Author Topic: Secondary Heating Problem on Daikin Duck Heat Pump  (Read 1934 times)

Offline ldeschenes

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Secondary Heating Problem on Daikin Duck Heat Pump
« on: May 14, 2015, 07:41:13 PM »
In our new condominium we have a Daikin Duck Heat Pump System. System components are: Outdoor Unit RZQ36PVJU9 (40,000 BTU/h), Indoor Unit FBQ36PVJU and Thermostat BRC1E72.

There are also Baseboard Heaters installed below the floor-to-ceiling windows that are controlled by the main system through a TRIAC RT850 Solid State Relay. The intent is that when the thermostat (via outdoor temperature sensor) senses the outdoor temperature is too cold for the heat pump to be used as the primary heat source, it automatically switches to baseboard heaters as the secondary heating source.

This works well for the condos on floors 4-5-6 as their Outdoor Unit is installed outside on the roof of the building.  In our case (2nd floor) the Outdoor Unit is installed inside in the garage and the temperature sensor never triggers the system to switch to the baseboard heaters as the garage temperature never goes lower than 60 Fahrenheit.

We live in Canada and temperature goes well below zero degree Fahrenheit. When this happens, it is very cold in our living area because of the large windows. Condos on higher floors are fine as their baseboard heaters take over.

How can we get the system to switch to the baseboard heaters either automatically or manually? Would there be extra components to be installed and/or setups to be made?

Offline scarey8

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Re: Secondary Heating Problem on Daikin Duck Heat Pump
« Reply #1 on: May 16, 2015, 08:13:24 AM »
With the garage temperature never going below 60 degrees F, that would be an excellent place for the outdoor units as there more than enough heat left in the air there and a perfect for heat pumps to perform.  Undoubtedly you are encountering a comfort problem, but the heat pump should be a blue to keep up.   I did a very similar system to what you are explaining with Mitsubishi products.  There were a few things to iron out on that system as well, typically with a heat pump system you have the option to switch between heat & emergency heat modes.  Doubtful that the Daikin system is setup that way as the Mitsubishi system didn't offer that option as well.  Its not possible to just switch a thermostat out to a generic heat pump stat on equipment like that, the control signals are not the same as standard vac equipment.  The only way I could suggest you can force the electric baseboard heating on would be to "force" the heaters on, the heaters are more than likely setup to be activated when the room temperature also drops significantly below the room set point, try turning the heating set point up degree by degree until noticeable heat is found at the baseboard.  electric heat might be locked out indefinitely on your system though.   if that doesn't work you are at the mercy of your heating system and some significant reprogramming or creative wiring would be required to correct your issue.


Offline ldeschenes

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Re: Secondary Heating Problem on Daikin Duck Heat Pump
« Reply #2 on: May 16, 2015, 04:12:32 PM »
Thanks for your reply, Scarey8.

You are right, I also thing that placing the Outdoor unit in the garage would be more efficient that outside.
In fact, the comfort problem only happen in the middle of the winter because of our large windows.

I had try to force the "extra heat" the way you described but as you mentionned it looks like the electric heat is locked out and only s
tart if the temperature sensor stop the heat pump.

What do you think of these 3 "creative wiring" ideas:
1) Move the Heat pump temperature sensor outside
2) Install a switch that would replace the temperature sensor in order trigger the heat pump to stop
3) Completely disconnect the baseboard heaters from the HVAC system and control the TRIAC Solid State Relay with a standard 24volt thermostat

Offline scarey8

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Re: Secondary Heating Problem on Daikin Duck Heat Pump
« Reply #3 on: May 18, 2015, 11:19:14 AM »
Sounds as if the electric heat side of the system is only setup for "emergency heat" and not as an "auxiliary heat".  Long and the short of it, they will never work together.  One or the other or not both.  I wouldn't recommend moving the outdoor sensor or altering any of the interior wiring to the outdoor unit, with inverter technology and variable refrigerant flow style of system, I'm sure the unit would see some strange readings as it operates and probably lock itself out on safety.  Controls are programmed to look at typical system temperatures and pressures for a given temperature, if the temperature is sampled outside but the condenser is indoors the unit could interpret that as a fault.  I would go with your disconnection of the isolation relay from the system and control the two systems separately.  There is probably a way to mesh the two systems together but it will be a lot of trial and error, and that usually equates to costs.