Goodman heat pump runs continuously

In spite of a number of topics related to this subject, I don't believe I came across my specific situation. Happy to be pointed to an existing thread.



I have a Goodman heat pump. I recently discovered that it is running continuously in heating mode. It will heat up to the set temp and continue to run without increasing the temp until you see on the thermostat that the room temp drops one degree then it heats back up to the set temp. The thermostat will continue to display that it is heating. If I do decrease the desired temp to lower than the room temp, it will turn off. I have recycled two breakers in the fuse box associated with the heat pump, the breaker at the condenser, and the reset button on the thermostat. I have also switched the fan setting from auto to on to auto again. It also appears to me that the thermostat recognizes when it hits the set temp from a switching sound in the thermostat. Please let me know if there is any additional info that could help troubleshoot this or if you have any thoughts on the cause. Thanks.

 

Welcome to the forums.

You could try removing the stat from its base to see if problem goes away. If it does.... you have a stat issue. But more than likely that won't stop the blower which means you have a stuck sequencer for the electric heat. The sequencer is a timer/relay combination that turns the electric heat on and then the blower on with a call for heat. When the call ends... the sequencer turns off the heating coil and then the blower. It appears it may be stuck with the blower on.

Post the model number of the inside air handler.

 

Pete,
Thanks for the feedback. I'll try the stat suggestion and let you know. Question about the sequencer. Is this associated with the emergency heat? The mode I'm running in when this occurs is not when the emergency heat is on or even needed for heating. This is during heating using the heat pump itself. I just thought I'd confirm that. I will follow-up with the model number. Thanks again.

Walter

 

The sequencer is active when in E heat or AUX heat. AUX heat is activated when the room temperature is 3 or more degrees below the stat set point.

 

Well that's interesting and weird. Because this is happening just when the room temp varies 1 degree from the set temp. So for example, I set the temp for 65. The room will heat to 65. The fan keeps running and then eventually the room temp drops to 64 and then the room heats up to 65 again, and then the same process all over again. So would the E heat be active in this scenario? Sorry, just want to make sure you have all the right info.

Walter

 

If you can lower the set temperature and the fan stops. That would be a thermostat issue. Removing the thermostat from the base would confirm that.

 

Pete,

So I'm not sure I can accomplish what you are suggesting for the stat. The base is mounted to the wall and just acts as an attachment for the faceplate and board. See attached. I don't think you are suggesting I remove the board from the faceplate?

Also, I believe the model number was originally on the fan housing, but it is no longer legible. I did provide a photo of the entire assembly and the wiring diagram. I hope this helps. This is vintage 1998 stuff. I replaced the fan a few years ago and maybe a starter capacitor at some point. Otherwise it is working fine. I'd appreciate your thoughts.

Walter

 

Try just removing the G wire.

 

Pete,

So I removed the green wire on the thermostat and put it to the test. I set the desired temp to 66 with a current room temp of 64. After about 4 minutes, the temp hit 65. Another 4 minutes it hit 66. Then 10 minutes later it hit 65 and thereafter it toggled back and forth between 65 and 66 roughly every 20 seconds until I decreased the desired temp one degree after watching it do this for about 20 minutes and then it turned off. Does this help? Thanks.

Walter

 

Here's a scenario that could explain the symptoms:
-heat pump runs but doesn't satisfy the set point after 30 minutes (say)
- thermostat activates AUX heat because of the elapsed time or when temperature is 2 degree (say) below set point
- room warms to 1 degree (say) below set point, causing AUX to shut off because that's the way your particular thermostat works
- room cools because heat pump alone can't do the job
- repeat this never ending cycle

Depending on your thermostat you might be able to adjust the AUX temperature differences - or prevent AUX completely by disconnecting the control wire or disconnecting the AUX heater, to see if this could be what's happening .

If this is what's happening, you can get a different thermostat to hold AUX on until set point is reached - or ...

 

I appreciate the feedback. If it is actually being heated with AUX heat, which my thermostat provides no indication, would the compressor fan still run in this mode? In my current situation, the compressor fan currently runs. I was assuming that would be true when it is not in AUX mode (or defrosting). Also, my thermostat does not provide for changing the AUX range. I was really hoping that I could determine the actual cause of my problem as the heat pump otherwise has been working fine for heat over the years. Is it possible the thermostat is failing to control the use of AUX heat rather than needing to change the range? Or maybe there is a component in the control circuit that has failed? Thanks.

 

So I did a quick experiment. I set the thermostat for Emergency Heat and turned on the heat. The condenser fan did not run and the thermostat does display that it is in Emergency Heat mode. The display never reads Emergency Heat when it is not in that setting. Wouldn't that be the case if it was being used as has been suggested in the earlier posts? And if so, does this suggest that my issue is with something other than the Aux mode? Thanks again.

 

Correction. The compressor fan did not run.

 

AUX iliary heat is just that - it augments the heat pump when the heat pump alone, after running for a 'while' fails to meet setpoint or when the temperature difference between ambient and setpoint is more than a 'few' degrees ...

You'd like to know if the Auxiliary heat is cycling on and off while the heatpump is running. Can you try one of these ?
- measure the AUX signal to see if it is indeed cycling
- disconnect AUX and see if heatpump alone will do the job
- disconnect AUX heater " " "

-

 

Decent stats bring on the aux heat based on temp and heat loss, not a fixed timer.

It's normal for heatpumps to run continuously in cold weather since capacity is reduced at lower temps.

When it's slightly too cold for the heatpump to keep up on it's own, the temperature will drop a little until the aux heat comes on to bring the temp back up to setpoint.

Heatpump continues to run.

There's this idea that a heating system is there to "warm up the house" to bring it up to setpoint and shut off.

This is wrong.

The real purpose is to maintain the setting by running to supplying heat at an equal rate to heat loss. For the temperature to rise, there has to be surplus capacity, for temperature to drop, heat loss exceeds heating capacity.

Cycling happens when there's too much capacity for the load; the unit has to shut off to prevent overheating the space.

In your case, the heatpump supplies most of the heat that's needed at a lower cost than straight resistance heat, and what it can't provide - the heat strips supply by drawing a heck of a lot of current.. (often 60+ amps when on vs 8 to 15 amps for most heatpumps)


If your house is losing 25 000 btu/hr at 32 F outside and the heatpump is supplying 20 000 btu/hr, the temperature still drops slightly until the supplemental heat cycles on.

But the heat strips only need to supply 5000 btu/hr so may only need to be on a few minutes each hour.

Which saves a lot of energy despite having the heatpump run continuously.



If you don't like the temperature dropping before the aux heat comes on, you could get a good quality honeywell thermostat that works based on rate of change instead of temperature differential. Honeywells bring on the second stage of heat before the temperature drops enough to notice it.

This all being said:

It's possible your heatpump has a problem that has reduced its capacity, leading to more aux heat usage and a higher balance point.

Depending on the capacity of the heatpump and heat loss, you may start needing backup heat anywhere from 25 to 40f outdoor.

If you're using aux heat in the 40s or 50s, something's wrong.

Emergency heat mode is only for use when the heatpump is broken or it's brutally cold (think 10f and below).

The stat tells you it's running in emergency heat mode so you don't forget and get hit with a very high electric bill.

In normal mode, the stat may say aux heat on or something when the backup is on, or in some cases may not indicate anything.

 

This is all really awesome info. Many thanks. Additional data points to add are that this has been happening even when the outside temp is above 40. Also, the thermostat has not indicated that it is in emergency heat mode and the compressor is running the entire time (which I assume it wouldn't with the emergency heat on), and the heat pump never behaved this way before. Bottom line, I don't believe that I am using aux heat, so I'm guessing that either something is wrong in the control of the heat pump (maybe the thermostat) or there is some electrical component in the control circuit that has failed. I may just go the route of replacing the thermostat.

Is there anything in particular to look for in a new thermostat to ensure it is compatible with my system?

Again, many thanks.

 

I don’t the no the thermostat is the problem, and we surely don’t want to start replacing random parts and guessing.
Has the charge in the heat pump been checked by a tech?

 

It seems clear that your heat pump is not , well, pumping enough heat. Whether you want to attribute the system ability to maintain but not reach set point to AUX is up to you, but it'd be easy to prove or debunk ...

 

OK. I'm convinced. I will have a tech come out. Thanks.

 

It sounds like it's lost capacity.

The thermostat replacement would only be necessary if you want the aux heat brought on sooner without a noticeable temperature drop.

Yah, if there's a problem -> need to fix it. Needing aux heat above 40 is pretty bad.

The behaviour described is normal when there isn't enough capacity, either due to it just being too cold outside for it to keep up or due to an actual problem.
----------------------
Emergency heat mode should shut the heatpump off and run 100% elements. You may have a controls wiring problem, heatpump shouldn't be running when it's manually switched to emergency heat.

it should when calling for normal aux heat.

 

So after two visits by a tech, a leak has been confirmed in the outside condenser assembly. Given that the unit is about 20 years old, refilling it with refrigerant is not an option as a temporary solution. Replacing the heat pump seems to be my only option.

I assume that there probably is a thread on here with recommendations on heat pump manufacturers. The folks I am dealing with have quoted a Payne two ton unit based on my request that I did not want to buy the premium model. I'd appreciate it if someone could point me to a thread and will take any/all other advice. Thanks!

 

Read here on brands

https://www.angieslist.com/articles/...vac-brands.htm

 

When you buy a new heatpump, focus on the heating capacity numbers.

Some heat better than others. Ask for BTU/hr at 47f and 17f.

Efficiency is important, but what's more important is minimizing aux heat use.

Probably the best bang for the buck is a 14 seer/8hspf heatpump paired with an air handler with a ecm blower motor which nets 15 seer/9hspf.

The only downside is the ecm motor is expensive to replace after warranty. So if you're worried about repair costs single stage 14 seer with a regular blower motor in the air handler is the way to go.

Look for something with a sound blanket and high and low pressure switches to shut it down when there's a problem - prevents compressor damage.

You can also look into a unit with demand defrost which defrosts the outdoor coil only when really required vs every 60 or 90 minutes whenever the coil is at freezing or below.

Going from an older unit you should see a significant reduction in operating costs.

Let us know what you end up with.

 

Well the quotes are in and thought I'd share in case folks might be interested. I limited the quotes below to 14 SEER.

Installer #1
Amana/Goodman - $6148
Carrier (25HCE424) - $7226

Installer #2
Trane - $7429

Installer #3
Carrier - $6245

Unfortunately installer #3 did not provide the model # so it's hard for me to know how it stacks up with Installer #1. I will ask just to ensure I'm making an apples/apples comparison. Installer #3 also provided a quote on a Carrier 16 SEER for $6700 that seems tempting.

Any/all thoughts/comments appreciated.

 

If the contractor won't provide full model numbers and ratings, find another.

Need full outdoor unit and indoor models, kw of heat strips.

Ratings to compare -> cooling capacity, heating capacity and cop at 47f outdoor, heating capacity and cop at 17f outdoor, hspf.

SEER ratings not that important in a heating dominant climate and 16 seer may not be much better than 14 on the heating side.

cop is kw of heat delivered divided by kw of energy consumed.

You have to look at the heating performance data to do a good comparison.

There are also differences in how the units are made, quality and you won't know if it's a builder's quality unit or not.

There are differences in installation practices too, the contractor needs to properly braze protecting service and txv valves from heat, flow nitrogen to stop oxidization at the connections.

Need a proper vacuum pulled with micron gauge, need airflow set correctly for your duct system (duct system needs to be checked at quote to see if it can flow enough air for size of heatpump), proper charging techniques. (following manufacturer's instructions, using their charts, not just by pressure)

For a heatpump its more important to get a good install than for straight a/c.