New furnace required - advice welcomed

[Number_35]

If you run the blower motor all the time, the majority of your energy savings with ECM motors is because they can run at a lower speed for ventilation. So they might only pull 100W at the lower ventilation speed vs the 500W they might pull when running at normal speed. PSC motors are incapable of this, they use about the same amount of power no matter what speed they're running at, and they can't slow down as much as an ECM motor can.

My fresh air ventilation system is on a timer. I currently have it set to run 5 minutes per hour. If outdoor conditions are good (low humidity, mild temperatures), I'll set it to run continuously. If the HVAC system isn't running enough heating or cooling calls for it to run the set amount of ventilation per hour, then it'll turn on the HVAC system fan at low speed (and open the fresh air damper and turn on the fresh air fan to pull air from outside).

That's exactly what the tech who came by today said w.r.t. the advantage of an ECM vs PSC motor.

We run the HRV 24/7 (although not for the last couple of days, of course) - the house is pretty tight, and the humidity was way too high the first few winters - the tripanes would ice up really badly.

This part of world is bad for radon gas too, and regular air changes help reduce the effects significantly.

 

[Number_35]

Update: We decided on a new AirEase 70K BTU 2-stage 96%-efficient furnace, which was installed on Monday.

The primary reason was that trusted friends recommended the company.

It's a one-man operation, and the owner/installer was excellent. Very good guy. His price was good too, as expected with his low overhead.

As folks here said, the quality of the installation is more important than the brand of the equipment.

The furnace is very quiet, and keeps the temperature pretty even without a lot of drama. Looking forward to seeing future energy bills.

Thanks to all who contributed to this discussion!

 

[Skippy722]

If one has a tract house, one would do well to get an energy audit done. Thermal camera, blower door, and the rest of it.

Sometimes (maybe even usually) they're in such a hurry to slap those houses up that they forget things like caulk and insulation. I've seen it myself.

And then when all those issues get fixed, you might find that you don't need as big of a furnace or air conditioner...and your energy bills have gone done, maybe substantially.

Yep. My first house was like that… sloppy build quality and super leaky. Pretty sure the corner in the master bedroom didn’t have any insulation.

 

[brianl703]

Yep. My first house was like that… sloppy build quality and super leaky. Pretty sure the corner in the master bedroom didn’t have any insulation.

Did they leave beer cans in the walls? That's a sure sign of a kwality bilt home!

 

[97prizm]

If it's hot water heaters stay away from Rheem. Every one I've dealt with has been trouble. I've had 2 at the apartment complex that I work for go bad at less than 2 years old, on top of old ones. It's odd that alot of members on here dislike Lennox furnaces. My parents had theirs last 21 years with just 3M filters and occasionally blowing it out.

 

[brianl703]

If it's hot water heaters stay away from Rheem. Every one I've dealt with has been trouble. I've had 2 at the apartment complex that I work for go bad at less than 2 years old, on top of old ones. It's odd that alot of members on here dislike Lennox furnaces. My parents had theirs last 21 years with just 3M filters and occasionally blowing it out.

Rheem changed the gas valve they were using. That seems to be what was going wrong with them. Current models use a different gas valve.

 

[MHartfield]

Costco 90% of the time. I'm in the middle of moving from Southern Cal, to Bullhead City, AZ, where there is no Costco, but there are Smith's (Kroger). I see no difference in performance on my return trips across the desert. The gas in Bullhead City comes from either the So Cal, or Utah, pipelines via Las Vegas. I'm having a hard time with this "Top Tier" stuff, other than the fuel truck drivers tell me they dump a 5 gallon bucket of Techron into their 8,000 (?) gallon tank when they go to Chevron. Me thinks the "Top Tier" is simply a marketing mechanism.

 

[SubieRubyRoo]

Hello all -

I've replaced a few things on our furnace in recent years and kept it limping along, but the time has come.

It's a 30ish-year-old Carrier, natural gas, mid-efficiency, and it packed it in yesterday morning. In the past five years I've replaced the blower motor, the fan control board, and the heat-limit switch. I called a local indy company with good online reviews, and the tech was really good. He diagnosed a bad induction-motor assembly, which is pricey enough, but then also found the bulkhead to which the assembly mounts is very rusty. The heat-exchanger is not far behind.

Plus, the federal government is going to ramp up the carbon tax on all fossil fuels, including natural gas, so a more-efficient furnace is not a bad idea anyway. I doubt the old one is hitting its nominal 80% efficiency anymore.

OK, so I've accepted that it's time.

By law, all new furnaces here have to meet high-efficiency standards - I think 90% efficiency. The ones I'm looking at are nominally 96%.

Because of the high efficiency, the furnace vents out through a wall, rather than up through a chimney. The downside of this is that the water heater (also natural-gas-fired) is not allowed to use the existing chimney as-is - the chimney pipe diameter is too large for the reduced amount of exhaust that would be generated by the water heater alone. And therefore a chimney liner is required, which adds about $1200 plus tax to the total. (An alternative is to replace the gas-fired water heater with an electric one, but it's much more expensive to heat with electricity. The savings created by the more-efficient furnace using less gas would be offset by the extra cost of heating water.)

There's a tech from a competing company (another indy with a good reputation) coming to estimate the job tomorrow.

I think it will come down to the brand, unless there's a really significant price difference.

Company A is offering Daikan units.

Company B offers a rebranded Lennox line. Air Serve? Something like that.

My questions:

1. What are BITOGers' opinions of these two brands?

2. Company A has quoted two different levels of Daikin furnace - a mid-level model, and a higher-end one.

Besides a longer warranty on the higher-end one, the main difference seems to be a "variable-speed ECM" vs. a "multi-speed motor". Is this DC vs AC? Would the variable-speed ECM use significantly less electricity than the conventional motor? We run the furnace fan year round for the HRV, which uses the HVAC ductwork. The conventional AC motor does run up the electric bill, running 24/7.

Thanks in advance for your thoughts!

Have you checked out geothermal? Don’t know if you have the land for it, but it’s the only HVAC system that at some point will actually put you money ahead.

If not, mini-splits are the way to go.

 

[Number_35]

Have you checked out geothermal? Don’t know if you have the land for it, but it’s the only HVAC system that at some point will actually put you money ahead.

If not, mini-splits are the way to go.

I did, back c. 2006. We had been in the house almost 15 years at that point, had the original mid-efficiency furnace, and had no AC.

I had heard (erroneously) that a geothermal system was about $8K installed. I figured by the time I spent $4K on AC and $4K on a new furnace, I'd be farther ahead going with geothermal.

So, I was a bit shocked when quoted more like $35K all in. (Because a geothermal system provides heat at a lower temperature than a gas or electric furnace, a greater volume of air needs to be moved. The estimator told me that the plenum and ducts, sized for a natural-gas furnace, would have to be replaced or they'd whistle. And that would have meant ripping out much of our finished basement, and losing some ceiling height. No thanks.)

That's a lot of capital outlay to save, at best, $50/month. The payback would never happen - the interest on the loan or the lost opportunity cost of the capital would be much greater than the savings.

So then I looked at an air-source heat pump. $21K, and not available for any subsidies because in our climate it was considered an electric furnace, as it would use supplementary resistance heating almost all of the time.

So we had a conventional AC system (1-1/2 ton) installed the following summer (2007), and it's worked well for us. It was $2300 installed, not the $4K I'd originally anticipated.

And the old furnace turned out to only be at about half life. It worked until late last winter.

We're happy with the new furnace. It's too early to have seen much in the way of gas savings yet, but the electricity savings have been significant.