Replacing systems

[yeldogt]

This forum was a great help 5-6 years ago. After poking around I installed a zoned Bryant Evolution system in my house: NG Gas furnace/AC. This system is fantastic: unbelievably quiet, comfortable and very efficient ... I had one relay die this summer - covered by the 10 year warranty -- also suggested. The recommendations advising this system because of the conventional compressor and the better humidity control on the lower output has ben spot on.

I recently experienced a fire in another home that will be now be gutted and the two current old oil furnaces/ AC units will be removed. The house is a converted church and one of the units had the ductwork placed under the slab - obviously going. If I had natural gas available installing two Bryant systems similar to the other house would be on the top of my list -- maybe going to the heat pump versions ..... But the only gas available is propane. So I'm not sure what is the best way to start to think about this.

If I did the two Bryant/Carrier heat pump systems -- one would need to be zoned. What would I do about back-up heat? Is it crazy to think about installing an oil fired boiler and heat exchangers in air handlers? Then I could install a hot water storage unit. This house is not used all the time ...it is basically a weekend house -- and I don't use it much in the summer (but I want a well designed AC system). The reason I mention: I turn the heat down when I leave in the winter -- normally to about 57 -- Also turn off the water heater. When we return to the house I turn up the two systems to 71 and flip on the oil hot water heater. Hot water in about 15min and the house is fine in about an hour with the high heat from the oil furnaces ... this is not going to work with a heat pump and I don't want to have an electric water heater running all week.

So what to do ... I have a small detached studio that is heated by propane - it has a nice through the wall heater ..induced combustion (fan forced) heater about 83% efficient - and it costs me a fortune to heat the building with $4.50 gal propane in our area. I don't think I want to have propane back up ... but maybe in the end it would be cheaper to do the propane and install a heat pump water heater.

If I did the boiler I could also do some radiant heat ... I guess. I'm also wondering if installing a heat exchanger drops the efficiency of the heat-pump in any way.

So is it crazy to even think of using oil back up heat? I don't think I would be able to use two oil furnaces (if they even work with the Bryant systems. The one unit will need to be relocated to remove the under floor ducts and a proper oil flue for that unit would be difficult to install. In fact I would have to rebuild a proper flue/chiminy for the any new oil boiler .. Unless the direct vents units are reliable now.

Any thoughts ... or directions to point. Thanks

[jtrammel]

I would go with a dual fuel heat pump with propane back up. It will heat the house up quick with propane then maintain with the heat pump. You can do the same with an oil furnace. The deciding factor would depend on what each fuel source costs and remember that these prices fluctuate considerably but with the heat pump capability when propane/oil rates are high you can use the heat pump down to lower temps and when they are lower than electric you can use "emergency" function to run only the gas/oil for heat

[jtrammel]

Or you could get a 90+ efficient combi boiler with hot water coil and/or radiators/radiant flooring with domestic hot water and heat pumps for ac since they are only a few dollars more than straight ac and use heat pumps in milder weather 30-35F+ and boiler when cold. It all depends on what your electric vs oil vs propane rates are to know what will be most efficient for your location

[yeldogt]

I have not checked the current oil costs, the last delivery had to be about $4.50 gal and the Propane is close to $5 gal for my studio -- i'm about one hour north of Philadelphia -- so we pay .18+ per kilowatt. PECO

I think both of my buried oil tanks are going to have to come out -- naturally they are filled with about 1000 gallons of #2 Fuel.

Would it be more common to install two furnaces and a stand alone water heater vs a boiler / fan coils / storage tank? I am wondering if you can properly control a fan coil with a Bryant evolution system?

[Tommy knocker]

Dual fuel is a great set up and gives excellent options as energy costs fluctuate. Only problem with boiler set up, in this application, is you are not there alot in the winter. A heat failure could be catastrophic, busted piping and whole house rinse cycle. Something to consider.