Heat Pump vs. standard refrigerated A-C

Tony_8

> During a preseason furnace inspection/ service <BR>
> call yesterday, I had to condemn the unit after <BR>
> finding 3 cracks and a small hole in the Heat <BR>
> Exchanger. The wife was home and we discussed <BR>
> briefly some options for replacement equipment. <BR>
> Presently a grossly over sized furnace and a <BR>
> 'just right' standard, albeit outdated R-22 <BR>
> refrigerated A-C system. We discussed options <BR>
> such as condensing furnace, variable speed <BR>
> blowers, staged gas valves, UV air treatments, <BR>
> etc. Advised her I would work up some options <BR>
> after completing the heat loss/ gain <BR>
> calcs. Electricity costs 6.7 cents and natural <BR>
> gas is the only fossil fuel option available in <BR>
> our area. Hubby called me wanting to go with a <BR>
> heatpump, adding a nat. gas 'backup' heating <BR>
> appliance. Virtually a HP tied to a furnace. <BR>
> Lots of cool control options available, and a <BR>
> pretty unorthodox installation (using a HP in our <BR>
> region is about unheard of due to extreme cold <BR>
> winters, lots of wires to the controller, <BR>
> outdoor). What could one gain using a HP for the <BR>
> cool days, with a temp. limiter to operate the NG <BR>
> furnace on colder times vs. just a standard R-410 <BR>
> or high SEER R-22 AC unit? The only advantage I <BR>
> see is an installation costing hundreds if not <BR>
> 1000's of dollard higher than I can install other <BR>
> wise and a lot of wiring to install for one <BR>
> really cool controller, and a good learning <BR>
> experience for me.<BR>
> <BR>
> I am needing advice here. <BR>
> Thanks - Greg <BR>
<BR>

Greg Swob

Heat Pump vs. standard refrigerated A-C

During a preseason furnace inspection/ service call yesterday, I had to condemn the unit after finding 3 cracks and a small hole in the Heat Exchanger. The wife was home and we discussed briefly some options for replacement equipment. Presently a grossly over sized furnace and a 'just right' standard, albeit outdated R-22 refrigerated A-C system. We discussed options such as condensing furnace, variable speed blowers, staged gas valves, UV air treatments, etc. Advised her I would work up some options after completing the heat loss/ gain calcs.
Electricity costs 6.7 cents and natural gas is the only fossil fuel option available in our area.
Hubby called me wanting to go with a heatpump, adding a nat. gas 'backup' heating appliance. Virtually a HP tied to a furnace. Lots of cool control options available, and a pretty unorthodox installation (using a HP in our region is about unheard of due to extreme cold winters, lots of wires to the controller, outdoor). What could one gain using a HP for the cool days, with a temp. limiter to operate the NG furnace on colder times vs. just a standard R-410 or high SEER R-22 AC unit? The only advantage I see is an installation costing hundreds if not 1000's of dollard higher than I can install other wise and a lot of wiring to install for one really cool controller, and a good learning experience for me.

I am needing advice here. Thanks - Greg

flange

usualy you can get your utility to give the customer a more favorable rate for electric by installing a high seer heatpump. many also offer rebates on new system . this is a rather common install and really not very complicated. it gets used a lot in higher end homes, usually with oil as the backup. there are many units set up to work this way and the wiring isnt much different, the thermostat is usually a manual changeover and priced slighly higher. i would guess the added cost is around 5 or 6 hundred for the heat pump versus the standard condenser plus the duel fuel stat over a conventional.

jim lockard

heatpump

Greg I am all for condensing furnaces,2 stage gas valves and variable speed drives and yes I do a fair amount of Heat pumps with and without gas furnaces as a back up most all are where LP gas is the fuel.
I live in Virginia where the tempture is some what mild. Maybe with a low electric cost a heat pump would make some sense but not a high SEER A/C as I suspect your cooling season is less then 90 days per year.
A couple of Questions is the duct work sized for a heat pump? I understand you did a heat loss on the home but if you are stuck with an existing duct system then that is what you have to design your system around. A variable fan can help to over come a bad duct system true or at least make the most of it. Good Luck

Greg Swob

Thanks for the info-

As I stated earlier, this is simply not heat pump country. Too many deep cold winter days to make them viable for year round use. We do however see GSHP's installed in some instances- completely different animal of sorts. Typically our AC season starts in early-mid May to late Sept. and this year was just completed last week due to an abnormally warm fall.

Utility rebates do not exist. You are right, we are stuck with the existing ducting due to completely finished basement and the desire to not disturb any more than needed. Existing ducting is ample in most rooms and marginal in others for cfm needed.

I think I'll run some operating cost scenarios through Writesoft to help them make an educated decision, so long as they don't just confuse the issue.

Again, Thanks - Greg

Tony_8

what's your design temp diff ?

HP's work decent to about 20F. In WNY I figure about 65 % of the year it will handle the load. You need to know # of degree days for your area. Our problem is 15.5 cents/ KWH. GSHP or WSHP is the cat's meow.

tim smith_2

heat pump

I noticed the note about 5-600 extra for heat pump, just want to chime in and say you will probably have to count on more than that. The indoor coil will have to be changed most likely and definately recommended. So add for time for refer connections and new coil. Just an added note.

bb

Heat Pump Thermostat

Greg:

The Danfoss 8000 series stat would be a good solution should you go with the heat pump option. Combined with an outdoor sensor we have the ability to shut off the compressor below a given outdoor temperature. This would allow for the gas furnace to heat the house on the very cold days, but allow the compressor to heat on days when the weather permits.

bb

JackFre

HP & Furnace?

It seems difficult to get the duct systems to function correctly with two plenum systems. I know it can be sone but is IMHO a real hassle. Better, if the customer wrongly insists on a HP that a boiler be used with a hw coil in the duct work for second stage heat. Much simpler space saving option. What is the total heat load?