Heat Pump aux heat staging

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  #1  
Old 10-14-07, 08:44 PM
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Heat Pump aux heat staging

My brain is tired I am working on a Rheem 3 ton split system with a 2 stage 15kw auxilary heat package. I am using a honeywell focus pro 5220D 2H 2C t-stat. What I would like to do is have the auxilary be 5kw to kick in when the heat pump cannot maintain set temp by two degrees which is exactly how the t-stat operates now so no problem there, 5kw line is hooked to the aux terminal. My problem is that I would like to utilize all 15kw for emergency heat (this is where the problem is at) I can hook the line for 10kw up to the E terminal and that will work fine to get me 10kw but how can I utilize the other 5kw when the stat is set to emergency heat. The stat has a L terminal but it is always hot in emergency heat not just when the stat is calling for heat. I am thinking about adding a relay to L terminal that will tie the 5kw and 10kw wires together and then I can feed the power from E terminal line when the stat is calling for heat. Is there a better easier way. I am probably over thinking the whole thing Help. Note: 100 amp disconnect at the air handler services both the condensor 30 amps and the backup heat coils 60 amp 10kw and 30 amp 5kw. It would kick the 100 amp breaker at the main if I use all 15kw for auxilary while the heat pump is running. But of course in emergency heat mode I could utilize max backup heat coils If I could figure out how. I do not want to pull new service the main panel is full and the routing area is inaccessible anyway.
 
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  #2  
Old 10-15-07, 10:23 AM
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The additional relay will definitely work. That's all you need is a single pole, double throw relay with a 24 volt ac coil.

Although there are several ways to do this. I would connect one wire of the relay coil to the "L" terminal and the other to the transformer common.

Remove the wire that currently connects to the stat's "w2" terminal, and connect it to the relay contact's "common" connection. (NOT the transformer common)

Connect one end of a new piece of wire from the relay's normally closed (n.c.) connection and the other end to the thermostat's "w2" connection.

Connect one end of a new piece of wire from the relay's normally open (n.o.) connection and the other end to the stat's "y2" connection. You will now have two wires connected at "y2". The one you added here and the existing emergency heat control wire.

In this setup you will not trip the breaker because all heat strips only come on in emergency heat setting. The stat locks out the compressor in this situation.


Good luck !!!
 
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Old 10-15-07, 06:48 PM
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You are killing yourself on this..

Wire as you plan on, and when the home owner turns on Emr Heat, the t-stat will power up the Aux, about a min later, it will then power up E.. Both heat will be on.
 
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Old 10-16-07, 07:16 AM
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Wink

What did I miss here??? When you go to Emergency heat the 30 amps at the compressor should not be on????? That L on a Rheem is for the malfunction light
 
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Old 10-16-07, 07:30 AM
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PS, L on Honeywell is for the Red LED light letting you know there is trouble like Ed has stated.
 
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Old 10-16-07, 07:07 PM
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Jay and everyone thanks for the replys. I quess I will have to do some checking on the honeywell t-stat sequence of operation. I will look at it this weekend when I have time. From what I was seeing the E G and L terminal (not the aux) are the only ones hot when the t-stat was in emergency heat mode (no power to aux) now I am wondering if maybe the t-stat will energize the aux terminal if the temp differential is greater than two degrees or something. Anyway I hate that the honeywell people do not include in the box a complete sequence of operations booklet for the t-stats they sell. Maybe I can find something online somewhere or worst case I will do some electrical checks to see exactly what it does do in the emergency heat mode. I will post back results but it will probably be sunday night as I am working 6 days a week you guys have a good week.
 
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Old 10-16-07, 08:17 PM
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I put my meter on the Vision Pro, and took a reading with it set up in Heat pump mode w/ Aux heat.

I don't recall on how much of an off set I had.
 
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Old 10-17-07, 10:23 AM
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Originally Posted by Mr Fixit View Post
Jay and everyone thanks for the replys. I quess I will have to do some checking on the honeywell t-stat sequence of operation. I will look at it this weekend when I have time. From what I was seeing the E G and L terminal (not the aux) are the only ones hot when the t-stat was in emergency heat mode (no power to aux) now I am wondering if maybe the t-stat will energize the aux terminal if the temp differential is greater than two degrees or something. Anyway I hate that the honeywell people do not include in the box a complete sequence of operations booklet for the t-stats they sell. Maybe I can find something online somewhere or worst case I will do some electrical checks to see exactly what it does do in the emergency heat mode. I will post back results but it will probably be sunday night as I am working 6 days a week you guys have a good week.

now you have me curious. can you post the complete HW model # ? and also what stat are you removing?
 
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Old 10-18-07, 06:19 AM
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Anyway I hate that the honeywell people do not include in the box a complete sequence of operations booklet for the t-stats they sell.
Sometimes the instructions are vague, or are missing certain information. In some cases the information is wrong, especially on a few of the intermittent pilot controls.
 
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Old 10-18-07, 01:00 PM
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new honeywell focus pro 5220D t-stat daddyjohn on a new 3 ton heat pump split system. Old system was already removed when I got there. I will not be back there until Sunday after church to check it, I simply wired it so that aux pulls in the 5kw heat coil relay and the E terminal pulls in the 10kw for right now. Was interested in utilizing the entire 15kw for emergency mode but ran out of time the other day. It had me scratching my head. If the honeywell 5220D does not energize the aux terminal in emergency heat mode I will either need to use a differnet t-stat (3 stage?) or maybe use a relay like a Mars 685744-90370 switching relay SPDT. Looks like the following wire routing might work with the relay to get me 15kw in emergency heat mode plus isolate any back feed to the t-stat (which may not be a problem anyway). 10kw existing relay to new relay terminal 2 - 5kw existing relay to new relay terminal 4 - t-stat terminal L to new relay terminal 1 - common to new relay terminal 3 - t-stat E to new relay terminal 5 and finally t-stat Aux to new relay terminal 2. Dont want to buck across the trans and burn it up so need to be careful with all that no doubt.
If you dig out some sequence of operation info for this honeywell focus pro 5220D t-stat please let me know. At this point I am planning on doing field checks to verify which t-stat terminals are active in each mode, the supplier is no help as they just changed from Heil to Rheem products and have only sketchy factory info from the Rheemote site. Not Much Help LOL thats what mr fixit told me to tell you
 
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Old 10-18-07, 03:27 PM
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Let me ask my friend at Honeywell, and see what he says on the FocusPro. I"ll post back.

I tested it on a VisionPro, and turned on Emrg heat, Aux first came on, about a min later E powred up.
 
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Old 10-19-07, 01:22 PM
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I shot an e-mail over to Honeywell, and this what I got back.

In Emergency heat mode--E terminal is 1st stage heat and Aux terminal is
2nd stage heat, compressor (Y and Y2) is locked out.
 
  #13  
Old 10-19-07, 02:46 PM
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yup jay you are exactly correct I was at the supply house today and picked up a honeywell Vision Pro 8320 It actually powers up the E terminal first then IF YOU HAVE ENOUGH PATIENCE and wait about a minute the Aux terminal powers up so I would have to assume that the focus pro 5220D does exactly the same thing, everything appears to be good LOL. Should work great just the way it is wired Thanks for your help everyone I certainly picked up some info on t-stat operation, this was quite a exercise. Still wish the t-stat manufacturers would throw a bit more info in the box though for people like me that need it in laymans terms. I gotta work on that patience thing I quess. And I will certainly be checking that focus pro out on sunday afternoon you will hear about it if it is different but I am betting everything is good now. Thanks for confusing the issue saturn
 
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Old 10-19-07, 06:52 PM
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:-) Glad to help you out!

We are here for one another.
 
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