--- title: Controlling underfloor heating with a heat pump without a buffer --- [Skip to content](https://knowledgebase.grenton.com/en/controlling-underfloor-heating-with-a-heat-pump-without-a-buffer#main-content) - [English](https://knowledgebase.grenton.com/en/controlling-underfloor-heating-with-a-heat-pump-without-a-buffer) - [Polski](https://knowledgebase.grenton.com/pl/sterowanie-ogrzewaniem-podłogowym-przy-pompie-ciepła-bez-bufora) English Show submenu for translations [New ticket](https://knowledgebase.grenton.com/en/kb-tickets/new?hsLang=en) [Customer portal](https://knowledgebase.grenton.com/wsparcie?hsLang=en) ![Logo\_Grenton\_Main\_2020\_RGB\_v1.0-1.png\]](https://knowledgebase.grenton.com/hs-fs/hubfs/Logo_Grenton_Main_2020_RGB_v1.0-1.png?width=200&height=94&name=Logo_Grenton_Main_2020_RGB_v1.0-1.png) Open main navigation Close main navigation - - [English](https://knowledgebase.grenton.com/en/controlling-underfloor-heating-with-a-heat-pump-without-a-buffer) - [Polski](https://knowledgebase.grenton.com/pl/sterowanie-ogrzewaniem-podłogowym-przy-pompie-ciepła-bez-bufora) English Show submenu for translations - [New ticket](https://knowledgebase.grenton.com/en/kb-tickets/new) - [Customer portal](https://knowledgebase.grenton.com/wsparcie) - [Trainings](https://www.grenton.com/cooperation/trainings.html) [Trainings](https://www.grenton.com/cooperation/trainings.html) Hello. How can we help you? - There are no suggestions because the search field is empty. 1. [Knowledge Base](https://knowledgebase.grenton.com/en?hsLang=en) 2. [Manuals](https://knowledgebase.grenton.com/en/manuals?hsLang=en) # Controlling underfloor heating with a heat pump without a buffer For a heat pump without a buffer to function properly, one of the heating loops must always remain open. This article demonstrates how to prepare the logic to achieve this effect. 1. For each heating loop, create a virtual `Thermostat` object. If you need help with their creation, check out [this article](https://knowledgebase.grenton.com/virtual-object-thermostat-object-manager-configuration?hsLang=en). In our example, the thermostats created are: `Thermostat_LivingRoom`, `Thermostat_Bedroom`, and `Thermostat_Kitchen`, corresponding to the heating loops in the living room, bedroom, and kitchen. The thermostats will control the actuators via relay outputs: `Loop_LivingRoom`, `Loop_Bedroom`, and `Loop_Kitchen`. 2. Designate the heating loop that will remain open when all others are closed. In our case, this will be `Loop_LivingRoom`. 3\. Create a script that checks the states of all actuators except the duty loop. If all actuators are off ([logical product](https://knowledgebase.grenton.com/creating-a-logical-sum-and-a-logical-product?hsLang=en) is zero), the algorithm will stop the thermostat managing the duty loop and then activate its actuator. If the condition is not met, the algorithm will restart the duty loop thermostat. Example script (`SCR_Duty_Loop`): ``` if (CLU->Loop_Bedroom->Value==0 and CLU->Loop_Kitchen->Value==0) then CLU->Thermostat_LivingRoom->Stop() SYSTEM.Wait(1000) CLU->Loop_LivingRoom->SwitchOn(0)else CLU->Thermostat_LivingRoom->Start()end ``` where: - `Thermostat_LivingRoom` is a virtual `Thermostat` object (with output `Loop_LivingRoom`) that is dedicated to switching on unconditionally while the other actuators are off. - `Loop_Bedroom`, `Loop_Kitchen` are all actuators in the installation except the duty actuator (in this case, `Loop_LivingRoom`). Assign the script to the `OnValueChange` events of all actuators except the designated duty actuator. ![](https://knowledgebase.grenton.com/hs-fs/hubfs/image-png-Feb-19-2025-09-54-45-8281-AM.png?width=614&height=453&name=image-png-Feb-19-2025-09-54-45-8281-AM.png) ![](https://knowledgebase.grenton.com/hs-fs/hubfs/image-png-Feb-19-2025-09-54-14-4514-AM.png?width=615&height=454&name=image-png-Feb-19-2025-09-54-14-4514-AM.png) 4. In the final step, upload the configuration to the CLU. - [Installation guidelines](https://knowledgebase.grenton.com/en/installation-guidelines?hsLang=en#main-content) - [How to Prepare Electrical Installation](https://knowledgebase.grenton.com/en/installation-guidelines?hsLang=en#how-to-prepare-electrical-installation) - [Reference devices](https://knowledgebase.grenton.com/en/reference-devices?hsLang=en#main-content) - [Integrated Device](https://knowledgebase.grenton.com/en/reference-devices?hsLang=en#integrated-device) - [Most Common Mistakes](https://knowledgebase.grenton.com/en/most-common-mistakes?hsLang=en) - [Electrical Installation](https://knowledgebase.grenton.com/en/electrical-installation?hsLang=en) - [Manuals](https://knowledgebase.grenton.com/en/manuals?hsLang=en#main-content) - [Gate Modbus](https://knowledgebase.grenton.com/en/manuals?hsLang=en#gate-modbus) - [Training](https://knowledgebase.grenton.com/en/manuals?hsLang=en#training) - [SW Applications](https://knowledgebase.grenton.com/en/manuals?hsLang=en#sw-applications) - [Gate HTTP](https://knowledgebase.grenton.com/en/manuals?hsLang=en#gate-http) - [Smart Panel](https://knowledgebase.grenton.com/en/manuals?hsLang=en#smart-panel) - [Configuration](https://knowledgebase.grenton.com/en/manuals?hsLang=en#configuration) - [myGrenton interfaces](https://knowledgebase.grenton.com/en/manuals?hsLang=en#mygrenton-interfaces) - [Virtual Objects](https://knowledgebase.grenton.com/en/manuals?hsLang=en#virtual-objects) - [Gate Alarm](https://knowledgebase.grenton.com/en/manuals?hsLang=en#gate-alarm) - [Intercom](https://knowledgebase.grenton.com/en/intercom?hsLang=en) - [FAQ](https://knowledgebase.grenton.com/en/faq?hsLang=en#main-content) - [FAQ](https://knowledgebase.grenton.com/en/faq?hsLang=en#faq) - [About Grenton](https://knowledgebase.grenton.com/en/faq?hsLang=en#about-grenton) - [Price list and documents](https://knowledgebase.grenton.com/en/price-list-and-documents?hsLang=en) [![Grenton logo](https://knowledgebase.grenton.com/hs-fs/hubfs/Logo_Grenton_variants_BIG_2020_plus_RGB_v0.2-02.png?width=400&height=100&name=Logo_Grenton_variants_BIG_2020_plus_RGB_v0.2-02.png "Grenton logo")](http://grenton.com) Copyright © 2026, Grenton Sp.z o.o.