Switch from gas to electric forced air heating after solar?

[DanKegel]

The house is ~110 years old. It would be difficult to seal up windows and doors without compromising historic integrity/charm, though the attic (where the furnace is located) could be better insulated.

Also pretty similar to my situation - my house is 104 years old and a designated cultural landmark. Look up bronze spring weatherstripping - that's period-appropriate and can help with a lot of leaks.
Do you have / want air conditioning?

[silversaver]

Installing a solar system to save money, but using electric heating over gas to waste money. Where is your saving after all?

[Sol Jolla]

Curious, who is determining that a ~20 year old system needs to be replaced? We're also in coastal San Diego and our current "Payne" is ~30 years old and works great. I have a 1980 vintage rental in hot Riverside with the original unit that still does the job. Granted the 1980 unit is overdue and likely expensive (probably a SEER 6 or 7) to run, but the tenant hasn't complained. Our home unit is probably a SEER 8 or 9 and does fine, especially since we only use it a few days a year. I barely maintain it, service maybe once every 4-5 years.

Thanks very much, everyone. A few more details: The house is ~110 years old. It would be difficult to seal up windows and doors without compromising historic integrity/charm, though the attic (where the furnace is located) could be better insulated. When we purchased the home a few months ago, during a pre-sale inspection, we were told that we couldn't expect much more life from the furnace based on it being 20 years-old.

[Sunking]

Assuming a house in isolation:
If you use natural gas, you're emitting co2.
If you use solar, you're not emitting co2.

Am I missing something?

Yeah a lot. Sun does not shine at night when you need heat in SD, you are buying power. Nor does a small 6Kw system generate enough energy to run a heat pump during most of the day. Generating electricity to use as heat is extremely inefficient on the order of 20% or less from plant to heat pump. Using NG at Point Of Use is nearly 100% efficient. Using electricity takes 5 units of energy to make 1 unit of energy from NG. Your way pisses away a lot of money and resources with much higher emissions.

So why do you advocate pissing away money, using precious resources, and a heavy polluter. You ought to be ashamed of yourself.

[DanKegel]

Wrong, dead wrong. There is no more efficient means of heating with NG compared to a heat pump. Not only less expensive, but more efficient which means less emissions.

Assuming a house in isolation:
If you use natural gas, you're emitting co2.
If you use solar, you're not emitting co2.

Am I missing something?

[Sunking]

Unless your goal happens to be to minimize your carbon footprint, in which case heat pump style heating and good insulation is probably a better choice than gas for some things. (I'll probably never switch away from a gas stove; they're too good, they don't actually burn much gas, and switching to electric would be an anachronism in my 1912 house.)

Wrong, dead wrong. There is no more efficient means of heating with NG compared to a heat pump. Not only less expensive, but more efficient which means less emissions.

[DanKegel]

If you have Solar, Gas heat is ideal. Switching to electric heat would be going backwards. When you have Solar electric, you should cook, heat and hot water with gas.

Unless your goal happens to be to minimize your carbon footprint, in which case heat pump style heating and good insulation is probably a better choice than gas for some things. (I'll probably never switch away from a gas stove; they're too good, they don't actually burn much gas, and switching to electric would be an anachronism in my 1912 house.)

[Ian S]

If you have Solar, Gas heat is ideal. Switching to electric heat would be going backwards. When you have Solar electric, you should cook, heat and hot water with gas.

Gas dryer too.

[Willaby]

We have a ~20 year old forced air gas central heating system nearing the end of its life. -

Curious, who is determining that a ~20 year old system needs to be replaced? We're also in coastal San Diego and our current "Payne" is ~30 years old and works great. I have a 1980 vintage rental in hot Riverside with the original unit that still does the job. Granted the 1980 unit is overdue and likely expensive (probably a SEER 6 or 7) to run, but the tenant hasn't complained. Our home unit is probably a SEER 8 or 9 and does fine, especially since we only use it a few days a year. I barely maintain it, service maybe once every 4-5 years.

[Logan005]

If you have Solar, Gas heat is ideal. Switching to electric heat would be going backwards. When you have Solar electric, you should cook, heat and hot water with gas.

[J.P.M.]

With your mild climate an air-air heat pump will work well and cover both your heating and cooling needs (and re-use your existing duct work but I would have it checked for leaks and sealed while you're at it). Geothermal will be overkill. As Dan noted it's a good time to add some insulation, replace door thresholds/seals, etc. If SoCal homes are anything like NorCal homes they're like swiss cheese from an air leakage standpoint :P

It's almost always more cost effective to not use something than to get more of it. Hence, reduced use followed by conservation measures are almost always more cost effective first and second steps before new equipment, especially PV.

From what I've seen, most homes in So. CA are energy sieves and built in the days of cheap energy. Title 24 helps a lot, but those improvements take time to work their way through the housing stock. If most current homes around here were in a cold climate, the annual HVAC bills would be a lot higher. A 40 deg. F. delta T on heating is about 2X as hard to moderate as 20 deg. F delta T for cooling.

[Sunking]

Agree NG is the way to go.

[J.P.M.]

I don't believe electric forced air heating is the right way to go because it is probably the least efficient way of heating. Air as a medium has just about zero resistance and will find it's way out through leaks or whenever an exterior window or door is opened and closed. My house is 60 years old in coastal southern California. I'd added insulation to both the attic and exterior walls, and have tackled leaky doors and windows with improved weatherstripping. When we remodel the house, I'm planning on installing electric (possibly nat gas fueled) radiant floor heating in the bathrooms and bedrooms (they are all adjacent to each other). I've also installed a ceramic wall heater in our sunroom that keeps the room comfy during the winter on only .4kW/hr. I would definitely check out some books from the library and talk to some efficient home designers before open the wallet.

Always minimize the load before replacing equipment as you have done, and always educate before loosening the purse strings.

Stick with natural gas if available. Whether radiant heat floor or forced air or boiler circulation, CH4 fired equipment is almost always the most cost effective way to heat a home. Radiant floor heating is nice, but if done with electric resistance, the fuel cost is very high relative to nat. gas. Ceramic heating is electric heating. Stick with nat. gas if at all possible.

[J.P.M.]

1.) Do not use electric resistance for space heating. The most cost effective thing you can do at this time is get your present heating system checked out. It's probably something like 70% efficient or so when running properly, and will provide heat for about 1/3 or so of the cost of electric resistance heat. If it ain't broke, don't fix it. Get it tuned up and then seal and insulate the ducting.

2.) If you think moving to electric resistance heat will save you money, think again. It won't.

3.) If you are near the coast in San Diego, you have little need of either heating or cooling relative to the rest of the world. Your HVAC bills are quite small.

4.) If you still want to do something after the tuneup, first figure out what you currently spend in a year on heating and cooling total. Then, seal and insulate, with the emphasis on sealing as that's the easiest and least expensive. Figure as a 1st approx. that a new heat pump to replace the current gas furnace and A/C will save you about 20-25% of what you currently pay. Then, price such a heat pump system, and get bready for a long payback period.

While you're at it, add insulation to your existing water heater tank. Probably 6 month payback or less.

[maximizese]

I don't believe electric forced air heating is the right way to go because it is probably the least efficient way of heating. Air as a medium has just about zero resistance and will find it's way out through leaks or whenever an exterior window or door is opened and closed. My house is 60 years old in coastal southern California. I'd added insulation to both the attic and exterior walls, and have tackled leaky doors and windows with improved weatherstripping. When we remodel the house, I'm planning on installing electric (possibly nat gas fueled) radiant floor heating in the bathrooms and bedrooms (they are all adjacent to each other). I've also installed a ceramic wall heater in our sunroom that keeps the room comfy during the winter on only .4kW/hr. I would definitely check out some books from the library and talk to some efficient home designers before open the wallet.