Performance issues - boiler vs. forced air
I own 2 homes, my primary residence and a small vacation home. Both in Illinois and have relatively similar climates.
Primary residence is ~2500 sq. ft. raised ranch, average insulation, new windows and heated to 68 degrees via a 15 year old nat. gas forced air furnace. We also have nat. gas water heater and stove.
Vacation home (this is only our 2nd year in this house...so I'm not overly familiar with all the details), ~1400 sq ft. ranch with full finished basement (~1400 includes basement), average insulation...ancient/crappy windows and is kept at 50 degrees during the winter via a 1996 nat. gas boiler with 3 heating zones (1 downstairs, 2 up). We also have nat. gas water heater.
We just went through a particularly cold strech here in Illinois...and during this period the vacation home actually used more natural gas (by actual Therms...not just by price) than my primary home...which floored me. I had thought that nat. gas boilers are more efficient and it seems like a 14 year old boiler isn't THAT old.
So, just generally speaking, where do I start to look? Can windows and doors make THAT big of an impact? I can't imagine how the previous owner could have even survived the gas bill at full-heat 24/7. Is the theory that a 50 degree home should take less heat than a 68 degree home somehow flawed?
Odds are that a 14 year old boiler is not more efficient than a 15 year old furnace. How the boiler is tuned and controlled could make a difference in how much gas is being used. I would blame the boiler before I blamed the windows.
An oversized boiler can cost extra to operate than one that's sized correctly due to cycling on and off excessively. I also would take a close look at the boiler.
Use the biggest hammer you like, pounding a square peg into a round hole does not equal a proper fit.
Get an energy audit performed on both homes. Understand the energy impact of the air leakage measurements, insulation insufficiencies, equipment issues, and get cost benefit analysis of various improvement options. Don't rush.
Since everything is working you can develop a blueprint to implement as you see fit.
Nice that you are looking at this with the luxury of time. Most people make these decisions under duress. This could help you cut the energy bill on both homes in half, increase their value and make them much more comfortable.
Which makes more sense to you?
- turning your thermostat back and being uncomfortable. Maybe saving 5-10%
- leaving your thermostat where everyone is comfortable. Saving 30-70%
DO THE NUMBERS! Step on a HOMESCALE.
What is comfort? Well, it AIN'T just TEMPERATURE!
Energy Obese? An audit is the next step - go to BPI.org
, or RESNET
, and find an auditor near you.
I hear this all the time even with a properly sized boiler. The fact is boilers do much heating that does not go into the space. A water system tipically uses 20-30% more energy than warm air. I see 50% reduction in heating costs when a really old boiler is switched to a 98% gas furnace. I do not believe combustion efficiency tells the whole story.
Aire Serv of SW Connecticut- Gas heat, dual fuel and central a/c systems installed and serviced
You might try installing the Intellicon HW+ Heating economizer. We have had success providing and average of 20% savings for our customers with these units. We carry the entire Intellidyne product line and this is our 3rd best performing economizer. That being said, we are located in Toronto Ontario and target large commercial and industrial clientele with 10 ton systems or larger. However, pretty much all of the units have yielded 10-15%.
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Your right in both your assumptions. Its less expensive to maintain a lower temp in the house. This is assuming its for expended periods of time, not just set at 50 until it gets to 50 then set back to 70, then back to 50.
Also yes, windows, doors, insulation play a huge roll in a house.
Put it this way. I do work in a certain condo complex near me and the really really cheap people that live in the center of the building can maintain 60-62 degrees in the winter with the heat set too off (no heating cost). Only because they are insulated by 70+ degrees on 5 sides of them. Same goes with the A/C, and certain people only run it too knock down the humidity. The tighter the home is, and the better insulated it is will lower its heat loss, and lower its heat requirements and therefore lower its heating cost.
The home would need to be assessed too determine its heat load requirements. Then you can address problem areas be it insulation, leaky windows doors etc...
I agree with Cynicx as our last apt was like his condo exp.
Newly built in '07 so it is safe to assume insulation was used as much as possible considering 2" x 6" construction and sprinklers in the ceiling. We lived on the second floor of three. So I had neighboors up & below and even a west facing end unit which meant one outside wall running the length of our unit and another running the width(1200 sq. ft.) We never used heat unless it was really cold outside at night(anything below 20F). I could leave the heat off all day and come home to a 72-73F apt. even with a 30F outside temp.
That place was tight as a safe. Used a nifty Gas/Ac unit as well. It had a condensor like car and I believe used a condesing gas furnace. The unit was outside right next to my apt. and you could feel the exhaust but it was was barely warm. It exited via metal P-shaped pipe.
I hope to get our current house as tight as that was.