Anyone on here that has any experience with hybrid heat systems?  We live in Des Moines, IA and our house is older, built in 1930's, with basically no insulation in walls but attic insulation has been brought up to R40 I believe.  Our home is ~3600 sq. ft and we've had several bids for geothermal (averaging $20k to $25k) and hybrid heat is around $10k.  My concern is heating consistency without insulation in the house with a heat pump or geothermal heat pump.  We've looked at insulating the walls as well but the bids have been over $10k for this plus there ia concern about possible asbestos in the plaster walls.....so do not know if insulating is a reasonable/feasible option. 

In addition, our electric company provides a steep discount (from 9 cents down to 2.9 cents/kwh during October through April) with geothermal or hybrid heat .  Based on this discount, I figure the cost savings between geothermal and the heat pump would be nominal -- the main cost would be how much the high efficiency gas furnace would need to be used -- which is hard to estimate with winters here.  Any thoughts from anyone??  Thanks in advance for the info!

I would say your first priority is to insulate that house. I had the exact same issue with a house built in 1950. I brought a house along the New Jersey shore that was proably originally meant to be a summer house only. After I moved in, I added an outlet in a bedroom for my computer and was suprised to find zero insulation inside the exterior walls.  That first winter was rough, when a strong wind blew against the house, I litterly felt a breeze inside the house. That summer I fixed the problem, I drilled small holes around the asbestos shingles nails on the outside of the house and removed two rows of singles from the outside of the house, one at the top and one at the bottom around the whole house. Then drilling holes into the walls from the outside into the wall cavities I had a Foam contractor inject foam into all of the walls. My house was only about 850 sq ft and it cost me 3k, but the difference in winter was night and day. The natural gas heating bills were much lower and the house much more comfortable. If your going to do anything, resolve the insulation problem first, it will be the biggest energy improvement/cost savings even if you still heat with propane. A new geothermal system will have to be oversized to make up for the heat loss from the uninsulated walls making it much more expensive to install and operate.

I was lucky the foam contractor was willing to work with me, I was able to then replace the shingles on the outside of the house, replace the ones that were broken with non-asbestos replacement shingles from Home Depot and I even got a Paint store to match the original paint color, so I only had to repaint only the two rows and not the whole house. Normally this work is done from the inside, by drilling hole on the inside walls and injecting the foam there, leaving you with hundreds of holes in the walls that have to be fixed. I continued to improve the house over the next few years by replacing all the old windows with replacement windows.

I can't stress this enough, Insulate, any other home heating improvement will be a complete waste of money until you do.    

Thanks for the information!  I did look at some of the spray foam insulation that you were describing.  Any concern that you had or were aware of with old wiring being pushed too close together with this method?  I know I had read it somewhere that that can happen and part of house still has old wiring.  Our exterior house on the first level is brick -- so we'd have to insulate through the plaster walls which one of the construction engineers I know said can be an issue with asbestos with that age of plaster as it was used in certain applications back then and we'd have to have it inspected for that.  All these issues with an old home!   Thanks again for the help and info. 

I'm not aware of any problems with the foam damaging the wiring.  What I used was Icynene® spray foam insulation, it's two chemicals that when mixed together form a reaction and it turns into foam.  When it is sprayed into the wall cavity it's just like liqiud, it will sink to the lowest point of the wall. It's important to seal the area below the floor with foam (in the crawl space or basement) otherwise it will just soak right thru the floor and expand in your basement or crawl space.  As it begins to expand in the wall it will find and expand in every opening it can find. I had to replace a number of outlets and switches because the foam expanded into the electrical box and in some cases foam was coming out of the outlet plugs. Once these outlets/switches were replaced, they worked fine, there was no damage to the wiring. The foam is pretty soft and you can remove clumps with your hands or chip it away with a screwdriver, just don't nick the wiring.  As the foam expands it will try to force its way out of the hole you injected the foam into, you have to hold you thumb over the hole and force it to expand up the cavity. Once the reaction stops, you inject another shot of foam into the top hole. It's a slow process, you have to inject enough foam into the cavity to fill it, but too much foam will put too much pressure on the wall and could cause it to crack. It's better to spray a little in at a time and see what the results are. I did have one wall crack, but it was a hair line crack that wasnt noticable once I painted the wall. 

It was well worth the effort, I did as much work as i could myself, the contractor drilled the holes and injected the foam, I did all the prep, clean up and repair work required. 

Years later I completely remodeled the bathroom, which involve demolishing it the the wall studs. I found 2 of the four wall bays completely filled, one 3/4 filled and one 1/2 filled with foam. Not too bad considering I didnt have to distrub the tiled bathroom wall and the kitchen wall, which would have been the most expensive to repair. You will likely get better results since normally the contractor makes 3 holes inside and I only did it with two. While it's unlikely you get every wall bay filled, it will be 90 to 95% better an no wall insulation.    

The foam chemicals may well not harm the wiring insulation, but that misses a significant point. Wiring, particularly old thin wiring with iffy insulation, may well depend on free air immediately around it to dissipate heat while rated current is flowing. In other words, if you encapsulate in high R-value foam old wiring formerly running free in empty stud bays, and a teenager with big hair runs an 1800 Watt hairdryer for 30 minutes, you could have a problem - an electrical fire.

I don't mean to be an alarmist, just advising of a potentially hazardous situation. I just built an ICF house, and electricians cheerfully tucked their cables into narrow slots in the block foam, which I expected, but I'm not sure is contemplated by the NEC. As a precaution, I specified that there be no 14 Ga cable in the house - everything is 12 Ga or better.

Icynene Foam, though, is a WONDERFUL product. I've put an acetylene torch to it myself. It won't burn. Not even sustain a flame while the torch flame is on it. It turns black from the carbon in the flame, but WILL NOT burn. (maybe it will at higher temps than an acetylene torch) It's a water-based product, and is GREAT for insulating.

Icynene is good stuff.

I like closed cell polyurethane even more - double the R-value per inch over Icynene, closed cell mean it acts as a vapor barrier, and it is rigid enough to add considerable strength to whatever panel it is applied to.

I tested a chunk of it with a torch and it doesn't burn when flame is removed. Certianly smells horrible, though.

Is that smell from deadly gases? I know polyurethane puts off some nasty gases in fires. Is that the same type you're talking about?

Does anyone know of any closed cell, water-based foam insulation?

I am in the same situation - we have an old house we are renovating and adding to.  As part of the renovation, we are looking into geothermal to heat the new space and cool the entire house.  We also have numerous problems with insulating that could mean it will be years before we can complete all of the insulating.  (We have to do this peice by peice so we can continue to live in the house while it is being done. 

Back to the original question which nobody seems to be addressing... does anyone have experience with hybrid systems?  We have an existing hot-water baseboard heating system in much of the old house, are there issues with continuing to use that as well as new geothermal heat on our new floor and geothermal cooling for the entire house? 

The obvious disadvantage is maintaining two systems.  One possible advantage is that we'll have a reasonably good backup system. 

I'm looking for anyone with experience on this or any insight into how sizing for these systems is accomplished.

APB

I guess you need to define what you mean by a hybrid system as there are lots of possible variations.

Yes, a definition would be nice.

Typically when people talk of a Hybrid system, they mean an air source heat pump coupled with a fossil fuel furnace. Please don't fall prey to this idea. It's not as good, efficient, comfortable, green, safe as geothermal.

APB, the type of hybrid you're talking of seems not really to be a hybrid. Rather, it seems that you'd just have 2 systems for 2 parts of the home. Yes the geo can cool the entire house, and heat the new part. It's a good idea. It's better than just sticking to the boiler for the new part.

Actually, my personal situation is a little tricky, so please forgive the long post.  But I guess what I am trying to say is that sometimes there are really good reasons why you might want to have dual systems.   I am looking for whether anybody has done this before and how you might go about engineering thermostat settings, etc. 

Here are the specifics:

Before renovation:
Existing 2 story brick home with baseboard hot water and A/C installed in attic with ducts descending through 2nd floor closet space to 1st floor.  Basement has no heat or cool, but is tolerable for most of the year.

After renovation:
Attic  becomes finished space with dormers.  A/C is removed in order to finish attic.  Solar PV installed on new roof.

So the primary goal is to heat the 3rd floor which has really good insulation (R60 roof) and cool the entire house - which currently has no A/C.  The secondary goal is to replace our oil furnace which is getting really expensive. 

Tricky part:  No room for ductwork.  The only places where ductwork is really feasible is from above.  The first floor has almost no room to pass ducts through.  Because the basement is finished, installing ductwork there is very tricky. 

There are a lot of options including a bunch that don't include geothermal, but I was wondering how this would work with a geothermal air handler in the second floor closet space utilizing those duct runs from the A/C.  I'm just not sure how well the ducts would be able to distribute the heat downward to the first floor, so I'm wondering if it would be possible to use baseboard hot water on the first floor on the existing or downsized boiler and size the geothermal system to handle heating only the top two floors, but cooling the entire house.   My understanding is that in NJ, it is easier to cool then heat with geothermal, and I'm trying to figure out ways to minimize drilling since it is so ridiculously expensive here.  But I'm not sure how much of the drilling costs are setup in my case and how much are costs per foot. 

Also, it would be nice to have a backup system just in case we encounter any problems. 

APB

They make split geothermal units, where you could have the compressor in the basement and have freon pipes run to where the air handler unit is, I beleive it's only slightly less efficent than an all in one package unit. As far as rooms/floors were you don't want to install duct work (there always room for duct work, just box out corners of the room for it) consider installing wall units that heat/cool each room seperately.    

As far as using Geothermal for Baseboard heat, forget it, max temp output for a Geothermal 120 to 125 degree F, mininum temp for hot water base board 160 degrees F. Also I don't understands why so many prople was to keep there old/existing systems for a "backup" Geothermal technology isn't new, You don't have to worry about it breaking down so long as its sized / installed correctly. If backups are so important to you, do you have a spare car just in case the other one breaks down? A spare frig just in case, so you can keep your food frozen? I guess you could keep the existing system until your happy with your new system, but in my opinion it's a waste of money, it's going to cost more to install around the old system and cost to have to removed later, leaving it will waste space in your house.   

  

The Hybrid System that we have been getting information on is the air source heat pump/gas furnace Infinity system from Carrier.  Our current system is 20+ years old, single stage.  We've noticed in the cold winter months here in Iowa, we usually have to supplement our upstairs with a space heater in the master bedroom.  The $20 space heater fan actually keeps the room very comfortable.  We're hoping the different stage heaters will allow more even, continous heat that help decrease our space heater usage.   Has anyone else noticed better, more consistent heating with these multistage blowers?  

My other issue is that regardless of insulation or not, wouldn't we still save money upgrading to a higher efficiency furnace and use of a heat pump or geothermal with almost 70% reduction in electric prices during the winter months here in central Iowa?  The information on the air source heat pump that I've looked at states still efficiencies 250-300% down to an outdoor temp in the mid-teens for the new heat pumps.....a far cry from our 90% efficient 20 year old furnace that I'm sure isn't that efficient anymore.

I just am wondering if anyone has one of these hybrid systems to see what their experience is with them and if they noticed improved heating and if it was worth the investment.  The system doesn't seem to much more than a new A/C/furnace combo anyway -- an additional $2000 or so. 

Thanks for any help and all the answers already given.

Those are lab tests. Also, the capacity is reduced at those outdoor temps.

Someone posted on this forum about air source vs. geothermal heat pumps. They pointed out that when running the compressor down to an outside temp of about 40 deg. or lower, the defrost cycle will have to run to defrost the outside air source heat pump. That's because it is taking enough temp. out of the air to be below freezing.

Now, with air source heat pumps running in the low teens, or even at 32 deg. F., this defrost cycle is just going to work the compressor harder than a geo compressor. Because that air source compressor works in such harsh conditions, it'll last fewer years than a geo's compressor. The compressors may be the same model from the same manufacturer. But if they have the same useful life, the geo compressor should outlast the air source compressor by double.

On your 90% efficient system, that also was a lab test. Most likely, you've never had that efficiency, anyway.

Geothermal systems are typically, not always, different. Because most geo contractors try to do the actual calculations and install what SHOULD be installed, instead of installing the code minimum, geothermal usually sees its listed efficiencies.

Usually, people think they're getting a good deal with these "hybrid" systems. They'll save money compared to being just fossil fuel. (fossil fool-hybrid) However, they won't be anywhere near what geo will save them.

Does anybody know if DX has a split system?  This seems to be my best chance for getting it installed because accessibility to my backyard is only possible with small drilling equipment.  I'm not sure that a split is possible with them because of their design, however. 

As for boxing out corners... There is no way that I will convince my wife that it is OK to take a corner out of her already very small dining room or living room.  Besides, since the basement is finished with 6'4" ceilings, where are you gonna go once you get down there?  You'd have to rip out and re-orient a good part of the basement.   Other suggestions are things like ripping out our chimmney to use as duct runs and putting in a fake chimney on the exterior of the house, but both of those options sound really expensive. 

What are thoughts on radiant heat under the 1st floor?  The ceiling of the basement would have to get ripped out, but that is just drywall work.  1st floor is old hardwood floor, can this be retro-fitted from underneath?  There is quite a bit of wiring running through the floor joists, though usually it is through center or lower on the joist.

My concern with a backup system is just serviceability.  Because of high cost for local Geo drilling, I am looking into possibly out of state - which would make service contracts difficult.  But I see your point, it would certainly be better to go with one system. 

I think I've seen ads for radiant tubes in FineHomebuilding that can be retrofitted beneath would. It may involve aluminum flashing as well to spread the heat out. Note also limits on carpet and carpet pad on the floors above - those act as insulators reducing radiant heat transfer.

Other than that, geo is quite compatible with radiant as many radiant systems get along with ~100 F water - geo is good at that. Radiant often allows lower thermostat setpoints since it eliminates cold floors.

I am in a very similar situation where I'm trying to figure out if Geothermal is an option.  We are buying a 4800 sf Victorian built in 1904 in St Paul, Minnesota.   The home was recently renovated and consists of a finished basement, 1st and 2nd floors, and a 3rd floor finished attic.    They did a VERY poor job reinsulating the attic, so our first course of action will involve hiring an insulation specialist to fill the insulation gaps and stop the massive air infiltration gaps.  Our second step will involve filling side wall insulation gaps.   Our third step would be installing geothermal (if its even an option).

 The home is heated with a relatively new nat gas boiler (80% efficiency) with original radiators.   The recent reonovaiton included adding a high velocity air conditioning unit with the blower sitting up in the attic with small ductwork fanning out into the 2nd and 1st floors and the compressor outside at ground level.  We are in the same situation as AlexPBrown ... It is highly doubtful that we'd be able to add new ductwork to the house.   So we are pretty much stuck with radiator heat and high velocity ducted AC.  I heard that there are companies that sell geothermal units which can handle both air and radiant systems.   The most promising is Econar with their GeoSource DualTEK system.     It sounds like there is some disagreement among forum members whether it is actually feasible for geothermal systems to properly heat an old hydronic/radiator home.   Does anybody have any further opinions on this? 

The last huge potential deal breaker for my situation ... We live on a small city lot (60X140) with little room for drilling.   What kind of sq. ft area is required for vertical drilling?   Does anybody have experience with drilling in tight city spaces?  How large is the drilling equipment?  How close can you drill to other structures?

I'm not aware of any disagreement on geo coupled with radiators. Basically it is extremely unlikely that your radiators will provide sufficient heat at the temperatures the heat pump will provide without some sort of supplement.  With the heat pump at max temperature you may get 20-30% of the original rated output of the radiator depending on the design. Most radiator systems were oversized to begin with and adding insulation will make them even more so, but even with that they will probably still be undersized. The only way to know for sure is to do an accurate heat loss calculation and then determine how much radiation you have. You can get tables that list radiator output vs water temp and size for just about any radiator you can imagine at heatinghelp.com. You may have to extrapolate to get down to 115-120F water temp, though.

APB,
EarthLinked DX is a split system. It would work wonderfully for you.

As far as the DX drilling, we have been able to fit it on MANY tiny lots. Where are you located APB? There may be a DX driller near you. If so, they'll usually have a small rig that can fit in small spaces.

It's recommended to stay at least 10' from the foundation of a building with bore holes. If there's no basement, then you could most likely get closer. We drilled one about 6.5' from a foundation of a garage. We had to drill all 5 holes in a line, barely 8" onto this guy's lot. It was a tight fit, but our 25' long, 8' wide track-mounted rig got the job done (with very minimal impact, too).