RE: RE: RE: RE: Re: [EnergyPlus_Support] How to model a ventilation system with air heat exchanger

---In EnergyPlus_Support@xxxxxxxxxxxxxxx, <energyplus_support@xxxxxxxxxxxxxxx> wrote:

You can't always generalize...

To use the simple ventilation object, you would ventilate one zone and then use zonemixing objects to simulate the interzone air exchange (mixing). The "zones" in a single family house are more often connected via "large" openings, i.e. there is no weatherstripping on the room doors (only on those exiting to outside).

You start getting into aspects of modelling accuracy. The best options my be in an AFN type simulation.

...by the by, the Controller:OutdoorAir is rather tricky. I need to read the documentation several times on that section, before I set it up.

goodluck

---In EnergyPlus_Support@xxxxxxxxxxxxxxx, <energyplus_support@xxxxxxxxxxxxxxx> wrote:

I found out what ERV means, energy recovery ventilator.

It seems very similar to the ZoneHVAC:OutdoorAirUnit that I tried before, I believe this system does not represent a real system because there are fans and exhaust fans for all zones individualy,

I would guess a real system only uses one fan for the house (or maybe by floor) Does anybody know this for sure?

But nevertheless I think I will use the ZoneHVAC:OutdoorAirUnit for each zone because the results look more or less resonable

---In EnergyPlus_Support@xxxxxxxxxxxxxxx, <energyplus_support@xxxxxxxxxxxxxxx> wrote:

Hi Jean,

Thanks for the reply. Option 3 to use IdealLoadsHVAC with heat exchanger seems like a good option, however simplified.

Option 4: what do you mean by ERV?

I tried to change the Controller:OutdoorAir (Min = Max flow rate), but even so the air temperature increases after the mixing box

In my setting the heat exchanger is before the mixing box, so I would like the air temperature to be the same, so that when the air arrives in the rooms the temperature is the output of the air temperature after the heat exchanger and no more than that

Controller:OutdoorAir,

OA Controller 1, !- Name

Relief Air Outlet Node, !- Relief Air Outlet Node Name

Air Loop Inlet Node, !- Return Air Node Name

Mixed Air Node, !- Mixed Air Node Name

Outside Air Inlet Node, !- Actuator Node Name

0.033, !- Minimum Outdoor Air Flow Rate {m3/s}

0.0033, !- Maximum Outdoor Air Flow Rate {m3/s}

NoEconomizer, !- Economizer Control Type

ModulateFlow, !- Economizer Control Action Type

19., !- Economizer Maximum Limit Dry-Bulb Temperature {C}

, !- Economizer Maximum Limit Enthalpy {J/kg}

, !- Economizer Maximum Limit Dewpoint Temperature {C}

, !- Electronic Enthalpy Limit Curve Name

4., !- Economizer Minimum Limit Dry-Bulb Temperature {C}

NoLockout, !- Lockout Type

FixedMinimum; !- Minimum Limit Type

Thanks,

Ann

---In EnergyPlus_Support@xxxxxxxxxxxxxxx, <energyplus_support@xxxxxxxxxxxxxxx> wrote:

Option 3: IdealLoadsHVAC with heat exchanger and or economizer

Option 4: I think there is an ERV option which is probably what you're after.

can I use the OutdoorAir:Mixer without mixing the return air?
Yes. The ControllerOutdoorAir object will deturmine how much mixing occurs (you can define DOAS requirements this way).

Mit freundlichen GrÃ¼Ã?en- Sent from my iPhone (excuse the brevity)

i. A.
Jean Marais
b.i.g. bechtold
Tel. +49 30 6706662-23

On 23.10.2013, at 10:24, <welma.pereira@...> wrote:

Dear All,

I am modeling a house that has a ventilation system with an air heat exchanger. My problem is to find out which EnergyPlus object to use for that. I have tried two options

Option1: model an air loop with an AirLoopHVAC:OutdoorAirSystem object

Option2: use a ZoneHVAC:OutdoorAirUnit object

The problem is that using Option1 I can use a heat exchanger like HeatExchanger:AirToAir:SensibleAndLatent for example but I also need to use an OutdoorAir:Mixer, and that is bad because the incoming air should not be mixed with the return air.

can I use the OutdoorAir:Mixer without mixing the return air?
can I use the AirLoopHVAC:OutdoorAirSystem object without using the OutdoorAir:Mixer?

If I chose Option2 according to the example file OutdoorAirUnit.idf I need to define a fan for each zone which I think does not represent a real system, you would probably have just one fan to ventilate the whole house or not?

My ultimate question is which system is better to represent a ventilation system of a house with an air heat exchanger?

Does anybody have to do that before?

Thanks.
Ann