Dedicated A/C or a Heat Pump Alongside a Gas Furnace?

[yelbike]

"are they installing an outdoor sensor for the thermostat? Even if its an addtional cost, it would be small and definitely worth it."

- an outdoor temp sensor was included

"Can I ask what brand you are going with and why? "

- we went with Trane- the local dealer has a very good reputation and came highly recommended

Frank

Trane is a great brand....but they are usually more costly to repair as they dont use common parts. Most parts are made in house.

 

[Retired Iron Peddler]

my neighbor put in new electric furnace with heat pump. he's not happy because the airflow is noisy and it feels drafty. he says the installer set it up on med/high fan speed and told him that's best. I told him to set it to low fan speed during HP operation and higher speed during cold weather... but he won't listen cause he thinks the installer knows best. so he listens to the wind noise coming from the registers and grumbles.

I guess some people just don't have common sense.

Pete

The Lennox heat pump we had installed 6 years ago is very quiet. We have to listen carefully to hear it running. The fan speed runs on low on the heat cycle and the only time we hear it is when it's either on the defrost cycle or the emergency heat cycle. On the cooling setting, the only time the fan runs faster than low speed is when the compressor goes on high speed. The 2-speed compressor runs most of the time on low speed even when it's 100 degrees outside. Our house is very well insulated and was custom built 6 years ago with energy efficiency a primary consideration.

Bill

 

[kenmac]

"
"Can I ask what brand you are going with and why? "

- we went with Trane- the local dealer has a very good reputation and came highly recommended

Frank

I went with Goodman.Very happy with Goodman

 

[pclausen]

My 16 year old system (Trane XE1000 10 SEER 4 ton outdoor unit w/ a X90 120,000 BTU gas furnace) finally bit the dust. The furnace actually caught fire and melted down all the wires inside of it.

I had been considering a ground based system where I was going to do the loop myself, but since the old furnace died and the house has been on the chilly side this last week, I was forced to go with a conventional system, although a very efficient one. The new system will consist of the following pieces:

Trane XL20i 4 ton heat pump (contains both a 2ton and 4ton compressor) 19.00 SEER and 9.0 HSPF
Trane XV95 2 stage (49,500/76,000 btu) gas variable speed furnace - 95 AFUE
Trane XL950 thermostat with outdoor temp sensor

So I'll have 4 stages of heat:

1 - heat pump using 2ton compressor
2 - heat pump using 4ton compressor
3 - gas furnace using 49,500 btu
4 - gas furnace using 76,000 btu

I'm trying to figure out what the sweet spot temp would be for me to switch to gas for heating and if stage 3 is actually more efficient than stage 2 for heating. I guess I'll have to play with it once it is installed and check usage logs on the thermostat, which is basically a computer running linux with a 7" color touchscreen that is wall mounted.

The XL20i heat pump and thermostat are Trane ComfortLink II communicating, meaning that just 3 wires are used between them for all functions. The XV95 furnace is not however. That feature is only available on their modulating model XC95m. Since the furnace is just for secondary heat, and the efficiency is the same anyway, I could not justify the additional expense. So I had to get the relay panel that takes the 3 wires from the tstat and controls the furnace via closures like an "old school" tstat. I'll still get data from the tstat on furnace run time and stage being used, etc.

Given my large utility bills ($2000 annually in propane and $500 electric bills during the hot summer months), I'm hoping this system will pay for itself in a relative small number of years. So I'm trying to squeeze as much efficiency out of it as I can.

I'm keeping my fingers crossed that this new Trane system will be as trouble free as my old one was for 16 years until is finally died a spectacular death.

Install is taking place this Thursday. Installer did extensive load calculations, and found that I really only needed 3.5 ton and that the 120,000 btu furnace was way overkill. I'll be happy to post some details of the install and observations once the system is up and running. I plan to also use this tstat to control my radiant floor heat zones.

 

[dschuffert]

I built a new house in 2010 and put in a Climatemaster Tranquility 27 Geothermal heat pump for both heating and cooling. I have absolutely no regrets. I have two stages of heating and cooling and then electrical resistance heating as a backup. The geothermal engineer worked with my architect to ensure I had the proper insulation to take advantage of the heat pump - this is crucial. I have 2X6 studded walls with 1.5 to 2 inches of foam, the remaining cavity filled with cellulose (non-toxi paper), and then all the seams sealed with foam. I then have OSB sheathing on the outside of the house, an air gap, and then brick from ground to soffit. I also put in Anderson C400 windows.

I have six vertical wells going ranging from 125 feet to 300 feet that makes up my geothermal field. This is one extra well over the engineering spec. This combination of heat pump, insulation, windows, and field keeps my 6,000 square foot home very comfortable all year round along with under $100 per month in heating and cooling costs. Other than testing I haven't seen the resistance backup in use yet - this backup heat would cost a fortune in electricity - it is a 100 Amp resistance backup heating unit.

The Climatemaster system uses and ECM motor for the fan that runs 24X7. It is a high volume, low pressure, system. Every room in the house (ranch) stays within 1 degree of any other room in the house. Given this is a low heat temperature that maintains the temperate as opposed to a hot wire or frame I haven't had a need for a humidifier in the winter like I did when I was heating with propane.

I am also heating my hot water with a GE Heatpump hot water heater. I now have no gas anywhere in the house. I do have a 500 gallon propane tank dedicated to my backup generators, but nothing inside the house.

My calculated payback on this system is 3.8 years. The 30% federal tax credit helped accelerate the payback to 3.8 years.

 

[Bikewanderer]

My 16 year old system (Trane XE1000 10 SEER 4 ton outdoor unit w/ a X90 120,000 BTU gas furnace) finally bit the dust. The furnace actually caught fire and melted down all the wires inside of it.

I had been considering a ground based system where I was going to do the loop myself, but since the old furnace died and the house has been on the chilly side this last week, I was forced to go with a conventional system, although a very efficient one. The new system will consist of the following pieces:

Trane XL20i 4 ton heat pump (contains both a 2ton and 4ton compressor) 19.00 SEER and 9.0 HSPF
Trane XV95 2 stage (49,500/76,000 btu) gas variable speed furnace - 95 AFUE
Trane XL950 thermostat with outdoor temp sensor

So I'll have 4 stages of heat:

1 - heat pump using 2ton compressor
2 - heat pump using 4ton compressor
3 - gas furnace using 49,500 btu
4 - gas furnace using 76,000 btu

I'm trying to figure out what the sweet spot temp would be for me to switch to gas for heating and if stage 3 is actually more efficient than stage 2 for heating. I guess I'll have to play with it once it is installed and check usage logs on the thermostat, which is basically a computer running linux with a 7" color touchscreen that is wall mounted.

The XL20i heat pump and thermostat are Trane ComfortLink II communicating, meaning that just 3 wires are used between them for all functions. The XV95 furnace is not however. That feature is only available on their modulating model XC95m. Since the furnace is just for secondary heat, and the efficiency is the same anyway, I could not justify the additional expense. So I had to get the relay panel that takes the 3 wires from the tstat and controls the furnace via closures like an "old school" tstat. I'll still get data from the tstat on furnace run time and stage being used, etc.

Given my large utility bills ($2000 annually in propane and $500 electric bills during the hot summer months), I'm hoping this system will pay for itself in a relative small number of years. So I'm trying to squeeze as much efficiency out of it as I can.

I'm keeping my fingers crossed that this new Trane system will be as trouble free as my old one was for 16 years until is finally died a spectacular death.

Install is taking place this Thursday. Installer did extensive load calculations, and found that I really only needed 3.5 ton and that the 120,000 btu furnace was way overkill. I'll be happy to post some details of the install and observations once the system is up and running. I plan to also use this tstat to control my radiant floor heat zones.

After much experimentation on my air source heat pump I left it at about 50 degrees. Natural gas was too cheap not to burn. With propane I think I'd start at around 35 degrees and go from there. Your fuel costs will be higher for the backup heat, so the break even point will be different for you. Remember that you'll have additional wear and tear on the compressor when operating in heat pump mode - you can hit the same number of operating hours in 8 years instead of 16.

 

[TheGoose]

Why did you go with the GE water heater instead of using the available de-superheater option of the Geo? I thought free hot water was one of the best aspects of a geo-unit?

I built a new house in 2010 and put in a Climatemaster Tranquility 27 Geothermal heat pump for both heating and cooling. I have absolutely no regrets. I have two stages of heating and cooling and then electrical resistance heating as a backup. The geothermal engineer worked with my architect to ensure I had the proper insulation to take advantage of the heat pump - this is crucial. I have 2X6 studded walls with 1.5 to 2 inches of foam, the remaining cavity filled with cellulose (non-toxi paper), and then all the seams sealed with foam. I then have OSB sheathing on the outside of the house, an air gap, and then brick from ground to soffit. I also put in Anderson C400 windows.

I have six vertical wells going ranging from 125 feet to 300 feet that makes up my geothermal field. This is one extra well over the engineering spec. This combination of heat pump, insulation, windows, and field keeps my 6,000 square foot home very comfortable all year round along with under $100 per month in heating and cooling costs. Other than testing I haven't seen the resistance backup in use yet - this backup heat would cost a fortune in electricity - it is a 100 Amp resistance backup heating unit.

The Climatemaster system uses and ECM motor for the fan that runs 24X7. It is a high volume, low pressure, system. Every room in the house (ranch) stays within 1 degree of any other room in the house. Given this is a low heat temperature that maintains the temperate as opposed to a hot wire or frame I haven't had a need for a humidifier in the winter like I did when I was heating with propane.

I am also heating my hot water with a GE Heatpump hot water heater. I now have no gas anywhere in the house. I do have a 500 gallon propane tank dedicated to my backup generators, but nothing inside the house.

My calculated payback on this system is 3.8 years. The 30% federal tax credit helped accelerate the payback to 3.8 years.

 

[DKCDKC]

I'm way out in the country. Natural gas was not an option. In 2001 I went with Waterfurnace ground source with loops buried 6 ft down outside. The system provides free hot water in the summer and supplemental hot water in the winter. The house is 3000 sq ft, ranch over conditioned crawlspace, lots of windows, average insulation, and has a small woodstove in primary living area. The stove provides the warmer area for those who want that, and supplemental heat on really cold days. I had an intake for the heat pump installed directly above the stove area and the stove actually helps throughout the long, skinny house. I get the unit checked out every other year - mostly topping off the water in the loops. No significant problems over 10 years - aside from a switch that forced backup heat on for a week several years back - cost $100 or so. No complaints really. Heating and cooling seem to cost from $1,000 to $!,500 a year best guess. Wood costs me nothing (Folks cut it for me on shares. And stove is used at night only several times a week during winter.) A lot lower than similar houses here in the mountains of Virginia, even those with two stories and better insulation.

I like ground source and will probably replace the unit with another using the same loops if it goes.

 

[Sigarms]

Trane is a great brand....but they are usually more costly to repair as they dont use common parts. Most parts are made in house.

Most parts are brought in from Mexico or China (including Trane).

Ultimately when deciding to go between a straight heat pump or dual fuel (and the added cost of a furnace for second stage heat), you should look at your fuel costs as well as your operating tempertures to give you and idea of what kind of ROI you're looking at (if you're on LP it's a no brainer if you're in a colder climate).

 

[dschuffert]

Why did you go with the GE water heater instead of using the available de-superheater option of the Geo? I thought free hot water was one of the best aspects of a geo-unit?

That is a great question. The main reason was my demand and my secondary reason was still proving out that Geothermal would work in my application. In the next year or two I plan to put another water storage tank between the GE water heater and the Geothermal unit. I have the hot water generator option on my Climatemaster but I do not have it powered right now. It circulates water at 125 degrees. I'll have the Geothermal heat the water in the secondary tank. The secondary tank will then feed my GE tank which will then supply the house. This will give me additional capacity and further reduce my energy costs to supply the home with hot water.