This is likely due to the backup being OIL HEAT, not electric. And many of these things can also be set by the installer, who knows what some incompetent bozo did. But the system under discussion has electric resistance heat. It would be incredibly stupid to have a heat pump system designed where if the heat pump can't heat fast enough, it shuts off the heat pump and just uses electric resistance heating. Why on earth would any rational designer do that? You have the heat pump putting out 4x the heat for the same energy used and you're going to turn it off? Not only will it take longer to get the temp up without the heatpump, it will also cost more.
conditioning during the peak usage times as set by the ToU billing with my utility. The problem I have is the heat pump not ramping up the temperatu re fast enough when it comes back on and the backup straight electric heat coming on. This uses maybe three times the amount of electricity during th e time it takes to get up to temperature.
self. I'm wondering if anyone makes a programmable thermostat that deals w ith this issue. If the problem is caused by the thermostat not letting the heat pump run long enough that is easy to fix. If the problem is caused b y the heat pump itself, then the way to deal with it is for the thermostat to run the heat pump in bursts short enough to keep the back up heat from r unning.
ments. I've seen something about two stage heat pumps, but whatever that i s, I don't have one. So the way to get more heat out of the pump is to run it longer. But that's not the issue. The heat pump isn't "straining" or undersized. It just has to run for a while in order to bring the temperatu re up and the thermostat is designed to treat that as a condition where it needs to run the backup heat.
this.
electric backup wiring arrangement. There are actually a number of wires, one for heat, one for cooling, one to run the fan, one to bring in power a nd I believe a common.
Agree. The typical thermostats available on the market do control the aux heat though. I bet Rick's does too.
IDK, but it's possible. For example, two stage gas furnaces can do something similar. Ideally whether it fires at high stage or low should be done by the thermostat, because only it has the complete information, which is the desired temp and current temp. But it takes an extra wire for two stages and there may not be one available. So, two stage furnaces have a setting where instead, the furnace makes the call. If set to that mode, if the furnace runs more than a certain number of minuts, ~7, then it will switch to high. Obviously inferior to the other method, which can put it into high immediately.
Yes, I suggested that too. With a wifi computer and a program running on a PC, it could monitor and control it. But first I would download the inst all manuals for modern thermostats and see if they address this. You would thi nk at least some would. The obvious way would be with a setting where the thermostat estimates how long it will take to get to the target temp and if that takes longer than X minutes, then it adds aux heat. And X is programmable. This seems like something that some manufacturers would have addressed. They could also have something related to time of day for customers that have different rates at different times of day. Like if the electric is cheap, or it's 6am and you want to make sure the house is warm when you get up, maybe you want a one hour period, if it's expensive or afternoon you can live with 3 hours.
My thinking is, the thermostat sees a high delta between the house temperature and the set temperature. In order to correct that (for your comfort) it turns on both heat pump and auxiliary heat.
I suspect there is a wire from the thermostat to the control board, that develops an output when there is a high delta, this output tells
the control board to turn on Auxiliary heat.
The truth may lie elsewhere, but that's my analysis.
On page 47 of the Thermostat manual, if this is the manual,
It says,
"SPECIAL FEATURES Hybrid Heat (heat pump with a furnace system only)This thermostat works with the Carrier Hybrid Heat systems offering maximum comfort and economy by automatically controlling whether your system delivers heating with the heat pump, with the furnace, or with both options working together."
Page 52 Hybrid Heat (heat pump with a furnace system only)page 47........This Carrier heating and cooling system concept offers maximum comfort and economy. When a Hybrid Heat system is installed, the thermostat automatically controls whether your system delivers heating with the heat pump, with the furnace,or with both options working together. Mikek
Heat pumps don't work well below around -4C due to the coefficient of performance, so unless it is geothermal they often need to be shut down usually due to icing.
so run under two other conditions. One is the system detects ice on the ou tside coils. With a 40 degree cut off, your system might not worry with de icing. The other condition is when the system runs long enough that it dec ides the heat pump is not doing the job and switches to backup heat. Opps, another condition is if the inside temperature drops too far bellow the se t temperature.
hermostat. Set the temperature and bulb 1 would control the heat to keep t he temperature. But if the room (hallway as the case may be) temperature d ropped too far the second bulb switch would close and the backup heat would come on.
s the temperature up slowly enough to not kick in the backup heat.
r installer. With the last system I bought I found I could not even get in fo from the company who made it. They always referred me to the "installer ", like I was not worthy of information.
Doesn't say anything about electric back up vs. oil, etc...
One very good reason to not run the heat pump with the backup electric heat is the power required. They have separate breakers, but the electric coil s in my house are 10 kW or 40 amps requiring a 50 amp circuit. The outside unit would require a 30 amp breaker. Just how much can you wire into a pa nel before it becomes a problem? If the kitchen were drawing 5 kW or more, the hot water heater was running at 10 kW (or more) and the dryer was runn ing at 8 kW, that's pretty durn close to the house hold max. Throw in an i ron fire up the microwave and a few light bulbs and the main breaker might blow. One of my other houses, only having 100 amp service, might have blow n the main breaker before the dryer was turned on, but for the fact it has oil backup.
--
Rick C.
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---- Tesla referral code - https://ts.la/richard11209
Why are you arguing that. I understand why you are trying to shut down the auxiliary heat.
They have separate breakers, but the electric coils in my house are 10 kW or 40 amps requiring a 50 amp circuit. The outside unit would require a 30 amp breaker. Just how much can you wire into a panel before it becomes a problem? If the kitchen were drawing 5 kW or more, the hot water heater was running at 10 kW (or more) and the dryer was running at 8 kW, that's pretty durn close to the house hold max. Throw in an iron fire up the microwave and a few light bulbs and the main breaker might blow. One of my other houses, only having 100 amp service, might have blown the main breaker before the dryer was turned on, but for the fact it has oil backup.
Not helpful info.
So, do you think or can you find out, if the Thermostat has a separate output when the thermostat has a high differential to fire up the oil furnace? Mikek
also run under two other conditions. One is the system detects ice on the outside coils. With a 40 degree cut off, your system might not worry with deicing. The other condition is when the system runs long enough that it d ecides the heat pump is not doing the job and switches to backup heat. Opp s, another condition is if the inside temperature drops too far bellow the set temperature.
thermostat. Set the temperature and bulb 1 would control the heat to keep the temperature. But if the room (hallway as the case may be) temperature dropped too far the second bulb switch would close and the backup heat wou ld come on.
mps the temperature up slowly enough to not kick in the backup heat.
our installer. With the last system I bought I found I could not even get info from the company who made it. They always referred me to the "install er", like I was not worthy of information.
r
s
he
heat is the power required.
I'm saying the thermostat might not run both heats at the same time if the back up is electric because it would be a very large load at one time, 15 k W.
I took the thermostat off the mount and took some photos. Maybe I can dig up a manual. I have no other way of knowing what the thermostat will do, b ut I can assure you that there is not a special output for "high differenti al temperature". There is a signal to turn on the heat pump and a signal t o run the electric coils. The furnace may or may not cut off the heat pump when the coils are on regardless of what the thermostat does.
I appreciate the help, but I'm not looking for someone to reverse engineer my heating system. Originally I was asking if anyone knew about a thermost at that would ramp up the temperature in a way that would not trigger the b ack up heat. If I have to roll my own thermostat I'm sure I can figure out what I need to know to make it work.
The connector has the standard labeling of thermostats. The model is TCONT
802AS32DAA Trane. I found manuals for it but they don't offer a lot of ins ight. I think a lot of this stuff is cut and dried and hasn't changed in 5
0 years or more. So they don't tell you any of the standard assumptions in the manuals.
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Rick C.
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The basic limitation of course is your incoming circuit breaker rating, typically 200A at 230V CT, for several decades now. If you run low on room for high-current 230V dual breakers, it's time to have your electrician install a second panel. We had a full panel with two 30A, and one each 40A + 50A breakers. Our electrician moved some single lines to a second panel, and powered it from a new 60A dual breaker. Now we have some room to grow. If I need to add an 11kW 50A breaker for my plug-in Prius, he can move over a few more circuits. If you're suffering with 100A service, get upgraded!
You seem to misunderstand the problem. Even with 200 amp service it is muc h easier to run out of head room if your heat system is drawing 70 or 80 am ps. On a cold night, a family using hot water, a stove, the clothes dryer and a hair blow dryer may well be over the limit! I'm pretty sure I went t hough that with numbers and all.
It is seldom a matter of panel capacity. It is more often about the servic e.
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Rick C.
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also run under two other conditions. One is the system detects ice on the outside coils. With a 40 degree cut off, your system might not worry with deicing. The other condition is when the system runs long enough that it d ecides the heat pump is not doing the job and switches to backup heat. Opp s, another condition is if the inside temperature drops too far bellow the set temperature.
thermostat. Set the temperature and bulb 1 would control the heat to keep the temperature. But if the room (hallway as the case may be) temperature dropped too far the second bulb switch would close and the backup heat wou ld come on.
mps the temperature up slowly enough to not kick in the backup heat.
our installer. With the last system I bought I found I could not even get info from the company who made it. They always referred me to the "install er", like I was not worthy of information.
e
at is the power required. They have separate breakers, but the electric co ils in my house are 10 kW or 40 amps requiring a 50 amp circuit. The outsi de unit would require a 30 amp breaker.
The breaker is sized significantly higher than the operating load to handle the brief start-up current. It's probably pulling more like 15 or 2
l also run under two other conditions. One is the system detects ice on th e outside coils. With a 40 degree cut off, your system might not worry wit h deicing. The other condition is when the system runs long enough that it decides the heat pump is not doing the job and switches to backup heat. O pps, another condition is if the inside temperature drops too far bellow th e set temperature.
lb thermostat. Set the temperature and bulb 1 would control the heat to ke ep the temperature. But if the room (hallway as the case may be) temperatu re dropped too far the second bulb switch would close and the backup heat w ould come on.
ramps the temperature up slowly enough to not kick in the backup heat.
your installer. With the last system I bought I found I could not even ge t info from the company who made it. They always referred me to the "insta ller", like I was not worthy of information.
se
our
d,
s
ems
ng
the
s
c heat is the power required.
e back up is electric because it would be a very large load at one time, 15 kW.
Might be this, might be that. RTFM.
0
g up a manual.
Duh! I would have done that first.
I have no other way of knowing what the thermostat will do, but I can assur e you that there is not a special output for "high differential temperature ". There is a signal to turn on the heat pump and a signal to run the elec tric coils. The furnace may or may not cut off the heat pump when the coil s are on regardless of what the thermostat does.
r my heating system. Originally I was asking if anyone knew about a thermo stat that would ramp up the temperature in a way that would not trigger the back up heat.
Go figure. Instead of reading the manual for the thermostat you already have to see what it does, what can be changed by programming, you want to look for a new one.
If I have to roll my own thermostat I'm sure I can figure out what I need t o know to make it work.
NT802AS32DAA Trane. I found manuals for it but they don't offer a lot of i nsight. I think a lot of this stuff is cut and dried and hasn't changed in 50 years or more. So they don't tell you any of the standard assumptions in the manuals.
That looks like the Honeywell VisionPro series. The VP series doesn't have a setting for what you want, so the Trane one probably does not either .
Does it just come on when the Heat pump comes on? Probably no, I think you said it only comes on with either a long run of the heat pump, or if the system has been off a long time. One or the other, could you define that better for me?
What would cause you to want the oil furnace to come on?
Can you you just put an on off switch in the oil furnace turn on signal line? That way, if you want oil heat just flip the switch.
If I have to roll my own thermostat I'm sure I can figure out what I need to know to make it work.
Have you looked at this page?
Does it apply to your thermostat setup?
I'm especially curious about #5. #5. Choose appropriate Balance Point Temperature in Installer Setup Number 0350.
There might be more info to glean from this thermostat setup page.
On a cold night, a family using hot water, a stove, the clothes dryer and a hair blow dryer may well be over the limit! I'm pretty sure I went though that with numbers and all.
That's why I have nat gas, avoid all those problems. Not that I think it's actually a real problem with a 200A service, mind you. With the heat pump/electric heat pulling 80A, it still leaves 120A for the rest of the house, which would work for me. But if you really insist of having a service sized to absolute worst case, sized to turn on all ovens, water heaters, dryer, washing machine, hot tubs, 6 hair dryers and the heat pump with elect aux at the same time, then I guess you should have a larger service.
l also run under two other conditions. One is the system detects ice on th e outside coils. With a 40 degree cut off, your system might not worry wit h deicing. The other condition is when the system runs long enough that it decides the heat pump is not doing the job and switches to backup heat. O pps, another condition is if the inside temperature drops too far bellow th e set temperature.
lb thermostat. Set the temperature and bulb 1 would control the heat to ke ep the temperature. But if the room (hallway as the case may be) temperatu re dropped too far the second bulb switch would close and the backup heat w ould come on.
ramps the temperature up slowly enough to not kick in the backup heat.
your installer. With the last system I bought I found I could not even ge t info from the company who made it. They always referred me to the "insta ller", like I was not worthy of information.
use
our
rd,
s
ems
ng
the
s
c heat is the power required.
the back up is electric because it would be a very large load at one time,
15 kW.
10
,
w
dig up a manual. I have no other way of knowing what the thermostat will d o, but I can assure you that there is not a special output for "high differ ential temperature". There is a signal to turn on the heat pump and a sign al to run the electric coils. The furnace may or may not cut off the heat pump when the coils are on regardless of what the thermostat does.
eer my heating system. Originally I was asking if anyone knew about a ther mostat that would ramp up the temperature in a way that would not trigger t he back up heat.
In the typical install, the thermostat makes the call, because it has the best information, ie what the set temp is, what the actual is, how long it's been running already. The Trane thermostat he has looks just like the Honeywell Vision Pro series and that's how they work. He also says that the thermostat has a wire for aux heat, that settles it for me.
It has gotten confusing. I thought he was saying that the aux heat only comes on when it's needed, to supplement the heat pump. Now he's saying that it may shut off the heat pump when it comes on, which makes no sense to me. You'd think he'd know how it behaves.
Maybe I'm confused here, but I thought the system he's talking about is a heat pump with aux electric heat. I think the oil furnace was a previous house. And he doesn't want the aux heat to come on during certain periods, when electric rate is high, that's the whole point. Here are two scenarios where that happens:
1 - You leave the house during the day for 8 hours, set the temp back to save energy. Now either you come home or it's programmed to get back to normal temp at say 5PM. So, now the temp is 65, the desired is 70. The thermostat sees that and invokes aux heat to get it there as fast as possible. If you are there, you could get around that by raising it maybe 2 deg at a time, but then that's a pain too.
2 - Same as 1, but setback over night. The fact that heat pumps can take a long time to recover and this issue leads many to not set them back overnight.
He could do that, but then he has to remember to work the switch and it's not exactly desirable. Like I've said a couple times now, an obvious solution is for these thermostats to have an option where it estimates how long it will take to reach the set temp and then only invokes aux heat if it will be longer than X minutes, where X is user programmable. That kind of does it. A further refinement would be to factor in time of day. Like you may be willing to live with a 3 hour ramp during the day when you're not likely to be there, but not at 7AM when you're getting up.
CONT802AS32DAA Trane. I found manuals for it but they don't offer a lot of insight. I think a lot of this stuff is cut and dried and hasn't changed in 50 years or more. So they don't tell you any of the standard assumption s in the manuals.
=18#manual
The balance point affects the swing between on and off. I don't see it solving his issue.
Yes, it would seem to me that the thermostat would have a separate wire going to the control board for Aux heat. And that's what turns on the aux, weather it's electric or oil.
Then the question is, How does the thermostat determine, "when it's needed". It might help if he listed the setting install on the page,
starting with Setup Number O170.
Now he's
Maybe he needs to start fresh. I was hoping I get answers to each question I ask and that would help pin point what's going on, hasn't happened yet.
After some time the back up heat comes on and the electric meter spins like a top.
After some time? How much time, is it the exact same amount of time every time? IF yes, then I must be a signal from the Thermostat or on the control board to turn on the aux heat.
I see this, here,
OPERATION IN HEAT MODE When the outdoor temperature is below the Compressor Lockout Temperature, only the Auxiliary Heat operates.
When the outdoor temperature is above the Auxiliary Lockout Temperature, only the Compressor operates.
See Fig. 21. COMPRESSOR ONLY Above 50*
-------------------------------- BOTH COMPRESSOR AND AUXILIARY HEAT Above 35* and below 50*
-------------------------------------- AUXILIARY ONLY Fig. 21. Heat Pump Operation with Lockout Temperatures Set. Below 35*
When the outdoor temperature is between the two temperatures, both the Compressor and Auxiliary Heat operate
Can you check to see if you have the outside temperature sensor? It will connect to S1 and W1 in your thermostat and be a separate pair from outside to the thermostat.
ill also run under two other conditions. One is the system detects ice on the outside coils. With a 40 degree cut off, your system might not worry w ith deicing. The other condition is when the system runs long enough that it decides the heat pump is not doing the job and switches to backup heat. Opps, another condition is if the inside temperature drops too far bellow the set temperature.
bulb thermostat. Set the temperature and bulb 1 would control the heat to keep the temperature. But if the room (hallway as the case may be) tempera ture dropped too far the second bulb switch would close and the backup heat would come on.
h ramps the temperature up slowly enough to not kick in the backup heat.
sk your installer. With the last system I bought I found I could not even get info from the company who made it. They always referred me to the "ins taller", like I was not worthy of information.
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n dig up a manual. I have no other way of knowing what the thermostat will do, but I can assure you that there is not a special output for "high diff erential temperature". There is a signal to turn on the heat pump and a si gnal to run the electric coils. The furnace may or may not cut off the hea t pump when the coils are on regardless of what the thermostat does.
ineer my heating system. Originally I was asking if anyone knew about a th ermostat that would ramp up the temperature in a way that would not trigger the back up heat.
he
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I think they typically base it on how big the temp delta that it has to close is. If it's one or two deg and the system has not been running a lot just to maintain, then it uses heat pump only. If it's more than about 2 deg or it's been running most of the time just to maintain the temp, then it uses both.
=12#manual
Like I said, that thermostat is surely made by Honeywell, it looks just like the VisionPro Series. I have one, I looked at it's settings and there is nothing there to control aux heat, with two exceptions
1 - You can enable or disable it
2 - If you have an optional external temp sensor, you can disable it above 40 to 60F, where you get to set that temperature. The idea being if it's say 50F outside, you know it works well enough that it can heat without aux heat and you're willing to wait. I pointed that out before, it would be a partial solution to disable aux heat some of the time, if he sets it to 40F, at least it would not come on part of the time. But maybe that is actually a solution for most of the time. When it's below 40F out it may take so long to get the temp up with just the heat pump that you'd want aux on anyway. But hooking up an outside sensor could be a big issue and his thermostat may not support it. You'd think some thermostats would have more prog control over when it comes on, like at least how big the temp delta has to be.
will also run under two other conditions. One is the system detects ice o n the outside coils. With a 40 degree cut off, your system might not worry with deicing. The other condition is when the system runs long enough tha t it decides the heat pump is not doing the job and switches to backup heat . Opps, another condition is if the inside temperature drops too far bello w the set temperature.
o bulb thermostat. Set the temperature and bulb 1 would control the heat t o keep the temperature. But if the room (hallway as the case may be) tempe rature dropped too far the second bulb switch would close and the backup he at would come on.
ich ramps the temperature up slowly enough to not kick in the backup heat.
Ask your installer. With the last system I bought I found I could not eve n get info from the company who made it. They always referred me to the "i nstaller", like I was not worthy of information.
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can dig up a manual. I have no other way of knowing what the thermostat wi ll do, but I can assure you that there is not a special output for "high di fferential temperature". There is a signal to turn on the heat pump and a signal to run the electric coils. The furnace may or may not cut off the h eat pump when the coils are on regardless of what the thermostat does.
ngineer my heating system. Originally I was asking if anyone knew about a thermostat that would ramp up the temperature in a way that would not trigg er the back up heat.
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And what do you think you see in the manual? I see that it has the option I told him about yesterday and that I just mentioned here again. Which is if you have an external temp sensor, you can disable aux heat above a temp between 40F and 60F, that you can set. That was from the Honeywell, what you posted shows similar, though it might allow as low a setting as
35F. That would probably do what he wants some of the time, probably most of the time.
l also run under two other conditions. One is the system detects ice on th e outside coils. With a 40 degree cut off, your system might not worry wit h deicing. The other condition is when the system runs long enough that it decides the heat pump is not doing the job and switches to backup heat. O pps, another condition is if the inside temperature drops too far bellow th e set temperature.
lb thermostat. Set the temperature and bulb 1 would control the heat to ke ep the temperature. But if the room (hallway as the case may be) temperatu re dropped too far the second bulb switch would close and the backup heat w ould come on.
ramps the temperature up slowly enough to not kick in the backup heat.
your installer. With the last system I bought I found I could not even ge t info from the company who made it. They always referred me to the "insta ller", like I was not worthy of information.
use
our
rd,
s
ems
ng
the
s
c heat is the power required.
the back up is electric because it would be a very large load at one time,
15 kW.
10
,
w
dig up a manual. I have no other way of knowing what the thermostat will d o, but I can assure you that there is not a special output for "high differ ential temperature". There is a signal to turn on the heat pump and a sign al to run the electric coils. The furnace may or may not cut off the heat pump when the coils are on regardless of what the thermostat does.
eer my heating system. Originally I was asking if anyone knew about a ther mostat that would ramp up the temperature in a way that would not trigger t he back up heat.
The only way to determine that is to instrument the whole thing and make me asurements. I've not done that because it doesn't change the solution. Th e backup is coming on either because the temperature is too far from the se t point, or because the heat has been running too long. The former can onl y be from the thermostat, the latter could be implemented in either.
???
Nope, I don't know. I've not opened the furnace and put a volt meter on th e various components to see exactly when what runs. I don't plan to either . Not useful info.
When it is needed, but I don't have an oil furnace in this house. It has e lectric backup.
Ok, you have completely missed the trolley and are headed to city center of off the mark ville.
CONT802AS32DAA Trane. I found manuals for it but they don't offer a lot of insight. I think a lot of this stuff is cut and dried and hasn't changed in 50 years or more. So they don't tell you any of the standard assumption s in the manuals.
=18#manual
Seems to.
Not sure what you are talking about "Balance Point Temperature". It says 0
350 is for "Heat Pump Compressor Lockout". Doesn't sound useful to me.
=12#manual
I haven't found anything other than settings that have already been dealt w ith.
--
Rick C.
--++ Get 1,000 miles of free Supercharging
--++ Tesla referral code - https://ts.la/richard11209
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