My house is 135 years old.  It is drafty.  I am remedying the situation slowly, but it still has air leaks.  My oil furnace that is roughly 28 years old needs to go.  It has broken multiple times this winter and it is horribly inefficient.  The previous owner of this house went quite far in updating it as far as changing the interior layout, all the walls are drywall, all the wiring is new and on 200 amp service, almost completely updated plumbing, a well insulated addition, vinyl siding (under which I believe there is a house wrapping material) and even a few new windows.  I'll finish updating the windows eventually.  For now I've got the plastic sheeting sealing the windows.  I want to take up the floor in the attic and reinsulate  with new insulation of a higher R value, I'm going to chase down air leaks and foam them up, and I'll remove the siding and house wrap the house if it is not already done. 

But, new heat is a must.  We'll survive this winter on oil.  Come spring we need a replacement.  I'm very much leaning toward wanting geothermal heating and cooling.  Do you think that even with a leaky home, geothermal would still be a wise option?  I'd like to avoid running the aux heat as much as possible.  I am sealing the home, and will continue to insulate it too.  If I can't satisfactorily keep the heat in my home myself, I'll hire someone to help.  But, would it be a stretch on a geothermal system to heat a leaky home in the mean time?  I would assume the installer would size the system based on my leaky home, which would then leave me with a system larger than necessary once my home becomes more efficient.  Sound correct? 

Relatively small home at 1680 sq feet (including the well insulated addition).  Already have insulated duct work in the basement and attic.  The house is located in central Maryland.  As mentioned in my other thread, I believe I have plenty of room for a horizontal loop, and I think with the water table I sit on, I have the option of an open loop system perhaps. 

So give me an honest opinion, would you install a geothermal system if you had my home? 

Correct me if I'm wrong, but the paybacks on a geothermal system would be faster in less than efficient homes anyways. 

I to live in a 100 year old house. Fixing the butcher job that was done in the sixties is a slow proccess. We have been remodeling now for 14 years, I guess that qualifies as a hobby or an obsession at this point.
If your house is in-effeciant you need to heat and cool it as cheaply as possible/geo. With todays two stage units you should be able to get a unit that is sized for your load now, and run in first stage only when your envelope is sealed up better. The retro fit market is where I am seeing the biggest goofs being made. Some things to avoid:
Running geo through un-improved fossil fuel ductwork
wrong infiltration numbers on manual J
wrong type of gshx for application
Hiring the new guy on the block

Hope this helps

That does help a lot. I definitely need to do something about my ductwork. The returns are horrendous on the current setup. The downstairs return is literally directly above the furnace and the upstairs return is all the way on the other side of the house and up through a wall to make it to the 2nd floor. Guess which return the furnace draws all of the air from? It will be simple enough to fix, but someone certainly didn't think when they put it in.

Do a load calc. Then rerun it for the house you hope eventually to have. Size the geo for the future house, and add enough aux for the present house. Aux strips are dirt cheap, and you can always not use them later as house is tightened up. You can even remove some of the aux stages from the ductwork (perhaps starting with 20 kw but later dropping to 10 kw) since that will reduce restriction on airflow and thus blower power.

I have an installer coming out Monday to size up the place.

The single biggest mistake you can make in a retro-fit is sizing anything for what you do not have. Strip heat is cheap to install, but not to operate. If the OP tightens up his envelope over time, the differance between now and later could be a ton or more. I would not want to operate that kind of strip heat ever. The money spent on strip heat operation would be better spent on changing out the whole unit later to a smaller size unit to meet new load calc.

I suggest doing all of your air sealing and adding insulation where necessary before changing your heat system. You could even have a energy auditor come out in the winter time to go around the home with a heat camera to see the areas you are losing energy from air leaks/lack of insulation and also do a blower door test. If you plan on replacing windows and siding, that would be the best time to check the insulation in your exterior walls on the original house. You could add insulation if needed since the siding would be removed, it would be a lot easier to do it at that time, along with caulk, foam, & tape. Also consider adding rigid foam board on the exterior prior to re-siding the house, this will give you more insulation value, help air seal even more, and reduce the thermal heat loss through the framing of the house (studs, headers, & bond). Also check the bond insulation, in basement/crawlspace and air seal that area... if budget allows have that spray foamed (closed cell), or cut rigid foam board to size and put in between floor joists against the bond, sealing with spray foam in a can.

Is rigid foam better than using fiberglass insulation batts? I have a leaky house with fiberglass pieces inbetween the joists all around the basement walls above the cement. Some has come out, or been pulled out by critters over time, so I am planning to replace it.

yes.

Rigid foam is better than fiberglass, but has to be tight & edges foamed for it to function at all. Far better is spray foam at your sills. Best idea is to do what Jere says- you'll spend far less on a good audit and air sealing your house than trying to heat all that outside air you're dealing with. The auditor will do a blower door test so you can actually see & feel where the air is coming in. Deal with that first so you can really tell how your present furnace works when given the chance.

We need something new as soon as spring comes. I'm tired of replacing this or that on the current furnace. I keep having to pull the oil pump off to clean it too. The firebox is falling apart. I went 3 days earlier this winter without heat while I searched for a new motor for the burner. Come spring, that furnace will be in a scrap yard.

I can spend upwards of $10,000 on a replacement furnace and air conditioner and then add the cost of a propane tank being installed on my property or I can spend about $14,000 after all of the credits and rebates for a geo system. I am not going to have another oil furnace installed.

And yes, I will have a professional come out to find out where my insulation and sealing lacks, but only after I take care of the leaks and cold areas I already know exist. No reason to pay someone to point out the obvious leaks I already know about.


I like waterpirate's line of thinking for sizing the geo for my current leaky house and downsizing later on as I make my house more efficient. Engineer's idea for sizing for a sealed house and adding aux strips to compensate until then sounds pricey in the long run with our electric being 9.2 cents per kw and going up. Jere, to check for cold leaks inside and warm leaks outside, could I simply bring a thermal imaging camera to my house and get a pretty good idea myself? I'm a firefighter and have access to some pretty nice thermal imaging cameras. I wasn't planning on replacing the siding, just removing some of it to make sure the house is wrapped and adding wrap and foam as necessary. The eave space above the addition butts up against the back of the house on the 2nd floor and I have access into it via a small door for storage. I've already added 2" thick foam insulation to the back of the door. I can see that the previous owner has some foil coated styrofoam insulation against the outside of the original tongue and groove walls of the house insulating the house from the unconditioned eave space. I'm hoping he continued this application around the entire house.

Eric's recommendations may be colored by his much lower than average installed cost per ton, and perhaps a bit of an allergy toward strip heat.

Using his example, lets run some numbers on a system short on heating by one ton: Making up a ton with strips requires about 3 kw. The ton shortage only shows up in fairly cold weather, not the entire heating season. To figure this exactly for an average winter would require knowing the balance point of the system and a bin analysis (hourly temperature data). But for the purposes of a back of envelope calculation lets go with 200 hours in January and 100 each in December and February, totaling 400 hours per season.

400 hours of operating an extra 3 kw of strip works out to 1200 kwh. If that strip heat were instead covered by geo operating at a COP of 4 (a bit generous for deep winter operation) the geo would use 300 kwh. That's a delta of 900 kwh, and at $0.09 per kwh, that's $81 per year. Shorting a system a ton might save several $k in loop and unit costs, so the $81 is easily covered even at extremely low interest rates. That or divert the several $k toward weatherization, reducing the load.

A smaller unit likely operates more quietly and its longer run cycles result in more even distribution of heat.

Then there's summer - Heating load likely exceeds cooling load in Maryland, so a system sized for winter design will almost certainly be oversized for cooling, resulting in poor dehumidification. A two stage unit helps with this, at extra cost, but proper sizing results in most comfortable cooling

Much will depend on the present duct system. Ductwork sized for fossil-fired hot air distribution may not suffice for geo without strips. Geo alone needs much higher airflows than fossil since it heats air less, typically no more than 30 F rather than 60 F or more

Everything you say is true, guilty as charged.  But I consider myself an expert when it comes to older homes, especially those more than one story with balloon frame construction.  I only shine the light on mistakes that I see being made repeatadely when it comes to these(special homes).  At the end of the day you are in control of how you want to spend your money, and how much you can spend now.  14 years ago I did not yet fully believe in geo and replaced a gas hydronic with a oil hydronic when hho was .98 cents a gallon.  A glaring mistake in retrospect.
  The rehab of older homes by those who love them never goes the way of the episodes of this old house.  Everything is a trade off based on time and economics, over an extended period of time, sometimes years.  Interview and hire some local talent to help you wade through your specific situation and roll the best dice you can through.
Eric

I agree that running 10s of kw of strip heat for years while slowly renovating an older home is a bad idea destined to produce huge power bills.

I have limited experience with older homes, but enough to know that nothing is as at seems from the get go, nor costs what it should, nor goes per plan.

Retrofitting properly sized ductwork is the critical element ensuring geo success.

As the owner of an older leaky home, I was faced with the same decision last year.

This is where the expertise of a professional helps a lot. Without any modifications in sealing up my home, my home called for somewhere between a 3.5 and 4 ton geo unit. I worked with my contractor and found that if we added insulation to my attic space, some minor basement insulation and a new garage door (our garage door opens to the basement) we could use a 3 ton unit.

My husband and I blew in attic insulation. We rented the blower and bought the fill from the local home improvement store for a total of $640 building our attic insulation from R-4 to R-40. This was well worth the cost and time. We still have not added the basement insulation or garage door.

Last season we used ~$120 extra in electricity costs by using the electric heat strips to heat our home for a small portion of the time. Paying this extra amount for even a few of years is fine with me. I am certain of the extra cost because I paid to have submeters placed on my system so I know how many KWhrs the heat strips use.

These are choices that each homeowner must make (especially those of us with old leaky homes). I used to stand in front of my closed window on a windy day and my hair would blow away from my face... now THAT's leaky! We decided to pay a little extra in electric costs in the first few years, but your situation may be very different. Either way, having a good understanding of what changes you could make now that may lower the size of the geo system is important.

case by case is the way to handle old homes. A geo pro who takes the time to do a heat loss for you can likelyt show you the best direction to reduce the load of your envelope with the click of a mouse.
Energy auditors will do this as well, but I like the idea of the load being generated by someone who also has to back the performance of your heating system.
I'm a proponent of the electric aux. over tons and tons of extra geo, but a real pro can show you what that will cost (again with the click of a mouse).
I'd sooner see you get a used furnace for now than grossly over size your geo.
Good Luck,
Joe

The problem that I see is the infiltration number is greatly variable based on wind speed. The more the wind blows the higher the balance point in terms of temprature outside. Is there a way to address this in the software?
I agree that the most bang for your buck is improving the envelope.
Eric

Lots of great things to consider here guys. Thank you. I have the first company coming out in about 2 hours to let me know his thoughts on geo for my home.

The last few days have been especially chilly! 40+ MPH winds for 2 days with temperatures in the low teens before the wind chill factor. Like Ona, you could stand by one of my windows and feel the breeze with the window closed. I have since stuffed felt weather stripping in all of the major cracks and packing taped around the entire window and frame. The blow dryer plastic sheets didn't last long on our windows since the double sided tape came unstuck. My window frame to wall does seem well sealed up though.

I have been thinking about blowing in insulation in my attic. It does seem relatively inexpensive all things considered. Would I need to raise my plywood floor in the attic higher than the true dimensional 2x8's it's resting on for a good R value?

Blown in insulation for attics is measured in FEET to get something worthwhile in R-value.

Maybe get an Inspection and quote from a foam spray specialist. More money but less space requirement.

Insulating Windows are going to be next. Start on the North facing side and do a few along as budget allows.

Dick