Preheat coil requirement in baseline

Hi Samer,

Having in mind that this is part of an Energy Efficiency standard, I would think it would be logic to place it on the outdoor air stream but only after the heat recovery. Heat recovery would "do its job" and only then, if needed, the pre-heat would "kick-in".

As per having a heating coil in the mixed airstream, I guess that you already do for systems 5-8, so indeed you need to have 2 coils:

1) pre-heat coil in outdoor branch after heat recovery with setpoint of 11ºC dT difference to heating setpoint;

2) Heating coil after the mixing box (without a standared defined setpoint) to make sure you don't suply unconfortable temperatures (probably, the same as the LAT from the main cooling coil;

That's my view and I hope it helps!

Hi Samer,

Thank you for commenting. Sorry if I wasn't clear about it. Regarding energy efficiency, it is clear to me that having a fixed pre-heat coil before or after the energy recovery could make a huge difference in energy consumption (depends on your climate zone, obviously). I would say the difference is more than little... 

As for before or after the mixing box, my point is: the pre-heat coil has a fixed LAT setpoint and should be 11ºC less than heating setpoint (ususally 10ºC as setpoint usually is 21ºC) and, from where I see it, should be before the mixing box (regardless of energy use). 10ºC is a temperature of disconfort when supplied to a space, so there should be another heating coil after the mixing box that heats the temperature just enought to avoid the disconfort (usually, matching the LAT for cooling).

Not sure if you agree, but there it is my opinion, hehe.

Thank you!