Re: [EnergyPlus_Support] Thermostats of radiant systems

From: Athinodoros Tzoulis <a_tzoulis@xxxxxxxxx>;
To: EnergyPlus_Support@xxxxxxxxxxxxxxx <EnergyPlus_Support@xxxxxxxxxxxxxxx>;
Subject: Re: [EnergyPlus_Support] Thermostats of radiant systems [2 Attachments]
Sent: Mon, Dec 30, 2013 4:36:04 PM

Hello again,

Sorry for sending repeatedly but I cannot make the simulation running properly.Â

As I told you before, I have modelled a radiant floor and I want the water supply temperatures to be based on outside temperature. I have done thisÂ in the lowtemperatureradiant object by checking outdoor dry bulb temperature in the temperature control.

I also want to have a thermostat in the zone based on the operative temperature in order for the system to operate only when the inside temperature is at the range that the thermostat allows. In the Controls and Thermostats Group I have added a dual setpoint thermostat.Â

The system is taking only the control temperatures of the radiant systemÂ Â in the lowtemperatureradiant objectÂ into account. I think that the thermostat is overriden by the contol temperatures of the radiant system.

I also send you the idf file and some results. I would be very glad if you could check the points that I have mentioned in the idf file.

I have created the model initially in Designbuilder and then I adjusted some things in EnergyPlus.

Â Thank you very much in advance

Best regards,

Athinodoros Tzoulis

On Wednesday, December 18, 2013 9:07 AM, "jeannieboef@xxxxxxxxx" <jeannieboef@xxxxxxxxx> wrote:

Yes. Your idea is correct...are you quite new to e+? Check out the examples in the example folder. There is a thermostat object called something like thermostat:duelsetpoint...that's what you want. A thermostat object referances a schedule that you must define. That schedule holds values that represent the temperature setpoint values at which heating will kick in (cooling setpoint schedule is seperate and is seperately defined). Conceptually, it is only against these setpoints and the current zone air temperature that the programs calculates the heating or cooling loads on the zone. That is the normal setup.

It should be noted (as previously mentioned by me) that the radiant object has another totally seperate setpoint schedule(s) which it referances and uses (but it could referance the same as those of the thermostat).

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

i. A.

Jean Marais

b.i.g. bechtold

Tel. Â +49 30 6706662-23

On 17.12.2013, at 18:37, Athinodoros Tzoulis <a_tzoulis@xxxxxxxxx> wrote:

Â

Let me explain it a little more clearly.
The water supply temperature is depending on the outside temperature in the lowtemperatureradiant object by checking outdoor dry bulb temperature in the temperature control. However, I want the system (, loop or pump) to operate when the inside temperature is below a certain temperature . Which setpoint or thermostat should I add?
In the Zone HVAC Controls and Thermostats group I have added a thermostat. Which system does it trigger?

Moreover, is it possible to set the high control temperature for heating higher than low control temperature for cooling in lowtemperatureradiant object?

Thank you in advance

Best regards,
Athinodoros

On Tuesday, December 17, 2013 8:27 AM, "jeannieboef@xxxxxxxxx" <jeannieboef@xxxxxxxxx> wrote:

Â

It sounds like you are using setpomtmanager:scheduled. There are many different setpoint managers that you can use instead. I think you want setpointmaneger:outdoorairreset (I may be writting the name incorrectly).

As for your second worry...the pump will turn on if there is a demand from the users. There will be a demand from the users if the zone temperature falls below the setpoint defined by the setpoint schedule that is referanced in your lowtemperatureradiant object, not the zone air thermostate (although you can use the same schedule for both).

I suggest you look at the examples.

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

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

On 17.12.2013, at 01:03, Athinodoros Tzoulis <a_tzoulis@xxxxxxxxx> wrote:

Â

Hi everybody,

I am trying to model a radiant system. I want to have the water supply temperature of the heated floor depending on the outside temperatures. According to the energyplus documentation the water supply temperature can linearly fluctuate between the heating high water temperature andÂ Â the heating low water temperature.
My first question is that when I try to see the results (Zone:Heated Floor Hot Water Inlet Node) in Results Viewer I do not see this fluctuation. The temperature that this output gives is the temperature of the setpoint manager in the hot water loop. Is there another output that gives me this result?
Secondly, apart from the fact that I have the setpoints for the water supply temperature depending on outside temperature, I also want to have a setpoint for the whole loop (or the pump) depending on inside temperature. So, if the inside temperature is below 20oC, I want the system to switch on, but providing the water supply temperature according to the outside temperature setpoints. Is that possible? I see in the IDFeditor that the 20oC setpoint is used in the Setpoint Manager:Scheduled but I cannot see the proper results. The system operates depending only on outside temperature.
Can you please suggest me a way to model this? Please be as simple as possible because I am a new user of energyplus.

Thank you very much in advance
Athinodoros Tzoulis