Gas and Oil Home Heating Furnaces - changing location of NG heater/furnace

These are long-term plans:
We have a 10x10 area (off the kitchen) which houses the electrical/water heater/furnace. I'd like to use this area for a pantry/location for our frig and freezer. The water heater looks really old and furnace is newer but the home inspector said the outside section was old.

Electrical: panel just upgraded from fuse to breaker
Water heater: I haven't been able to find production info on the present NG model (Republic (Erie,pa) SN 59:88930) but was considering replacing with a tankless NG outdoor unit.
Furnace: Carrier split system (I believe that is what they are called - furnace in 10x10 and ac outside). Like to replace this system (when EOL) with an attic installation.
Ducting: everything in the attic
Possible attic install location: Gable end of roof, steps (attic acess) could be installed in carport with minimal problems. Location would be in the attic directly above present location. Give or take a couple feet for ducting requirements.


Since this will be done when the units need replaced does this replacement plan make sense? Is there anything I'd need to worry about?
Below is a ascii drawing of the area of the house. If it helps.





Ascii Art:
____________________________________
| |
Kit | 10x10 |
| |
_____|________|
|
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| Carport



Thanks

The plan sounds reasonable to me except I've never seen an outdoor tankless water heater.

The plan sounds reasonable to me except I've never seen an outdoor tankless water heater.

I've never heard of one either. Depending on the climate you live in you need adaquate insulation to prevent the water from freezing.

Yes the are available. We see them here..Mild weather.


http://www.houseneeds.com/shop/HeatingProducts/WaterHeating/AquaStar1/aquastar250sxomain.asp

Thanks all, i was wondering if my thinking was way of base. I'm gonna get some qoutes on replacing the water heater for next year. Then look at a furnace replacement in the future. Since I'm changing the location I can probably get a new furnace installed and the AC switched in the winter while the orginal furnace is running. Then do a complete switchover the following spring. Make sense? When is the best time of year to buy a furnace? Is there one?

Thanks

Just a comment on the tankless heater. Check before buying on the availability of parts and service. Many plumbers do not work on tankless heaters even though they install them. They are a whole different animal. We see a lot of complaints here at DIY on them so it would pay to know where you stand before putting out the money for one. Good luck on your project.

I generally prefer to do optional change outs in the spring before it gets so hot up in an attic. Doing the heater & A/C at the same time will save you money because it is easier for the contractor to do all at once.

Only thing I haven't seen mentioned or addressed.

You mentioned you want to move the furnace up into the attic and add a tankless water heater. Be sure to mention the furnace move and what you are looking at when you want the tankless unit quoted.

The gas line has to be sized for all appliances. No reason to have it done twice. You will find these outdoor tankless units can use some gas. You can have the furnance connection stubbed out for the new location at the same time for an easier install.

Just a thought and good luck...