Question: Is a 2 stage Variable speed furnace worth the investment?

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Answer #1:

For me it was. I wasn't really thinking about potential cost savings though. It was the fact that the fan ramps up slowly at first and doesn't immediately give you one big burst of the cold air that had been sitting in the air ducts. The opposite being true in summer with a burst of warm air that had been sitting in ducts.

Answer #2:

It is a more efficient system. So over time yes.

I love mine.

Answer #3:

after working on furnaces for 38 years my answer would be NO,,,any money u save on elec will be eaten up by very expensive service calls as the parts are way more expensive for these furnaces and they are not as dependable,,,take it from a pro

Answer #4:

In a word, yes.

We have a modulating boiler and have also installed similar units in our previous house and summer house - which have run for 23 and 20 years respectively without any problems - we expect the same from our present unit (Weil-Mclain Ultra).

Modulating and variable-speed units are very efficient, the technology has long been proven and the controls are no longer exotic. The present generation of service techs are comfortable with them - especially so as they can diagnose them with a lap-top (and so can you with the right connector), and even correct most problems from the same lap-top.

We ran the calculations on our conversion for our present unit as follows:

Existing Boiler: 400,000 BTUH oil-fired unit at 60% AFUE.
Replacement Boiler: 230,000 BTUH Gas-fired 98% AFUE
Alternate Replacement: 300,000 BTUH Gas-Fired 85% AFUE

Cost per season of operation (estimated based on history): 55,555,500 BTU of required heat into the house.

With oil: 130,000 (BTU/Gallon) x 0.6 (net per gallon) = 78,000.
55,555,500/78,000 = 712 gallons of oil.
712 x 2.29 (contract price available) = $1630 for one season.

With the WMU boiler: 100,000 (BTU/Therm) x .98 = 98,000
55,555,500/98,000 = 566 therms.
566 x 1.17 = $662.00
Savings over oil: $968.
Savings over alternate boiler: $102.

With the alternate boiler: 100,000 x .85 = 85,000
55,555,500/85,000 = 653 therms
653 x 1.17 = $764.00
Savings over oil: $866.00

Cost of boiler installed (installation labor the same for either boiler - the difference is in the price of the boiler):

WMU = $7,500
Alternate = $5,200

Assuming a stable relationship between gas and oil prices, the payback on the WMU is seven years, 9 months.

The payback on the alternate is just over six years.

The payback between the alternate and the WMU is a bit over 22 years, six months. But that is at the present price of natural gas - as that price rises the payback gets faster.

Expected boiler life for either gas unit: 30+ years.
Expected boiler life for the existing oil-fired unit optimistically: +/- 5 years.

You pays you money, you takes you chances.

Answer #5:

Your question was very informative, allow me too add my opinion

1. A variable speed motor is much beter than the regular PSC motors which are either on at a 100% or off, not only more efficient, but quiter as you said, and also help provide better comfort. The best thing about variable speed motors is also the worse thing. A variable speed motor has the ability to overcome higher than normal duct static pressures. Which everyone has if they are using a pleated filter of better. The filters catch a lot of dust, pollens but in doing so catch a lot of the air itself, or in sense cause a restriction in the airflow. The old PSC motors would put out less airflow sense the airflow would be restricted, However the variable speed recognize the return air restriction and will ramp up to maintain design airflow. The bad thing about this is the motor will wear out quicker ecspecially if the total staic exceeds 1.0 in. wc. Most house using a pleated filter or better will operate from what I see just barely under this, so be sure to keep the filters clean. Also variable speed motors cost atleast two to three times as much to replace, and parts have to be shipped.

2. Your gas savings will be coming from the higher efficient furnace design and not the 2-stage design. The 2-stage design allows for more consistent temperatures in the house and does this by just running more in the lower stage. So I believe the costs of running a single stage unit half the time offset those operating costs of running the lower end stage on the 2-stage, which will run twice as much.

3. I don't think goodmans are bad. They have definitely gotten better since they recently bought out Amana a few years back.

4. Gas Man has a point. A majority of my service calls are for furnaces less than 10 years old. Newer furnaces have more parts, more safety switches and electronics that just don't seem to last. The older furnaces only needed a thermocouple and a cleaning every 5 years, and oil every year.





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