How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Phil Your Own Question
Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 7542
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
Type Your HVAC Question Here...
Phil is online now
A new question is answered every 9 seconds

I have a Bonaire unit the supply temperature does not go

Customer Question

I have a Bonaire unit the supply temperature does not go above 29deg C
JA: Did you double-check the thermostat? And what about the unit's filters?
Customer: Already checked all good
JA: Do you plan on doing the work yourself?
Customer: I am a technician
JA: Anything else we should know to help you best?
Customer: Discharge pressure is 275psi suction pressure is 53 psi
Submitted: 3 months ago.
Category: HVAC
Expert:  Phil replied 3 months ago.

Hello, tell me the approximate age of the Bonaire unit, and its application (though the wall or ducted etc) I need a lot of details, Bonaire made systems of all types for 40 years.

We can go from there.

Customer: replied 3 months ago.
The age of the unit is 8 yrs. Its a ducted reverse cycle ac..model is BO12RS..
Offcoil temp 34degC
Return Air 15.6degC
Expert:  Phil replied 3 months ago.

are those temperatures in heating mode?

Expert:  Phil replied 3 months ago.

I am not finding the manual in my files, is this a water cooled or air cooled unit.

So far it looks to be doing well at at a 19C temperature rise in heating mode. What problems are you having with it?

Customer: replied 3 months ago.
This is a reverse cycle heat pump.
All the temperatures are in heating mode.
Expert:  Phil replied 3 months ago.

Hello again, so far with the temperatures and pressures you have given it sounds like it working about like any heat pump should with 34C supply air temperature. (when not in electric booster heat mode).

Tell me why you have mentioned 29C off coil (supply) air temperature, you would see that only if the house were in the 10C range, OR if the outside air temperature was going much below zero C and the electric booster heaters were not installed, or if installed were not coming on for one reason or the other.

Customer: replied 3 months ago.
The 29deg temperature is the air coming off the supply vents whereas the 34 deg temperature is off the coil.
This is where the confusion. The customer advised that the unit was working fine when it was installed. If there was any issues when installation was done then that would mean its a design issue. I had the customer on the phone and the unit tripped,thus reset coming on the ir remote controller. The fault was F1 04.
Expert:  Phil replied 3 months ago.

Hello, you can save an hour on this by telling me what the code read out for F1 04 is.... these codes are helpful indeed, about 30% of the time, the other 70% of the time they can be misleading or in more than a few cases, entirely bogus.


Regarding the temperature loss in the supply air ducts from 34C to 29C... the duct is either not as well insulated as it should be, OR... its leaking badly...OR its very long, and it is very cold outside and the velocity is so low that the air is cooling off.

There is another factor, thermometers are all 1 or 2 degrees C off either way, high or low, if you are using two different thermometers, one could be reading high, the other low, and that would give you a bogus result.

When measuring the air at a register the thermometer must be placed inside the register, not outside where the room air mixes with the supply air and gives a false read.

Let me know, we can go from there.

Customer: replied 3 months ago.
The thermometer probe was placed inside the register.the ducts are long.The airflow from my point of view is ok..Since the ducts are under the house i was not able to go to all places to check the ducts.
So if say just because the length of the is long and the temerature drops due to this what can be done to solve this. By the way what does F1 04 mean....
Expert:  Phil replied 3 months ago.

Hello, you can go under the house with a roll of 1 inch thick fiberglass duct wrap, and first look for air leaks, and repair those, then wrap the duct with at least one more layer of this duct wrap.

Fault codes


I didn't see that fault code listed in the manual, in that case it is usually on a sticker next to or on the unit wiring diagram.

Some reports have it as an 'over temperature error, fan kept running on high speed due to a furnace over heat situation, but that is just someone elses opinion, I have not seen any reference to my self.

Related HVAC Questions