Second Furnace for dual fuel

Garasaki

Oh I see.

Well then I suppose you could do that although I don't know that I've ever seen anyone with a blower upstream of a fan, I imagine because the venting of the combustion byproducts would be a problem but you could get a separated or indirect combustion unit to do this.

Then you would not really be able to use this to replace your electric resistance heater.

You appear to be trying to accomplish several things at once, which is an admirable goal, but your only telling us one thing at a time

Daltex

Why not just replace the air handler with the furnace and remove the resistance heat altogether? This leaves the HP working until defrost or the balance point is reached then the LP would kick in.

I guess I'm just wondering why leave the old AH in the loop.

Fix ductwork first, then replace AH with furnace then your done.

beenthere

Dual fuel LP systems are seldom cheaper to oprate then a HP with electric aux.

yuri

If you live in a rural area/have some land have you considered geothermal. High initial cost but apparently is the cheapest to run in the long run. May have some decent rebates from your federal government or utility companies. see:WaterFurnace

JohnH1

Ok Here is what I do.
Note: I would not do this for a customer as it is not approved because it has never been tested by the factory. (I checked with them)

I run a dual fuel system but my evap is set in the return and furnace next. So now if I need aditional heat my furnace kicks in to supliment as the heat pump continues to operate. I have a 2 stage heat pump then a 2 stage 90% so I have 4 stages of heat.
The system is set up as a electric system. The only problem I could think of prior to installing it was the heat exchanger may swet durring the summer with cold air across it. But with it being a 90% the secondary heat exchanger (stainless steel) takes the brunt of the hit.
Then being sealed combustion helps the primary since very little air flow unlike a natrural draft furnace. I have run for 2 years now with no problems and no swetting on the heat exchanger. I think it is the best of both worlds. Additionally if this is done a furnace is not approved to come after the evap so you can possably void your furnace warranty.

AndrewF

Only because this is a new AH as of August and I didnt think this far ahead at the time I purchased it.


Yes, I have plenty of land to do geothermal. I did not research it as much as I should have, but the initial cost was part of the reason I didn't pursue it.

My old house was older than this house and I had a HP installed there and loved it. The electric bills were extremely reasonable, so using part of that experience here was why I didn't go Geo.

__________________
-Andrew
DIY hobbiest