnected for the boiler system?

Everything else is wired up and ready to go.
 
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Old 01-11-14, 01:24 PM
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what do I do with the yellow wire? It is currently connected to 5 on the zone valve (where the NC connects from the relay)?
Better double check your wiring. The NC from the relay goes to SIX , NOT FIVE.

You only need the wires shown in the diagram.

There should be only TWO wires coming down from the thermostat. The YELLOW should NOT be connected at the thermostat. The YELLOW should NOT be connected to the zone valve or the relay.

At your new thermostat, you should connect wires to ONLY the R (which is jumped to Rc) and the W terminals. Suggest use RED on the R and WHITE on the W.

DO NOT CONNECT THE GREEN AND YELLOW.

Connect the RED (R) wire from the thermostat to terminal FIVE on the zone valve.

Connect the WHITE (W) wire from the thermostat to one side of the relay COIL.

Other side of relay coil goes to terminal ONE on the zone valve.

Relay C goes to 5 on the ZV

Relay NC goes to 6 on the ZV

Relay NO goes to 4 on the ZV
 
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Old 01-11-14, 01:29 PM
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From reading I am under the impression that the yellow wire is for cooling so would this be left unconnected for the boiler system?
Your OLD thermostat was a THREE WIRE thermostat. The Yellow wire in that thermostat cable had been used as the third wire to control your three wire zone valve.

With modern thermostats the color YELLOW is generally used for A/C system COMPRESSOR, that's why you are getting confused. You don't need or want the yellow wire connected to anything.
 
  #18  
Old 01-11-14, 01:39 PM
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Thanks for the reply. I had a typo, everything is wired correctly. Thank you for the response and explanation. One thermostat down, two to go!
 
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