Gas Heat vs. Electric Heat

You are absolutely correct in your conservation efforts. I applaude your energy frugality.

I just wanted to point out, however, that if everyone turned off their HVAC during the day while at work, the combined load around 4 to 6 pm may be more than the Texas power grid could handle.

That said, perhaps we should have that capacity built into the power distribution system.

How would an all-electric concrete home fare in colder climates, such as the northeastern U.S.? States like Vermont pay relatively high rates for electricity, but are lacking in natural gas pipelines.

That sounds great environmental sensitivity. Some while back I was impressed with the use of scrap tyres used in 'Adobe' type house construction. There is a good page with links on Wikipedia. http://en.wikipedia.org/wiki/Earthship

It would be nice if life's decisions were all easy and straight-forward. I have a gas furnace which is supposedly 'high efficiency'. I'll give it this - the heat loss up the stack is minimal. The chimney connection is just a little bit warm to the touch at the point it comes off the furnace. The hot air plenum is much hotter.

Where I live (in Alberta) gas was cheap and electricity medium. Since then we have deregulated electricity and gas prices have risen as well. Now gas is medium to high priced and electricity prices are nonsense. (For a while, or meybe even still, we were paying $30 million per hour more than the negotiated rate to Enron thanks to government corruption.)

Water pipe based heating through floors may be more stable. Leak need to be prevented and some fresh air should also be injected all the time. We are not living in a boiler. We need good fresh air - low on Radon and low on CO2. Moisture contents also may be a probelm with heating/cooling system. Comfort and quality air is what you need and it comes at cost. Savings are good, but not at the cost of health.

Shyam

Exhaust temperatures in older gas furnaces were in the range of about 175 degrees if I recall correctly. However, modern gas furnaces are way more efficient. To the point that you use PVC pipe to exhaust the combustion gases and a fan is required because there is not enough heat to create a draft. Also the pipe can exit the structure horizontally. They are much better than they used to be.

I switched from an elec hot water to a gas fired tankless hot water system and the savings have been dramatic

Ed,

Although you make a good point about the Delta T decreasing, and therefore the rate of heat loss to the environment decreases, shame on you, as a Professional Engineer, using anecdotal "evidence" to support your claims, and from only a very few cases. You should know better! With so many factors, involved how can you generalize like that?

Also, some of the others make excellent points you seem to have overlooked entirely, basing your conclusion for today's energy decisions on the results of yesterday's technology.

Also, you ignore totally the geo-political and economic factors. Yes, it may be more costly some places to heat with gas, say in the Pacific Northwest, where there is abundant hydro-electric and they are far away from most major gas pipelines, so naturally there will be a different set of economic rules in effect.

What is funny is that you base your conclusion in part on your own home, but admit that a substantial part of the energy savings is because your home is very well insulated, much better than most!

And, I do not know about Houston, but here in Missouri the electric utilities charge different rates for primetime usage than for off-peak usage, just like Cellular phone rates! That is why so-called "set-back" thermostats have become so popular. Temperatures usually ARE lowered when no one is home. Same thing in businesses that have no people working at night.

But there are many other reasons you would not want to turn your heat totally off just to conserve energy. For instance, in winter, even a well-insulated home will eventually reach freezing temperatures, which could burst water pipes, cause stud contraction leading to cracking of plaster and drywall "mud" at the seams. In summer you have the reverse effect, as a normally dry interior becomes very humid and swells up causing compression cracking, mold growth, and windows and doors to stick.

I am curious Ed, which engineering field is your PE in? It certainly can't be HVAC!

I'd have to say, I agree with STL.

There is no question that gas is more efficient than electricity (from the grid) for heating of both water and air. This was true even before our highly efficient crop of furnaces and water heaters appeared. The reason for this is that the powerplants are only about 50% efficient in burning fossil fuels to run turbines to generate electricity. Even cogeneration only bumps the figure to near 80%. The plant itself uses some of the generated elec (several percent) and line losses are about 8-9 percent. So, of the heat content in a pound of natural gas, only 40-60 percent or so makes it to your home in the form of electricity. Furnaces and water heaters, on the other hand, are virtually always more than 90% efficient, typically 95%.

I once achieved a sustained 80 mpg in a friend's 1986 Lincoln Continental (which was equipped with a trip computer). Does that mean that Lincolns can be relied upon to acheive that mileage routinely?

Was the electric water heater well insulated and in a heated area therefore keeping the water warm so little heating was needed? How much energy was being used per minute btu's by the electric versus the gas water heater? Was the gas water heater old and had scale build up on the bottom which will lower efficiency and increase time to heat water drastically? How was the gas water heater vented and was it on an outside wall? It must have had a fair breese from the outside to blow out the pilot light regularly.

Nowdays the tankless types seem to be having better ratings than the old style for water heaters. Gas water heaters have their problems which have to do with scale buildup and improper ventilation but poor maintance and installation are not proper factors for comparing energy use. The electric water heater would have done very poorly if set outside and had scale build up to the point that it burned out the bottom element.

It is very nice that you have an exceptional home but that does not help most of the people out there. Yes there is an energy savings to turning off the ac or the heat when away but why stop there just suffer through it and live without either now that is energy efficient. While we are at it take cold showers they will cool you down in the summer and wake you up in the winter. The problem here is that most houses are not insulated well enough so what we end up with is a house that may take several hours to reach the comfort zone. We are paying for both the hardware and the energy to be comfortable and often it takes only a few dollars a day to keep a house at a modest temp when everyone is away. This can be helped along by changing the thermostat to a better energy saving setting when away and shutting off rooms not being used when you first return home. We tend to shut off the bedrooms and bathrooms and leave the main living areas for the hvac to maintain a reasonable temp. When the climate becomes severe either hot or cold the interior needs to be kept within some kind of limits on temperture range.

Finis

Mostly true, but don't badmouth ALL gas heaters.
'Hydrotherm`, (if IIRC), made a unit so efficient
that it condensed the water of combustion, and was
approved for use with a plastic flue pipe back in the '80`s.