Need a weed-wacker for my heating bills

August 14, 2006 6:24 AM

I'm looking for a take-no-prisoners strategy to reduce home heating bills.

I just prepaid for this winter's allotment of heating oil, and my head is still reeling in agony.

Fortunately, I'm about to contract for a big addition of office space to the house, and I'll be able to tweak the current setup -- within reason.

I'm thinking of an all-out rezoning of the heat system. A new zone for the new offices used by me and my wife, of course. But also a new zone for the existing living room (which we don't use), and for my new basement DVD room. The latter will be attached to a timer that kicks in at four pm, so I can watch a DVD at five. This zoning layout will allow us to cut unused rooms off of the system, maintaining them at a low, low 45 degrees (to keep the pipes from freezing). We'll also have all zones except the bedroom shut off at night.

I'm also thinking of swapping my 17 year old oil-fired boiler for a new one, hoping that 17 years equate to a big jump in efficiency. Other options are to switch to geothermal, natural gas, electric, or propane, but these all factor to a higher cost than heating oil. Geothermal's not doable in my (ultracold) climate, it seems. So I'm sticking it out with hotwater baseboard, heated by oil.

Is the multizoning layout (five or six in all) a practical and logistically possible idea, or is it totally wack? Does it make $en$e to swap the old boiler for a newer model? Any other, out-of-the-box ideas?

posted by Gordion Knott to home & garden (9 comments total)

Have you considered a programmable thermostat? (Self-link, but lookit dah grafs!)
posted by unixrat at 6:36 AM on August 14, 2006

Zoning isn't usually one of the top suggestions, so I'll reiterate them, although you may already have done it all. I recently replaced a 30 year-old gas furnace and am in the midst of insulating as part of a Canadian EnerGuide for Homes evaluation. But I am not a HVAC professional.

First, insulate! Don't just throw it in willy-nilly, but more insulation is better.

Second, air loss. Cracks, gaps, etc. In conjunction with insulation, a vapour barrier also helps stop drafts in addition to preventing condensation from forming and rotting your frame. Even just caulking baseboards and windows can make a measurable difference.

Third, a new furnace. I would suggest getting a new one, although 17 years isn't that old and I don't know anything about oil furnaces. Certainly gas furnaces have improved and I find it tough to believe that gas would be more expensive than oil - my understanding is that it's usually the other way around. You can get oil furnaces with 92% efficiency ratings, which is about as good as it gets with gas furnaces as well. If you're currently running at 80% efficiency, you could conceivably cut your oil usage by 10% or so. Take the time to calculate a simple payback - divide the cost of the new system by the estimated savings in oil. If it's over 20 years, it may not be worth it. Having not seen your furnace, a 17 year-old oil furnace probably runs anywhere from 60-90% efficiency, depending on what kind of model it is. If it was top-of-the-line 17 years aso, there won't be a huge difference with a modern furnace. Certainly any reputable furnace dealer will assess your current system as part of a quote and let you know if it's worth it.

Also, you might want to talk to an expert who can suggest whether moving to forced air would be better than radiators. It sounds crazy, but it is possible to retrofit forced air in a home. But it is a big deal and again, I really have no idea whether it would be better. Everyone I know who retrofit forced air did it to get rid of a hundred year-old boiler/rad system and did other renovations as well.

Finally, zoning will only cut your usage a lot if you keep some areas permanently cooler than others. And if there isn't much air exchange between the zones. Dropping the temperature overnight will save some oil, but that will be mostly offset by needing to burn more to heat it up again in the morning. The least energy is used when an area is kept at a constant temperature. Keeping some rooms cold all winter should help some. Good luck!
posted by GuyZero at 6:44 AM on August 14, 2006

There are some good tips here about improving the efficiency of baseboard heaters. In my personal experience you can make big gains by making sure the hot water pipes are insulated if they run through unheated areas.

I'm not sure about the efficiency of baseboard heating, it always seemed to me that putting a heater on an outside wall was a questionable decision. It makes the room more comfortable because the outside wall isn't as cold, but it seems like it would transfer a good deal of heat to the outside through the wall. I put a radiant barrier behind my stand up steam heat radiators, but your baseboards are probably attached to the wall. If you are going to insulate anywhere, you might consider putting extra insulation in the wall behind the baseboard heater.

GuyZero: Most analysis I've seen says that turning down the heat and turning it back up again saves energy. That's partly because you are not paying for the energy in the room, you are paying for the energy that is lost to the outside. The energy lost to the outside is proportional to the difference between the inside and outside temperature.
posted by jefeweiss at 7:31 AM on August 14, 2006

I don't know if you need to replace the whole furnace. Your oil dealer would be able to check it out, if you have a good cast iron unit, it should be fine.

These same oil guys might recommend a burner upgrade. Some of the newer ones are very efficient.
posted by Marky at 8:34 AM on August 14, 2006

Guy Zero or jefeweiss, can you cite any research on your thermostat strategies? I have oil fired hot water radiators, and I thought that turning the temp down a couple of degrees is a way tosave, but then I gets to thinking about how much energy is used heating up all that water to raise the temp. So I wonder if it is more efficient to maintain the higher temp or reheat?
posted by Gungho at 8:55 AM on August 14, 2006

Is your home newer or older? Adding insulation and replacing the windows can save you big bucks, but they cost even bigger bucks. Sealing up your house in the fall--weatherstripping the windows and doors, checking the basement and attic for air leaks, etc., is cheap and effective.

The biggest and easiest money saver is of course turning down the thermostat. Buy a nice electric blanket and you can set that programmable thermostat to bring the temperature way way down at night and back up before you wake.
posted by LarryC at 8:57 AM on August 14, 2006

If you're willing to wear a warm hat and/or fingerless gloves indoors, you should be able to turn the thermostat waaay down. Plus a sweater or two of course.

Maybe your addition can employ south-facing windows to catch some sun.
posted by exogenous at 9:26 AM on August 14, 2006

Actually, the US Government agrees with jefeweiss. My bad. However, that's probably for gas forced-air systems, which are the norm these days. It's may be true for boiler systems as well, but they don't say specifically.

But you're still better off permanently lowering the temperature or improving your insulation if that's possible. Especially insulating your hot water pipes - that's a huge source of heat loss.
posted by GuyZero at 10:26 AM on August 14, 2006

Check into flash water heaters;
see
http://www.kk.org/cooltools/archives/000593.php
posted by dragonsi55 at 2:21 PM on August 14, 2006