Hello Guys,
I have the following HVAC system for one of the buildings and it is dual duct VAV system:
- Two cooling fans supply the whole building and each fan has evaporative cooler and a hot water coil after the evaporative cooler. The hot water coil is connected to a boiler and will be abled once the outside temperature is below 60F to maintain the required supply air temperature in the cooling duct.
- One heating fan that supply the whole building and this fan has gas fired furnace to maintain the required supply air temperature in the heating duct.
- The cooling and heating fans are connected to dual duct with dual duct VAV boxes in which the VAV box will mix the cooling air and the heating air to maintain the room temperature.
My question is when I select "Evaporative Coolers" as the cooling source in the DD Wizard I don't get hot water coil as a heating source. I get only "Furnace" or "Electric Resistance". When I select the "Furnace" in the heating source and select "Dual Duct Air Handler with HW Heat" in the system type, no boiler and hot water loop are added to the model and in the "Air-Side HVAC" tab there will be no furnace symbol but hot water coil.
This is a bit confusing. Can anybody help me out by advising how can I model the above system in eQuest? The .pd2 and .inp files are attached.
Regards
Ahmad
Good morning Ahmed
The number of mechanical systems available in the eQUEST wizard is a smaller subset of the systems available in the detailed interface. They are aimed to cover the most typical HVAC systems. Often you will end up making modifications in the detailed interface to more correctly model the system under consideration.
The system you describe is quite innovative with the cooling coming from evaporative coolers.
My recommendation would be to set your cooling to a more conventional chilled water system. In that way, the wizard will set up your duct VAV system.
[cid:image001.png at 01D7C008.F4B31F50][cid:image002.png at 01D7C009.DD5CBCC0]
This does however mean that in the detailed interface you will have to disable the chilled water loop the wizard creates. I would further recommend that you set the dummy chiller to air cooled to prevent the creation of a condenser loop and its ancillary pumps and cooling tower.
Note that eQUEST typically sees evaporative cooling as a precooler rather than primary cooling. That is why I suggested disabling rather than deleting the chilled water loop. You can set the chilled water pump or the loop availability to an always off schedule. The evaporative precooler will be set to run ?Together? with the cooling such that it will carry the load as far as it can.
[cid:image003.png at 01D7C00A.5B5286A0]
Regards,
Brian
Footprint
Brian Fountain
Associate
Thanks Brian for the help but what about the gas fired furnace in the heating fan? Is there a way to add it to the system you suggest or the hot water coils will represent all the gas consumed for the space heating and no need to add a furnace?RegardsAhmadSent from my Galaxy
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The hydronic heating in the cold duct could be added as a preheat coil an the primary heating in the hot deck set to furnace (in the detailed interface).
[cid:image001.png at 01D7C00E.A94C8B40]
Perhaps the above diagram better reflects the system you describe.
The hot water loop control could be set to ?Snap? on outdoor air temperature of 60F such that for temperatures above that value the hot water loop would be off.
Footprint
Brian Fountain
Associate
d 416 572 8501 m 416 562 6831
Thanks a lot Brian for the help. It seems it works as you suggested but how can I disable the chilled water loop in the detailed mode? wrote:
Regards
Ahmad
On Wednesday, October 13, 2021, 11:48:32 PM GMT+11, Brian Fountain
The hydronic heating in the cold duct could be added as a preheat coil an the primary heating in the hot deck set to furnace (in the detailed interface).
?
?
Perhaps the above diagram better reflects the system you describe.
?
The hot water loop control could be set to ?Snap? on outdoor air temperature of 60F such that for temperatures above that value the hot water loop would be off.
?
Footprint
Brian Fountain
Associate
d416 572 8501 m416 562 6831
?
Thanks Brian for the help but what about the gas fired furnace in the heating fan? Is there a way to add it to the system you suggest or the hot water coils will represent all the gas consumed for the space heating and no need to add a furnace?RegardsAhmadSent from my Galaxy
-------- Original message --------