keadog Based on your options, GT should be in the trade space. It sounds like you are in a rural area. We built in a rural area in 2007 and have a Gt system - propane was our only other option (we only use that for cooking and tankless hot water). Here are some lessons learned from my expereience: 1) Make sure you factor in the cost to run the electrical service to your home AND make sure you get enough amperage. The GT heat pumps need quite a bit of current on start up - my 5 ton heat pump requires a 70 amp circuit and my 3 ton heat pumps require 30 amps. Once the heat pumps start they draw less current - but you still need to factor the start up load into the overall needs for the house. The added cost for additional amperage is relatievly cheap when they install - but very expensive to add later. Based on your house size I would reocmmend a 400 amp service if you go with GT. 2) If you do chose GT, I strongly recommend a propane auxilliary heater instead of the electical heat packs. Have the system wired so that a small backup generator can power the thermostats, the HVAC fan, and the propane heater ingition. That way, when the power goes out you can still have heat. An alternative is to install a larger backup generator that can drive your GT heat pump and loop but that might not be cost effective. Either way - make sure you factor in a backup heating system into your plans. 3) Make sure that the company who is doing the GT system has been in the business for many years AND is available to provide service. These systems have to be designed properly and must be tailored to your specific site and house design. They are expensive and you need to have it done right AND have a reliable company that can service it when needed. If you can't find a highly rated local company to install and maintain the system then I would not recommend GT. 4) Make sure you factor in the building envelope: windows, doors, sealing and insulation into the overall HVAC design. If the envelope isn't tightly sealed and insulated well you won't be happy with a GT system. 5) Do your own research on the Heat pump manufacturers - use this site to ask the experts on the proposed equipment. Make sure it is a quality product. 6) Ask the HVAC contractor what type of monitoring system they provide so that you know that the system is working as efficiently as designed. Mine had nothing and I had to add indicators such as pressure and temperature guages over time. Goodluck with the build.

I'll try to answer some things as best I can and comment on all these items (appreciate all the input!) I had everything checked out/cleaned last year, there are no functionality issues that I can tell. I used gas for part of the winter last year and also the geo, both heated just fine, geo also cools just fine. It just worried me that the previous owner used the gas rather than the geo when I had assumed geo is so much more efficient. He ran the tstat in EM mode to force gas only (which is what I am doing now). I would like to use the geo if it makes sense to. Is it safe for the equipment to run geo with a setback? Maybe a large enough setback that the gas does the leg work in order bring the initial temp back up, then the geo maintains? The home is very well built and sealed, energy audit was done and insulation in key areas was added. The previous owner did all this and left me with a packet of info on all of it. The geo is a Bard, I'll have to double check the model. I know nothing about how the loops are run and honestly I'm still not 100% on the open vs closed. I will ask the previous owner who installed the geo therm unit and maybe I can get some answers. There is a manual about the unit but I don't recall seeing much more than that regarding the loops and such. Fairly certain the blower is variable. When I have the temp the same 24/7 it it is constantly moving air but at pretty low even speed. The sprinkling may be an unnecessary variable I/he threw in here. It is not part of the geo system as far as I know. Previous owner mentioned the lawn sprinkler system and that he watered every day for 5-6hrs (large yard) and that this may have led to whatever pump went out that he had to replace. The way he explained it made me think that the main well was feeding the sprinklers, geo, house, everything and the figured he had overworked it or something. Maybe this isn't how it works and these things all have their own pumps. The meter the tech installed last year I think shows PSI and when I have pulled the ring to make it show a reading it always between 5 and 6, normally around 6. I think this is good? I'm trying to understand why the owner would install a nice new nat gas furnace on top of the geo but I think it all goes back to whatever pump failed and him thinking that it would put less stress on it. -I'm glad to have to have options! But wondering how/if/should I try to figure out a way to utilize both? Smarter tstat? I know there are a lot of holes here and I apologize for that.

tigerdunes: Thanks for the link. I don't think I'm using it correctly, though. I entered $2.49 for "Oil per gallon" and $1.30 for "natural gas per sq ft" and it said gas would cost $153 versus oil $2.20. My gas rate is reported per therm. Know how I can convert that to cu ft? Also, I'm not really trying to compare my boiler against their furnace. I'm guess I'm trying to figure out if natural gas could heat that other house for less than $2200. What would be the cost of the amount of natural gas required to create the equivalent heat as 853 gallons of oil? In order to provide estimates, I believe the utility company wants to come inside and get some on-site info, something hard for a house I don't yet own. Juliekcmo: The house in question has an oil furnace. Ductwork in place, etc. I'd love to swap in a high-eff gas furnace, if the cost is reasonable and the payback isn't too long. Provided gas heat really is significantly lower than oil. Elec is not an option. Not sure prices in your area, but here in MA its crazy. We have 2 elec baseboard heaters in our basement rec room that we run for a few hours a day during winter months. During those months the elec bill shoots up over $100 (from it's usual $30-ish) I can't imagine anyone being able to heat a house with electric without going broke. If I were building from scratch, I'd be interested in ground-source heat pump, given the tax credits available. But for retrofit of oil, the gas utils seem to offer the b best discounts.

Heat loss calculations look at the building envelope, not the load between floors. You could apply basic heat transfer principles and calculate each space on its' own and estimate heat loss and usage, but this would be a theoretical exercise and have very little legal standing. No one would or should pay utility allocations based on a unsubstantiated calculation. Where you really need to start is with the landlord/tenant laws for your state. Depending on what is allowed your options, best to worst, would be: 1) Split up utility services (gas, water, electric) by apartment and require tenants to have their own account. 2) Submeter utilities with additional gas/electric/water meters and chargeback tenant. That mean's one main feed to the building with separate in-line meters that you log and allocate a portion of the monthly utility bills based on the reading. 3) Remove the upstairs thermostat. You can replace the thermostat with a space sensor, and then remotely set the thermostat to an agreed temperature above the legal requirement. The most important part of all this is the state laws. Some states don't allow submetering. Regardless of what you choose you need to get the tenant to accept it in writing in their lease.