Several questions: The main issue seems to be the two transformers not being phased. If you just switch one of the transformer secondaries, why would that not solve the problem? Some in the industry say ECM motors should not be twinned, Why? Does the iO system fix that.When is a back draft damper needed? Are there any other control issues besides transformer phasing?
In most cases, yes, swapping one of the transformer secondaries will fix a phasing issue, but if someone in the future does work on the system, has to rewire anything, replace a transformer, etc… you could end up with the same situation again. Because of this, full electrical isolation between transformers by using relays is always the best solution, by solving the problem now, and preventing further issues down the road. ECM blowers can present a challenge IF there is a possibility they will change their fan speed on the fly in response to pressure or airflow, AND there is a shared supply duct. If this is the case, there is the potential that the two blowers will begin fighting each other, and you could end up with fans ramping up and down unpredictably. This Twinning Board doesn’t have any way to sync fan speeds or prevent that from happening, and we would not recommend using it in that case. If the ECM blow simply has different fan speed based on the input it gets (Heat, Cool, Stages, etc…) then it should work just fine. A backdraft damper would be recommended anytime you are twinning systems that are not identical, or in some cases if you are going to be staging the twinned units (i.e. Unit A is stage 1, Unit B is Stage 2). The reason being if the fans do not start up at the exact same time, there is a possibility that the lagging fan could start blowing backward. Backdraft dampers help prevent this possibility.
can i use this in a dual heat pump twinned? currently have one honeywell prestige operating the units as one heat pump stage one and the other as stage two. will this work the same?
Excellent explanation. Could you also make a tutorial with the installation?
Several questions: The main issue seems to be the two transformers not being phased. If you just switch one of the transformer secondaries, why would that not solve the problem? Some in the industry say ECM motors should not be twinned, Why? Does the iO system fix that.When is a back draft damper needed? Are there any other control issues besides transformer phasing?
In most cases, yes, swapping one of the transformer secondaries will fix a phasing issue, but if someone in the future does work on the system, has to rewire anything, replace a transformer, etc… you could end up with the same situation again. Because of this, full electrical isolation between transformers by using relays is always the best solution, by solving the problem now, and preventing further issues down the road. ECM blowers can present a challenge IF there is a possibility they will change their fan speed on the fly in response to pressure or airflow, AND there is a shared supply duct. If this is the case, there is the potential that the two blowers will begin fighting each other, and you could end up with fans ramping up and down unpredictably. This Twinning Board doesn’t have any way to sync fan speeds or prevent that from happening, and we would not recommend using it in that case. If the ECM blow simply has different fan speed based on the input it gets (Heat, Cool, Stages, etc…) then it should work just fine. A backdraft damper would be recommended anytime you are twinning systems that are not identical, or in some cases if you are going to be staging the twinned units (i.e. Unit A is stage 1, Unit B is Stage 2). The reason being if the fans do not start up at the exact same time, there is a possibility that the lagging fan could start blowing backward. Backdraft dampers help prevent this possibility.
Thank you. Awesome clear answers.
You can not twin ECM motors. If you do you WILL regret it.
can i use this in a dual heat pump twinned? currently have one honeywell prestige operating the units as one heat pump stage one and the other as stage two. will this work the same?
do these require separate transformers or can it be powered by transformer in furnace?
It is recommended that the twinning kit uses its own separate transformer.
Can this be used on a icp furnaces model N9MP2125J20A2?
Yes. It should not be a problem. Depending on the application you may need backdraft dampers.