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Old 12-19-2014, 01:21 PM   #1
sacto929 OP
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HVAC -- Repair, Rebuild or Replace?

Perhaps there are some HVAC experts in the asylum who can shed some light for me. I have aging HVAC systems in my residence and at my rental property. I am wondering about the pros and cons of continuing to repair issues as they creep up, more complete rebuilds or wholesale replacement of said units.

Residence:
2 units, Coleman L8T08016UHB11A and L8T06012UHA11A
~12 years old
Maintenance tech says the blower motors are getting old, with the smaller one leaking oil, and the hot surface ignitor on each one is turning white.
Quote to replace blower motor: $710
Quote to replace HSI: $156 each
Parts per repairclinic.com: $195/$154 for blower motors and $35 each for HSI

Rental:
Can't find the model and specs at the moment, but I'll update later...
~18 years old
No furnace problems that I know of, but the evaporator coil freezes up in the summer and was told that the compressor contactor and capacitor need to be replaced. Price was going to be ~$400. It costs me ~$250 to have them come out to fix the evap coil situation.
Parts, IIRC, were around $90 total.

As I write this out, I seem to be making up my mind to due the work myself, but as with many folks, I have very little free time as it is. My questions to our expert panel are the following:
  • Are there any special tools required to do this work?
  • Are there any special precautions I need to take, other than turning off the power first?
  • Are there any particularly helpful books or websites to review first?
  • What am I missing?

On the replacement option, I don't know what these systems cost, but I'm guessing in the neighborhood of $8000-12000 each. I don't have that coin laying around and would really like to delay replacement as long as practical.

Thanks in advance!
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Old 12-19-2014, 01:36 PM   #2
troidus
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I though evap coil frosting was from low refrigerant level.

AFAIK, the only reason to replace the air handler is if the firebox burns through and you can't get parts any more. My Lennox set is from 1991 and is still plugging away. I just wish it were quieter with the fan running.
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Old 12-19-2014, 05:09 PM   #3
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I've often wondered about this myself. I have a 10 seer Rheem heat pump with propane backup that is 14 years old. It got it's ass run off in the winters for the first 5 years, but the house stays naturally cool in the summer so a/c usage was light. After the first 5 years it didn't run nearly as much because I installed a pellet stove and primarily used it to heat the house. But after 10 years I moved into another house and now only use the place for weekends/vacation, so the heating system is once again being relied upon to keep the house from freezing as it sits through the winter. I set the heat on 52 and generally burn about 250 gallons of propane per season keeping the house from freezing. Since I don't live there It is unknown how much the heat pump runs because the propane backup kicks in at 34 degrees and the compressor shuts off.

I'm a maintenance fanatic and have replaced the capacitor once & the contactor twice. I clean the igniter and flame detector every year and clean the condenser coils every couple of years. I've cleaned the injector nozzles once and there was no appreciable buildup. I generally clean out cobweb buildup on the circuit boards both inside the furnace and outside of the house in the compressor housing. Since I drain the plumbing and fill all the traps/toilets with RV antifreeze before I lock the place up each winter it's not an absolute tragedy if the place freezes, but I'd rather not have to go there. I keep wondering if at some point I should just replace the entire system before it fails, or if I should just wait until a failure that isn't worth repairing occurs. If I should replace the entire system before it fails, how long should I expect it to last?
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Old 12-19-2014, 05:47 PM   #4
Walterxr650l
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No special tools are required for replacing things like a blower motor, Contactor, capacitor, or Hot surface igniter. Some nut drivers and screw drivers, should be all you need. Maybe some wire strippers and crimpers, if you need to change any of the wire connectors.

Quote:
Originally Posted by sacto929 View Post
Maintenance tech says the blower motors are getting old, with the smaller one leaking oil, and the hot surface indicator on each one is turning white.
If you mean the Hot surface igniter,

Those are very brittle. They are easily broken if bumped, or bumped into something when while installing them. I don't think I would replace an igniter that was still working, but I do think that having a spare on hand would be a good idea.

If you meant the Flame sensor.

Any white corrosion on this can usually be cleaned off with some fine sandpaper or emery cloth and it will be fine. Just be careful not to bump the igniter while you do this.

On the refrigeration side of the system, (frosted up coil), special tools (and license) are required to work on it.

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Old 12-19-2014, 08:27 PM   #5
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Quote:
Originally Posted by Bueller View Post
I've often wondered about this myself. I have a 10 seer Rheem heat pump with propane backup that is 14 years old. It got it's ass run off in the winters for the first 5 years, but the house stays naturally cool in the summer so a/c usage was light. After the first 5 years it didn't run nearly as much because I installed a pellet stove and primarily used it to heat the house. But after 10 years I moved into another house and now only use the place for weekends/vacation, so the heating system is once again being relied upon to keep the house from freezing as it sits through the winter. I set the heat on 52 and generally burn about 250 gallons of propane per season keeping the house from freezing. Since I don't live there It is unknown how much the heat pump runs because the propane backup kicks in at 34 degrees and the compressor shuts off.

I'm a maintenance fanatic and have replaced the capacitor once & the contactor twice. I clean the igniter and flame detector every year and clean the condenser coils every couple of years. I've cleaned the injector nozzles once and there was no appreciable buildup. I generally clean out cobweb buildup on the circuit boards both inside the furnace and outside of the house in the compressor housing. Since I drain the plumbing and fill all the traps/toilets with RV antifreeze before I lock the place up each winter it's not an absolute tragedy if the place freezes, but I'd rather not have to go there. I keep wondering if at some point I should just replace the entire system before it fails, or if I should just wait until a failure that isn't worth repairing occurs. If I should replace the entire system before it fails, how long should I expect it to last?
I used to work in HVAC, I have been out of it for over 10 year; but here is my take on that.

As long as that heat pump's refrigeration system is tight, (you aren't having to ad refrigerant every year or two), just keep doing what you are doing. If you ever have a failure that requires cutting into the refrigeration system to fix, think about replacing the whole system at that time. A good tight system can last a long time, and a new system wont automatically be more reliable. You may at some point want to go to a higher efficiency system, but it doesn't sound like you are using it enough for the payback on that to be very quick.

Walter
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Old Yesterday, 08:17 AM   #6
kfsinc
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See my answers in line with your questions. As always, YMMV and you are getting what you pay for. That said, I was an HVAC tech in a previous life.

Quote:
Originally Posted by sacto929 View Post
Perhaps there are some HVAC experts in the asylum who can shed some light for me. I have aging HVAC systems in my residence and at my rental property. I am wondering about the pros and cons of continuing to repair issues as they creep up, more complete rebuilds or wholesale replacement of said units.

Residence:
2 units, Coleman L8T08016UHB11A and L8T06012UHA11A
~12 years old
Maintenance tech says the blower motors are getting old, with the smaller one leaking oil, and the hot surface indicator on each one is turning white.
Quote to replace blower motor: $710
Per your pricing below, motors aren't that expensive. The new fangled super efficient blower motors don't pay out so skip them. Make sure you get the exact replacement size and mounting (frame), and the exact connector. That will save you lots of hassle on the install. Figure two hours for the first one and one hour for the second one if you do it yourself. It's an easy job if you're semi-competent mechanic.
Quote to replace HSI: $156 each
Parts per repairclinic.com: $195/$154 for blower motors and $35 each for HSI. I wouldn't be in any hurry to replace the HSI, but would have one or two in stock. Maybe an hour for the first one, and less for the second one. Buy the part on line.

Rental:
Can't find the model and specs at the moment, but I'll update later...
~18 years old
No furnace problems that I know of, but the evaporator coil freezes up in the summer and was told that the compressor contactor and capacitor need to be replaced. Price was going to be ~$400. It costs me ~$250 to have them come out to fix the evap coil situation.
Parts, IIRC, were around $90 total.

If the contactor is getting weak, I'd replace it. Weak contactor can lead to fire or bad compressors. Capacitor failure could be caused by the bad contactor. Both are pretty easy to fix. Be carful of that capacitor, they can bit you . Freezing evap coil is a symptom of leak, poor airflow caused by dirty filter or coil, bad expansion valve, and a few other maladies. The $250 fix is probably worth the money given it's a rental.

As I write this out, I seem to be making up my mind to due the work myself, but as with many folks, I have very little free time as it is. My questions to our expert panel are the following:
  • Are there any special tools required to do this work?

    Nope, as mentioned below, a nut driver would be the only thing. Volt meter would be nice. The refrigerant work (on the rental) will require a licensed pro so as to keep the EPA happy.
  • Are there any special precautions I need to take, other than turning off the power first?

    Don't let your tools cross the terminals on that capacitor, it might spark.
  • Are there any particularly helpful books or websites to review first?

    I'm sure there are youtube videos showing how to replace blower motors.
  • What am I missing?

    Give them all a good vacuuming out and general cleaning.

On the replacement option, I don't know what these systems cost, but I'm guessing in the neighborhood of $8000-12000 each. I don't have that coin laying around and would really like to delay replacement as long as practical.

From what you've said above, I see no need to replace them.

Thanks in advance!
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Old Yesterday, 10:10 AM   #7
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Quote:
Originally Posted by Walterxr650l View Post
I used to work in HVAC, I have been out of it for over 10 year; but here is my take on that.

As long as that heat pump's refrigeration system is tight, (you aren't having to ad refrigerant every year or two), just keep doing what you are doing. If you ever have a failure that requires cutting into the refrigeration system to fix, think about replacing the whole system at that time. A good tight system can last a long time, and a new system wont automatically be more reliable. You may at some point want to go to a higher efficiency system, but it doesn't sound like you are using it enough for the payback on that to be very quick.

Walter
Thanks for the response! Since I've never had to add any refrigerant I'd consider the system to be tight. I know when I replace it I'll be looking at a considerable upgrade since we've finished another 1200 SF since building the house (when the original system was installed). Assuming it's reasonable to keep the existing system I'd rather not incur what I know is going to be a very expensive upgrade until I have to.
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Old Yesterday, 11:28 AM   #8
sacto929 OP
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Quote:
Originally Posted by Walterxr650l View Post
If you mean the Hot surface igniter,

Those are very brittle. They are easily broken if bumped, or bumped into something when while installing them. I don't think I would replace an igniter that was still working, but I do think that having a spare on hand would be a good idea.
Yep, this is the part I meant. I misread the maintenance tech's handwriting. That was also the part that showed up from my Google search...thanks for the correction.
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Old Yesterday, 11:35 AM   #9
sacto929 OP
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Quote:
Originally Posted by kfsinc View Post
See my answers in line with your questions. As always, YMMV and you are getting what you pay for. That said, I was an HVAC tech in a previous life.
Walter and Karl, thank you very much for the helpful replies. I would consider myself reasonably competent with wrench, or nut driver in this case. I just like to gather as much information as possible before undertaking a new project.
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Old Yesterday, 12:14 PM   #10
kfsinc
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Quote:
Originally Posted by Bueller View Post
Thanks for the response! Since I've never had to add any refrigerant I'd consider the system to be tight. I know when I replace it I'll be looking at a considerable upgrade since we've finished another 1200 SF since building the house (when the original system was installed). Assuming it's reasonable to keep the existing system I'd rather not incur what I know is going to be a very expensive upgrade until I have to.

You may have a new leak - check the lines very carefully, or you may have a very slow leak and finally reached the 'too low' level of freon so that it's now freezing up. The only way to know is with a gauge set. Be aware that if you do have it checked and they need to add freon, it will be expensive. R22 is being phased out and has sky rocketed in price.

Take a very close look at airflow over the coil -- if a return or supply duct got blocked, the fan is running too slow (two speed fan running on slow speed?), or the coil is dirty, you will get ice. Note that checking the indoor coil is a big PIA in most cases. Allow an hour or more.

Also check the airflow over the condenser coil (outside). The coils need to be relatively clean and free of dirt/leaves/gunk. Make sure the condenser fan is running.

A quick test for problems is to check temperature drop over the indoor coil. Measure the temp of return air and supply air, close to the air handler. It should be in the 15 to 20 degree range. More or less indicate problems.

By adding 1200 sq feet you've significantly changed the cooling load. If the original system was sized correctly you will need a new/bigger system to handle the greater space.

Good luck!
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Old Yesterday, 03:24 PM   #11
Bueller
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Quote:
Originally Posted by kfsinc View Post
You may have a new leak - check the lines very carefully, or you may have a very slow leak and finally reached the 'too low' level of freon so that it's now freezing up. The only way to know is with a gauge set. Be aware that if you do have it checked and they need to add freon, it will be expensive. R22 is being phased out and has sky rocketed in price.

Take a very close look at airflow over the coil -- if a return or supply duct got blocked, the fan is running too slow (two speed fan running on slow speed?), or the coil is dirty, you will get ice. Note that checking the indoor coil is a big PIA in most cases. Allow an hour or more.

Also check the airflow over the condenser coil (outside). The coils need to be relatively clean and free of dirt/leaves/gunk. Make sure the condenser fan is running.

A quick test for problems is to check temperature drop over the indoor coil. Measure the temp of return air and supply air, close to the air handler. It should be in the 15 to 20 degree range. More or less indicate problems.

By adding 1200 sq feet you've significantly changed the cooling load. If the original system was sized correctly you will need a new/bigger system to handle the greater space.

Good luck!
I think you may have confused the posts - I've never had a heating or cooling problem. I was just trying to figure out when I should replace a nearly 15 year old system. Being an ex auto tech I do have a leak detector, gauges, and an evacuation pump, and could likely deal with a leak if I had one. Though I haven't priced it, I believe you about the cost of R22. We went through the same thing with R12 in the car business.

You are correct that I'm going to have to go bigger when I do replace it, but mainly for heating - not cooling. The house is in the woods and is built into the side of a hill and generally doesn't need a lot of help staying cool. But nonetheless, I'm trying to heat over 3500 SF across 2 floors and suspect I'm going to be looking at dual systems when I upgrade. My main complaint with the existing system is tired air at the ends of the longer duct runs and inconsistent temperature across the house. The lower level is always cold in the winter despite being well insulated.
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Old Yesterday, 07:29 PM   #12
BillsR100
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I had the HVAC replaced in my house about 2 years ago. 5 ton unit, approx $8,500
Previously I completely replaced the AC in my Dodge Dakota truck myself. It works great.
I thought about replacing our home HVAC myself after doing tons of reading and watching HVAC install videos on youtube. I realized that the operation principal and methods for replacing a home HVAC is very similar to replacing the one in a car (especially evacuating the system, knowing how to read the vacuum gauges) which I previously did successfully.
When the AC guys came to my house, I helped them for 2 days doing the replacement of the entire blower unit (heat and air) and the outside compressor.
I could have done it myself and kinda regret not doing it myself, If you lean or know how to use/read the vacuum guages, know ho to read a simple volt meter, it wasn't that technically difficult, but like I said, I learned by doing it on my truck.

Edit: I forgot to mention, our old HVAC was 20+ years old, my HVAC bills were almost cut in half after the replacement with a new modern one. I was surprised.
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