View Full Version : HP w/ fossil backup
09-25-2005, 10:21 AM
I am planning on getting the system replaced in my home Currently 4T a/c and 100btu old nat gas furnace.
I've seen people talk about duel fuel which is the way I think I should go here in Missouri.
I've started reseaching this however as it seems not too
many systems are around. I only talked to on installer
who hasn't put in a system like this but said it isn't any different than a reg. heat pump system only that he would put in a 2 stage thermostat. Should I stay with someone who has worked on this type setup? I've looked for info here
which has been helpful. One thing i've never heard talked about but is a TVX used w/ a heat pump? they talk about how useful it is in a A/C sytem is that true in HP as well?
09-25-2005, 11:59 AM
You would need a thermostat with an outdoor sensor and dual fuel control capability. Most on here like the Honeywell Vision Pro TH8320 for that.
MO is an excellent place for dual fuel. Decent winters, good electric rate.
09-25-2005, 12:04 PM
I am not sure if your system would come with a TXV at the indoor coil but it can easily be added to the system. It would definetly be what I would recommend on this system. As far as controls, like the Bald one says Honeywell vision pro is the easiest way to go. No need for a fossil fuel kit with this tstat just an outdoor sensor, simplifies things a great deal.
09-25-2005, 12:20 PM
There are many dual fuel capable thermostats, but I prefer the seperate dual fuel control installed near the furnace. Service technicians generally keep heat pump thermostats on their van and the seperate dual fuel controls can be easily bypassed for temporary heat. I am not a big fan of relying on one digital control controlling everything. I am not saying they don't work and carrier has had a similar control that has operated very well for many years, but this is my opinion.
If you install a furnace and heatpump with a 2 stage thermostat without a dual fuel control, the heat pump and furnace would run at the same time and the heat pump would essentially destroy itself because it could not reject any heat. Find a contractor familiar with dual fuel systems.
09-25-2005, 12:23 PM
By the way, there are thousands of dual fuel systems installed in our area. They are installed in practically every new home due to the breaks the power companies give to builders for installing them. They work very well if sized, installed and set up properly.
09-26-2005, 03:45 PM
The Honeywell thermostat has a setting that will shut the heat pump off at what ever pre determined temperature you choose (with an outdoor sensor). You will need 3 heat and 2 cool if you have a 2 stage furnace. Go to the Honeywell site on the internet.
I just went through this exercize myself.
09-26-2005, 03:47 PM
By the way..........the site was pointed out to me by travisfl from this forum and many thanks to him for the info.
09-27-2005, 11:21 AM
Thanks the honeywell looks awsome hopefully functional and durable as well. Anyone on have experience with White Rogers
they make a 3 stage also. http://www.whiterogers.com/pdfs/04_Cat_pages/04_Cat_pg_177.pdf northof49 you said you looked into this type system did you have one installed or are you a contrsctor? If you have one how is it working out and what climate are you in. Also can anyone tell me if they
are supposed to use a TXV valve, the guy that came out mentioned a piston? is that better or not than a TXV for metering. It will be in conjunction with a 13 seer scroll
compressor HP and I'll probably go with the 2 stage Nat
gas VS furn. Thanks for your replies. I'd hate to pay all this money for for a system I'll have to live with for a long time and not be happy with it.
09-27-2005, 11:35 AM
Running my feet off today..........but will answer your questions tomorrow.
09-27-2005, 12:16 PM
Subdewd, to answer your TXV question...I'm not sure about all manufacturer's, but most require a TXV on the heat pump systems. The manufacturer should clearly specify what metering device the system is designed to work with.
TXV's are better metering devices, in my opinion, since they are able to adjust refrigerant flow depending on the conditions. A piston type metering device is a fixed size regardless of conditions.
[Edited by amb4081 on 09-27-2005 at 12:18 PM]
09-28-2005, 09:46 PM
I am a consurmer but I installed a 16 seer heat pump and 2 stage furnace myself with the exception of putting in the R 410A.
Definitely use a TXV.
I live in Kelowna, B.C. Canada. Our design temperatures are 90 degrees F for summer and -5 degrees F winter. Humidity is 80 % winter and low teens in summer. We are just above Tri-Cities, Washington.
The top of the line WR and Honeywell are quite similiar for performance. The general consensus on the board was that the Honeywell was more user friendy so I went with it.
As you probably saw in the Honeywell manual you can set your thermostat to lock out the heat pump at what ever temp. you want. (What you deem is economical).
Search this forum under Thermostats and you will find all the helpful info that I received from the regulars.
As far as how it works..........we are not yet into our heating season but I don't forsee any problems.
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