Do I need to have this redone? Should I? Attic Installation LG Low Static Ducted Heat Pump

ChrisJ

What I've been told is that excessive static pressure is known to burn up ECM motors.

I have no idea if it's true or not.
But I would treat it as it is, because the cost isn't cheap or even reasonable to replace an ECM motor. And if your ductwork exceeds the spec the manufacturer calls for and they check it, you're up a creek.

Last I knew, an ECM blower motor for my air handler was $800 vs $100 for a normal one. Again, not a pro, and my numbers could be far off but to my knowledge they aren't.

KC_Jones

Curious if there has been any further developments on this? Any resolution?

Mustangman

We have installed just one low static unit. The word low static is key. I looked up the submittal for the low static and I think someone is not being up front with you. Set from the factory minimum external static 0.10 WC and Maximum static .20. Not sure how your tec came up with his numbers.

Mustangman

One thing about low, medium and high static ductless unit. They are exactly as stated. The low static is 300 cfm and low static so you really don't feel much air movement. That's the complaint I have had. The mid and high static units I haven't had a problem at all. The future is now leaning toward ductless outdoor heat pump matched with a full size air handler you would use with a regular split system.
Its actually not a hard sell. You are getting great SEER and HSPF you get with a ductless system, but with an air handler that can heat and cool a 3,000 square foot home. The catch with ductless systems, they have no back up heat. A full sized air handler can be fitted with electric heat so if your outdoor unit stumbles a little, in the very cold weather, it stays warm inside.

pecmsg

ECM motors Surge under high static. 1st they'll free spin because they can't grab enough air then less than a second later, they bog down as the TESP pressure decreases. Constant fast and slow all over less than a second. This tears up the electronics and the motor.

GGross

Yup makes you wonder if the installers thought the static pressure didn't matter, what exactly they thought the words LOW STATIC meant in the description. The wall control also wants you to set the TESP (total external static pressure) on set up

pecmsg

They don’t know and don’t care. 

Get the job
Get it in as quickly as possible
Get the check and leave. 

pedmec

What model number do you have?

centralMA

No resolution. The most recent email from them:
“The ducted system was checked and our tech confirmed that everything is operating correctly. If in the future there is a problem during the warranty period and we find a part(s) failure due to improper materials, manufacturer defect or improper installation then the failed part(s) will be covered at no cost to the homeowner."

Basically them saying they are done working with me on my concerns. No one else has come out since the tech I posted about on March 4th. They took a couple weeks to get back to me and I have been figuring out how I am going to move forward.

My model number is LDN127HV4. I am uploading its specifications submittal.

An employee I talked to from another company (off the record) said they should have put in a mid-static unit. Others have suggested that online. I am uploading submittal of what I think would be that mid-static unit (LHN128HV1). It has the same size nominal cooling capacity of 12,000 Btu/h. The heating capacity is 15,000 Btu/h which is 1,200 Btu/hr higher than low static unit I currently have (15,000 vs 13,800)
I have an 18,000 unit downstairs and a multi 30,000 unit outside.
This mid-static unit has a Maximum external static pressure of .59 inches water column! Wow. If that was what was installed, there would be no static pressure issue? It is 10lbs. heavier and rated amps are 1.7 vs .8.

As an aside, the installation has kept the upstairs warm this winter.

GGross

The mid static units are rolling out to replace some of the low static units in the lineup. They could have chosen that model, but they wouldn't have known why they were picking it, just that the supplier changed the model number on them lol.
Likely they just get lucky with functional installs and lackadaisical building departments that aren't requiring a manual D (duct sizing), customers that don't know any better. Based on their response to you they aren't qualified HVAC installers, whether they are licensed or not, they lack the basic fundamental knowledge set to charge money for installing hvac systems, basically just down the road handyman level skillset.

did they pull a permit for this install at all?
are they actually a licensed HVAC company?

centralMA

Yes, mechanical and electrical permits were pulled and issued. Yes, Licensed. LG Platinum Pro Dealer. 4.6 stars with 221 reviews on LG site.
Vetted and recommended by both a local energy non-profit and a local for-profit energy consulting company.
It has recently come to my attention that the company changed ownership in 2021; possibly playing a role in why the work is so bad but the reputation is so good.

I understand that installing the correct ductwork to get the low-static unit to operate below maximum E.S.P. is a costly project. I am wondering if advocating to replace the low-static unit with a mid-static unit is more cost-effective. I am going to be using a mediation service provided by the attorney general's office next. The company can voluntarily engage or not so we will see what comes of it.

centralMA

Update…

I have had three companies come to give me quotes on what it would take to rectify the installation. Lowest at $5,150. Highest at $10,692. While there is consensus on the fact that the low-static unit cannot stay as is, different companies took issue with other different things and proposed different solutions.. 

The owners of one of the companies that came out, coincidentally, used to run the operations for the company that did my crap installation. Apparently, when that company was sold in 2021, the first thing the new owner told them to do was to add three crews. They already had 5 which they thought was a good number to maintain quality control. But the new owner (some business guy, not an HVAC guy) wouldn’t hear it. Anyway, after working for him for a year they bailed and started their own company because he was terrible. So how about that.

Unfortunately they didn’t seem to understand what external static pressure meant. I was trying to educate them but it wasn’t working. They kept saying they needed to “build the static pressure” to push air through the system. Regardless, they want to switch out the low-static for a mid-static, and from how they are describing they would redo the ductwork (and some photos online), regardless of whether they understand static pressure, it seems like the work they will do will make it a moot point. 

The other company I am considering going with definitely does understand static pressure but seemed less tuned into smaller mistakes.

Next step is to get the original company to pony up the money for me to pay one of them to make the changes.

centralMA

I asked the company to cover the cost to have other contractors fix the installation; $10,000. They asked for info on what needed to be addressed so I sent them the below email. And then I sent them a second one I'll post into the next comment.

Hello,

The required repairs/changes/corrections include:

Install a mid-static unit in attic (replace the low-static unit)
Install proper plenum transitions
Increase return grille size
Fix drain line
Remount 1st floor head so it is level
Install wired remote thermostat for 1st floor handler
Repair/restore attic damming and insulation

Amongst other things.

I have consulted with multiple professional sources about this low-static unit and the high static pressure of the system. The unit and ductwork need to be changed to have an air handler unit in the attic that is operating within its design parameters.

“External static pressure is the measure of resistance in the ductwork. The maximum external static pressure is set to help make sure that you are delivering enough conditioned air to rooms served by your ducted system. This helps both with comfort and the proper function of the equipment and contributes to the system’s energy efficiency. If the external static pressure exceeds the maximum, that means you are introducing more resistance into the system than the heat pump is prepared to handle. This will make the heat pump need to work harder…”

The external static pressure of the ducted system is above the unit’s “Maximum External Static Pressure”.  Therefore it is not operating within its design parameters. The external static pressure is too high for the ducted unit. The compact-ducted unit is operating outside of design parameters--with consequences for energy efficiency and equipment performance.

centralMA

Second email:

Hello,

I have attached the estimates for the work to be done.

In my last email, I talked about the external static pressure issues. In this email I am including some details on the first floor unit and remedies required. 

We are not contesting that the sizing of the unit is adequate for the size of the first floor. And we agreed to accept a level of temperature unevenness on the first floor.

What we did not agree to accept is a wall unit that constantly short-cycles and is unable to heat even the room it is located in. That possibility was never discussed with us as a risk.

I know now that the thermistor on the wall unit is on the upper right hand corner of the handler. Which is tucked into the corner of the room. Prior to the installation I had no idea about where the thermistor would be and how it would impact the performance.

We are still willing to live with uneven heat distribution, which is why we are pursuing the option of running a wired remote thermistor to a more central location.

Like I said, the problem is not that the kitchen area or the area by the front door was uncomfortably cold. It was explained to us that those areas might be a few degrees cooler (I should say, that even if that were the case, to expect an extreme difference of 5+, 10+ degrees was certainly not communicated to us. Up to 5 degrees difference at most. More like 2 or 3 degrees difference. In any case, that is not the actual problem at this point.).

The problem is twofold.

One (1) problem is that during milder temperatures, the unit will repeatedly turn on and very quickly turn off before turning on again (short-cycle).

A second (2) problem is that the room where the air handler is located was not able to stay warm when it got cold outside (around 32 degrees and lower). This is even when we set the unit to its highest set point of 86 degrees to avoid the short-cycling that occurs when set to a more reasonable target temperature (If we made the set point a more reasonable mid 70’s degrees, the short cycling issue would come into play).

Installing a remote thermistor would move the temperature reading out of the corner and into the center of the house, where it can assist the air handler in not immediately reaching its set point when it begins pushing air.

The second required part of the puzzle is to remove refrigerant charge, check for leaks and recharge to manufacturer’s specifications. There is every reason to justify taking this action. One justification is how many things were done wrong by the original installation team. In addition to the outstanding issues, the original team:

-left a leak in the return refrigerant line coming out of the wall unit

-installed a too-small-diameter of a return duct

-installed drastically under-stretched and overly-long ducts

Like I said, this is in addition to the outstanding issues.

It is extremely warranted, as proposed in the estimate we received, to remove the refrigerant charge, check for leaks and recharge to manufacturer’s specifications. Warranted by: 

(1) Some of the extremely obvious stuff that Endless Energy has identified (like how the attic drain line does not have enough pitch), and the other issues listed above, demonstrates an error-ridden (including very basic errors) original installation. This leaves no reason to have confidence in their refrigerant work, and every reason to doubt it;

(2) An already identified known leak;

(3) The existing performance issues and inability to keep the room warm.

Thank you,

P.S. Attached Estimates do not include verbal estimate of additional $300 for HVAC to purchase and program 1st floor remote thermostat.

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Fun! I am not optimistic they well respond favorably. At which point I guess I'll have to get a lawyer involved

KC_Jones

Thank you for the update!