HVAC-Talk: Heating, Air & Refrigeration Discussion banner

Daikin Heat Pump + AUX Heat Question

13K views 29 replies 4 participants last post by  Bazooka Joe  
#1 ·
Hi all,

I've got a Daiken indoor and outdoor setup in conjunction with an AUX heat source. The heat pump is set to lockout at -5 Celsius meaning the AUX is meant to take over below -5. I'm finding the AUX is doing most of the heating below -5, but the heat pump will still kick in despite the outdoor temp being well below the lockout temperature.

Any thoughts?
 
#2 ·
Call the company who installed your system, thinking you have a one year labor warranty? Didn’t they explain the sequence of operation under different scenarios before collecting their money?
 
Save
#6 ·
You didn't provide any information about the system other than the brand, and that particular brand is a very big one with tons of very different models, so unless you give more information it's going to be hard for us to help you. Model number of system, what thermostat you have, etc.

Are you sure the lockout set was actually a heat pump lockout? Maybe it was just an aux heat lockout. Ie. below that temp aux heat is allowed to operate. Not that the system must heat with aux heat alone.
 
#8 ·
Indoor unit is FXTQTAVJUA and outdoor unit is RXTQTAVJUA. Using Daikin One Plus thermostat. Aux heat lockout is set for +15 celcius and heat pump lockout is set for -7.5 celcius. I'm assuming this means that below -7.5 only AUX heat will be used, between -7.5 and 15 a combination of the two can be used, and above 15 only the heat pump will be used?
 
#9 ·
Sorry about that. AUX heat are radiators controlled by the Daikin One Plus thermostat. Interestingly too the indoor unit fan does not run when the AUX unit is providing heat. The indoor unit fan will only run when AUX heat is set to the primary heat source...
 
#11 ·
Hot water. Sorry for my lack of knowledge here. Just wondering if there's a quick setting I could check before the techs arrive and/or get a second opinion on whether the setup will function seamlessly (which I also understand is hard to do without seeing it). Basically heat pump is supposed to lockout around -7.5 celcius so that the hot water radiators take over to heat the house. Heat pump and radiators are controlled by a Daikin One Plus thermostat. Would like the indoor unit fan to run as normal when AUX heating is running, though this doesn't seem to be an option. Indoor unit fan will only run (apparently) when AUX heat is set as primary heat method (as per a Daikin manual I found online), which I find quite odd. I think this has to do with the fact that the AUX heat cannot require the use of the indoor unit fan... still doesn't make sense why the fan is allowed to run when AUX is primary heat though.
 
#12 ·
Thinking because yours is somewhat of a odd system?? ( at least in the USA to a degree ) to have the dedicated thermostat control a external hot water source ( not attached to the Air Handler ) like electric heat strips inside the Air Handler as an example, maybe the Contractor is not familiar with the set up you have and hooking it up to function? IDK is that a popular set up in Canada, your system as an example?
 
Save
#14 ·
Thinking because yours is somewhat of a odd system?? ( at least in the USA to a degree ) to have the dedicated thermostat control a external hot water source ( not attached to the Air Handler ) like electric heat strips inside the Air Handler as an example, maybe the Contractor is not familiar with the set up you have and hooking it up to function? IDK is that a popular set up in Canada, your system as an example?

Appreciate the responses. Yes, it is quite an unusual setup. Supposedly the units will need to be setup with two stages of heating (which they currently aren't - it's currently just heat pump + aux). First stage will be heat pump, which will lockout at a certain temp, second stage will be aux heat. Contractors are still unsure if the indoor unit fan will run while calling for heat when the outdoor unit is locked out. We shall see when the necessary parts, etc are installed.

My inclination is that it won't work, in which case it might be easiest to have the aux heat controlled by a separate thermostat. When I want to lockout the heat pump and use aux heating I could manually switch the indoor units over to cooling mode with the set point set quite high so the units aren't actually cooling. This would force the indoor unit fan on while the radiators do their thing while simultaneously preventing the heat pump from heating. This seems like a band aid solution for something that should be able to be handled by the units themselves though.
 
#17 ·
Will likely be what will happen.

Maybe they need to hire someone more familiar with external control wiring to mate them together or contact Daikin Technical Rep. for direction. Course Daikin may say that’s not in their wheel house as the radiators where already there and have nothing to do with being a Daikin product?
Daikin is supposedly coming out to view the issue *soon*, but I suspect you're right: they may look at the issue and be like "that's not our problem".

Question for clarity. Apologies if this question isn't allowed - it's simply one out of interest as I try to gain some knowledge as to what I should be asking the tech when they come out (I've never used heat pumps before). Should the indoor fan run when a heat pump is locked out? Or does it make sense for the indoor units to stop blowing air when the outdoor unit is locked out? From what I gather (based on my reading of Daikin support manuals) the AUX heat cannot require the use of the indoor fan. Daikin's support manual is clear that if AUX heating is set as the primary heat source and the heat pump is secondary, the indoor unit will continue to circulate air at a fan speed defined by the user. This seems to be working no problem. Where things are a bit iffy is when the heat pump is locked out. When the aux heat is set as the primary heat source AND the heat pump is locked out the fan no longer runs. Then fan will only kick back in once the set point is reached and the aux heat has shut off.

So confusing.
 
#16 ·
Maybe they need to hire someone more familiar with external control wiring to mate them together or contact Daikin Technical Rep. for direction. Course Daikin may say that’s not in their wheel house as the radiators where already there and have nothing to do with being a Daikin product?
 
Save
#19 ·
Installing contractor doesn't have an answer. Questions have now gone back to the equipment provider/Daikin. What I do know is that no temperature sensor has been installed in the indoor unit. All temperatures are recorded by the external thermostat (this has been set by the residential field settings).

What confuses me is that the indoor unit fan will run when no call for heat is coming from the auxiliary unit (despite the heat pump being locked out). This to me suggests something is wired/setup wrong. Hopefully the Daiken tech can figure this out.
 
#20 ·
You don’t have a normal Heat Pump set up, so not sure how on answer your question. You may want to have them check emergency heat mode also. As an example only if the outdoor section fails in mid winter for whatever reason and it’s above the switchover set point, typically there is a emergency/auxiliary heat at the thermostat that you physically put system into and it’s suppose to lock out the OD unit, and run your Air Handler ( with auxiliary heat strips running at 100% capacity if you had heat strips ) Seeing your auxiliary/emergency is radiators ( convection? ) you may want to have them check that or ask them if my outside unit fails in the middle of the winter, what happens, does the Air Handler lock out also and it runs 100% ( convection? ) radiators? Is that what you have? several convection radiators throughout your residence?

As an example only, have 3 zone ( three thermostats ) hot water baseboard ( low profile ) convection heaters throughout my residence.
 
Save
#21 ·
You don’t have a normal Heat Pump set up, so not sure how on answer your question. You may want to have them check emergency heat mode also. As an example only if the outdoor section fails in mid winter for whatever reason and it’s above the switchover set point, typically there is a emergency/auxiliary heat at the thermostat that you physically put system into and it’s suppose to lock out the OD unit, and run your Air Handler ( with auxiliary heat strips running at 100% capacity if you had heat strips ) Seeing your auxiliary/emergency is radiators ( convection? ) you may want to have them check that or ask them if my outside unit fails in the middle of the winter, what happens, does the Air Handler lock out also and it runs 100% ( convection? ) radiators? Is that what you have? several convection radiators throughout your residence?

As an example only, have 3 zone ( three thermostats ) hot water baseboard ( low profile ) convection heaters throughout my residence.
I have the exact same setup. 3 zones (three stats) and convection hot water radiators. I just tested the emergency heat mode - rads will kick on fine, but air handler is off. Something isn't right. Perhaps there's a wire or something on the physical board in the air handler that needs tweaked. I'm assuming if there was an electric heating coil installed in the unit as auxiliary heat the indoor unit would have to continue to run to push that heat out. Maybe the aux heat not getting hard wired to the indoor unit control board is confusing it. The Daikin One Plus thermostat is meant to act as a controller to manage all software settings. Got to love trouble shooting. Appreciate your help!
 
#22 ·
Why is that a bad idea to have the Air Handler shut off during emergency hear? Aren’t you happy with just the radiators/baseboard prior to having this system installed. I have a Heat Pump also, I personally don’t like running the blower fan when my baseboard is on, I like the warmth from the convection heat and not the air moving around my residence, course I’m a old timer and don’t like cooler air moving around my house if running the blower fan while my baseboards are on,….but hey that’s me..
 
Save
#23 ·
You raise a good point. I'm not sure how to answer your question... I guess I just like the constant circulation of air (and well, without our air circulating the HRV system is kind of pointless, haha). Personal preference I suppose.

One last question and I'll stop bothering you, I swear! If my AUX heating was an electric heating kit installed inside the air handler, would the air handler most likely stay on when the emergency heat was activated? Or is the electric kit considered AUX only and not emergency? Of course, this is hypothetical. Just wondering if having something hardwired to the air handler would change how the emergency heat/lockout works.

Thanks again!
 
#26 ·
“Water heating coil installed in one of the indoor units”

What does that mean?? Such as a existing Air Handler? or……like this? I have this also, a hydronic kickspace heater with a dedicated blower assembly ( mine is under the kitchen sink cabinet and blows the air out of a grille on the kickboard ) mine is hooked to one of my zone thermostat that also controls one zone of baseboard.

https://www.google.com/url?sa=t&rct...ww.beacon-morris.com/twin-flo-kickspace-heater&usg=AOvVaw15KiyJyZ9-2ZXv5J1-Gn3V

https://www.beacon-morris.com/Theme...BeaconMorrisTheme/images/products/Residential/TwinFlo/Twinflo-Install-Floor.png
 
Save
#28 ·
Well,…if the Contractor put that Daikin brand new coil you listed downstream of the FXTQ Air Handler with new zone valve feeding coil and new wiring, then thinking your Contractor along with Daikin Technical Rep. responsibilities to get at least that part to work? You should have a labor warranty for that, no?
 
Save
You have insufficient privileges to reply here.