I have 2 Lenox systems slightly over 3 years old. These are XC21 & XC15 AC units with G60V gas furnaces. When we experience a power outage, it is very difficult to reset the units so that the air handler works. The last outage caused one of the G60V units to fail. The tech has ordered a new motor and control module. These units are on surge protectors. What is happening here and should I be expecting the other unit to fail? At the young age of these units, I didn't expect to be needing replacement and repair. Are other owners reporting similar problems?
Type of HVAC: Other
Tech has diagnosed and parts are on order.
All work to be done by licensed professional. WE KEEP GOING UNTIL YOU HAVE THE INFORMATION YOU NEED, I come and go. This is step ONE.
Welcome to Just Answer, there are no time limits with me, we can discuss this as long and in as much detail as necessary.
The basic issue is that a surge protector plugged into the wall next to the Furnace must be able to pass current to run the blower motor... and that not sensitive enough to protect the 24volt printed circuit card and its processor chip.. thats the problem
Its worse in some areas than others depending on the local grid, and any factories on the same power lines and lightening strike issues
A multi stage approach to surge protection is best.
I will post some links
Outages occurred before the surge suppressor was installed and resets were always difficult. The AC would start up, but the air handler would fail. Usually, flipping the circuit breaker would work. The last outage was when the power company replaced the transformer not a lightning strike.
There are a dozen different options, including asking the power company to fit surge protection into your meter for an added charge of $5 a month or so... but its a manual reset when it trips you have to call in the utility.
We can begin by looking at the link above.. just to get oriented.
Beyond that much smaller capacity surge protection can be attached to the 24 volt control transformers on your AC units for more or less bullet proof protection against spikes.
We haven't addressed why it is so difficult to get both the AC and the air handler to work together following a power outage. So far, the AC units always come up without an issue. I will look at the link now.
We can discuss these issues in as much length as necessary.. it is just that typing on more than one issue a time gets confusing.
Basic data on electronic controls... they are fragile... any electrical surge can cause temporary or permanent disruption.. these are micro electronic circuits inside the chip... the 'wires' are only a few atoms of copper or gold wide.. invisible to the naked eye...and not field diagnosable.
These issues are diagnosed by a process of elimination... if the control card has the inputs it needs verified, and is failing output the proper signal called for when those inputs are active..then replacing the control cures the problem in most cases.
Surges in power can damage the micro circuit solder connections. these can heal sometimes as current arcing across them can regenerate the connections. That is the sort of thing you are looking at with many but of course not all inexplicable electronics failures
that damage is about a tenth the diameter of a human hair... the picture is an electron microscope scan of a typical damaged wire in a micro processor.
If the damage does not go all the way across the wire, it can sometimes heal. such damage is cumulative however.
The printed circuit wires you can *see on the card, merely connect the outputs of the micro circuit chip to the edge of the card where the heavier inputs and outputs connect.
I will contact a licensed electrician regarding whole house surge suppresssion. In all but the most recent outage I did not experience equipment failure, and then only one unit. I have had several issues associated with a power outage, with no equipment failure and reset by circuit breaker. I haven't had outages caused by lightning strikes. Just ones due to downed lines, disconnect to replace the transformer. Would these types of startup be any different than resetting the circuit breaker? My non-Lennox neighbors aren't having this issue.
It is the chip you are protecting with surge protection... a surge protector big enough let heavy power pass into the home to run motors, is not fully sufficient to protect these micro circuits even though they can help significantly.
Even the smaller surge protection that you may have your furnaces plugged into are often inadequate.
A circuit breaker offers virtually no surge or spike protection, it will only trip in extreme cases after the damage has long since been done to the electronics in the house.
Regarding the electrician, about 10% are up to speed on how and why to do whole house surge protection and why... a much lower percentage are up to speed on how to protect microcircuits as the level I've mentioned. Same is true for HVAC technicians. You need a truly good man to handle your surge protection needs... Ive done that for living. and can steer you in the right direction.
None of this involves pat answers or solutions though.. its tricky business, with false claims for devices, and with failure prone surge protection devices on the market.
I believe that you are saying that my units are very fragile and get hurt by any outage. It would seem that this should be a wide spread problem. I believe you, but none of my neighbors have had my problems.
To address your question regarding the neighbors AC units not failing while the Lennox units are failing.. here is a summary..we can dig into the details later.
The more features, bells and whistles on a system the more it can be profitably sold for, Lennox targets that market.
The more complex features the more failure prone the system is
Some units on the market have no electronics at all in the outside unit, and just minimal electronics in the furnace inside... the higher efficiency the furnace the failure prone it tends to be.
I get it. How should I proceed?
Other factors are the utility company transformers, these can suffer from lose connections... the neghbors may be on a different transformer... its a virtually endless list.
How to proceed, start with whole house surge protection. Hire a world class electrician to install it.
Thanks. I guess I'm living on borrowed time with the second unit.
I'm ready to accept. Just waiting for your final reply.
How to proceed, start with whole house surge protection installed by a superb electrician who knows all about whole house surge protection and can discuss the limitations issues relative to the electronics as I have been discussing....
The final reply arrives after you have a full and complete answer.. thats still in progress
Protecting the printed circuit cards in the HVAC units can be done by having the 110 volt x 24volt transformers in each furnace wired to a cord with a cord cap (plug) on it... and plugging it into a computer surge protector.. so that the furnace now has two plugs, its original plug that used to power everything in the furnace...but now powers everything *but the transformer.
It seems to me that Lennox should have implemented this approach as a standard feature.
Here are the economics issues... in todays competitive market, a manufacturer can net $200 to maybe $500 net profit on a furnace and condensing unit
The failure prone printed circuit cards on the other hand can be made in China for less than 5 or 10 dollars, sold wholesale to the unit manufacturer for $30 to $50 and retailed for $250 to $400..and the entire stock kept in a shoe box.
Its a bit like ink jet printers... spectacular performance for sure.. cost under $200... but you will spend that much per year in ink cartridges once you get locked in by buying the printer.
Todays modern furnaces have many such components.
The fan relays for instance used to be separate items $7.. it took 5 minutes to change one. now they come soldered into the printed circuit card... one hour to diagnose, half hour to change, and $250 or more for the part.
There are all kinds of issues with the single plug in computer surge protector... the lower the amperage rating and faster it acts to 'clamp' any spikes the better it is... a good computer store carries them. You want one made for 110v and under 5 amps total load, with a clamping voltage under 400 volts... the microseconds it takes to clamp is crucial... you are looking for the shortest time possible. The buy that one and try it.
If you get one thats good for 20 or 30 amps...it will not offer good protection to your control card.
Thanks. Do you have anything else to add?
To maintain your warranty get Lennox approval
You can stay in touch for follow up later on the same dime if needed.
Retired HVAC/ Electrical & Boiler contractor. Industrial