I have a Carrier 25HNA 636 heat pump (two stage piston compressor) and a Carrier CA58VMR Oil furnace. Due to the oil furnace not capable of using the infinity control (a digital control), the system uses the Carrier "Edge" Thermostat. It has capability of selection of the minimum operating temperature for the heat pump. The heat pump is operational quite low and sometimes seems to operate while the oil burner is firing. Since the oil burner is obviously below the "A" coil, it seems rather futile for the heat pump to be operating. Could it be operating in defrost mode or something? I cannot seem to find any decent "how should this system operate" information. Calls to Carrier get me to some operator who does not know what an ac or heat pump is and says see your dealer. The dealer is also of no help but simply an installer. Surely someone out there knows how the Carrier heat pump-oil furnace combination is supposed to work.
Can anyone tell me what an ideal switchover temperature from heat pump to Oil furnace is and how this system is designed to operate? I have tried and cannot get decent answers from Carrier. I would think this is a function of the heat pump efficiency/ temperature curve and the cost of electric and oil at the time. So far I have at least learned that there is an general efficiency of about 400% down to under 100% for heat pumps (temperature based) but have no temperature tie-in for the Carrier unit. The heat pump is a 3 ton unit with a reating of 16 Seer and the oil furnace a Reilo burner with an 81% efficiency.

Most heat pump systems will utilize the auxiliary heating source to temper the air during defrost-if this is the case you should notice that the outdoor fan has stopped while this is occurring. The ideal switch-over temperature will vary depending on the relationship between the heat pump's current output and the current heating requirements of the individual structure. There is no one-size-fits-all answer to that.

Most heat pump systems will utilize the auxiliary heating source to temper the air during defrost-if this is the case you should notice that the outdoor fan has stopped while this is occurring. The ideal switch-over temperature will vary depending on the relationship between the heat pump's current output and the current heating requirements of the individual structure. There is no one-size-fits-all answer to that.
What I am looking for is information on the carrier CA25HNA 3 ton unit. With all heat pumps there is an efficiency drop as the outdoor temperature decreases. If I can find this efficiency vs outdoor temperature curve for the CA25HNA then I should be able to calculate the temperature at which it is less costly to run oil heat than the heat pump. I could then using the Edge Thermostat tell the unit when (at what outdoor temperature) to run oil and no longer use the heat pump. Doesn't anyone have technical specs on this Carrier unit? CArrier does not seem to have them or maybe is just not willing to provide them.
The running of the two heat sources did not involve a "heat pump fan off" condition.

If both heat sources are operating at any time other than defrost, the thermostat may not be configured correctly for a dual-fuel system. Continued operation in this fashion will likely lead to system damage. The performance data you are seeking will probably be found in a Carrier Architects & Engineers reference.

Call the contractor that did the install. You as a homeowner have no business adjusting anything and Carrier will not talk to you unless you have a verfied dealer/service access number which I cannot give out since it is for my use only. In order to get that number you have to attend various classes on there equipment. I get a pass on that requirerment since they have known who I am for over 40 years and do testing on there products.

A infinity control will operate with a oil furnace you just have to know how to wire around the situation. So whom ever told you that was wrong.

You really have to know what you are doing to make adjustments on the equipment you have and I suggest again that you call the dealer that did the install. If for some reason you do not get along with that dealer call another Carrier and pay to have the work done properly then back bill or see the dealer in court for your money.
When you play with the equipment you are playing with a possible warranty violation. I have seen many units that failed due to improper settings and if they are not the original settings as logged by the dealer Carrier can void the warranty if they so choose.

Depending upon how the equipment is installed you can put that heat pump out to lunch when firing fossil fuel. So this is one reason why you should have the dealer do the adjustments. Sorry but that is the way it is.

I think I agree with your installer That is that the infinity control won't work with the non Infinity oil burner.

Nonetheless, attached is the balance point curves:

And your oil burner data:

105 ---
70,000 Btuh with 0.40 gph nozzle
91,000 Btuh with 0.50 gph nozzle
105,000 Btuh with 0.65 gph nozzle

120 ---
119,000 Btuh with 0.75 gph nozzle
140,000 Btuh with 0.85 gph nozzle
154,000 Btuh with 1.00 gph nozzle

You really should let the professionals adjust your system if it is in need of it. If your installer says he doesn't know how then he shouldn't have installed it in the first place. I find it odd that a company would install a system in your home that they do not know how to adjust/repair. Even though K.I.S.S. provided you with the numbers you were looking for I hope you take the advice from myself and others on this board and call in for ON SITE repair. This is not a DIY project and a little bit of knowledge can be a dangerous thing.

To use the worksheet you will have to do a Manual J calculation for the house and combine that with the relative costs of heating with each fuel.

Program to help do a manual J: http://www.hvaccalc.com/

BTW
1 kWh. =. 3412 BTU
MBTUH Thousand British Thermal Units per Hour

Your oil furnace should have consumption data and BTU/hr data. Convert them all to costs (double Y plot) on the Y axis (cost for oil, cost for electric) and...

Actually I'd make a graph using relative costs when done.

You might also have to change your thermostat to get better control to something like a Vision Pro that does dual fuel.

Defrosting in a dual fuel setup could use the burner without the condenser fan running outside, but this is only possible with an integrated system.

In this system, the way it's designed, it is in your best interest not to operate the oil and HP simultaneously.

Have fun.

My final point: I'm not sure I should have provided you with the data, but you do seem curious enough and somewhat knowledgeable from your original post.

I do think that oil and HP at the same time doesn't make sense. I don't know what stat you actually have, so I can't be of much help.

A competent installer should have taught you how to set the balance point based on relative gas/oil prices. I don't see anything wrong with that.

He probably didn't do a manual J, nor manual D and just sized it based on the difference in efficiency and what was being replaced.

I'd call the contractor back and ask him:
It doesn't make sense that the HP and oil are operating at the same time. Why is that so? What can we do about it?
Is the system installed correctly? Why didn't you install/discuss a Carrier Infinity Hybrid system vs. what I got?

Ask him how to set the balance point based on the relative prices of gas and oil?

I think I agree with your installer That is that the infinity control won't work with the non Infinity oil burner.

Nonetheless, attached is the balance point curves:

And your oil burner data:

105 ---
70,000 Btuh with 0.40 gph nozzle
91,000 Btuh with 0.50 gph nozzle
105,000 Btuh with 0.65 gph nozzle

120 ---
119,000 Btuh with 0.75 gph nozzle
140,000 Btuh with 0.85 gph nozzle
154,000 Btuh with 1.00 gph nozzle

I think I agree with your installer That is that the infinity control won't work with the non Infinity oil burner

The VMR series has a variable speed blower.

NOTE:


[/SI
Model 58VMR/58VLR ECM



variable-speed blower motor –
ensures consistent airflow and
temperature maintenance,
helping to keep rooms more
comfortable while improving
air quality.

The use of a Network Interphase Module (NIM) or (SIM) available from Carrier or others will allow the combo to use a Infinity Controler System. At the university we are currently controlling a two stage heatpump with a old Becket burner/no fire just control activate counter with Infinity and no problems. We also have the WiFi/Ethernet module. Nice to control from a lap top. We will soon be doing the Skytel setup. I will be able to have some fun with that from home or anywhere in the world.


Now if you go to Carrier school for all the classes 37 of them at last count you would know how to set a system up properly.

The reason for these statements is the poster was lied to by the installer to start with. Who knows what else is wrong with the system or its adjustments. I always try to post in consideration of my do no harm to the equipment policy. Carrier has and will refuse warranty coverage when homeowners play with the settings or modify the control system. There is a non-defeatable log on that unit if you know how to bring it up with the correct plug in test tool. This can tell the Carrier Corp exactly what was done for controls/events etc when this info is transmitted to them. Yes big brother is watching but only of you know where to look.

Carrier and related companys have one the most advanced control system on the market. They are proud of that fact and do not want the hacks to damage there reputation. The poster made a great decission by buying a Carrier unit to start with so I will not be a party to its possible destruction.


"Never underestimate the difficulty of changing false beliefs by facts."
Henry Rosovsky-Harvard

Based on Carrier's information, the NIM is required for the following. It doesn't fit the requirements.

The following devices do not
Have communication ability and the NIM is required to control:
• A Heat Recovery Ventilator / Energy Recovery Ventilator
(HRV/ERV) (when zoning is not applied).
• A non-communicating single-speed heat pump with Infinity
Furnace (dual fuel application only).
• A non-communicating two-speed outdoor unit (R-22 Series-A
Unit).

Based on Carrier's information, the NIM is required for the following. It doesn't fit the requirements.

The following devices do not
have communication ability and the NIM is required to control:
• A Heat Recovery Ventilator / Energy Recovery Ventilator
(HRV/ERV) (when zoning is not applied).
• A non-communicating single-speed heat pump with Infinity
furnace (dual fuel application only).
• A non-communicating two-speed outdoor unit (R-22 Series-A
unit).


Yes old news.

All you do is add a relay. Look at the literature dated 08/05/2008. The furnace has the variable speed blower but the relay just kicks in the burner/2 wire on a call for 2nd stage heat. Been there done that. My understanding is that info is in the latest class.

Can't find the 50HNA, but I can see how it's possibly doable on the 25HNA. I've never checked if the contact inputs like Y1, Y2, G,and W are actually outputs too.

That would be really cool if they are. Are they?

Can't find the 50HNA, but I can see how it's possibly doable on the 25HNA. I've never checked if the contact inputs like Y1, Y2, G,and W are actually outputs too.

That would be really cool if they are. Are they?

They can be setup that way. There is much more to that controller than meets the eye but most is off at the factory default setting. You have to wake up the board for more. There is a reason for this. It is called future expansion but only at the right time. The main problem now is having enough people who really know the system the way it is if they expanded it much more confusion would follow if you know what I mean. Did you get the two emails with the toys enclosed? There are some other products not in the pipe line waiting for the correct opportunity/time. As mentioned no need to muddy up the water when 99% cannot work on what Carrier has out there now properly. We are entering a world where the HVAC mechanic is no longer going to get by with a hammer and a $ 3.99 meter on sale.

Way too many of these little guys are messing up the systems now so if they added more toys it will be worse. Some of the warranty controllers sent to us once hooked up to the computer tell a very interesting tale indeed. There are some really great techs on this board that help all the posters out but sometimes I hesitate to answer some of the questions for fear of my answers not being understood correctly. I guess that is part of the game since I especially hate to turn down a no heat question.

Yea. Got the toys. Virtual playthings.

I guess the moral, is you have to play and be able to "see" what the options are or be thouroughly trained. I suppose, then in the OP's case, that once the HP is discovered, then an option of aux heat and what type (electric/fossel) becomes available. Then you could use Y2 to control the secondary heat source. That makes a LOT of sense.

When you have a gas system, it asks about an AC, but it doesn't let you choose a manually controlled heat pump. In this case, you have to use a NIM to get dual fuel.

AT some point though, the relative costs of the fuels should be addressed.

I would assume, that once you know heat loss and the burner capacity. You can then determine the time required for the burner to be on. From there, you can convert to gals of oil.

So, I guess the double Y would be KW and gallons and outdoor temp.

There should be one intersection with heat loss and hence the balance point.

But, since the system is non-linear, it's hard to set the actual operating point (outside temp) and base the decision on cost.