efficiency of electric furnaces.... new vrs old

[lakelivin]

Re: efficiency of electric furnaces.... new vrs old

Just curiosity. I'm in northern NC, so have a couple of hot humid months and a couple of cold months. <br /><br />I live out in the country so choice was propane or heat pump when I built about 10 years ago. Went with heat pump, no complaints. TOTAL electrical bill ranges from about $50 to at worst maybe $180 for a really hot or cold month(just me living here). Was reading about geothermal when I had my place built and curious as to how far it had progressed. Just seemed like it would be super efficient once installed. Pay to run the blower and compressor, heat/ air basically free. <br /><br />Was wondering if it was starting to be used more, seems like it was a rarity when I was checking it out years ago...

 

[Snookster]

Re: efficiency of electric furnaces.... new vrs old

Your conception of free heat is wrong. The only advanatge geothermal brings is (for the most part) consistanly better quality heat as the temperture that is available for the heat pump to ABSORB heat remains higher (more heat content) & results in better performance.<br /><br />The only free heat configurations are passive & solar. Passive has been used succesfully in weatern states where an entire rock wall is constructed behind large glass windows... durring the day radiation heats up the mass - at night a blower moves air over or thru the mass to heat the home. Passive can also include loops into deep cold wells or springs where cooling can be harvested durring summer months. This can help but will never deliver temps below the dew point so the opportunity for humidity removal does'nt exist - the best you'll be able to maintain is the conditions in a cave.<br /><br />Solar pannels are avaible in hundreds of configurations & if done properly can heat your water & even produce electricity.<br /><br />Your HP is'nt a bad chioce for your area, but if you had quality gas heat - you'd never go back. When you're ready for a replacement take a good look at hi effiency gas (98%+ effieciency) + hi effieciency AC (13+ R410A) The Carrier two speed infinity is an incredible machine.. a little pricey but an exceptional machine.

 

[fixin]

Re: efficiency of electric furnaces.... new vrs old

Snookster...Just curious would gas be your pic?Is there a difference in efficiency between Nat.gas and LP?

 

[Snookster]

Re: efficiency of electric furnaces.... new vrs old

Being a mechanic I like dependability & performance. Oil heat actually has the highest btu output, but pumps, nozzels, cad cells, primary controls, barometric dampers, ck valves, odor, high voltage transformers, ingnition issues and effiecancy (most all oil furnaces are at 70-80% AFUE.)all make it less than desireable unless you're getting a GREAT deal on oil.<br /><br />Gas on the other hand is easy to work with. No odor issues. Performs reguardless of the ambiant temp (where heat pumps don't) have very, very few moveing parts,(thus are very dependable) terrific temp rise (typical 60-100 degrees vs electric & heat pump at 30-60 degrees), outstanding AFUE @ 90 - 98%. Gas is also all domestic -- we don't by it from Iraq or Iran. A good gas furnace will typically last 20+ yrs where the best heat pump is shot in under 10.<br /><br />Natural gas is preferd just because of ease of use (no tanks,) LP - yes a tank is a hassle, but it can be burried. If you bury a tank you buy the tank -- yes a couple of bucks..... but now ANYONE can fill it. The advantage here is competition --- how many suppliers of electricity are there??? Now look in the yellow pages for LP gas -- competition keeps prices down. Also - once you have gas you can convert addtional appliances as needed.... NEVER run to fill up a LP tank for the grill... switch over your pool heater, water heater, stove, dryer. <br /><br />All furnaces come from the factory set up for natural, the orifices & value diapham need to be changed to run on LP. Natural gas pressure runs 3-6" WC where LP runs 13-15". Some municpalities require black iron vs. galvinized vs. copper - so ck local codes for pipeing & do'nt screw with the venting unless you know what your doing, also.... all combustion products require.. AIR - so make up combustion air is required unless you choose a high end direct vent product. <br /><br />There is no performance differance from natural to LP furnaces however, altitude (IE in the moutians) can impact performance overall.<br /><br />FYI - years ago durring the oil embargos I converted fleets of trucks from gasoline to dual fuel w/ LP.<br /><br />Does this help?

 

[fixin]

Re: efficiency of electric furnaces.... new vrs old

Snookster....Thanks.You definitely Know your Field.I'm sure your expertise will be greatly appreciated here.Glad to have you aboard.

 

[lakelivin]

Re: efficiency of electric furnaces.... new vrs old

Snookster, not trying to be arguementative, just understand better. Seems like I've been hearing people complaining about the rising cost of natural gas (and I assume propane has gone up as well).<br /><br />Like you say, given that geothermal does give you a constant temp to draw from (at what I assume would be a reasonably efficient temp for the heat pump to cool or heat), wouldn't that be a strong candidate as far as efficiency for places with extreme weather conditions (deep south or far north)? <br /><br />Is that wrong, or is it that other factors make it a less than practical solution for locations with extremely high or low temps? <br /><br />I'm guessing some of the negatives would be heat quality (but I'm assuming diff between gas and geothermal wouldn't be as extreme as diff between gas & regular heat pump since it's sucking heat from mid 50 degree temps all of the time as compared to trying to suck heat out of, say, 35 degree air). <br /><br />Also know that installation is expensive and that you need the right land configuration to sink the coils. And heard you about reliablility/ longevity of furnace vs. heat pump. But if you've also got central air, wouldn't you have some of the same issues with the central air compressor as the heat pump, mitigating that advantage of a furnace somewhat? <br /><br />If any of the above is valid, still seems like there might be a practicality issue in that geothermal just isn't used much so I imagine there aren't many contractors using or familiar with it, which has gotta drive up price.<br /><br />Again, sorry if I seem overly persistent, just trying to differentiate the practicalities from my perception of the concept. Just seems like if it wasn't too impractical or expensive to install, someone in south Florida, say, should be able to save a hugh amount on cooling costs with someting like geothermal.

 

[Snookster]

Re: efficiency of electric furnaces.... new vrs old

Lakelivin - <br /><br />Yes gas has & will rise in price, in some areas like the Tennesee Valley area where they have hydo electric - the cost of gas can be higher than electric. You'll have to do some hoework as to energy cost in your neck of the woods. <br /><br />Here's the math:<br /><br />Oil - 138,000 BTU p/ gal X AFUE (annual fuel ultilization effiecancy) = BTU OUTPUT IE: 80% This is the heat you can use - the rest is up the chimney.<br /><br />Natural Gas - 100,000 BTU p/ therm X AFUE = BTU OUTPUT<br /><br />LP Gas - 98,000 BTU / gal. X AFUE = BTU OUTPUT<br /><br />Electric strip (resistive) - 3,412 BTU p/ KW X 100% effiecancy = BTU OUTPUT<br /><br />Heat Pump - 3,412 p/ KW X COP (this is'nt the exact formula but it'll get you there). NOTE @ what temp the COP rating is will vary the COP<br />= BTU OUTPUT. One more note - <br /><br />If you do a load calc on your home... IE: requires 120,000 BTU's of heat X # of heating hours for your area (I don't have my books w/ me right now) you can evaluate the TTl demand / cost.<br /><br />IE: 120,000 BTU's (required to heat your home to 75 when it's 30 outside) X 2,000 heating hours (from my recollection for your part of the world) = 24,000,000 BTUs annually.<br /><br />Do the math based on cost of energy (above) & you can ID the most practical heating source for your home. Don't forget utility rebates etc.<br /><br /><br />Geotherrmal has become popular all over the US as it does offer some advantages... NO outdoor condesing units - more consistant performance - typically less labor to install (initial install cost with wells or well field can be prohibative). Unfortunately, heta pumps - water sourced or not the temperture rise will never compare to fossil fuel. Also - as life has it -- anything you touch with water has a maintence issue, scaleing -oxidation eats these guys up. Also - watch closely the EXACT amount of electricity you actually USE. If you live next to a water fall, where you get free unlimited water supply - then the COP of the geothermal heat pump would be accuate... however if you need to run a 3/4 HP pump just to deliver water to your geothermal unit instead of a 1/4 hp fan - you might not be that far ahead of the program.<br /><br />I know several quality contractors in your neck of the woods that could give you sage advice.

 

[lakelivin]

Re: efficiency of electric furnaces.... new vrs old

Thanks Snookster,<br /><br />It's not an issue for me personally, just curiosity about the concept in general. Given that my total utility bills (electricity is all I have) range from $50 - $180 per month (and probably average around $100 per month) I can't believe there is anything that would make a change in the near future worthwhile for me as far as payback in energy savings.<br /><br />Plus I've got a fireplace with a blower that heats more like a woodstove than most fireplaces I've seen. It will pretty much heat the whole house (don't know what the technical name is, but it's the kind where you have to burn with the door closed, has a catalytic combuster). I intend to use it much more this winter since I got a bunch of free seasoned hardwood from a friend. That will cut down heating costs considerably if I use it during the times temp drops below 30 (a few times in my area, but not too bad). <br /><br />It seemed like geothermal would make more sense in extreme areas like the far north or deep south, where there are many months of extreme cold or extreme heat than in my area. If I ever move and think about buiding again I'll run the calculations you suggest and use them to help make a decision as to best way to go.

 

[Snookster]

Re: efficiency of electric furnaces.... new vrs old

No problem - call me if I can help.

 

[dhammann]

Re: efficiency of electric furnaces.... new vrs old

I guess it depends on what area of the country your in but in NC natural gas is no longer a bargain. Years ago North Carolina Natural Gas and Carolina Power & Light (now Progress Energy) were in fierce competition against each other until Progress Energy bought out North Carolina Natural Gas!!!! Guess what happened? Progress Energy has built a number of gas fired electric generating plants and has created a gas supply shortage for the residential users. I used to be an HVAC contractor and I tried to push natural gas as a bargain and it was at that time. Progress Energy is not totally dependant on foreign oil (48% nuclear and the rest going to coal and natural gas and 2% hydro) so no other energy source can compete with them. This is a complete turn-around of the way things used to be. Natural gas is limited in supply due to it’s pipeline delivery network and prices were always based on demand. Industries always had to pay a surcharge during peak periods to insure that the residential users could be accommodated. Now the electric utilities are creating the demand and putting the surcharge on the residential consumers! I hate to admit it but electric heat is competitive with gas and the heat pump will beat it. But remember what happened in California!!!!!

 

[Snookster]

Re: efficiency of electric furnaces.... new vrs old

You're right Dee -differant parts of the US will have various energy cost. So you swore off HVAC contracting?? - I can't blame you, with hundreds of Mom & Pop shops, hot dogs from up north that are'nt sure if they're retired or not, inspectors that could'nt find their *** with both hands if they had long arms & no legs, the big box marketing efforts & of course the internet shopping... life has been intresting.