RE: [EnergyPlus_Support] simultaneous heating and cooling in the condenser loop

List the schedule values to find out. Because the zone level is not season controlled, all the plants are not seasonal controlled.

When ever you need neating and cooling at the same you get into this type of unknown conditions. For example, VAV cooling with reheat. When one uses electgricity for reheat. the problem does not show up. If you share the reheat with the Winter heating coil operation, similar condition may appear.

This is what I was referring to in my first reply.

There is a warning in EPlus that HP should not be operated below 5°C and water system should be drained in Winter.

The use of basin heater is logical for a small system. The compressor unit of a heat pump system have heaters as well.

One should check with the real system from a manufacturer to get the additional information.

The tower heater will not turn on when he ODT is not in the freezing range.

I did not run the weather file, but with a few DesignDay objects so that you can adjust the temperature easily to verify. In this way, you only need four or five days of data to be reported and plotted side by side on the same chart to compare. Your graphs does not make sense to me. Too much repeated information.

It is very easy to control the simulation temperature with the DesignDay objects. Of cause, the object name should be unique, and the schedule daytype can also be customized. The sun can be turned on and off as well.

I was looking for a basin heating field for the tower, and has not found it yet.

Dr. Li

To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: ery.mailinglist@xxxxxxxxx
Date: Tue, 6 Mar 2012 19:40:12 -0700
Subject: Re: [EnergyPlus_Support] simultaneous heating and cooling in the condenser loop

Dr Li, I do not understand your explanation.

Are you talking about the type of thermostat that is always 4 in the expanded file? I am not talking about the zone level temperature control. Yes, I know that the tower does operate (legitimately) in winter, when the water loop temperature is ABOVE the range.

The problem that I raised is that the main tower will also operate when the water loop temperature is BELOW the range. I run the models for two weeks, one in winter and one in summer, under Boise weather. To force the model to have the water loop temperature BELOW the range, I have to disable the insulation on the external walls. Then the water loop temperature falls BELOW the range. At this condition, only the boiler should operate. But it turned out that the tower also operate.

Thanks,

Ery

On 03/05/2012 05:07 PM, YuanLu Li wrote:

I did not realize that the discussion was on the template IDF,
HVACTemplate-5ZoneWaterToAirHeatPumpTowerBoiler.idf.

I tried the simulation, and I found that the result was simply showing the heating required to keep the tower water from freezing.

About 3kW of power is needed to heat the water to 15°C, when the ODT was -17.6°C. The power changes with the ODT value. Less power when the ODT is higher. The mass flow rate is constant, probably because the capacity of the circulating pump of the cooling tower is constant. The tower fan was off.

The template looks like one simulating a 2 pipe system for the zone using two coils fed from the same mixed loop.

The water to air HP is used for cooling only, but the tower is not turned off when ODT is below zero.

With type 1 and type2 seasonal control, the tower will be disabled, and the heating of tower may not appear.

It is no a template error. It is reporting correctly, that the tower needed heating in Winter.

The HP was not adding cooling to the heating mixed water loop.

When simulating the HP directly, the required heater fields are all listed.

I have not used the water tower object in Winter, and have not found the field for heater yet.

This is the reason why I said that the template method is not easy for beginners to use for more complex or non conventional combinations, using default type 4 thermostat.

I do not know how to force the template to use seasonal control on expansion. The user provided seasonal heating and cooling setpoint objects are sometime replaced by the template expansion. (Not always.)

The problem may not show up, if the template location was not for a cold place like Chicago.

Dr. Li

To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: linda@xxxxxxxxxxxxxx
Date: Mon, 5 Mar 2012 10:39:48 -0700
Subject: Re: [EnergyPlus_Support] simultaneous heating and cooling in the condenser loop

We are posting a defect report and will be looking into it.

At 10:34 AM 3/5/2012, Ery Djunaedy wrote:

As a follow up, these graphs show the problem: the cooling tower operates at the same time as the boiler. The plant component temperature graph is very revealing if you compare the deltaT between the boiler and the cooling tower.

Any insight on this is greatly appreciated.

Ery

On 03/05/2012 06:06 AM, Linda Lawrie wrote:

Are you reporting at a detailed level so you KNOW there is simultaneous heating and cooling or is it just happening over an hour?

At 04:50 PM 3/4/2012, Ery Djunaedy wrote:

I am referring to the example
HVACTemplate-5ZoneWaterToAirHeatPumpTowerBoiler.idf. The cooling tower
and the boiler configuration from the HVAC template always results in a
simultaneous heating and cooling.

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