Scheming to reduce oil heating costs

[joesxm3]

With the cat gone I am giving some thought to a spartan (or should I say Alaskan) winter life style.

I had been reluctant to turn down the heat when I was out during the day, but now it seems I should be able to.

I am wondering if there is a trade off in how low one can turn the heat down compared to how much extra it takes to get the heat back to nominal when you return home in the evening. I am thinking that severely lowering the heat and then cranking it up will cancel the savings.

I have oil hot water heat and have four zones in my house. I am considering disconnecting one zone which heats my 24 x 12 foot den that was an addition to the main house. This portion only has a crawl space and not cellar, so the water pipes go through the crawl space and potentially can freeze.

The den has a wood stove and I am thinking that I would be more agressive about burning wood when I am home in the evening sitting in the den. I have a pile of wood sitting around so it is virtually free. The problem is if I run the wood stove, the oil zone shuts off and while the room is toasty, the water pipes are cold and might freeze.

Does it seem feasible to disconnect or shut down one zone and drain the water from the pipes? There are four zone pumps and it would seem that each zone has its own pipe run out to the zone and then back to the furnace. Does that sound right?

I just started thinking about this, but I am pondering two strategies: 1) just shut down the den zone and let the den get heat from the other downstairs zone by air circulation when I am not burning the wood stove; 2) Add in some electric heating that would be used to maintain a minimum temperature in the den. This may involve dismantling the oil water heat radiator baseboard units, but I sort of like the idea of just shutting down and leaving the system intact. I will have to look into this more.

Another question involves the possibility of reducing the size of the oil burner nozzles to try to make the furnace use less oil. Is that possible? Can it be bad for the furnace?

Any input on this will be appreciated. Thanks.

Joe

 

[REWahoo]

Have you considered moving further south?

 

[Gumby]

Have you considered wrapping the pipes in the crawl space with electric heating wrap? I don't know what the relative cost of the added electric use versus the reduction in oil heating would be, but just heating the pipes seems less expensive than heating the entire room.

 

[cute fuzzy bunny]

I'll also suggest the boring other end of the spectrum that many people dont consider as much as they should.

Have you insulated your house well enough? Oil is gone the minute it burns, but insulation lasts dang near forever. Its cheap and easy to install.

A week with some rolls of insulation, an insulation blower and some cellulose, and a bunch of caulking and insulating tape just might save you more every year than any other scheme.

Burst water pipes are very bad news. Draining and refilling hot water systems and getting all the air out of them so they dont sound like a bad marching band is also not a lot of fun.

 

[Max Power]

I'm in line with CFB. The most bang for your buck would be to insulate the crawl space area so that the threat of frozen pipes would be eliminated. Yeah, you don't want to think about draining pipes and then getting all the air out when the water goes back in. The number one place to spend money is for insulation, making sure you have enough in all areas. Eliminate places where you might be getting air leaks. Have you got reasonably new windows? If not, just replacing a few at a time as budget allows will pay big dividends. We had an 8 foot sliding glass door to our back deck, installed when the house was built in 1994. We've since taken that out and put in a single 36" door to the deck and sheetrocked and insulated the rest of the wall. It's amazing how much warmer it is now, just with that change.

 

[cute fuzzy bunny]

If you cant afford to replace windows, you can also use Al's bubble wrap trick. Even some heavy tight fitting drapes can do wonders.

If your floors and pipes arent insulated, you can foam board them or run some wire and tuck fiberglass roll under the wire. Put another foot or so in your attic. Foam inserts behind the a/c outlets and switches. Caulk up all the seams and cracks.

 

[joesxm3]

I will have to crawl under and check but a quick glance shows that there is insulation on the bottom side of the den floor (i.e. the top of the crawl space).

If I remember correctly the water pipes themselves have that black insulation that goes around the pipe and is about half an inch thick. I also think that I may have tried to pack fiberglass insulation around the pipes where ever I could.

I think that the pipes, however, are below the main insulation.

When I say crawl space I mean "crawl" space. There are cement foundation walls, but the floor is dirt and it is probably only two or three feet maximum from dirt to house floor.

I am not sure if it is possible to put insulation against the cement foundation walls.

The idea of the electric pipe wrap heating sounds like it might have some possibilities, especially if I were able to only turn it on when I was burning the wood stove and felt that the hot water was not circulating.

I have never had any problem with the pipes freezing, even when I have lost power (and furnace) for six or eight hours during the winter. During that time I burned the wood stove.

Maybe I am overestimating how cold it gets inside the crawl space. It just occurred to me that I could install a thermometer inside the crawl space that transmits the temperature to a reader inside my house. That way I could know for sure what is going on and monitor the condition. I bet that these days you can even get a battery powered thermometer that transmits to the receiver without wires.

As far as the rest of the house goes, my insulation status is as follows:

I replaced all windows with modern double pane gas filled windows and have honeycomb blinds on most of them.

I stripped the sides of the house down to the plywood and installed vinyl siding. The house is circa 1960 and the walls are not that thick, but the contractor concluded that we have done as much as possible to insulate the sides of the house. I can't remember if he put something under the siding, I think he may have put some backing material that had some insulating value, but not the hard core insulation board I wanted to because he said it would raise the siding too far from the house and require that the window frames be extended etc. etc.

I have two layers of fiberglass insulation in the attic crawl space. The contractor had suggested that I could put more up there and that I really should remove the existing and maybe blow in some, but they quoted me a really massive price so I figured I would do something myself - but of course never got around to it.

I try to block all the leaks, but there are still some I can attack. That will be a project for September.

Bottom line - As usual I probably should avoid anything really drastic. I think that getting some facts by putting in the thermometer and considering the electric pipe wrap will be a good first start. For all I know the crawl space may not be as cold as I think when I am running the wood stove.

Thanks for all of the prompt replies.

 

[Martha]

I live too far north for people even to consider having plumbing in a crawl space, but isn't that a huge heat loss to have radiator pipes in an unheated space? Any way to re-run the pipes in a heated area? How cold does it get where you are?

Can you drain the zone so there is no water in the pipes?

 

[cute fuzzy bunny]

I know some thermostats take remote 'probes' that are wired in to help the furnace make decisions around whether to run or not based on temps in different zones. I wonder if theres a setup that would let you stick one of those probes up under the insulation next to your water pipe and let you fire the furnace if the temperature next to the pipe dropped below 35-37 degrees.

That'd be a lot cheaper than running electric tape pipe heating all winter.

 

[cute fuzzy bunny]

By the way, you might get some advice at www.hvac-talk.com. They're an ornery bunch and wont help you with any DIY stuff, but they'll answer basic "what would you do/buy/can this be done" sorts of questions.

 

[samclem]

I know some thermostats take remote 'probes' that are wired in to help the furnace make decisions around whether to run or not based on temps in different zones. I wonder if theres a setup that would let you stick one of those probes up under the insulation next to your water pipe and let you fire the furnace if the temperature next to the pipe dropped below 35-37 degrees.

That'd be a lot cheaper than running electric tape pipe heating all winter.

CFB, you need to get away from California and experience some cold! Almost all the common heat tapes sold now to keep water pipes from freezing have a built-in thermostat. They only come on when the thermostat gets below 40 deg F or so.

joesxm,

I think the heat tape for the pipes is a good idea, but if it were my house I would worry a lot about the tape failing (how would you know?) and the pipes bursting. I like the tape for occassional "oops" situations, but I'd be worried about depending on it without either a temp alarm on the pipe or some redundant system.

If it is often fairly cold (below 10 deg F) where you are, it will really be worth the effort to blow at least 6" of cellulose insulation on top of your fiberglass insulation in the attic. Both cellulose and fiberglass have approx the same R-rating (R3 to R 3.5), but the open weave of fiberglass allows fairly serious convective air movement to occur when the temp gradient across the insulation approaches 60-70 degrees. This significantly cuts the effective R-value of the fiberglass. Cellulose is denser, and air doesn't flow through it nearly as much under these conditions, so it serves as a "cap" on your fiberglass. Though 6" only has an R-value of approx 18-22 it might also add about 30% to the effectiveness of the fiberglass you've already got when things get really cold. And, blowing the cellulose in is a fairly easy DIY project if you've got access to the existing insulation in the attic.

It is definitely possible to add insulation to your crawlspace walls. It won't help much unless you also close off any vents in your crawlspace. This is a controversial step, and many people believe it will lead to moisture problems. Many others (who I agree with) believe that crawlspaces can be effectively insulated IF you do things right and pay attention to the details to prevent water vapor condensation issues. An insulated and sealed crawlspace can be considerably more dry than a vented crawlspace, and will save a lot in heating costs.

Here's a good info sheet on this issue from Building Science Corporation--they know what they are talking about.

It's too bad you couldn't get some foam insulation installed when you had the siding done. Even 1/2" of the stuff has an impact much greater than it's R-3 value might suggest, since this foam greatly reduces the thermal bridging and heat loss through the wood studs of a typical wall.

Regarding your question about reducing the temp when you leave the house: this always saves energy. There's no "catch up" energy penalty imposed for having to heat up a cold house--the oil furnace is not less efficient just because it is burning longer to bring things up to temperature.

Have you considered an electric blanket or a small portable room heater (or electric baseboard heat) in your bedroom? Even though electricity is an expensive way to heat, heating just a small room at night instead of the whole house can save quite a bit of fuel oil.

Best bang-for-the-buck: Caulk

Good luck and stay warm!

 

[cute fuzzy bunny]

CFB, you need to get away from California and experience some cold!

Hey, I lived in Boston for 32 years. I think I got it

Never wrapped a pipe though. We kept them in the basement next to the coal furnace that had a big oil injector welded into the coal door around 1950.

 

[Notmuchlonger]

Hey in an hr some of us Californians can be up in the cold or in 1.5 hrs be at the beach

 

[limpid lizard]

I have been to many a fire caused by those pesky electrical heat tapes. Use with caution!

And in Idaho, it is not uncommon to see the concrete foundation walls insulated with fiberglass batts stapled to the sill and hanging down. A dab of something like liquid nails keeps the bottom against the stem wall.

 

[Telly]

I am wondering if there is a trade off in how low one can turn the heat down compared to how much extra it takes to get the heat back to nominal when you return home in the evening. I am thinking that severely lowering the heat and then cranking it up will cancel the savings.

There is no tradeoff, heat loss is heat loss. The overall cost will be lower for turning it down, then back up again later... but this would NOT be true if you would have had a Heat Pump. With a Heat Pump, when turning up the heat, the large temperature differential from the present low temp to the desired set point temp would kick on the electrical resistance (backup) heater, which would be an energy-cost loser.

But don't forget about your refrigerator. In ambient temps below about 55 degrees or so, they won't run often enough to keep the freezer compartment reliably cold enough. If you have the instruction or installation papers from the refrigerator, they probably specify the actual minimum ambient temp for your unit.

 

[Telly]

I think that the pipes, however, are below the main insulation.

When I say crawl space I mean "crawl" space. There are cement foundation walls, but the floor is dirt and it is probably only two or three feet maximum from dirt to house floor.

I am not sure if it is possible to put insulation against the cement foundation walls.

Been there, done that when I lived in a cold climate.

Shallow crawlspace, dirt floor, cement block foundation walls, pipes in crawlspace, vents as missing blocks.

What I did:
Leveled off the dirt so there were no big hills or holes, and covered the dirt with 6 mil thick plastic. Overlapped the sheets and taped all the seams with the proper tape that will stick to polyethylene. Lapped it up a few inches on the foundation walls. This created a good vapor barrier.

Installed one inch thick white foam beadboard on all of the foundation walls. Used Great Stuff foam in a can as the adhesive. Made an outline of the sheet on the foundation wall just in from where each foam board edge would be, then an X or two across the middle. Pressed the foam sheet into it good, and propped a board or two up to hold each one while foam cures. Then went and foamed the sheet to sheet joints. I chose the white beadboard for a reason... they are not vapor proof. I could have used more expensive foam board that had an aluminum foil barrier sheet on it and a higher R-value, but they are impervious to moisture. I wanted any moisture that somehow made it up past the floor vapor barrier to be able to exit in winter, when I had the foundation vents closed up and insulated from inside.

I also insulated any wood area, like the band joist on top of the sill plate, that is exposed to the outside. Even though that area was insulated outside under the siding, I did it anyway since it is near the edge.

It made a real difference, a lot warmer, the pipe heaters never came on on real cold nights anymore. And in summer any "crawlspace smell" was gone forever.

 

[joesxm3]

Wow -

I never expected such an enthusiastic response to this post. Thanks to everyone for the excellent advice.

I will digest the advice, consider the plan and move carefully. I suspect I will have more than one winter to worry about this given the way oil seems to be going.

This zone is definitely a heat loss problem. The oil heat in the den has trouble keeping the room warm even with the thermostat cranked up. I think it is because of heat loss through the pipes in the crawl space. That might argue for simply disabling the zone and adding electric heat and using the wood stove more.

The people I bought the house from were pretty cheap and made a lot of deceptive cosmetic changes to help sell the house. If they were willing to pay for the wood stove they probably had a reason. They also left a shed full of wood, so they must have been using the stove.

I suppose I should eventually bite the bullet and put more insulation into the attic.

 

[travelover]

I would second or third the advice to insulate the walls in the crawl space and add plastic sheeting over the dirt floor. The plastic makes it a lot easier to work under there (cleaner and you can slide on it), and it will contain the moisture that naturally evaporates from the dirt. The ground is a heat source and if the walls are insulated well, the pipes should not freeze. I did this to my wife's house and it make a world of difference in comfort as far as cold floors and wait time for the warm water tap. I did block the vents, but left them accessible so they could be reopened in the summer if needed, though with the plastic, it was amazing dry.

You might also want to get an indoor/outdoor thermometer with a wireless remote (about $15) . Attach the remote to the pipes to a place where you can replace the batteries occasionally, but that will accurately measure the colder place the pipes are exposed to. On cold nights look at the recorded low temperature to see if future action is needed.