heating system profile

[Giov]

Hello,

I have problems in creating a reliable temperature profile (room with radiators) by changing the heating system schedule in Apro.
I'm trying to change the daily profile typing the daily formula, but the results are extremely static due to the heating set point. The maximum temperature value reached in the room is the heating set point temperature. This is not through in reality. In this way is not possible to evaluate overheating (due to solar gains or thermostats adjustment).
How can I simulate a more reliable temperature profile in a room with radiators? The real temperature in the room might be higher than the heating set point.
I do not know if the problem is clear...

thanks

[chaffinch]

Hi,

My understanding is that with Apache when you specify a setpoint Apache gives exactly that (as a minimum) for the room temperature, regardless of whether the real heating system can achieve it. Apache then determine the associated loads associated with achieving the specified temperature.

The room temperature could still go above the setpoint though if the other room gains (e.g. solar) are high enough. If you haven't done so already it would be worth checking the results for these other gains to see if they are coming out as expected.

I think you can use the ApacheHVAC module to simulate other heating characteristics e.g. warm-up times, the effect of having limited room radiator input or poor heating control where the radiator stays on regardless of room temperature. For thermostat changes you may have to build this into the standard setpoint profile or run a parametric analysis.

Hope that helps.

[Giov]

Hello thanks for the prompt reply.
The problem is that the temperature doesn't go above the heating set point. If I set 20 as a temperature set point, it doesn't mean that the rooms has always the same temperature...sometimes due to the solar gains the temperature increases for a while and it decreases again after 10 or 15 minutes.
- In my simulation, temperature reaches as max value the set point temperature (20°C) while the real monitored temperature goes up to 22°C if solar gains occur; and than it decreases again...
- Further, when people are in the room, for few hours, they change the thermostats. This means that they fix another heating set point, but even if I use the modulated formula profile, it is not possible to change the heating set point.

Summarizing, if the temperature in the room goes above the set point temp, it is not considered within the simulation

thanks again

[Complex Potential]

Hi Giov

Assuming your model location is set to somewhere in the UK mainland then it sounds like there's something else wrong in your model. For a heating only, occupied room to never go above 20C all year sounds wrong so have a check to see if the room is seeing a cooling load. If it is, that could explain it.

If not it must be something else, so take a good look at vista.

CP

[Giov]

Sorry I'm sure I have been not clear.
I'm calibrating my Ve model on the basis of a monitoring campaign results. I measured for a short period (1month) indoor temperatures and relative humidity in several rooms in the building I'm modeling.
What I observe from the model is that the temperature pattern is different since the software, due to the heating set point, does not consider possible overheating.
Sometimes solar gains and thermostats variation might increase the room temperature...

[Complex Potential]

So what you're saying is that your modelling results dont seem to match reality very well? Unfortunately, computer models are based on repeating patterns and set rules whereas reality is chaotic. Trying to get the two to match can often be extremely difficult.

That said, there could still be some fundamental error in your model which is causing the results to look wrong.

[RossThompson87]

Hi, I'm not sure I fully understand the problem.

One thing that might be helpful is by default IES assumes unlimited heating capacity. If you limit this on a room by room basis to real values (e.g. radiator sizes) things may become a bit more realistic.

Ross

[Giov]

Thanks a lot RossThompson87,
I'll try to adjust the heating unit capacity and the heating plant radiant factor.