Hello all,
My house currently has electric heat. It’s two story, 1600 sq. ft split evenly between the top and bottom floors. My central air handler needs replacing so I’m toying with the idea of replacing it with a central air/furnace unit. Electric heat works good and bills during the coldest months (Illinois) run $250. I have a few questions:
- What is the lifespan of electric heaters? They are about 40 years old.
- Is electric heat a bad idea?
- The only place a furnace could go would be unconditioned garage or upstairs closet. Is this a bad idea?
Thanks,
Nils
Replies
Your answer will depend on a number of things:
How long will you stay in the house?--long enough to get a payback?
How much does gas cost in your area? You'll need to compare $/BTU for electric and for gas, remembering that a gas furnace will be about 90% efficient, at best, possibly 78%. And from there, you lose efficiency due the duct system; in many cases, system efficiency will be 60%, or lower. And that can affect any system, gas or electric.
What will installation cost? New gas line, furnace vent system, duct work, likely electrical work.
Don't install the new furnace in the garage, if you can avoid it. You'll lose efficiency if it or any duct work is installed in unconditioned space.
Answers
What is the lifespan of electric heaters? This, like most questions about the lifespan of equipment, depends on the conditions of use, cycling, etc. 40 years is more than I would give as an average.
Is electric heat a bad idea? Possibly, but not likely. In IL, we pay about $0.08 kWh in the non-summer months. Propane costs over $2.5 a gallon and NG is over a $1/therm. Your local utility costs will vary. The only reason that electric (resistence) heating could be considered bad is due to the cost compared to that of natural gas or LP. Refrigeration cycle-based electrci heating (i.e. a heat pump) is a very cost effective way to heat above freezing. This poses a problem in IL.
Good things about resistence electric heat are:
99.999% efficient
no venting, piping or freezing concerns
running wire, even 6-3 is many times easier than black pipe and B-vent.
First cost is usually half that of gas fired appliances, always much less
Electric heating coils usually last 2 to 3 times as long as gas heat exchangers
Installing gas fired appliances in unconditioned spaces is not prefered and must be taken into consideration to select the proper equipment. Not necessarily a bad idea, but a more careful installation is required and high efficiency units (i.e. condensing furnaces) should be avoided. The duct work should be sealed very well and the venting as short as possible. Drains/traps that would collect condensate in the cooling season should be dry by the time freezing temperatures arrive, but busting traps is a concern.
When my house was all electric baseboard, my highest winter electric bill was near $400. It made economic sense for me to convert to a gas furnace while I was upgrading to a central system.
not sure I agree
>Installing gas fired appliances in unconditioned spaces is not prefered and must be taken into consideration to select the proper equipment. Not necessarily a bad idea, but a more careful installation is required and high efficiency units (i.e. condensing furnaces) should be avoided.
Primarily, just for discussion, I don't think this is as absolute as your statement makes it out to be. We have a condensing furnace (92% efficiency rating, IIRC) installed in our garage. It's outside of the heating envelop of the house, but since there are some water pipes running thru there, some heating is necessary. Most of that is provided by leakage from the rest of the house. We do have a baseboard electric to keep things above freezing in the most severe weather. If a gas furnace is installed inside the heating/cooling envelop, makeup air has to be provided. True, there are furnaces that provide their own combustion air, but I'm not sure how common that is. They were totally unavailable the last time we had to do an upgrade. Esp, when the OP said he may be looking for used equipment, I think assuming an exterior source for combustion air is a bad idea.
When in a secondary area, the balancing & cycling of providing exterior makeup air doesn't impact the heating envelop &, just speculating, might actually aid the overall efficiency.
Units that have combustion air to them are fairly common I think. It precludes having a separate duct and the associated issues.
"When in a secondary area, the balancing & cycling of providing exterior makeup air doesn't impact the heating envelop &, just speculating, might actually aid the overall efficiency. "
Yes, you're speculating. The inefficiency of the unit being in an unconditioned space offsets the notion that you aren't filling your furnace room w/ unconditioned combustion air. Most furnaces aren't really designed (efficiency wise) to sit in cold air. They aren't insulated or otherwise enclosed to minimize heat loss ... so you end up w/ a metal box in freezing temps trying to heat the house. I think this may be the reason for the comment made to avoid putting it in the garage.
Actualy, the main reason for not putting a furnace in an unconditioned space this far north is that virtually all ductwork leaks to an extent, and ductowrk (and furnaces) are necessarily less than optimally insulated, so you end up leaking a lot of hot air and heat to the outside.
In addition, a condensing furnace has a condensate drain, which must be somehow kept from freezing. On a sunny winter day, if the sun angles are right and the drapes are open (and the house is well-insulated), a furnace may not run for several hours, even though it's zero outside and 10F in the garage. Plenty of time for the condensate drain to freeze and crack the trap.
Codes haven't quite caught up with condensing furnaces, so you get a lot of different rules (and interpretations of the rules) on how much "make up" air or other ventilation is needed in the furnace area. In our area the interpretation is that a (2-pipe) condensing furnace in a conventionally framed house needs no extra ventilation so long as it's in a sufficiently large utility area.
Your agreement
is immaterial. Installing gas fired appliances in unconditioned spaces is not the first choice of any knowledgeable individual, ever. There are some uninformed folks out there that will disagree. I didn't say that it could never be done under any circumstances. I said it is not prefered. In your case you have some heat, so it is not an unconditioned space. Try subjecting your condensing furnace to -10 degF for a season and let me know. How much is the replacement/reapir cost, that is, because it will not survive. IF installing condensing appliances in a freezing enviroment is the only viable option, provisions to protect the unit must be provided.
The small amount of makeup air required for gas burning appliances is significantly less that infiltration leakage experience by most stick-built structures. For high efficiency units, sealed combustion (i.e. ducted combustion air and flue) is very common. The differnces in combustion and thermal efficiency are insignificant.
When you say "efficiency" you
When you say "efficiency" you mean output energy / input energy?
Right. And, as Tim points out, electric resistance heat is virtually 100% efficient--at the heat exhanger. From there, in a ducted system, efficiency can drop dramatically, whether gas or electric due to lost airflow as a result of leaky ducts or ducts losing heat in unconditioned spaces.
Gas furnaces seldom burn at the peak efficiency they're rated for, but since (natural) gas is usually cheaper to buy, you will likely pay less per delivered BTU. But that's not all there is to the story of total cost. Often, the payback time is about when it's time to buy a new unit.
The trouble, in your case, comes from the fact that an HVAC contractor is likely going to be far more eager to sell you a new system than to simply replace one component, i.e., a new electric resistance air handler, which is comparatively cheap. Assurances of low heating/cooling bills may not pan out when all costs are factored in.
Are folks using
heat pumps in your area? You get a lot more for your energy dollar with a heat pump vs. electrical resistance.
Heat pumps are used, but usually are supplemented with gas.
I see
from your posts below that you have electrical resistance heat..... baseboard heaters.
Without duct work in place, the easiest electric heat install that will cost less to operate is a ductless mini-split heat pump. Fujitsu, Mitsubishi, Daikin, and others make these units. You can get 2-3 times more heat from them per watt than you can from a resistance heater. You might want to spend some time looking at these online, and learn how they work and what's out there.
You could install gas heaters that don't require ductwork. I put a Hampton gas stove in our house, it looks like a wood stove but uses propane. If you have NG available it might be an option. I did my own gas piping and installed the flue, so it was fairly cheap to do.
heatsource
Last year I visited friends in Germany. They had a pellet furnace on the second floor that heated the whole area without any ducts, fans, etc. Even in energyexpensive Germany the pellets costs pennies a day to heat the upper floor (ca 1200sqft).
The lower level was heated with hotwater infloor heating.
The owner said if he had to do it again (as in building new) he would use electric radiant floor heating hooked up to a photovoltaic roofsystem and be selfsufficient.
Heating costs are ever relativ. There was a time when people had to go into the cellar to fetch coal to heat their stoves. Then they said: get rid of it and convert to oil - so much more convenient, no more ashes to clean out. Fill the tank only once a year. Then the oilcrisis hit and they discarded the oilfurnaces and changed to gas. Now they tell us that nonrenewable engergy will be expensive. If they would not drag their feet with PV systems we could have clean constant energy and be independent of utility companies dictating rates and taking money out of our pockets.
I worked with an architect who belonged to the SolarSociety of Canada. Their mandate was to find a solution to store energy from light. We know already how to get energy from light but have not come up with how to store the energy in sufficient quantities other than having fields of batteries. He said their government grant was 50 000 /yr. The Toronto Opera gets over 4 Million. That tells you where their priorities are.
In Germany the PV systems are highly subsidized to the point where the HO can even get money back from the utilitycompanies if they are tied into the grid. But as long as the taxpayer can be milked for hydroprojects....
"The owner said if he had to
"The owner said if he had to do it again (as in building new) he would use electric radiant floor heating hooked up to a photovoltaic roofsystem and be selfsufficient."
That has to be one of the dumbest things I've heard in a long time. Converting PV electric into thermal energy has got to be one of the most inefficient methods of using solar energy! WOW!!
And your architect friend ought to know better. Converting the suns heat to electricity to reconvert back into thermal energy is generally just a dumb idea and a poor use of that resource. Why not just heat water w/ the sun? Too cloudy? Well clouds also mean you have to have a LOT more PV area, too.
PV is all well and fine, but I tend to be an advocate of using the right techology for the best applications and generally avoiding misapplication of the technology.
PV is not the end all answer to energy problems, for sure. I know you didn't probably intend it, but your dialogue makes it sound like that is what you advocate.
PV should be at the bottom of the list of good energy technologies to apply (read this carefully). I'm not anti PV, but it is very expensive relative to e.g. windows, insulation, caulking, low flow shower heads, etc. etc.
I'm glad they are doing more research and I commend your friend for his involvement. The gov't needs to subsidize this kind of stuff as much (or more) than they do the oil industry.
PV use
agreed, but if it is free and available in unlimited quantities, who cares
We look for efficiency and durability only if it costs us. I remember the time when we suggested to the HO to increase the R value in exterior walls. At that time (late 60s) it would cost about 400 to go from R7 2x4 wall to R20 2x6 for a 1200 sqft bungalow.
400 bucks? you know what I can do for 400 bucks (and he moved his finger on the imaginary thermostat)?
Today he would kiss the ground if he had to pay only 400 for better insulation.
It's all relative. As for now, the Germans love PV. Their government grant covers the payment for the equipment. The utility company pays them a guaranteed price for 25 years. The equipment is paid off in 10 years. After that the HO has to maintain the equipment for the 25 years (repair, replace, renew) but all "income"is taxfree. There are farmers who got rid of all their livestock and plastered the land with PV. Many retired in Spain or Southern France, living the life of Riley.
"agreed, but if it is free
"agreed, but if it is free and available in unlimited quantities, ... "
That is even more laughable than your first statement. PV is not free, period. And don't tell me that with gov't and utility subsidies that it essentially is free. NOTHING is free ... 1st and 2nd laws of thermo.
Unlimited quantities???!!! Even more laughable. The sun may be considered 'unlimited' resource for all practical purposes, but limitations are in the surface area of the PV modules.
While I'll support PV over some of the other energy source resources, we have to avoid jumping on that glitsy, sexy bandwagon of PV energy source at every chance we get.
It is comendable that Germany seems to have this thing about applying PV systems. Maybe their energy costs are like 2-3 times what we pay on average. Economically it would begin to make sense. PV is nice. It is NOT free ... far from it. It is not without it's down sides.
IMO we need to embrace technologies in an intelligent way and not slather them everywhere like it was Tom Sawyer painting a fence.
agreed
I think it is very obvious that I did not refer to the present heating/energy situation
As we have seen from the "evolution" wood - coal - oil - gas we will have to wait to see where this is going in the future. Ultimately we will always be looking for the most economical heating/energy source and only the dollars in your pocket will determine that
It seems obvious to me there was nothing particularly obvious about many of your statements. I must be missing something (you're probably saying 'well that is obvious'). Apparently you feel it was obvious ... but obviously it wasn't to me.
Most economical heating and energy 'source' is still what it was 30 years ago: conservation ... the elimination of waste and the reduction of need/demand.
Economics of energy in the U.S. has been heavily swayed by government (read "taxpayer") subsidies of various industries ... the most prominent one is obviously oil. (at least I think it's obvious, but I've been surprised to hear people that really don't think so).
Most economical heating and energy 'source' is still what it was
30 years ago?
Way much more than that tight time period.
Many eons ago, man *or woman for that matter* looked for a place to make a home. Caves, hollows in the rock, ledge or hillside........didn't make much difference. The less building the better. Take cover, add heat (or cool) and you've got a home.
Now? not so much. We can build it anywhere, any shape, any thing. And that technology coupled with the best systems you can put in it still take it part way.
What's been lost in building over time is proper siting. Nothing to putting it on the street, square to the road, make it look good, pc. of cake.
Or, "we want the view". Walls of glass for the view-pointing north.
Take that same house that would have been on the street, site it so you have some view, orient it to pick up as much solar gain (free) as you can in the winter while shading it with overhangs, tree shade etc, and place it on the site in such a manner as to resist (at least naturally repel) the prevailing wind. Put the room configuraton together to fit your life style along with the path of the sun to enhance it.
Not everyone can be as lucky as some of the early builders. Takes a bit of work and thought, but properly siting a house can reduce energy consuption in an economical and simple way.
Really.
Absolutely ... I agree w/ everything you said.
Germany has to import most of its energy, and much of that comes from Russia, which is not a very reliable supplier. They view it as a major national priority to become more energy independent.
(The US, on the other hand, seems to want to become more and more dependent on foreign energy sources.)
Hope you're not implying that because of Germany's convictions, that it is reasonable to routinely promote using PV for thermal ... and no, it wasn't particularly 'obvious' that the poster had mixed up the technologies ... IMO his statement was crystal clear ... i.e. obvious.
And yes, the US seems to have their priorities still misdirected. Lots of talk of green and conservation while we continue to seem to have value for McMansions and ignore simple economical conservation in favor of something more glitsy like PV.
Hope you're not implying that because of Germany's convictions, that it is reasonable to routinely promote using PV for thermal
Definitely not. But I do believe it's reasonable for a government to promote PV in general.
As to the German guy's statement, we're getting it about 5th hand, with a language barrier, so no telling what the guy literally said, much less what he was thinking about. I'm just saying that something got confused along the way. I sincerely doubt that anyone in Germany is using PV (or being encouraged to use it) for general heating on any large scale (though certainly there may be some space heaters plugged into the arrays here and there).
implying
that was the feedback I got from the German friend.
They are looking forward (and some have already) to heat their homes with PV.
It is very complicated and expensive to run gaslines in 13 story housing complex constructed with concrete and brick. But they all have electrical lines (220 V) even for their TVs. They (and we) will always want to have electricity in our homes. Why not use it if the source is available? There are some very fancy wall heaters on the European market. The very advanced ones are actually radiant wall units.
Yes, they want the utility grid as a back up but only where space (property) for individual home owner is limited or restricted.
re comment
Your are absolutely right, that was the mainreason to ensure a reliable supplier. They were cut off already once.
So here is the situation: A PV manufacturer can supply the required system . The owner buys/finances the system. The utility company allows you to tie into their grid and pays you a guaranteed amount for all the energy to supply to them. If the excess over your own demand pays for the monthly payment everyone benefits. The owner will eventually own the system, gets paid for energy supplied. Does not even have to pay taxes on the "income"
On the other side of the pond: A PV system for a "normal" home here in BC cost ca 35000 C$. The owner is not allowed to tie into the grid. Gets no rebate or incentive. At (present) 6cents/kw they say the paypack period is over 40 years assuming the rates remains steady.(not likely). If I would be a manufacturer looking at such a market I would say I do not have a market here and look elsewhere.And that is just mighty fine with the oil and gas suppliers. Go ahead and insulate and weatherstrip your house to the umpteenths all we have to do is raising the price for gigajoules and kilowatts. btw. the utility companies applied for another increase for April. Politically not correct ot raise prices during the heating season but when demand is low few will complain about their energy bill then, by the time October rolls around for the next heating season they are well entrenched and can say: energy prices remained constant.
Will be interesting to see what Dow comes up with their PV roofshingles
At least the PV owner does not have to worry about the sun raising the price
That is quite obvious
Yeah, the scenario you describe is why the government (state and federal) needs to get more envolved to encourage PV. Subsidies are one side of it, but regulations are the other -- require utilities to pay for backfed power, etc.
As it is, while the US had the edge on manufacturing PV arrays ten years ago, we've lost that edge and likely all PV manufacturing will have moved out of the US in another 5 years. This was one of the last high-tech manufacturing industries that the US had.
I suspect what the guy meant to say (either he was confused in saying it or you were confused in hearing it) is that he'd go with a rooftop solar collector and in-floor radiant hydronic heat (possibly even using the floor mass for heat storage). Rooftop PV wouldn't provide enough power to heat a structure, since so much energy is lost in the light->electricity conversion process. And PV doesn't provide power at night, when heat is most needed.
(But I agree that the US is really dragging its feet in utilizing PV. Europe and China are way ahead of us. Those "green jobs" that were talked about a few years ago are going to be in China, I'm afraid.)
I dunno, Dan
"The lower level was heated with hotwater infloor heating.
The owner said if he had to do it again (as in building new) he would use electric radiant floor heating hooked up to a photovoltaic roofsystem and be selfsufficient."
Sounds like PV thermal heating to me ... not sure where there might be confusion on what he meant to say.
The life of electric resistance heaters is pretty much unlimited. They will eventually burn out, but you can't predict whether it will be tomorrow or 20 years from now.
Electric resistance heat does not get substantially less efficient as it ages. Various factors might add up to 2-3% loss of efficiency, but not worth worrying about.
Electric resistance heat is not a great idea in Illinois, You're likely paying 50-100% more than what you'd pay for gas. (We have a 2000 sq ft house in MN and pay about $150/month for gas at worst.) And I suspect that your power comes mostly from coal, meaning that your "carbon footprint" is pretty large.
A heat pump is viable in most of Illinois, and is worth considering. You still end up using some resistance heat in the coldest months, but roughly cut your heating bill in half at other times of the year (plus the unit doubles as an air conditioner). The equipment could be installed in essentially the same space as your current setup (though of course the compressor would go outside). The downside is that a heat pump is probably your most expensive option.
The new high efficiency gas furnaces are compact and don't need to be installed where a conventional flue is available. Such a unit would likely take up some more space than your current air handler, but not much more. Plastic vent and flue pipes would have to be run out a side wall, but they can generally run 20-30 feet before they get to the wall. Certain venting requirements need to be met for the utility closet, but they are not unattainable.
I wouldn't advise putting a new unit in the garage or another unheated area in your climate. And any significant change from its current location will require extensive (and expensive) rework of your ductwork.
You may be able to take the opportunity to get the new system "zoned" for separate control of upstairs and downstairs, depending on how your existing ductowork is configured.
I would strongly advise against getting used equipment, unless you know it pedigree. You can get a new high-efficiency gas unit for under $1500, and you'll generally spend another $500-1500 on installation and accessories. Buying used is unlikely to save you more than $500 or so when all is said and done.
What Dan said.
And I would emphasize his advice against buying used heat pump equipment., unless it's virtually free and even then it might not be the best course of action. There have been significant advances in HP efficiency in recent years, even since ours was installed in 2005.
We need to define some
terms to be on the same page. Efficiency means the amount of heat transfered to the space divided by the amount of energy paid for. Effectiveness not yet mentioned by me, is the abilty of the system to put that heat where it is useful.
Someone pointed out, that a ducted (i.e. forced air) system loses efficiency, which I agree, but it actually loses effectiveness. The overall system efficiency should take into account the puump or fan energy required to distribute the heat to the space, but does not affect the thermal efficiency of the "heat producer", be it an electric element or a gas fired heat exchanger.
As electric resistence heating coils age, they oxidize (corrode to a degree). The amount of energy consumed is the square of the current times the resistence and is expressed in watts. Regardless of the surface condition of the element, this does not change. What does change is the resistence. Whene the surface corrodes it transfers heat less effectively and operates at a higher temperature. This raises the resistence and therefore raises the energy consumed. This is a very, very slight change. Most likely, an older electric resitence heating element will by the contactor wearing out. If the corrsion becomes severe enough, there will (should) be a high limit that will trip or disable the element.
> This raises the resistence
> This raises the resistence and therefore raises the energy consumed.
You'd never get past freshman circuits if you believe that.
So
if I increase R in the I^2R equation, it doesn't get bigger?
Hello all, Thanks for the
Hello all,
Thanks for the excellent feedback.
I think I need to clarify something. My heaters are electric baseboard heaters underneath each window of the house. How does that affect things? Are they more or less efficient than a forced air resistance heater?
Thanks for any help, and pardon my ignorance on the topic.
Nils
Doesn't matter
I thought that's what you meant. It really doesn't matter. With baseboards distributed throught the house, you probably have the benefit of a thermostat for each room and can only use the heat you need, when you need it. Electric baseboard heater last longer than most homeowners. The only difference between a baseboard and a heating coils in an air handler is how the air is circulated.
Pretty much a KWH of electric heat is a KWH of electric heat, whether it's a resistance furnace, baseboards, or 10,000 Christmas tree lights. All the same (so long as you keep the drapes closed, at least).
Electric baseboard does have the advantage of being "zoned" (with a thermostat in each room, generally), and it puts the heat along the perimeter of the building, where it's needed most.
I think we were led astray because you mentioned an air handler. Is that just for AC & ventilation?
Air handlers for A/C only
I have two air handlers for A/C only, one for each floor. One is located in the attic and one is located in the crawlspace, as is the duct work. (Stupid design I know.) The attic one has literally rusted apart and is being held together with wire straps, 2x4s and duct tape. It leaks water like a seive and thus needs to be replaced. It's original to the house. Rather than have to purchase a brand new system (quotes were running $5K+ for one floor) I was hoping to find some decent used R-22 equipment and reclaimed R-22 to replace the air handler without having to replace the condensing unit. The condensing unit for that air handler is newer, about 10 years old. The crawlspace air handler is quite new.
The reason the previous homeowners place the units in the crawl space and attic was because there's no room downstairs (other than an adjoining garage).
Under those circumstances you're probably better off spending more time/money on air sealing the structure (and the ductwork), vs upgrading.
However, you may want to consider replacing one of the two systems (preferably the downstairs unit -- heat rises) with a condensing furnace or heat pump. Most condensing furnaces can be installed sideways (or even upside-down), so they can fit into relatively short spaces. Ideally you'd build a "room" of sorts around the unit, vs leave it open to the elements. And even if enclosed this way, it would probably be wise to have heat tape installed on the condensate drain trap (if a condensing furnace is used).
It's generally possible to remove the A coil from the existing air handler and install it in a new one, maintaining the "balance" between A coil and compressor unit. Of course, you'd still need to pump out and recharge the system, since the pipes would need to be cut.
Thanks to all for your advice and help. I've found the information very informative.
Thanks for participating.
Nils
Electric baseboard heaters
will be the most efficient electric resistance heating you can get. You have the benefit of a zoned sytem; they last a long, long time; use no fans; are silent; have no losses thru ducts and are not located in unconditioned space. If one of them fails, you still have a warm house, and the cost to replace the failed heater is small and is a DIY-friendly job.
You have be careful about placing furniture or other combustibles too close, but otherwise, they're a great heat system for electric resistance heating. But not as cost-effective as gas in most localities.
At some point it should be said that the OP may be better off investing his money and effort into improving the insulation and sealing of the house. A house of that vintage can generally be tightened up by a factor of two with appropriate care -- sealing air leaks into the attic, residing with housewrap (carefully taped around windows and doors), caulking cracks, removing inside trim and foaming around window frames, etc.
I'm confused ... you start by saying central air handler needs replacing ... implying a central electric furnace ... then you say it's electric baseboard ... which is it?? Are you implying central cooling and only baseboard heating? Now you have to replace your central ... what? A/C coil? Fan? Fan motor? Compressor?
Electric is 100% efficient ... and will last a VERY long time.
Others have indicated ... get your electric cost and your gas cost and compare them ... on a Btu basis. Electric generally tends to be very expensive compared to gas ... even with the combustion inefficiency taken into account. If you need help with this let us know ... but get the average unit cost first. If you have a different summer electric cost, get the winter rate for heating.
See my post above for answers to your questions.
Looks like I pay $0.077 per kWh ((bill - taxes) / kWh). Before I canceled my gas service (got rid of my only gas appliance, a dryer) it looks like I was paying about $1 / therm.
NO free lunch. Not no how, not no where
next ya gonna tell me that if I put a wind turbine on the top of a Prius and use that to charge the battery..........etc....
central IL heat pump trade study.
If you can open excell and do math, this will answer most of yur questions.
What if I can't open Excell and do math at the same time ?
;o)
(Rather like walking and chewing gum...)