I had a trane xe1200 dual fuel system, that i replaced with a american standard heritage 15/95 vs furance.My old system would use the heatpump certain amount of time and if the tempature would not increase the furance would come on.but it have to be a 4/5 degree change in temp. for this to happen. my new system just run the heatpump know matter how much i make changes to the tempature.is this the new way these system operate. or can i get my installer to change it.
How dual duel work
proofturn
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I had a trane xe1200 dual fuel system, that i replaced with a american standard heritage 15/95 vs furance.My old system would use the heatpump certain amount of time and if the tempature would not increase the furance would come on.but it have to be a 4/5 degree change in temp. for this to happen. my new system just run the heatpump know matter how much i make changes to the tempature.is this the new way these system operate. or can i get my installer to change it.
Let me rephrase this question, there was allot more interaction with the heatpump and the furance.they was operating like one unit, if the heat pump could not increase temp. in amount of time the furance would respond.now it like two seperate units, the heatpump runs until the tempature outside get below 40 degrees then the furance comes on.my old system had a board that attached to the furnace the regulated when to switch between the two system. my new stsem is controlled by the thermostat. is it anyway i can change back to the old way.
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Some of the new thermostats can be set to turn on the furnace on outside temp, or inside temp below setpoint (with an adustible time delay). Talk to you installer he probably has a reason he set it up this way.
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The set-up can be real confusing. If my custumers start making adjustments on there own my patience can get thin in a hurry.
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oops! wrong there their.
Dual fuel systems should be installed with a calculated 'balance point'. This balance point determines when the heat pump is no longer able to produce heat efficiently and thus, when the gas furnace should kick in.
This balance point is based on an outdoor temperature, not the temperatures your thermostat is set to.
Here's some more information: http://www.arthurhewett.com/id26.htm#hp_balance_chart
This balance point is based on an outdoor temperature, not the temperatures your thermostat is set to.
Here's some more information: http://www.arthurhewett.com/id26.htm#hp_balance_chart
Some people just don't like the lower air temp when the outdoor temp is near thermal balance point.
There is a trade off that people/customers must make between comfort and economy.
Got some dual fuels out, that the stat still brings on the furnace at 50 outdoor temp, when the stat comes out of recovery.
In some ways. I still like the idea of the stat bringing on the furnace by indoor temp. If the heat pump is running, and the indoor temp is dropping. Then at that time, the thermal balance point for the heat pump is above the current outdoor temps. This could be 10 PM. But at 10 AM the next day. At the same outdoor temp, the heat pump may be able to maintain indoor temp, because of solar gain. Hard for an outdoor sensor to allow for that.
Which is a nice thing about the IAQ thermostat. It can do balance point plus 2° droop.
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well, you want the lockout temp at or above balance point. No sence running the compressor when gas would be cheaper. But the heat pump could be efficiently holding 50F inside temp when you want 68F. So then you want to burn some gas even if it costs you. When the gas burner gets the inside temp up it would be nice if the heat pump would kick in what heat it can. Unless the realitively cool supply air bothers you. Then maybe you would rather burn more gas. It is complicated. and we havent even mentioned defrost cyceles yet!!!
Still the best way when the thermal balance point is higher then the economical point is, Is to set the stat to one temp and forget it. And set it bring in the furnace when the heat pump can't handle the heating load.
Thermal balance point varies between day and night.
Thermal balance point varies between day and night.
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depends on "best"
cheapest would be no heating system and lots of clothes. the pipes would freeze.
so shut off the water. no water bills even cheaper.
a coal stove would be cheap heat.
unless you have to pay someone to shovel coal.
I think the best way to stay warm would be in bed with a cute girl.
haven't gotten it to work 24-7 yet but still tying
cheapest would be no heating system and lots of clothes. the pipes would freeze.
so shut off the water. no water bills even cheaper.
a coal stove would be cheap heat.
unless you have to pay someone to shovel coal.
I think the best way to stay warm would be in bed with a cute girl.
haven't gotten it to work 24-7 yet but still tying
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I see BT's point here...
Most of the DF installs I do down here in the south use an ODTemp sensor to determine which heat source to call. Using this method does require a small compromise requiring the ODTemp change-over to be a little higher than max efficiency. Sometimes we need to remember that comfort is why folks have heating and AC... and if it does not feel good to them... well it does not work. Making it work sometimes means making it feel good as much as making it function properly.
As BT noted; at 10PM conditions are different than at 10 AM.
We've had customers complain no matter where you set the lockout. More and more we are setting the t-stat to unrestricted. It may not be as energy efficient, but it keeps us from doing so many calls to just adjust the lockout temps. We use A/S acont and Honeywell 8000 t-stats. This is the way the OP's original system was running from the sound of it. The t-stat droop controls the furnace.
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and defrost cycles still freak the custumer out.
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this is an observation not anything else.
if you are doing this then the customer is losing!!!
you need to properly sell the dual fuel on the efficiency of NOT using the back up gas heat.
if the customer, usually older folks, has never had a heat pump then we do not recommend one. they will never be happy with the long run times at lower register temps. this needs to be clear to anyone getting a heat pump.
if yo do not have lock outs then the customer needs to know that the energy savings that is advertised everywhere will NEVER be achieved.
I hate to try to dance around this issue with the customer AFTER the unit is installed, at that point there is little to be done.
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