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Will I benefit from a Lennox "modulating" furnace? Lennox vs Carrier vs Heil?

Will I benefit from a Lennox "modulating" furnace? Lennox vs Carrier vs Heil?


  #1  
Old 11-03-10, 06:10 PM
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Will I benefit from a Lennox "modulating" furnace? Lennox vs Carrier vs Heil?

Hello all,
We are going to be taking advantage of the great rebates on offer and replacing our 27 year old Whirlpool. We currently have bids on a Heil,Lennox and Carrier.

I had another company out today to give me a bid on a Lennox and they are going to price out a "modulating" SLP98UH (98.2 %eff Signature Collection)
The guy who was out claims it will help in distributing heat more evenly in our non zoned two story house. One main floor with a large finished walk out lower level. 3700 SF total. The guy was very thorough and professional in his inspection of our situation and his presentation. He brought up a few other issues other contractors had not. So, in short I was impressed with him.

Does anyone have any opinions on this model in particular and the claim that it could help with more even heat distribution in our home? Any comments on the worthiness of a modulating furnace vs a regular two stage? He will be emailing the bid in the next few days but I can sense it will be more expensive. Any thoughts will be greatly appreciated.

Regards,
wvdthree
 
  #2  
Old 11-03-10, 06:45 PM
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You may have a great dealer who was looking at things, and found them as well. I think they will be worth the extra money.

The Modulating furnace will give you the best comfort ever, and I've seen a lot great comments on modulating that other brands like Rheem and York.

Yes, it will be more money, but I think it worth the extra money for comfort.

I am guessing they did do a Manual-J (Load Calc) on your home to get the right size equipment.
 
  #3  
Old 11-03-10, 06:48 PM
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The burners in a conventional furnace are either on or off, and need to be sized to heat the house on the coldest day of the year.

For all the other days, the furnace is larger than it needs to be. To prevent the house from overheating, it may switch on three or four times per hour for a few minutes to maintain a relatively constant temperature.

A modulating furnace adjusts the amount of gas burned to the heat loss of the house. So on a cool day or a real cold day, the burners will be operating much of the time, but the amount of gas burned will be a lot less when the temperatures are moderate rather than cold.

The fan speed is adjusted to match the heat being produced by the furnace, so the fan operates a lot more of the time as well.

The result can be more even heat, since the fan keeps circulating air so there are less likely to be cool spots that develop.

The tradeoff is greater complexity of the furnace and greater cost. A furnace fan that may sell for $200 for a single input furnace might cost $600 to replace for a fan motor that has continuously variable speeds.

And while motors for single input furnaces have been perfected over decades and are highly reliable, the new fan motors are more likely to fail and need to be replaced.

Are you unhappy with the comfort level of your existing furnace? If so, that MIGHT be an argument for a variable input furnace. If you are comfortable with the furnace you have, a variable input furnace may improve that somewhat at significantly greater cost and complexity.

That's that's the way I analyZe the issue. Personally I think they've figured out how to do single stage condensing furnaces (circa 90-92% efficiency) pretty well. That would be my choice unless you are unhappy with the comfort level you have now.


Even if you are unhappy with your comfort level, that may well be because the furnace and ductwork need tuning up, rather than a problem that only a variable input furnace can solve.
 
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Old 11-04-10, 06:04 PM
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Jay,
Moved to Madison WI from Minneapolis four years ago and still miss it!! We have had five contractors out and not one has given a us a Manual J which from all I read seems to be a gold standard. In some respects I am left wondering if I am being quoted a "right sized" furnace without the Manual J having been done. Should we be ruling all of these folks out as they have not done the Manual J? Can you describe what it involves and is it really necessary in all cases of size estimation?

Seattle Pioneer,
As I mentioned the house is not zoned and the difference between the main floor and the lower level walk out is 8 degrees (??). Currently we do not spend much time there but know our son at some point will have his bedroom down there and we will all spend more time on that level. So yes,comfort could be better. Outside of that I wouldn't say the heating effect feels particularly spotty or has huge highs and lows. The furnace is 27 years old and taking advantage of the rebates seems to make sense. We just want to make sure we get the correct one.

Any additional thoughts will be welcomed.

Regards,
wvdthree
 
  #5  
Old 11-04-10, 06:12 PM
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It may be possible to increase the heat to the one cold spot by adjusting dampers on the ductwork or other methods.


This is kind of like the issue of how much to spend on furnace air filtering: if you don't have any health issues in your family, use the $.99 filter from Home Depot. If you do have allergies or other problems it might make sense to spend more.
 
  #6  
Old 11-04-10, 06:19 PM
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If you don't have luck finding someone who will do it, you can do your own for $50.

Download the program
and punch in all the info.

This will be asking how thick your walls are, how many sq feet your walls are in each room, and where they face, your attic insulation.. type of windows... ect.. It does take time, but in the long run it's worth it.

Example, in our home we had a 112k, furnace along with the gas budget plan of $190 a month.

I had it taken out, and the Manual-J said 60k was needed, I did the Trane 2 stage, and the comfort was by far the best we've felt. The new budget plan is now $70 a month.

Even tho we only used the large one for a month when we moved into the house the basement was blasted out hot, our far bedroom above the garage was cold since the system did not "Run" long enough to warm up that room, now every room are within 1˚ from one another, and I run the fan 24/7 while the system in heat mode.. Cooling leave the fan in "AUTO".
 
 

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