Any HVAC Experts On Board? Lennox?

[npalen]

Have a new Lennox mini split AC/Heat Pump installed for our 12' x 14' sunroom that has glass on three sides. The problem is accurate control of temperature as it has to get two to three degrees above the set point before the AC kicks on. Then it will freeze you out until it gets a couple degrees below the set point before shutting off.

The unit can be "controlled" with the sensor in the inside air unit or the remote when set to "follow me" mode but the problem occurs with either. Had similar issue in heating mode this winter although the unit did heat well even with outside temp of -20F.

I have tried adjusting the parameter called "F7 cooling temp compensation" which the manual for the remote describes as being related to "stratification", but that doesn't seem to help.

Just wondering if anyone might have some insight here as I do appreciate feedback.

 

[AWSubie]

How many btu is the unit? It might be that ur unit is oversized for the room. But u can google sizing of heat pumps and do the calculations yourself to determine if that is the case.

 

[npalen]

Forgot to mention, it's a one ton (12K BTU) and I suspect it is oversized. The installer/dealer suggested an 18K BTU but looking at the calculations beforehand suggested that even the 12K would be plenty.
He felt that all the glass would require more BTU's

 

[mark in portugal]

is your thermostat set in a good place?
Maybe the wall it's on gets heat from the sun, or just has a lot of residual heat in it.
The air gets cold, you get cold, but the wall and thermostat gets cold later.

I've had this problem a couple of times.

 

[Midniteoyl]

I'm thinking minimum run and rest times.. ? Also, a lot of newer t-stats like to have the anticipater settings at 1.5* - 2* instead of the more normal .75* - 1*. Double check that..

edit: menagerie-manor beat me to it. Phone call while trying to edit

 

[Menagerie-Manor]

As suggested the T-stat location can be an issue but also look at the thermostat instructions and see if the stat has an adjustable anticipator which sets the rate of temp rise or drop and either turns the ac on or off base on the temp change rate.

 

[AWSubie]

Many air handler blower motors have low, medium and high settings that are controlled via a switch or “speed wires” (located at the blower, not the thermostat) that can be connected depending upon the season.

Your installer should not object to testing fan speeds for you to find the most comfortable setting.

 

[npalen]

CAC / BDP RG57F3(B) SERVICE MANUAL Pdf Download

View and Download CAC / BDP RG57F3(B) service manual online. Wireless Remote Controller. RG57F3(B) remote control pdf manual download. Also for: Bgefu1.

www.manualslib.com

This is the service manual for the remote control. I have adjusted the F7 parameter to -2 which seemed to help a little in narrowing the band.

The frustrating thing is that this is an expensive unit that has the inverter technology controlling the compressor which supposedly will smooth the operation.

I've taken amp readings on the 230VAC supplying the unit and am amazed at the low power consumption of 2.0 amps or less when cooling. We have only had 90F max days so far so will be interesting how it handles long 100F days here in Kansas.

I've tried a number of "tricks" by placing the remote in various locations for temperature sensing as well as using the sensor in the wall air handling unit rather than the remote.

I believe there is an ambient temp sensor in the outside unit that supposedly anticipates the amount of heating or cooling needed.

 

[Sigarms]

I believe there is an ambient temp sensor in the outside unit that supposedly anticipates the amount of heating or cooling needed.

I'm not familiar with Lennox's mini splits, as they are private labled made by someone else, and it's hard to keep track of who they are using (use to be Gree sp? last I heard was Media) but you are probably right about the outdoor sensor as I know Daikin, Fujitsu and Mitsubishi all have outdoor temperature sensors.

If you paid a contractor to install the job right the first time, may I ask why hasn't the contractor taken care of the issue?

Even the cheapest mini split you can find (which I wouldn't touch with a ten foot pole) has a inverter compressor.

Again, not familiar with what Lennox is now using, but generally, on a mini split, you can figure the compressor will run at 70% less full rated capacity, so if you have a 12k indoor unit, I doubt the unit is oversized as it should run as low only needing 3,600 BTU/h on a regular basis.

Installing contractor should call lennox, set up a online call meeting with the service tech at a designated time that he is out there to look at the operation, and they should be ready to take his call and go over any possible issues. Even going by what I call the "goodman" load calc, a 12k mini split seems like it should work.

There is a whole set of possible issues which you shouldn't be responsible for IMO and the installing contractor should take care of.

 

[npalen]

I'm not familiar with Lennox's mini splits, as they are private labled made by someone else, and it's hard to keep track of who they are using (use to be Gree sp? last I heard was Media) but you are probably right about the outdoor sensor as I know Daikin, Fujitsu and Mitsubishi all have outdoor temperature sensors.

If you paid a contractor to install the job right the first time, may I ask why hasn't the contractor taken care of the issue?

Even the cheapest mini split you can find (which I wouldn't touch with a ten foot pole) has a inverter compressor.

Again, not familiar with what Lennox is now using, but generally, on a mini split, you can figure the compressor will run at 70% less full rated capacity, so if you have a 12k indoor unit, I doubt the unit is oversized as it should run as low only needing 3,600 BTU/h on a regular basis.

Installing contractor should call lennox, set up a online call meeting with the service tech at a designated time that he is out there to look at the operation, and they should be ready to take his call and go over any possible issues. Even going by what I call the "goodman" load calc, a 12k mini split seems like it should work.

There is a whole set of possible issues which you shouldn't be responsible for IMO and the installing contractor should take care of.

Your feedback is greatly appreciated. Good to know about the 70%.
Part of the problem is this is only the second mini split the dealer has installed. He is responsive but a big part of the problem is Lennox support.
He had Lennox on the hold line for over an hour the day of installation with a question and never did get to talk to a tech. Also, my understanding is that Lennox doesn't provide adequate written service info to their dealers.

I told him that I would try adjusting the cooling temperature compensation which I did and he will call Lennox when I get back with him with the results. He is a good dealer, it's just hard to get info from Lennox.