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Well, for those of you who have not followed our continuing saga, here is the short version. We are within a couple of years of retirement and have purchased (hopefully) our last home in the mountains of North Carloina. I've been here for two weeks with painters and other assorted folks getting things sorted out.

Well, this "artic vortex" as the news likes to call it has me thinking about the furnace. Currently the house has a 4 ton Trane heat pump installed. The compressor is 2002 and the air handler is 2004. Air handler is installed horizontally in the crawl space. Back up heat is supplied by resistance coils.

The current temperatures are unusual, but the current configuration just can't keep up. I like gas furnaces and had the Trane dealer come out to give me a price on switching it over.

One comment he made was that this furnace should have 4 coil packs providing the back up heat, but by the temperature coming out of the ducts he suspects one or more are not working. Surveying the complete install he also said the amount of return is not sufficient for the 4 ton with the number of registers installed.

His recommendation is to change the air handler to a gas furnace with the heat pump/AC coil installed. It will be programmable so that down to "X" ambient outside temperature the heat pump would run, then below that the gas furnace would take over. Or, I could manually go direct to gas.

Options would be 80%, 90% or 95% efficiency on the furnace.

Hopefully this,will be our last house, so I'd like to get it right. One other thought is that with my 15,000 KW generator I can't run this resistance heat, but could run the gas furnace. (The generator will move with us from the current home in SC)

So, thoughts?

Fix what we got and stay with resistance back up or switch?

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First of all, your AC guy shoulda examined the heat strips and confirmed that each one was connected and functional. Worse case is about 15 minutes to do that for your crawl unit.

FYI: each heat strip is about 4,000 watts, 16 to 18 amps at 240 volts. That translates into about 13,600 btu/hr each. I have only one connected in my air handler because that's all I need. 4 should be abundant for your house.

Your power plant can run 3 elements but not 4. 3 won't leave much for the rest of the house, mostly just the lights and wall receptacles.

As regards the return air duct in relation to registers, no AC guy should comment on that until he's got the results of a manual D calc in his hands. If he does, he's taking a SWAG. Besides, it's not a duct balance problem you're experiencing, it's the lack of sufficient heat, right?

Your last post in "Am I missing anything..." got me scurrying to re-examine my site. Good post.

Marc

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Thanks Marc!

I do think there is a balance problem as there is not even heating throughout the house. Plus, the main return register is in a closet behind a louvered door. I can actually hear the difference when the door is open or closed. According to him this return is being serviced by one 14" flex duct (the entire house is flex) and two other returns share a 12" flex duct line.

Him not verifying the heating issue is probably more my fault as I brought him out to specifically quote the gas furnace replacement as that is what I'm used to and really like. So part of me wants to go with the gas, but am I just spending stupid money for what I like/am used to?

If I do go gas, 80, 90 or 95% efficiency?

Glad I could help,with the other post. I just thought of something else and need to go back and edit it.

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Hey Tim,

I got back from Philly last month to find my home furnace croaked! I had been thinking about a new one, but the event pushed me to make a choice. I had gfa and replaced it with gfa. I have natural gas and a typical rambling walk out ranch with lots of southern exposure. I went with trane (every bldg we own has Trane/AmStd) just because I like them. 90% stripped down model. Did the cursory math and found the $2200 I saved offset abt 5yrs of efficiency and I am not going to care in five years!

In your case I likely would go gas and eliminate as much floppy duct as possible.

PS: Marc is right.

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It is a dollar and cents question as to what you pick unless you just want gas and are willing to pay the difference.

It would be a long time to get a return on investment on making the change now as opposed to when the a/c croaks and you have to make the purchase anyway.

Around here the typical life expectancy of a a/c unit is about 12-15 years with something similar for a heat pump.

Run the numbers for heating with heat pump vs gas depending on the fuel costs in your area.

Seems like I remember an online comparison program that would crunch the numbers if you supplied the fuel costs. I'll look for it and check back if I find it.

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Tim, personally, I'd fix the existing system and let it run till it croaked. You might have a bad heat strip or a bad sequencer, either of which is simplicity itself to replace. There's no economic reason to ditch a repairable system.

On the other hand, you might just find that you're one of those people who don't like heat pumps. When a heat pump is running properly, it's blowing 95 - 105 degree air out of the registers. Air that's that temperature feels cool on your skin. In general - and don't take this the wrong way - old geezers hate heat pumps because they "blow cold air." (The heat pumps, not the geezers - they blow hot air.)

The answer to your question will depend on what your expectation is. Are you more interested in comfort or economy?

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P

Tim, personally, I'd fix the existing system and let it run till it croaked. You might have a bad heat strip or a bad sequencer, either of which is simplicity itself to replace. There's no economic reason to ditch a repairable system.

On the other hand, you might just find that you're one of those people who don't like heat pumps. When a heat pump is running properly, it's blowing 95 - 105 degree air out of the registers. Air that's that temperature feels cool on your skin. In general - and don't take this the wrong way - old geezers hate heat pumps because they "blow cold air." (The heat pumps, not the geezers - they blow hot air.)

The answer to your question will depend on what your expectation is. Are you more interested in comfort or economy?

Well Jim, I think you have hit the target. In my current world, comfort wins.

The "old geezer" comment is right on point. I was driving a couple of years ago, listening to NPR (I would prefer Neal Boortz, but he retired) talk radio and thought to myself - I have become my father.

I like to be comfortable and I think the heat pump can keep up with reasonable outside temperatures but not when it drops. That is when I want heat, now.

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Tim,

See Les's post above. I got a few years on you and agree - comfort trumps economy. Global warming be damned, I am cold now!

Jim K is right on point for me; I do not like heat pumps.

I believe floppy any thing (ducts) needs replacement. Well, maybe some hats would get a pass.

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Tim,

See Les's post above. I got a few years on you and agree - comfort trumps economy. Global warming be damned, I am cold now!

Jim K is right on point for me; I do not like heat pumps.

I believe floppy any thing (ducts) needs replacement. Well, maybe some hats would get a pass.

Flex ducts is at about a 98-99% rate down here. Seldom see metal duct in new construction and if I do it is very 'spensive custom home. Cost to replace flex duct here would be a serious draw on the bank account.

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Tim,

See Les's post above. I got a few years on you and agree - comfort trumps economy. Global warming be damned, I am cold now!

Jim K is right on point for me; I do not like heat pumps.

I believe floppy any thing (ducts) needs replacement. Well, maybe some hats would get a pass.

Flex ducts is at about a 98-99% rate down here. Seldom see metal duct in new construction and if I do it is very 'spensive custom home. Cost to replace flex duct here would be a serious draw on the bank account.

You see orange board much?

Marc

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Tim,

See Les's post above. I got a few years on you and agree - comfort trumps economy. Global warming be damned, I am cold now!

Jim K is right on point for me; I do not like heat pumps.

I believe floppy any thing (ducts) needs replacement. Well, maybe some hats would get a pass.

Flex ducts is at about a 98-99% rate down here. Seldom see metal duct in new construction and if I do it is very 'spensive custom home. Cost to replace flex duct here would be a serious draw on the bank account.

Flex duct is about all I see In Okla anymore this younger generation has no clue how to even install rigid duct. Some of the mess I inspect is disgraceful. Had a home yesterday that had 7 drops fed from one 12" trunk line.

I ripped all of my flex out of my home a couple of years back and installed rigid supply and return. I did it in the month of July not very smart on my part. But I did leave my old unit operational and disconnected a flex trunk line in the attic to provide cooling while I worked [:D]

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Tim, you have natural gas in the mountains? Or are we talking propane?

they have Natural Gas in "town", but up here it's LP. Right now the only thing on my buried tank is a set of gas logs and the Weber BBQ grill.

Then to make an intelligent decision, you'll need to know your price per gallon for propane and your cost per kwh for electricity.

BTW, you can get much cheaper propane if you own your own tank rather than rent it.

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Well, for those of you who have not followed our continuing saga, here is the short version. We are within a couple of years of retirement and have purchased (hopefully) our last home in the mountains of North Carloina. I've been here for two weeks with painters and other assorted folks getting things sorted out.

Well, this "artic vortex" as the news likes to call it has me thinking about the furnace. Currently the house has a 4 ton Trane heat pump installed. The compressor is 2002 and the air handler is 2004. Air handler is installed horizontally in the crawl space. Back up heat is supplied by resistance coils.

The current temperatures are unusual, but the current configuration just can't keep up. I like gas furnaces and had the Trane dealer come out to give me a price on switching it over.

One comment he made was that this furnace should have 4 coil packs providing the back up heat, but by the temperature coming out of the ducts he suspects one or more are not working. Surveying the complete install he also said the amount of return is not sufficient for the 4 ton with the number of registers installed.

His recommendation is to change the air handler to a gas furnace with the heat pump/AC coil installed. It will be programmable so that down to "X" ambient outside temperature the heat pump would run, then below that the gas furnace would take over. Or, I could manually go direct to gas.

Options would be 80%, 90% or 95% efficiency on the furnace.

Hopefully this,will be our last house, so I'd like to get it right. One other thought is that with my 15,000 KW generator I can't run this resistance heat, but could run the gas furnace. (The generator will move with us from the current home in SC)

So, thoughts?

Fix what we got and stay with resistance back up or switch?

My recommendation depending on your finances would be a 2 stage 95% variable speed furnace, dump the heat pump, that way on the warmer days the heater would run on low stage, the benefit to this is longer run cycles and more even heat distribution, when the demand is not being met on low, on the colder days the furnace automatically switches to high to take of the isolated cold days that are not factored into the design temperature , also by switching out the heat pump to a regular AC Unit, the wear and tear by not running the compressor all year round would be reduced, also the AC units are also available in two stage , the same benefits would be available in the summer, this also assumes that the duct system is designed properly.

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Tim, you have natural gas in the mountains? Or are we talking propane?

they have Natural Gas in "town", but up here it's LP. Right now the only thing on my buried tank is a set of gas logs and the Weber BBQ grill.

Then to make an intelligent decision, you'll need to know your price per gallon for propane and your cost per kwh for electricity.

BTW, you can get much cheaper propane if you own your own tank rather than rent it.

You'll also need the heating value of propane which is 50,000,000 Joules per kilogram (2.2 pounds) of propane. 50,000,000 joules translates into 47,400 BTUs.

If you buy a furnace with 100,000 btu/hr input, it'll burn 4.64 lbs of propane (just over a gallon) per hour.

100,000 BTUs translates as 29 KWHs.

Here in Louisiana, 29 KWHs comes out to $2.26.

I dunno what a gallon of propane delivered to your house costs here.

Marc

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Don't think too much.

It's your last house. You want heat when you want it. Put in a big tank, a gffa 95%'er, clean up the flex, put an ice cube in a glass, fill with bourbon until the cube is covered, find comfortable chair with nice view, assume semi horizontal position, contemplate the miracle of finely distilled spirits and pleasant company in a warm house.

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Jim/Marc:

You are making my head hurt........

LP is 1.99 a gallon right now.

I just want hot air coming out of the registers.....

Electricity cost?

BTW, if you're really interested in comfort, have you considered radiant heat?

The last two houses we have remodeled the master bath and added radiant heat in the floor. The cats love it.

Don't think too much.

It's your last house. You want heat when you want it. Put in a big tank, a gffa 95%'er, clean up the flex, put an ice cube in a glass, fill with bourbon until the cube is covered, find comfortable chair with nice view, assume semi horizontal position, contemplate the miracle of finely distilled spirits and pleasant company in a warm house.

I like the way you think! I would probably replace Appleton Rum for the bourbon, but I get the idea.
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