Author Topic: Oil Boiler vs Geothermal Heating System  (Read 8421 times)

wanderingdomer

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Oil Boiler vs Geothermal Heating System
« on: March 08, 2016, 10:46:21 PM »
I'm looking for feedback about installing an oil boiler versus a geothermal system, as our oil boiler is toast.  We live in a 2600 ft2 log home in southeastern PA, about 20 years old, relatively windy as it's in the middle of a field.  During the winter of 2014-2015, we used 1,000 gallons of #2 heating oil, and that was keeping the thermostat at 58-62 degrees.  There were a couple times during single digit weather where the oil boiler (something like 125K BTUs) couldn't keep the house above 56 degrees (even with the thermostat set higher)--the house is horribly insulated.  Log homes in PA didn't have to adhere to normal insulation codes, so the 6" log walls are about R7, the 4" insulation in the roof is maybe R15.   There are two 275 gallon oil tanks in the basement.

The (dead) boiler is hooked up to an upstairs air handler and downstairs air handler.  The current ductwork is not really big enough for a single whole house (air or geothermal) heat pump that'd be big enough to heat the whole house.  There's no central air, but that's not really a concern (nice to have, perhaps nice to advertise if we sold the place in 10 years).  We refinished the outside logs this past summer and fall, and are half-way done with chinking the outside logs.  It will need a new roof within 2-3 years, and I intend to add at least 4" of polyiso insulation to bring the roof closer to a reasonable amount of insulation.  There is no insulation on the basement walls, about 40% of which is above grade.  We have a large wood-burning fireplace insert that's rated for a 2500 ft2 place--it kept the pipes from freezing when we had 0 degree temperatures a few weeks ago.  We envisioned this insert as helping to reduce the oil usage by about half (oil's currently $1.36/gallon) when the price of oil rises again.  Our water heater is electric--looks like it used to be hooked up to the boiler, but the water is slightly hard, so possibly they didn't want to wear out the boiler with water heating.

There is no natural gas within miles.  For the oil boiler, we have quotes between $7,800 and $10,000, depending on model, estimated to last 20 years, costing about $2500/yr to run at $2/gallon oil and using standard electric for hot water.  If we used wood for about half our heating, this should bring yearly heating down to about $1,750/yr.  A conventional heat pump would cost about the some as a boiler, but would cost as much to run--a boiler was suggested as a back-up anyway.  A large "high efficiency" air-source heat pump (good down to the single digits) would require additional ductwork and cost about $19,000, costing about $1,500/year to run, estimated to last 15-20 years.  This got me looking into geothermal.  We ended up with a quote for $34,500 (+$1,500-3,000 for electrical work) for geothermal, which amounts to about $26,000 after the federal tax credit (includes hot water heating and the electrical work), for a two unit x 3 ton system (one for upstairs, one for downstairs), closed system with vertical loops drilled.   This should end up costing about $1,250/year to run a geothermal heating system, the units should last about 25 years and the loops longer than I'll be around this earth.

If we move in 10 years, if oil is at about $2.50/gallon, and we use 1/2 wood heat, we'd be about $8,000 in the hole for geothermal, $11,000 if heating oil is $2/gallon.  Break-even for geothermal versus a boiler only (no wood, $2.50/gallon) is 12.5 years, 19 years for half wood/half $2.50/gallon oil, and 24.5 years for half wood/half $2/gallon oil.  I tried to look into whether buyers would pay a bit more for a heating system with cheaper heating bills (I certainly would for my next home), but it might not be a big selling point.  There is also a chance that we wouldn't move, or we'd hold onto the place and rent it out.  Although the electricity for geothermal may use non-renewable resources, I like not burning oil to heat my home.

Your thoughts/advice would be appreciated.

teen persuasion

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Re: Oil Boiler vs Geothermal Heating System
« Reply #1 on: March 09, 2016, 06:19:35 AM »
Following, since I'm interested in more info, too.

In 1999 we replaced our oil furnace with an oil boiler/ baseboard hydronic system, with the water heater piggybacked on it (indirect loop).  The switch in systems cost $10k; DH ripped out the old ductwork ahead of the installers coming in.  We have an 1840's drafty, big, old farmhouse.  We are remodeling, slowly, and adding insulation as we go, but there are cold walls in the remodeling area.  We are in WNY.

At the time we were replacing the heating system, we looked at all options: stay with oil, LP, geothermal, wood.  We talked with people at our town gov't, since we learned the town hall used geothermal.  They weren't seeing savings; apparently the electric resistance heating for colder periods was severely offsetting any advantages to the geothermal.  It was probably that they were early adopters, and part of the learning (what not to do) curve.

At the time oil was really cheap, .69/gal, so we stuck with it.  Now NG is much less expensive by comparison, but no access to NG here either.  Even with the drop in oil prices, we are still paying > $2.50/gal, down from >$4/gal a few years ago.  We installed a woodstove to cut our oil usage maybe 10 years ago.  We've gone from 1000 to 600 gal/year, but are around 700 gal a year lately.  We mostly use the woodstove in edge seasons to keep the furnace off entirely on cool days (well, except for water heating).

Predicting which available fuels will be inexpensive in the future is difficult.  Flexibility, I think, is the key.  We had considered dual fuel boilers, but didn't ultimately opt for that.  When prices spiked it would have been useful.

I think for you, and me, insulation is the key.  We need to tighten our house up, a lot.

spokey doke

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Re: Oil Boiler vs Geothermal Heating System
« Reply #2 on: March 09, 2016, 07:57:54 AM »
Besides the obvious recommendation to address the insulation and airflow issues you have...

We had a geoexchange system at our old place, replacing an oil furnace.  It was pretty amazing for its efficiency in heating and (especially) cooling.  The numbers quoted seemed to be pretty accurate for us, so it basically worked as advertized...But - it did struggle a bit with really cold temps, and ours was overspec'ed (we were told 'upgraded') and it was almost sounded like being on an airplane when it came on there was so much air moving around.  The latter took the shine off of the efficiency - but I think that was at least partly a matter of matching the capacitiy of the unit with the ductwork and the size of our house.

That is about all I can say as we are not there any more, and I don't have the numbers to quote you.

You might consider looking into a mini-split (or two) ductless heat pump system (we are shopping for furnaces now and these are on our radar and seem to have some advantages, esp. for folks without ducts).

Good luck

Prairie Stash

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Re: Oil Boiler vs Geothermal Heating System
« Reply #3 on: March 09, 2016, 09:29:47 AM »
You get better returns typically from upgrading insulation. How much would it cost to improve insulation? Then you'll have reduced heating needs which should decrease the costs of the geothermal, smaller unit. Insulation will ruin all your calculations.

With geothermal you would have significant electricity use. In 2-3 years it might pay to then install solar panels. You might as well price them out now to see if it would make sense, it further skews the calculations.  Spending on geothermal, new roof insulation, solar panels is going to be big money, will it pay? Typically larger solar systems have shorter payback periods.

I'd advise making a 5 year plan with all the expected costs. Geo/boiler now, insulation then solar panels.

CowboyAndIndian

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Re: Oil Boiler vs Geothermal Heating System
« Reply #4 on: March 09, 2016, 10:49:02 AM »
I've always wanted GeoThermal, but could not pay the huge price differential. In my neck of the woods, the GeoThermal for my house was about twice the cost of a regular system (5 years ago, it may be different now).

Some of the pro's of geothermal systems (compared to a traditional heating/cooling system).
  • Last much longer than regular systems. (All components are indoors, unlike traditional systems where the condenser is outside)
  • No burning to create heat, thus CO poisoning is removed
  • If you have Solar Panels, you could completely go off grid
  • Much better for the environment
  • Uses same hardware for heating cooling

Go ahead and do your cost analysis. If you know you are going to live in this house for a substantial amount of time, it may be worth it. In my case, I knew that I was going to sell the house and move away so it did not make sense.
« Last Edit: March 09, 2016, 10:58:08 AM by CowboyAndIndian »

BudgetSlasher

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Re: Oil Boiler vs Geothermal Heating System
« Reply #5 on: March 09, 2016, 04:05:11 PM »
We looked into geothermal last year using in the 2014-2015 winter as a baseline (a cold winter here). He have a better insulated house, but it is larger than yours and in a colder location, the end result is we used 1,032 gallon of oil that year. There are plenty of other differences between our houses, such as ducts, but the end result is we received a quote for roughly $34k before rebates for a 5 ton unit.

Our boiler is 27 years old but has been inspected and tested at 87 percent efficiency, so we did not have the baseline cost of replacing the boiler, also out boiler tops out at 80,000 BTU for 3,200 sq/ft.

We decided against geothermal figuring the money would be better spent elsewhere; we are slowly tackling those project as money is available.

Honestly if I were in your position, I would look at reducing your heating needs and thus the size of your system, before installing a new system.

Unless you are willing to frame in walls covered in drywall inside of the house and insulate them your walls are what they are, but you can take that attic insulation up to at least R-30, adding insulation to foundation walls is another good idea, having an energy audit and air sealing carried out would be helpful as well (air escaping probably makes up around a third of your heating cost). I am sure a good energy audit and blower door test will show you other places to save.

With our first round of upgrades (air seal rim joist, adjust or replace weather stripping, install an outdoor reset on the boiler, install or improve dampers on outside vents, and a few other minor things) we are down down about 10 percent per heating degree day this year so far. . .

Zaga

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Re: Oil Boiler vs Geothermal Heating System
« Reply #6 on: March 09, 2016, 05:45:02 PM »
Our story is pretty similar to yours, Western PA, old oil furnace, virtually non-insulated house.  We decided to go with the geothermal system.  Our ducts were just fine though, so that cost wasn't added to what we had to do.

The one thing the geo guy told us was that it would be a complete waste of money to put in a geothermal system without getting the house properly insulated.  So we did.  Best thing we ever did to this house, other than the new windows, was insulating it!  Such a difference!  Got the house insulated in September and the old heating oil system taken out.  The new geothermal system wasn't active until November 1st, but because of the insulation we were nice and cozy with just a bit of space heaters some nights.

If I couldn't afford to get the full geothermal system in, I would still do anything I could to get the house properly insulated. 

Total cost for our 3 ton, 3 vertical loop system, plus insulation, plus electrical, minus tax credits, worked out to a bit under $20K in 2011.  I wouldn't change a thing.  We heat our water in the summer and winter with the system (better than the alternative of electric hot water), our air is filtered so we both have far far fewer allergies, the house is humidified in winter and dehumidified in summer, which is better for both our lungs and the furniture and cabinetry.  All that, and our heating bill pretty much disappeared.  Yes, our electric usage went up slightly, but not paying for heating oil (using about 700-900 gallons per winter)has been wonderful.  Plus we have the a/c that we lacked previously, and a non-grumpy DH after a hot humid PA summer is worth a lot to me!

Yeah, and that 50 year old heating oil tank buried in our yard no longer worries me, since it's empty.  If it leaks now, I don't really care.

Reynolds531

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Re: Oil Boiler vs Geothermal Heating System
« Reply #7 on: March 09, 2016, 09:05:20 PM »
I only saw propane mentioned once in this thread. Is that a more effective long term strategy?

SKL-HOU

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Re: Oil Boiler vs Geothermal Heating System
« Reply #8 on: March 09, 2016, 10:19:22 PM »

You might consider looking into a mini-split (or two) ductless heat pump system (we are shopping for furnaces now and these are on our radar and seem to have some advantages, esp. for folks without ducts).

Good luck

You won't be able to heat your house with a heat pump in a cold climate like PA. Heat pumps are efficient down to about 47 degrees, below that the efficiency and capacity drop significantly. You would definitely need some sort of back up heating system.

CowboyAndIndian

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Re: Oil Boiler vs Geothermal Heating System
« Reply #9 on: March 10, 2016, 07:18:43 AM »
You won't be able to heat your house with a heat pump in a cold climate like PA. Heat pumps are efficient down to about 47 degrees, below that the efficiency and capacity drop significantly. You would definitely need some sort of back up heating system.

You are confusing an air source heat pump with a ground source heat pump.

The air sourced heat pump tries to pick up heat from ambient air, and as you mention, it does not work well below a certain temprature. It needs auxiliary heating, such as electric heating below a certain external temperature.

This discussion is about a ground source heat pump (aka GeoThermal) which uses heat from the earth (consistently around 55 degrees F), either with loops of pipes installed about 5 feet underground or by using a couple of drilled wells.

The ground sourced heat pump works well in all parts of the continental US. See this http://energy.gov/energysaver/geothermal-heat-pumps for more details.



With This Herring

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Re: Oil Boiler vs Geothermal Heating System
« Reply #10 on: March 10, 2016, 07:30:24 AM »
Posting mostly to follow.

After fixing the insulation issue, have you considered a masonry heater or a rocket stove?  You're planning to burn wood anyway.

SKL-HOU

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Re: Oil Boiler vs Geothermal Heating System
« Reply #11 on: March 10, 2016, 07:53:33 AM »
You won't be able to heat your house with a heat pump in a cold climate like PA. Heat pumps are efficient down to about 47 degrees, below that the efficiency and capacity drop significantly. You would definitely need some sort of back up heating system.

You are confusing an air source heat pump with a ground source heat pump.

The air sourced heat pump tries to pick up heat from ambient air, and as you mention, it does not work well below a certain temprature. It needs auxiliary heating, such as electric heating below a certain external temperature.

This discussion is about a ground source heat pump (aka GeoThermal) which uses heat from the earth (consistently around 55 degrees F), either with loops of pipes installed about 5 feet underground or by using a couple of drilled wells.

The ground sourced heat pump works well in all parts of the continental US. See this http://energy.gov/energysaver/geothermal-heat-pumps for more details.

You are right. I was thinking of the air source not ground source.

Jack

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Re: Oil Boiler vs Geothermal Heating System
« Reply #12 on: March 10, 2016, 08:05:25 AM »
You won't be able to heat your house with a heat pump in a cold climate like PA. Heat pumps are efficient down to about 47 degrees, below that the efficiency and capacity drop significantly. You would definitely need some sort of back up heating system.

You are confusing an air source heat pump with a ground source heat pump.

The air sourced heat pump tries to pick up heat from ambient air, and as you mention, it does not work well below a certain temprature. It needs auxiliary heating, such as electric heating below a certain external temperature.

This discussion is about a ground source heat pump (aka GeoThermal) which uses heat from the earth (consistently around 55 degrees F), either with loops of pipes installed about 5 feet underground or by using a couple of drilled wells.

The ground sourced heat pump works well in all parts of the continental US. See this http://energy.gov/energysaver/geothermal-heat-pumps for more details.

You are right. I was thinking of the air source not ground source.

The OP did list a conventional (air-source) heat pump with a backup boiler as an option in his initial post.

laughing_paddler

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Re: Oil Boiler vs Geothermal Heating System
« Reply #13 on: March 10, 2016, 09:02:18 AM »
I work as an educator at a place that helps people think about questions like these and have found this report to be helpful. While a bit dense, it breaks down the question into several scenarios across variables like: region (of MN, but still might apply to you), building size, retrofit or new construction, heat source that's being replaced, goal (carbon, cost). Check it out:

http://michaelsenergy.com/wp-content/uploads/2015/10/Minnesota-GHP.pdf
« Last Edit: March 10, 2016, 09:06:01 AM by laughing_paddler »