Rheem Heat pump not heating, wont shut off

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Old 01-24-13, 07:02 PM
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Rheem Heat pump not heating, wont shut off

Bought this house less than a Year ago, this is our first winter here and it has a new Rheem Heat pump with back up or aux electric unit as well..Had a few problems early on in the season where we didnt have heat. Would shut the entire system down and restart it and then we would have heat. Yesterday same problems, no heat, alot of times the aux heat would be on as well, when it did finally reach the theromstat setting it would not shut off...Called a local heating and plumbing company today and to say the least they had no idea of the workings of a heat pump. Told me everything was fine , needs to run to keep the the temp up...No Way...It does at time reach the setting on the thermostat but wont shut off, last night it ran from 8:30 pm till 11:30 am this morning.

Its a Rheem RPNL-036 JAZ with an electric aux heat back up system installed,any help?

Hate to call another worth less hvac company.

Oh it's also a Honeywell TH5220D theromstat
 
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Old 01-24-13, 08:56 PM
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In the subfreezing weather, the heat pump alone probably can't produce enough heat so the auxiliary heat gets activated.

Here's an example of how some thermostats activate auxiliary heat:
1) thermostat set at 70
2) temperature falls to 69, thermostat activates heat pump
3) temperature falls to 68 (because heat pump isn't enough for really cold outside temperature)
4) thermostat activates auxiliary heat to help out
5) temperature rises to 69
6) thermostat turns off auxiliary heat
7) if thetemperature rises to 71, then all shut off or... go to step 3

In other words the auxiliary heat is cycled off and on to help out but is not kept on long enough to satisfy the set point request.

THis could well be what's happening to you - to test, suppose you set the thermostat two degrees above where you really want the set point - for example if you want 70 set it to 72. This will force the auxiliary heat on - and the temperature will eventually reach 71, the heat pump will still run until you set the thermosat back to 70.

One cure is to get a different thermostat that does not turn the auxiliary heat off until the heat pump is also turned off, rather than when the temperature is closer to the set point. Or maybe your thermostat has a feature to control the auxiliary heat on / off characteristics - do you have a manual for it ?
 
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Old 01-25-13, 06:20 AM
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I looked the thermostat up online its a Honeywell TH5220D1029 I do have a nice PDF Manual that I pulled down from the Honeywell site. Has alot of details but I dont see where it can be set to turn and off the Aux heat unless I am missing something. It's extremely cold here this week around zero. Last night it would finally cycle a few times once I lowered the heat setting to 65 degrees, normally it will at some point reach the set temp but never shuts off..The aux heat was on last night until it reached the set temp but it wouldnt kick off until i lowered the set tempurature?
 
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Old 01-25-13, 06:26 AM
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this morning it appears that the aux heat isnt coming on..just shut the power off to the entire unit and then turned it back on again, theromstat is set for 68 and its 63 inside no aux kicked on? the heat pump and blower is running none stop.
 
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Old 01-25-13, 06:38 AM
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does emergency heat work ?
 
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Old 01-25-13, 07:04 PM
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how is the thermostat wired? Is it programmed for a HP with aux heat?
 
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Old 01-25-13, 07:39 PM
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Finally figured out a couple things, piece of insulation fell off the side and blocked the inlet of the blower, removing that helped however, also found there was a loose broken wire holder on the board which we resoldered and had to splice the wires to by pass the board for the aux heat to work, ordered a board today however now the aux heat works, direct wired to by pass the single stage aux heat now runs but now the unit wont shut off when it reaches temp. The Theromstat is wired for HP and aux heat, just wont shut off when it reaches temp????
 
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Old 01-25-13, 08:04 PM
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WHY WONT THIS UNIT SHUT OFF NOW THAT IT REACHES TEMPURATURE? Crazy, if you raise the set point it will heat up to that point but not shut off....!!!

Help!
 
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Old 01-25-13, 10:24 PM
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Does it continue heating PAST the setpoint? On most thermostats the thermostat will not shut off as soon as it shows the same indoor temp as the setpoint.
 

Last edited by hvactechfw; 01-26-13 at 12:49 PM.
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Old 01-26-13, 12:48 PM
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Possibly you misswired the AUX heat when you worked around the failed board - so that once energized it closes a relay which feeds back into itself .
Try disconnecting the splicing one wire at a time.
 
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Old 01-26-13, 03:38 PM
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I guess a couple things last evening it wasn't heating past the set point, it would however just keep runing and running, guess it was having a very hard time keeping up being it was 1 degree outside, around 5 am got tired of hearing it run none stop so i lowered it down to 65 degrees, the it strarted cycling correctly. Once I have the new board I should be all set, right now i have the first stage and second stage wired in (SPLICED) together as one heat as soon as it calls for aux they all come on at once, it also helped that it warmed up to 20 today.
 
 

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