Assistance with Selecting New Furnace/AC - Canadian TV, Computing and Home Theatre Forums
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Old 2019-06-15, 11:46 AM Thread Starter
 
Join Date: Jan 2005
Posts: 283
Question Assistance with Selecting New Furnace/AC

Thanks in advance for any assistance. Please feel free to comment on a single or multiple questions in this post.

The History: Purchased the house in 2009 from the original owner (built the house in 2007, lived in it and then flipped it). House is 2 story with a finished basement level – 3700 sq feet for top two floors. Original equipment is a KeepRite C9MPV125 Gas Furnace and a 4T Keeprite N2A3 13 SEER Air Conditioner. I have had both serviced annually since I have lived in the house, preventive maint replacement for minor issues on furnace and replaced a $600 part on the AC a couple of years ago. This season during the first heat wave about a week ago, we turned on the AC and in the am the house was still warm. There was no airflow from the registers which turned out to be blown capacitors on the ECM unit for the furnace motor. Repair estimate $1200 as the ECM is no longer available without replacing the motor. 2 weeks for parts availability. I should also add that there is usually a 3-4 degree difference in temps between main and top floor. We mitigate this by running the fan on constant in the summer when using A/C and wearing sweaters if required in the winter.

Questions:
1. Repair or replace furnace. I read that average life expectancy is 15 to 20 years but this never seems to occur…..in any case, with parts warranty expired it seems that parts will become harder to obtain. Is it worth repairing?
2. If I replace the furnace should I replace the AC as well. It is going on 13 years and I am expecting that it will start to be problematic.
3. Two Stage vs Modulating furnace (Ottawa area). I understand what each does and I am drawn to the potential to maintain constant temp specifically on the 2nd floor. Is this rational or am I falling for the hype?
4. Single vs two (or variable) stage Air Conditioning? Thoughts / Benefits? Hype?
5. Replace humidifier or re-use existing humidifier – I assume it should be replaced.
6. I have read and I think I agree that a reputable installer is more important than brand – got it. That said, thoughts on Lennnox Signature Series vs Amana/GoodmanAMVM97/GMVM97 vs KeepRite ProComfort Deluxe vs Napoleon 9700 Series?

Thanks again - Jason.

Last edited by jasonreg; 2019-06-15 at 12:05 PM. Reason: added detail
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Old 2019-06-15, 01:06 PM
57
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Quote:
Originally Posted by jasonreg View Post
1. Repair estimate $1200 as the ECM is no longer available without replacing the motor. 2 weeks for parts availability.

2. I should also add that there is usually a 3-4 degree difference in temps between main and top floor. We mitigate this by running the fan on constant in the summer when using A/C and wearing sweaters if required in the winter.
I hope the following comments help.

1. This seems high. Have you tried another quote?

2. Is this C or F? Some things to consider. Manually (or automatically) adjust the dampers in the ducting to increase airflow upstairs (decrease downstairs) in the summer (opposite in the winter). Consider a mini-split for upstairs. This may significantly reduce the power consumption. Our two-storey house is much smaller but we no longer run the central AC, relying on the mini-split in the upstairs hall to adequately cool our home. (I do run the central AC for an hour every couple of months just to keep it "lubed."

My 97% efficiency Airco HVAC system is now 29 years old and still running fine. We have had one minor repair over this time frame (vent motor). Newer stuff seems to not last like this. We added the Mini-split 10 years ago so that we needn't worry if the central HVAC had a failure and still haven't replaced the central. We run the central furnace in the winter during the day, but when we turn the thermostat down in the evening, it rarely runs with the Mini-split filling in overnight for our sleeping quarters, except for the coldest nights.

Running a fan full time adds hundreds of Watts to the A/C cooling load.

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Old 2019-06-15, 01:14 PM
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1. Lots of variables to consider and some unknowns. $1200 is an expensive repair. Assuming a 15 year life that's $600/yr. How does that compare to the cost of a new furnace? A new $4500 furnace works out to about $300/yr which would indicate replacing. Then there are efficiency savings.
2. If the external compressor unit has never been replaced then it is nearing end of life. I would replace under those circumstances.
3. A modulating furnace will provide the best comfort and efficiency. However, it will cost more and the extra efficiency compared to a two stage furnace will not provide great savings. It also will not solve the upstairs/downstairs issue. That will require upgrades to duct work or, preferably, a dual zone system. (Both very expensive.) Another work around would be to install a programmable thermostat that allows programming the fan. That way the fan would run continuously only when needed.
4. Similar to furnace.
5. Replace unless recently done.
6. Can't say as to brand. The product model is as important as brand since individual products can vary greatly in quality and reliability within a brand. An installer would know best since they have to repair the bad ones. Choose someone who has no brand loyalty.
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Old 2019-06-15, 02:44 PM Thread Starter
 
Join Date: Jan 2005
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@57 - agree the quote is high but it was the lowest of three quotes - part no longer in stock, must come from Tennessee and as a unit with a new (not required) motor - not much I can do. Temps in "C" - we do manage the vents as discussed - and it helps a lot but this is not a perfect system. I suspect that the air returns are not optimal though with a finished house there is little to be done in this regard. Mini-split is interesting - I will research that.

@ExDilbert - I agree with your first two points hence me leaning to a replacement of both systems. From what I read, I would have thought that a modulating system - since it will be running at a lower speed but more often - would help balance the temps - perhaps not then. Fully agree with the model comments. In all cases the versions I am looking at are (or are near) the top of their respective lines.
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Old 2019-06-15, 05:43 PM
 
Join Date: Mar 2006
Location: Port Stanley, ON
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Jasonreg

I've discovered that there isn't much long term reliability in any of the major brands of furnace units.

In our home, which was constructed in 1980, we've had top tier furnaces and we are now on our third which our HVAC tech has told us to start thinking about a furnace replacement. Sure, the major brands may advertise lifetime warranty on the heat exchanger, but it is almost as costly to disassemble a furnace in labor costs to replace a heat exchanger than it is to replace the complete furnace.

On a side note, our tech did mention that Rheem has the best furnace warranty of all makes on their top tier model.

Central A/C units usually last 20 - 30 years given routine maintenance as they don't see as much use. I once had a Lennox HS8-216 unit (2 ton) that lasted 38 years. It was running fine when we swapped it out. Only changed it out as it was inefficient.

HVAC stuff today has no long term reliability.

Delhi SFA 1483, Antennacraft Suburban VHF, CM7778
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Old 2019-06-15, 05:52 PM
 
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I had a Daiken air conditioner installed last year, came with twelve year parts and labour . I believe their furnaces come with the same.
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Old 2019-06-16, 09:19 AM
 
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Quote:
Originally Posted by buckycat View Post
I had a Daiken air conditioner installed last year, came with twelve year parts and labour . I believe their furnaces come with the same.
If you managed to get labor costs covered in your warranty, you did well. Most manufacturers will only pick up the parts cost on a 10 or 12 year warranty which costs a manufacturer diddly. But then again, most A/C units last 20+ years as they only see 4 - 8 weeks of use per year.

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Old 2019-06-16, 09:57 AM Thread Starter
 
Join Date: Jan 2005
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Thanks folks, very helpful indeed. I would appreciate the forum's thoughts/opinions (Pros/Cons/Reservations) about the following system:

Lennox SLP98 - 110000 BTU - Modulating Furnace
Lennox XC21 4T 21 SEER 2-Stage Air Conditioner
Lennox PC03S-16-16 - Pure Air System (Merv 16)
Lennox iComfort S30 Wifi Communicating T-Stat

It is high end to be sure but all opinions welcome.

Thanks - Jason
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Old 2019-06-16, 10:27 PM
 
Join Date: Mar 2006
Location: Port Stanley, ON
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Jasonreg

I have a high end Lennox furnace in my home. It is efficient and quiet. My G71MPP which just came out of the 10 year parts warranty last month has had the following replaced under warranty. Combustion air fan, Main board, 24 volt transformer, condensate drain trap.

I did some research and discovered Rheem has the strongest warranty in the business. Their R98V model comes with a Conditional Lifetime Unit Replacement warranty to the original purchaser and I also learned the heat exchanger in this model is removable/replaceable for serviceability. Some things to ponder if you intend to stay in your home longer than 10 years.

Here is a link to Rheem's warranty
http://cdn.globalimageserver.com/Fet...f-e2170d3f73fc

Delhi SFA 1483, Antennacraft Suburban VHF, CM7778
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Old 2019-06-17, 11:35 AM Thread Starter
 
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Helpful. Thank you.
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Old 2019-06-29, 02:49 PM
 
Join Date: Jun 2016
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Quote:
There was no airflow from the registers which turned out to be blown capacitors on the ECM unit for the furnace motor. Repair estimate $1200 as the ECM is no longer available without replacing the motor.
Considering the cost, I would be very tempted to try and repair the module - you have nothing to lose, would need a soldering iron and caps.

There's a current limiting thermister that can burn out if the ducts are undersized for the blower and it also replaceable - it should be checked.

I do find it very difficult to believe that the module alone isn't available. Call around and also see if the part is available online. The programming does have to match the furnace model though, not all parts with the same number will work.

Bad contractors will claim parts are not available to push you to replace - they make a lot more money on replacement than repair. The entire furnace at cost can be $1500 (maybe $2000 including materials) but a contractor will sell it for $4000 to $6000 installed.



-----------
As far as replacement goes, I think its a waste.

But if you insist, sizing needs to be considered. Where are you located?

125k btu is huge, even for a house of this size. A load calculation should be done and may reveal you only need 80k btu.

Modern houses have fairly low heat loss, heck even 1980s houses of this size in ontario used to heat on 100-110k low efficiency furnaces that have a rated output of 70 to 80k. 125k input at 96% has a rated output of 120 000 btu/hr -> huge!

Now if you're in a colder part of the country, you may actually need the BTUs of a larger unit.

You do not need to replace the a/c - a unit from 2007 is at least 13 seer which is pretty decent.
Even if you were to replace, there's little value in getting anything above 14 seer (which turns into 15-16 with an ecm equipped furnace) in canada.

To justify the XC21, you better be in the southern US.

Keep in mind, higher end units cost more to fix.

For a/c units, most 2 stage and variable machines have an expensive circuit board and ecm motor in the outdoor unit. The airflow is lower on low and cold air doesn't rise, so a 2-speed or variable capacity a/c can actually increase temperature differences between floors.

For furnaces, modulating uses a variable speed venter motor and the circuit board, a modulating gas valve. Repair costs will add up very fast out of warranty. Also, you have to use a very expensive communicating thermostat to take full advantage of the modulator. Think $500.

I think 2-stage, properly sized and controlled by generic 2-stage thermostat is the sweet spot, the best compromise between comfort and repair costs.

2-stage is available two ecm blower motor types - x13 and full variable speed. The x13 can be replaced with a generic ecm out of warranty, the fully featured variable speed automatically adjusts itself to get proper airflow as duct pressure changes, but is totally proprietary.

Mod is only available with variable speed.

Quote:
Lennox PC03S-16-16 - Pure Air System (Merv 16)
You don't need this unless you have severe allergies.

A MERV 8 media filter is good enough, its only there to keep the furnace and coil clean.
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Last edited by user_; 2019-06-29 at 03:13 PM.
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Old 2019-06-29, 03:17 PM
 
Join Date: Jun 2016
Posts: 77
Quote:
Amana/GoodmanAMVM97/GMVM97
Stay away from the high end goodmans/amanas, the manufacturer only allows for a 4-wire single stage thermostat and the staging is controlled by the circuit board exclusively. It's timed based on length of previous cycles and can only upstage, not switch between low and high.

The same style units are sold under the daikin name and aren't crippled like that.

The mod unit needs (*MVM96) the communicating stat to be used to its potential and modulate to match house heat loss.

The 2-stage (*MVC96) can do fine with a generic 2-stage thermostat.
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Old 2019-06-29, 06:54 PM
 
Join Date: Jun 2016
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Quote:
In our home, which was constructed in 1980, we've had top tier furnaces and we are now on our third which our HVAC tech has told us to start thinking about a furnace replacement. Sure, the major brands may advertise lifetime warranty on the heat exchanger, but it is almost as costly to disassemble a furnace in labor costs to replace a heat exchanger than it is to replace the complete furnace.
Honestly, the contractors are a huge part of the problem, inflating repair labour costs intentionally to make new equipment more attractive.

A heat exchanger replacement with the part under warranty shouldn't cost close to that of a new furnace.

It should be a few hours of labour at $100 to $150 an hour, maybe $600 to $900.

Your G71 should last 20 years if its set up properly and maintained.

It's absolutely disgusting how people aren't interested in repairing things any more - a pervasive problem.
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Old 2019-06-30, 09:09 PM
 
Join Date: Mar 2006
Location: Port Stanley, ON
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user_

What are your thoughts on Rheem furnaces and their lifetime unit replacement guarantee?

Delhi SFA 1483, Antennacraft Suburban VHF, CM7778
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Old 2019-07-01, 09:11 PM
 
Join Date: Jun 2016
Posts: 77
I'm not familiar with the warranty. I doubt full replacement includes labour, so it could cost $2000 to use the warranty.

I think rheem makes quality equipment for the money and know they use direct spark ignition which is better than hot surface. I'm not a technician though.

The down side of rheem is the stuff is all made in mexico - people who care about preserving middle class union jobs should not buy rheem.

Looks like daikin has the best warranty in the industry - 12 year parts. Made in the usa, and has more reasonable parts prices out of warranty than the rest. Down side - cabinet quality, it's a goodman product and while the parts inside may be good, the metal is probably very thin.

Rheem, lennox, trane etc likely heavier built.

Rheem and lennox have units that are sold in increments other than 40-60-80-100k btu -> great if in between sizes.
If 80k is too small, can get a 90ish k btu unit rather than jumping to 100.
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