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GSHP (water-to-water) with radiant heating and cooling

asked 2020-12-14 10:57:08 -0600

Mara gravatar image

updated 2020-12-14 14:13:31 -0600

Hello,

I'm currently using OS 2.9.1 and model a residential building as part of my bachelor thesis in which I applied a GSHP (which should be reversible, that means it provides heating and cooling) and connected it successfully to my secondary radiant heating loop.

However, when I add a water-to-water Heat Pump cooling object and create a secondary radiant cooling loop, no cooling is provided. Temperature Setpoint managers are applied for both -heating and cooling. How can I fix that problem?

GSHP loop with water-to-water Heat Pump (heating and cooling)

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Radiant heating loop (heating coil of heat recovery ventilation)

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Radiant cooling loop --> no cooling in the final results!

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The closest solution I found and implemented successfully was similar to link text where GSHP water-to-water for heating and water-to-air for cooling was used. But I would prefer if cooling is as well provided by a water-to-water object.

My prefered model (cooling yet not working) and my working model with water-to-air cooling (but probably as well heating) are included here: link text

I would appreciate so much a fast answer on how to modify my preferred model that as well cooling is provided by only a water-to-water Heat Pump!!

(PS: I sensed that with a central heat pump system I could solve the problem, but I couldn't modify it accordingly that optimal zone conditions are ensured...)

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Together with a fellow student, I have the model the exact same system like the one you use! We have tried to adjust many parameters like cooling capacity, water flow rate, using other setpoint managers, changing the temperature schedules ... but without success. I see you modeled a coil heating water in your radiant hot water loop (for space heating), is that to supply a shower/bath/ sink of does this have another function? We will keep you informed if we have found a solution.

Pieter_Proot gravatar image Pieter_Proot  ( 2020-12-15 05:09:09 -0600 )edit

Hello Pieter, thank you for trying! The heating coil I connected with the air loop with energy recovery ventilation. Eventually I should also connect a cooling coil to the cooling loop... but I doubt that would solve the problem

Mara gravatar image Mara  ( 2020-12-15 09:13:48 -0600 )edit

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answered 2020-12-18 11:52:36 -0600

Mara gravatar image

The best solution I found was to replace the Low Constant Radiant Floor by a variable one (even by using the measure AedgOfficeHvacRadiantDOAS and creating own HVAC again) and inserting my thermostate schedules. Like this cooling was also provided and my models deliver reasonable results.

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My fellow student and I tried to do the same in our model. We replaced the chiller and boiler from the measure that you mentioned with a heat exchanger (for resilient cooling) and a water-to-water heat pump for the radiant heating system. After running the simulation, we noticed the following things:

  • inlet temperature of the floor cooling was not always 18°C, as implemented. It was often higher.
  • outlet temperatures of the floor cooling system were to high at certain moments.
Pieter_Proot gravatar image Pieter_Proot  ( 2020-12-20 13:32:24 -0600 )edit

We also noticed that our zone air temperatures are still too high. I think the cause lies with the radiant system as well as the ventilation system with heat recovery ( possibility of night cooling). Maybe you experience the same problems or have some advice for us? If you have some advice, you may always contact me by email. (pieter.proot@student.kuleuven.be)

Pieter_Proot gravatar image Pieter_Proot  ( 2020-12-20 13:40:32 -0600 )edit

Hello Pieter, I'm not completly sure whether I understand your modifications correctly. For all three loops (DHW, radiant heating, radiant cooling) I used a heat exchanger, each connected to the GSHP loop (represented by the circles above and below the heat exchanger symbol -> select the respective heat exchanger under the tab "My Model"). Regarding the temperatures I unfortunately have no advice as in my model the zone temperatures are met. Did you implemented in the Low Constant Radiant Floor the temperatures schedules of the thermostates?

Mara gravatar image Mara  ( 2021-01-04 08:29:49 -0600 )edit

For the air loop with ERV measure I chose the type VentilationRequirements, a 250Pa constant volume fan and the setpointmanager temperature schedule by 20°C which significantly can influence the consumption.

Mara gravatar image Mara  ( 2021-01-04 08:31:28 -0600 )edit

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Asked: 2020-12-14 10:57:08 -0600

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Last updated: Dec 18 '20