|02-05-2010 03:23 PM|
Another issue you will run into running a heat pump alone would be on off-years like this year where you're seeing temperatures below freezing...a heat pump unit becomes ineffective typically below around 30*F. This means your heat pump is going to run constantly and STILL may have difficulty keeping up with the demands of your thermostat and you will want to make sure you have an auxiliary heater installed (ie an electric furnace, gas furnace).
A geothermal unit utilizes the ground temperature...so the outside air temperature will not affect it nearly as much when installed correctly. That means that technically you should be able to get away with running a geothermal unit and won't NEED an auxiliary furnace in the event of sub-freezing temperatures.
I dug my books out while writing up this reply... so just to confirm what the techs have told you.
As far as efficiency goes...propane is probably around 90% efficient with new furnaces (that's an estimate based on what's commonly used). Electric is 100%. A heat pump is 100% as well, but uses less electricity to accomplish the job (hence, cheaper).
According to the book, a heat pump unit produces more BTU's of heat per kw of electricity used compared to an electric resistance heater. In the example given, the particular heat pump mentioned produced 50,000 BTUs at 60*F outside air temperature and used about 4.4kw of electricity. If you had an electric furnace with a 4.4kw strip heater, both are 100% energy-efficient, converting all of that energy into heat, but the electric strip heater would have only produced 15,012 BTUs. ...which means the heat pump produced 3x more heat with the same amount of electricity.
...but once you get down to close to around 30*F, that heat pump may be producing LESS heat than an electric strip heater. That's where a geothermal unit would come in handy...it would produce about the same amount of heating/cooling year round.
Also an idea... call around and see if you can find some smaller HVAC companies or even just a guy who does it as a side-job (make sure you get references or only contact someone who's been recommended to you so you know he's not some hackjob). My old instructor owned his own business...he worked full time for Emerson Climate Technologies as a lab researcher (plus he taught 90% of the HVAC&R classes at my trade school) so he obviously knew what he was doing.
He didn't advertise it all over...but he also had a side-business doing heating and air conditioning installs for people. He was a registered business and fully insured...but just didn't have time to concentrate on doing it full time. He recently quit his job and went full-time (plus teaching part-time) but didn't make it 2 months before he got offered another full-time job teaching at another big trade school around here.
Anyway... we received numerous quotes from local businesses to replace our hvac system here at the house. We also got a quote from him. He beat the second lowest quote by almost HALF. He quoted us $4600. The next cheapest company was around $8-9k. The only reason he was so cheap compared to all the other places...he had very little overhead. The only bills he had in regards to the company was his insurance and he had a buddy who helped him out with installs so he took a small cut. All else was profit.
|02-05-2010 12:38 PM|
Well according to the guys here. (so far) A heat pump is a much more cost effective solution than propane....so I'll see. We live in a very moderate climate. Its rarely near freezing. this past month has been a very odd one for us. but apparently heat pumps put out 4x the heat per electricity used than the electric strips used in an old school electric heater.
I have 5 quotes in the works. so we shall see what they all come up with. Sadly I haven't been able to be at the house when the first 2 were there...had to do everything over the phone. the third one is coming back this afternoon after I get off work to go over everything with me.
The 4th and 5th are coming sat, monday (after work).
Looks like (as I suspected) I need a second unit as well - 2 story house.
so I shall see what kinds of $k I end up spending. I'm just hoping less than 10k. but I'm not betting on it.
I'm going to insulate the attic as its insufficient to say the least.
|02-04-2010 10:24 PM|
|02-04-2010 10:22 PM|
|02-04-2010 10:18 PM|
Also...just an FYI for those who say electric heaters aren't efficient. There's a difference between efficiency and cheap.
Gas furnaces are on average 70-90% efficient (they may go higher now, but there's still SOME heat loss going out your flue pipe)...electric furnaces are 100% efficient. Currently it is cheaper to use gas, but depending on energy prices, sometimes electric can be considerably cheaper than gas. Just some food for thought...
Gas is more comfortable IMO...electric tends to require the use of dehumidifiers as it tends to dry the air out considerably.
|02-04-2010 10:14 PM|
|jerryj||I live at 6500ft and have froze my ars off for many years.Ive heated my house with wood since I can remember.Last year we got forced air and my house was all electric the local propane co installed a tank for free and ive never been so comfy we still use as much wood as possible and heat the back rooms w the gas but the thermo is in the living rm so its warmed by the fire place so it only comes on when the fire goes out like 4 in the am then kicks on a couple hrs before we get up great efficient set up well worth the money.But we have a wood stove too not a fire place.|
|02-04-2010 09:18 PM|
I'm not a tech, but I am certified...unfortunately, very little experience in the field, however, I might be able to dig through my books and classwork and come up with some info.
I agree with you on your train of thought...if half the coils were running, you were pulling less electricity but for much longer. Whereas, if you plug in the other set of coils, you will pull twice the electricity, but it's not going to run constantly...and once your house hits the set point, it'll only run when necessary and far less than it is currently.
For unit sizing...let me check my books before I sound stupid...however, the term "ton" has nothing to do with your furnace as far as I'm aware (aside from making sure your blower is equipped to handle the cooling load). Ton is a unit of measure for COOLING capacity.
What you want to focus on is the required amount of BTU's of heat recommended for your house...and if you're going with electric heat, your heaters will be rated in KW.
I found a chart online (AC Direct - FAQ's - System Selection - Electric Furnaces -- this site has TONS of information regarding sizing including software you can download that can give you an extremely accurate recommendation for your heater/a/c unit sizing!)
According to the site...if you live in a warm climate, 30 btu's/sq ft is fine. A colder climate requires closer to 35 btu's minimum. So if where you're at in Texas is fairly warm most of the year, for a 2700 sq ft house, you're looking at around 25 kw (that's actually slightly oversized...it calls for closer to 23). If you have cold spells and wanna size it up (or if your house is poorly insulated...which I would work on fixing!)...30kw would be recommended.
For cooling capacities...for that size house, going solely off square footage...and leaving out all the variables, a general rule of thumb would be a 5 ton cooling unit. Does your house cool down pretty decently during the summer? If yes, then I wouldn't increase the size. If you go too big, you may actually pay more...plus it's hell on your a/c compressor since it'll often cause it to short cycle...AND since all new systems are R-410A systems, R-410A is more efficient and you'll notice that the house cools faster.
Also, if you do decide to replace your unit...being that you're in Texas, which I'm assuming doesn't drop below about 40*F very often, you're in prime territory for a heat pump system. Better yet...look into geothermal units. They are MUCH more cost efficient and they're not too much more price-wise anymore...newer systems can also be installed by drilling down deep into a narrow hole in the ground as opposed to tearing apart your entire yard like the older systems used to.
|02-04-2010 08:46 PM|
|flight risk||I am no tech...BUT... If I remember correctly, 1 ton per 500 sq ft, so you are not that far off. I agree that duel zones is by far better, but you might seriously look into the energy vamps that are stealing energy and power (insulation,windows, doors etc). I also agree that older units suck for efficiency. Just my .02|
|02-04-2010 08:14 PM|
|RedWrangler||OH, and I'd be checking the tax credits you can get for getting a greener system. It might help,|
|02-04-2010 08:13 PM|
|RedWrangler||You should check with them anyway about gas. Some energy companies will perform the install (At least the service to the meter.)at a discount or even free if you have enough applicances that will be using it.|
|02-03-2010 04:41 PM|
|mrcarcrazy||Issue is - there is no Gas at the house. I'd have to pay the gas company to get me a meter, run lines, etc. don't think I can afford that.|
|02-03-2010 04:33 PM|
|Jerry Bransford||If you end up replacing it, be sure to go gas. Electric heaters are, by far, the most expensive way to go. And work on the second floor the hardest, that's where any leaks or lack of insulation (in the attic!) are going to cause the most heat loss... heat rises.|
|02-03-2010 03:48 PM|
Second company has come out. THey said the other guy must have plugged them back in, as all four are now plugged in.
ANywho, he says basically what we all know:
5 ton too small
old inefficient unit.
Need at least 2 zones
So He's working me up a few different quote options. He said expect at least 8k for a basic 13 SEER 5 ton unit....so I'm likely looking at more than 10k.
I'm now even more stressed.
I'm going to call a few dozen more for quotes. The first guy said 4600 for a basic 5 ton unit. but I didn't trust him, so I'll call more and see what kinds of quotes we can get. I'm hoping and praying I can get this done for 6500 as thats my tax return...but we shall see. As I want it done properly (not just replacing the already too small unit with another too small unit.)
Last night I started on the sealing process. I got the front door sealed up, and all the windows on the first floor done... I have to get the two rear french doors sealed. (they need a thresh hold with rubber - currently just have wood.) then up to the second floor.
|02-03-2010 03:45 PM|
|schnutzy||another thing you can do as a cheap temp fix for any where that air is leaking a lil, is use painters tape to cover it up. it sounds kinda redneck, but it works great. our house was built back in the 50s and it leeks air like a bitch, and the heating system is original, and even though it runs great for how old it is, by todays standards it is absolutely horrible. we use blue painters tape and ran around and "sealed off" all the windows and doors and its keeping a lot of the warm air in, and the cold air out.|
|02-03-2010 03:42 PM|
You are on the right track thinking to plug in both heating elements. IF it is an old system, the fan running continuously is nearly as bad as the heating elements running at 50%.
It is too small of a unit also. I have a 5 ton system for my 1900 sqft.
In addition to checking everything Jerry said, look at where the thermostat is, and where the returns and vents are located. Get a thermometer and check various parts of the house vs. the thermostat. Closing some vents in unused areas or where it seems to be warmer can help too.
Oh, and gas is the way to go if you have to do an R&R.
|02-03-2010 03:17 PM|
|Jerry Bransford||Well that's out of my league but I think you're going about it in the right way by getting a second opinion. One thing I would do is to check your house over carefully for obvious sources of heat loss... windows not sealing properly, cold air coming in underneath doors, insufficient insulation in the attic, leaving rooms open that don't need to be heated, etc. My entire house is closed off except for the rooms we use and all the heat registers are closed off in the rooms we don't use so we aren't heaing unused parts of the house.|
|02-03-2010 02:43 PM|
I bought this house in November/December.
Its total electric.
first bill was 400.00
This bill was 700.00
House is ~2700 Sq ft.
5 ton unit.
the heater never really got things warm...after the first bill we kept the thermostat on 65. and the heater runs almost nonstop.
Had a HVAC guy out today. (I have a home warranty, so if the heater is shot I get one for free). He says. "well it is pulling 80 amps when its on. but only 1/2 of the coils are plugged in. SO that's why the air never feels "hot"... if the other 1/2 was plugged in it'd pull twice the electricty, and your bill would be even higher." He said that its not broke, its just old and inefficient. but wow, that's amazingly inefficient. I believe there is something wrong...
But that seems a bit off to me. to me if they were both plugged in it wouldn't have to run near as long to get the job done. so the bill would be lower. Sadly the house doesn't have a heat pump. and getting one means replacing everything.
I've called another company to come out and look at it (one not associated with the warranty company). so they can tell me if he was right or wrong.
I also am 98% sure that the 5 ton unit is too small for my house. I need at least 2 zones, and likely need 7-8 tons based on sq. ft., windows etc. My brother is an architect and has to deisgn systems when he builds buildings. He is supposed to come over this weekend and work out the formula that tells you how big of a unit is best. (apparently there is more to it than just Sq Ft.)
I'm basically looking for someone to tell me if the other 1/2 being unplugged is the right or wrong thing to do. I'm currently running space heaters in the rooms we are in. since I cannot afford a 700.00 Electric bill.
|02-03-2010 01:33 PM|
|Jerry Bransford||I'm no HVAC tech but I've repaired several forced air heaters & full house a/c systems & got them working when they were inop. What's up?|
|02-03-2010 12:56 PM|
|schnutzy||if you rnt able to get any help, shoot me a pm. my uncle owns his own company and i might be able to ask him about it, but it might take a while to get a response, he has been pretty busy with all the snow|
|02-03-2010 12:53 PM|
Any HVAC technicians here?
Hey guys/gals. I'm having an issue with my heater at the house, and I want to know if the hvac guy that the home warranty people sent out is full of it, or if he's right.
so if anyone is an HVAC tech and wants to help post up here and I'll post the story - its long.