Home HVAC Advice Needed

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I was under the impression that in warm climates with less furnace use, the payback for higher efficiency furnaces did not add up??
Price difference between a 80 percent and a 95 percent furnace is less than a grand. Now obviously thats my price on equipment and big companies will have things marked up more and probably have a bigger price difference. But still with the current price of energy why not upgrade? There is also talks that 95 percent may become the new federal standard for efficiency.
 
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Another difference between 80% and 95% furnaces is that 95% furnaces draw their combustion air from outside your house, while 80% furnaces draw it from inside the house.

That means that when your 80% furnace is running, the make up air for what goes up the flue is cold air from outside.

My old house had an 80% furnace, and when it got cold out and it started running, I had a humidity/temp display and I could watch the humidity drop from 30% all to the way 20% as the furnace ran. That only took a few hours!

My new house has a heat pump (natural gas not available here).
 
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Thank you.

This is the only return in the entire house:

View attachment 104861
I am not sure of the duct size, but it takes a 20x25x1 filter.

I was also advised by a tech that installing a two-stage system into a home where ductwork is undersized can be extremely problematic. Supposedly this can cause insufficient airflow to the second story (presumably during the 1st stage) and also reduce the lifespan of the units. Is there any truth to this?

Lastly, if I choose to install a 2-stage a/c and 2-stage furnace (with variable blower, such as a Rheem R96V), is there any benefit to doing this if I do not install the air scoop and damper?
I had a feeling you might just have a single return like that. Shame they didn't mount it in the ceiling so it could pull the heat out better. Really not aesthetically pleasing in the stairwell either but Ive seen worse.

With a two stage system the air flow on the first stage will be low and that could possibly make things worse for your rooms lacking air flow. That is true. Now I don't see that reducing the life of the equipment though.

The biggest advantage of two stage equipment is that is saves you money on your electric bill or gas bill. There are times when you don't need the full rated output of the equipment to bring the house back to the set temperature so it can do so in the first stage.

Now I cant say I feel any equipment type will solve your air flow issue to the second story rooms. An air scoop might help but I think a proper balance of the system with dampers would help more. Like I mentioned before if your individual supply runs have dampers adjusting them can make a huge difference. But I wouldn't be surprised if they didn't have them either. Adding them can be done fairly easily provided the main supply trunk is accessible. Another option would be a booster fan in the supply runs for the problem rooms.
 

JHZR2

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My house is in the southern part of Delaware and not that much different than the OP with respect to house size and climate.

My first floor is 6 ton heat pump and second level is a 4 ton.

You are talking about a 4 ton for your entire house?

Why the big discrepancy?
The climate in the Bay Area is way nicer than where you (and I) live.

I know a little about HVAC.

Here's what I would do (and have done in your situation)-

Install a single, "mini-split" multi-port heat pump condensing unit and two indoor ducted, multi-position air handling units inside. One for downstairs, one for upstairs. The most idiotic thing to come about in the last 25 years is the use of zone damper systems in residential construction where a single system serves multiple floors. They simply do not work. To equate that to your line of work, Mr. Critic - that is the same as putting 4 different wheels and tires on a single vehicle because the owner wants to drive over turf/pasture (wide turf tractor wheel/tire), go rock crawling (18" x 12" wide wheel with a 35" x 12.50 x 18 Patagonia tire; run highway speeds daily (20" x 9" wheel with Michelin LTX M/S tire) and an 18" steelie with a snow tire because the owner goes to the mountains on the weekends in January/February.

What kind of sense does that make? About the same as a single unit serving two-three floors.....


My suggestion - sounds like you need a 4-ton multi-port condensing unit and two indoor units, probably a 3 and a 2-ton. Brand? Daikin.

Your climate will support a heat pump very well. I suspect your power bill will reduce enough to pay the PREMIUM this system will cost over the same old chit that the contractors are suggesting to replace the existing.

Feel free to PM me if needed.



Edited.....



HOLY CRAP at those electric rates..... BTW, you won't need gas with my suggestion...


Also, I wrote a song about all this-


This was my thought as well. They are easy to install and get right, I did mine in my house because every HVAC guy asked obscene prices for simple installs.
 

The Critic

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Price difference between a 80 percent and a 95 percent furnace is less than a grand. Now obviously thats my price on equipment and big companies will have things marked up more and probably have a bigger price difference. But still with the current price of energy why not upgrade? There is also talks that 95 percent may become the new federal standard for efficiency.
Every single contractor I spoke to (4 different ones) tried to talk me out of the 95% efficiency furnaces. The consensus is that they are significantly less reliable than the 80% furnaces.
 
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Every single contractor I spoke to (4 different ones) tried to talk me out of the 95% efficiency furnaces. The consensus is that they are significantly less reliable than the 80% furnaces.
I know in your part of the country they are probably few and far between but around here they are pretty much standard. High efficiency furnaces have been around since the 80s. I still see some of the old ones from the 80s running from time to time. Certainly not uncommon to see ones from the 90s still going. I would say they are pretty reliable.
 
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Every single contractor I spoke to (4 different ones) tried to talk me out of the 95% efficiency furnaces. The consensus is that they are significantly less reliable than the 80% furnaces.
FWIW, my 95% York furnace was installed in 2017 (we moved in at the end of 2019) and it’s been rock solid for us so far… no tags indicating service on it other than the one they put on when they installed it. It’s still relatively new though.
 

JC1

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Critic,

Whatever you choose I hope they have stock and you're not left waiting for weeks to get the unit.

Do you have an idea of how many hours of use per day of the AC/furnace to see if going with the high efficiency will payoff for you (depending how long you live there).
 

The Critic

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Have you looked at government tax credits with a heat pump installation?
Nah, no heat pumps for me.

Critic,

Whatever you choose I hope they have stock and you're not left waiting for weeks to get the unit.

Do you have an idea of how many hours of use per day of the AC/furnace to see if going with the high efficiency will payoff for you (depending how long you live there).
Seems like availability isn't an issue right now, at least not for the units I am looking at.

This week has been fairly warm and we've been averaging 8-8.5hr/day of usage. The system often runs for 30-45 mins per hour after 10am.
 
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I’m not entirely sure heat pumps are that much cheaper to run. My coworker, who has a similar sized but 20 year newer house, has a closed loop geothermal heat pump system and his electricity bill at its worst was $120 more than my worst natural gas+electric bill, despite us keeping the same temperature in our houses. It makes sense for him since he can’t get natural gas to his house, but even paying $1.30-$1.50 a therm I’m coming out ahead.
 
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I do believe the variable furnace is not that reliable, and 2 stage is way more reliable. The electronics is the one that fried on those inverter stuff, a lot. They aren't automotive grade like the one in your Prius.

80% is probably a much better deal unless you really heat your house all the time in this climate.

AC wise, personally I'd add a mini split or a window AC to that specific room to supplement the rest of the house with a central AC.
 
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I don't know why you would use a high efficiency 2-stage furnace in your climate...2 stage A/C maybe. +3 on the heat pump.
From my experience, sometimes the duct work is needed for the big AC but they don't make something that is large ton AC but single stage small furnace. Having a huge furnace would likely make it very dry and cycling too soon, and therefore it is better to size the furnace with 2 stage and either bet on it running at the low stage automatically or hard wire it to run at low all the time. The AC would need to be sized big enough for the hot day.

I have a 3 ton AC single stage that's just barely big enough, with a 100K BTU single stage furnace, it sucks. I'd rather pick a 300K BTU single stage furnace to go with the 3.5 ton AC I should have gone with but they don't make it like that, so likely the ideal with be 3.5 ton with a dual stage 400-600K furnace.
 
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From my experience, sometimes the duct work is needed for the big AC but they don't make something that is large ton AC but single stage small furnace. Having a huge furnace would likely make it very dry and cycling too soon, and therefore it is better to size the furnace with 2 stage and either bet on it running at the low stage automatically or hard wire it to run at low all the time. The AC would need to be sized big enough for the hot day.

I have a 3 ton AC single stage that's just barely big enough, with a 100K BTU single stage furnace, it sucks. I'd rather pick a 300K BTU single stage furnace to go with the 3.5 ton AC I should have gone with but they don't make it like that, so likely the ideal with be 3.5 ton with a dual stage 400-600K furnace.
Stage 1 on a 2 stage furnace is usually 70-80% output so you will still short cycle the crap out of it at that size. One way to help things is to increase the fan speed for your cooling needs...I presume dehumidification isn't as much of an issue there so longer A/C run times aren't exactly necessary.
 
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From my experience, sometimes the duct work is needed for the big AC but they don't make something that is large ton AC but single stage small furnace.

They do if it has an ECM motor on it. My heat pump air handler has jumper settings for 1 through 5 tons, with low-medium-high settings for each one. That's 15 speed settings in all.
 
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I have a 3 ton AC single stage that's just barely big enough, with a 100K BTU single stage furnace, it sucks. I'd rather pick a 300K BTU single stage furnace to go with the 3.5 ton AC I should have gone with but they don't make it like that, so likely the ideal with be 3.5 ton with a dual stage 400-600K furnace.

My old house had a 2-ton AC with a 48K BTU furnace.

A 100K BTU furnace is quite large and would work with even a 5-ton unit, even if it only has a 3-speed PSC motor.

A 100K BTU furnace is also specified in this climate, which gets colder than where you live, for even 3000 sq ft houses.

A 600K furnace? Are you heating a warehouse or something?
 
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My old house had a 2-ton AC with a 48K BTU furnace.

A 100K BTU furnace is quite large and would work with even a 5-ton unit, even if it only has a 3-speed PSC motor.

A 100K BTU furnace is also specified in this climate, which gets colder than where you live, for even 3000 sq ft houses.

A 600K furnace? Are you heating a warehouse or something?
My old house had a 100k furnace and I forget what size AC but it was way too big for that 1200sq ft. Both the furnace and AC short cycled like crazy, humidity control was almost impossible. My new house, despite being 600sq ft bigger and 3 floors is far FAR more comfortable with its 60k furnace and 2 ton AC. If it’s 95+ out the AC will run for 15 hours (smart thermostat monitors usage), but it maintains 74F inside and 45-55% humidity.
 
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I’m not entirely sure heat pumps are that much cheaper to run. My coworker, who has a similar sized but 20 year newer house, has a closed loop geothermal heat pump system and his electricity bill at its worst was $120 more than my worst natural gas+electric bill, despite us keeping the same temperature in our houses. It makes sense for him since he can’t get natural gas to his house, but even paying $1.30-$1.50 a therm I’m coming out ahead.
But you are burning a fossil fuel and he is using electricity which could come from a solar farm or wind or other non fossil fuel sources.

Fossil fuel should be saved for important activities like power boating. 😁
 
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But you are burning a fossil fuel and he is using electricity which could come from a solar farm or wind or other non fossil fuel sources.

Fossil fuel should be saved for important activities like power boating. 😁
Most of our energy is from coal and natural gas, renewables are coming online but still represent a small portion of the overall supply
 
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I’m not entirely sure heat pumps are that much cheaper to run. My coworker, who has a similar sized but 20 year newer house, has a closed loop geothermal heat pump system and his electricity bill at its worst was $120 more than my worst natural gas+electric bill, despite us keeping the same temperature in our houses. It makes sense for him since he can’t get natural gas to his house, but even paying $1.30-$1.50 a therm I’m coming out ahead.

There are way too many variables to make a direct comparison.

Your house could be better insulated than his.

Your house may have more south-facing windows than his.

Your house may not be as drafty as his.

He may have an electric water heater and use more hot water than you.

And so on.
 
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