Frigidaire FFRH0822R1 AC/heat pump - What causes the resistance heater to kick in?

[michaelbluejay]

Model Number

FFRH0822R1

Brand

Frigidaire

Age

Less than 1 year

I bought 12 Frigidaire FFRH0822R1 AC/heat pump units for a large rental house, partially because they're rated to use only 775W to make 7000 BTU/hr of heat, vs. resistance heaters which use 1500W to make only 5115 BTU/hr of heat. Besides being more efficient, the house electrical system can't handle the load of 1500W x 12 units. To support that kind of load, I'd have to upgrade the service panel and run more circuits, at considerable expense.

Well, now I find that these AC/heat pump units also include a supplemental resistance heater which runs at 1400W. (It's rated at 1290W, but I measured it at 1400W. The 110W difference could be for the fan.) So now I have that problem about the units drawing too much power. So the question becomes, what causes the resistance heater to kick in? If I know, then maybe I can prevent that from happening somehow.

I've called Frigidaire several times but their phone system always says they're too busy to take my call. I emailed them but haven't heard back. The auto-reply to the email said that in the meantime I could use the Support Chat feature on their website, but there's no actual link or button to initiate a chat.

Here are the hypotheses I had, all of which I had to discount:

IDEA 1: When the differential between the source air and the set temperature is very high, then *both* the heat pump and the resistance heater run simultaneously, to supply lots of heat.
HOWEVER: I tested it and they run one or the other, not at the same time.

IDEA 2: When the differential between the source air and the set temperature is very high, the resistance heater kicks in to supply more heat, and once the differential is a smaller amount, then the heat pump kicks in.
HOWEVER: That doesn't make sense, because the heat pump generates *more* heat than the resistance heater.

IDEA 3: In my test it took 30 seconds for the heat pump to start blowing warm, and another 30 seconds for it to start blowing hot. So, the resistance heater might start the show, so the user feels some hot air and doesn't think the unit is broken, and then the heat pump takes over after a few minutes.
HOWEVER: Sometimes when I turn on the unit, the resistance heater never kicks in, only the heat pump runs.

I'm stumped.

 

[Dan O.]

FFRH0822R1

That model number may be incomplete. There may be more letters and/or numbers on the end. I found 7 different versions are starting FFRH0822R1__. Did you get it right off the appliance's model number ID tag.

I've called Frigidaire several times but their phone system always says they're too busy to take my call. I emailed them but haven't heard back.

It's unlikely Frigidaire's customer service would be able provide that information. Frigidaire does have a technical assistance line but it is only available to their factory service agents with a dealer ID number.



I do not know the answer to your timing questions. If you post one of the unit's complete model number I'll see if I can locate a service manual which hopefully would describe its operation.


Failing that, maybe you can just disconnect the electric heaters?

Dan O.

 

[michaelbluejay]

Amazon lists it as FFRH0822R1 and if you Google that there are a gazillion hits. One nameplate says FFRH0822R1E1. I didn't check every nameplate, I assume they're all the same.

I have the manual, it says nothing about how/when/why/how long the resistance heater kicks in.

I don't know how to disconnect the resistance heaters, and even if I did, they might be crucial to the operation of the unit somehow. (e.g., The heat pump might never come on unless the resistance heater can do its thing for some period of time or difference in temperature.)

 

[Dan O.]

Amazon lists it as FFRH0822R1 and if you Google that there are a gazillion hits.

That is the base model. It tells the basics about its features, chassis type, 8,000 BTUs, etc, but nothing specific to the exact model you're dealing with. It doesn't make a difference to Amazon (or any other dealer) if it's version 1 or version 10 while it might make a difference in specific details about it.

LINK > Frigidaire FFRH0822R1 Documentation

One nameplate says FFRH0822R1E1. I didn't check every nameplate, I assume they're all the same.

If they were bought at the same time from the same supplier, that is very possible. Yes.

I have the manual, it says nothing about how/when/why/how long the resistance heater kicks in.

You likely have the Owner's Manual that gives basic instructions for usage not the Service Manual that describes details of how the system is designed to function so it can be serviced affectively. Unfortunately I could not find any Frigidaire a/c service manuals newer than 2008 so I can't find out the specifics for that model anyway.


You may have to contact a Frigidaire factory authorized service depot or the selling dealer to see if they have access to that information (if there is even a service manual for it, there sometimes isn't). As I said, I'm quite sure Frigidaire customer service won't be able to help with what you want to know.


Dan O.

 

[Dan O.]

I don't know how to disconnect the resistance heaters,

A resistance heater is a piece of wire that heats up when power is applied to it (like a toaster). There will be 2 wires to power it. Maybe a technician could disconnect the heater on one of the units and test its operation?

If you were hoping to change the programming on the unit's electronic control, I think that is very unlikely.

JMO

Dan O.

 

[michaelbluejay]

Thank you very much for your help. It was more like, if the resistance heater is supposed to kick in only when there's a difference in the room and set temps of ≥4°F, then I could use a lower set temp, and then increase it as the room temp catches up.

I think I need the resistance heaters for those rare super-cold days when the heat pump can't extract enough heat out of the outside air, I just won't be able to run all the rooms simultaneously in that case.

 

[Dan O.]

It was more like, if the resistance heater is supposed to kick in only when there's a difference in the room and set temps of ≥4°F, then I could use a lower set temp

That's something a service manual would often describe, the detailed functioning of the control system. As I said, I can not locate a copy of the service manual for it. An authorized factory service technician might has access. I'm pretty certain just the customer help line wouldn't have access to such details.

In my test it took 30 seconds for the heat pump to start blowing warm, and another 30 seconds for it to start blowing hot. So, the resistance heater might start the show, so the user feels some hot air and doesn't think the unit is broken,

I did notice that the sales info for that model describes it as "Low power start-up conserves energy" so as not to stress an electrical supply.

When the compressor starts it draws the most current. I'm sure they wouldn't want both the compressor starting and the electric heater being on at the same time. So it would likely have to have the compressor for the heat pump start first and then the electric heater kick in after... even if the heat pump would be slower to get hot.

Either that or it could start with electric heat, turn off the electric heat while the compressor was starting and then turn the electric heat back on again... or not, depending on conditions.

I don't know if that knowledge helps you or not.

If the electric heater function had to be disabled most of the time, a manual switch might be able to be added to still allow the heater's use in very cold situations when needed. Alterations to the unit would however likely void its warranty.


Dan O.

 

[michaelbluejay]

Motor and compressor surge happens for a fraction of a second and doesn't stress an electrical supply in any meaningful way, except that some AFCI breakers are sensitive to it and could trip. There's also no energy savings from reducing the draw for a mere fraction of a second.

Once when I turned on the unit, the resistance heater started and the compressor didn't. I gradually reduced the set temperature until the compressor kicked in. I know it kicked in because there was an audible "bang" and the draw reduced from 1400W to around 700W, and the unit had an audible vibration/hum.

Another time I turned the unit on, the compressor started the show, with no resistance heater.

In the first case, I didn't think the problem would be that the differential between the room and the set temp was too high, because I powered on the unit and chose heat and it didn't start heating, presumably because the room was already warm enough. I gradually increased the temperature by 1°F at a time, and when it finally started heating, I got the resistance heater, not the heat pump that I expected.

I know front-line customer service reps likely won't have the answer, I was hoping they could escalate the request to engineering.