Anything will work for a 98yr (not very old) home.

Personally, I think air-channeling systems are unhealthy. I would switch to a radiant hot water system, which are also more efficient than air-heating.

Geo can be used as the heat source for radiant, and IMO would be pretty much the best system possible using "quasi" renewables. A separate forced air system would also use the geo for cooling. The real question is, does you budget permit the installation of such a system?

Hot water radiant is very comfortable, but I have never seen anything that shows hot water radiant to be more efficient than forced air heat. In a geo thermal, I would think the transfer efficiency would be similar, but in a gas heat exchanger setup, the high efficiency forced air is always more efficient than a high efficiency boiler.

Hot water radiant is also not able to react to temp changes as rapidly as forced air, so it loses a bit of efficiency if you are doing temp setbacks during the day.

Maybe I am missing something here.

Thanks for the responses. Unfortunately, it only reinforces that we do need some expert advice. Any ideas on how to find one?

Geo-thermal coupled with Radiant heat will be the best solution for you. Whether or not you can do geo or use the ductwork is someone local will have to decide. I advise going to the IGSHPA---Internation Ground Source Heat Pump Association's site. They will have a list of certified people in your area. Also look up Unico ductwork---it may be possible to snake it through the existing duct work to move the a/c air.

We're in the same situation - The house has only electric baseboards which we kept to the minimum temperature all winter, and we put a woodstove in the basement, but our electric bill was still over $2000. When we had looked at having natural gas put in, the cost of the duct work alone was going to be about $8000 (Cdn.). I would like to go radiant heat using a SOLAR water heater. I'm hoping to run pipes under the 1st floor, and if I can't for the second floor, I'm thinking about using old radiators instead. The cost of the solar water heater will be between 2 & 3 thousand, but then significantly lower electric bills!! Write back if you want more info along this line.

Do not be too quick to deride forced air systems in place of radiant heat on the merits of heath. In fact, a forced air system is much healthier than radiant heat. In a readiant system there is no provision for filtering or makeup air to reduce oxygen depletion. It is for that very reason that radiant is seldom used in publc building any longer.

It is for that very reason that radiant is seldom used in public building any longer.

Actually, the majority of new public buildings in europe use radiant heating.

Ther real reason why forced air heat is used most frequently in the US of A, is because it is just like most of us americans- CHEAP.

Check out the homeenergy magazine website. There's an article about a rehab project in Chicago with a reference to local sources. They list "Domus Plus" as a firm that's been doing energy efficient buildings for 25 years.

The "energy star" site also lists builders by location.

Although I prefer radiant heat in slab, it may not be the most cost-effective choice for rehabing a 100 year old house. Definitely check it out though. The cost has come down signficantly and it is very, very comfortable.

Radiant in slab is not very effective in older houses due to the poor insulation. If the house will be insulated very well, a radiant system can be used successfully. Without very good insulation the floor temp is to high. I have repeatedly done the calculations for older houses, and unless the radiant installation is after or with a very good insulation package it will not work well.
Radiant can save some money by allowing air temperatures to be set lower while sill providing good comfort. Set backs are not effective with radiant due to the large thermal mass in a slab installation.

davevt,
Thanks for your response. Since my original post, I found an energy-star energy rating company (through the Energy Star site), which performed an assessment last month. I chose them because they also provide referrals to contractors who can implement some of the recommendations made. Interestingly, when I first moved into my house (10 years ago), Domus Plus did an energy audit for me. But, at least then, they did not provide any referral services.

So far, my sense is that installing radiant heat would be prohibitively expensive.

It is possible to renovate an old house, room by room, working from the inside. You would remove the old lath & plaster, vacuum out the walls, and install new wiring, ductwork, and insulation. With that accomplished, you can put up new sheetrock, and finish out the room. Ductwork can be set up to accomodate a forced air heating system, and also central air. It might take three months to complete the first room. This approach would only be practical if you were able to do the work yourself. And it would only be worth the effort if you intended to live in the house for 20 years or more. If you sold the house, say five years after completing such a project, you likely would not get a fair return on your labor and investment.