Vent-Axia Sentinel Kinetic Summer Bypass – Settings & Configuration Guide
The Vent-Axia summer bypass is the free-cooling feature built into the Sentinel Kinetic range that helps stop an airtight Irish home from overheating in warm weather. When the conditions are right, it diverts air around the heat exchanger instead of through it, so cooler outdoor air is delivered straight to your rooms without recovering unwanted heat. This guide explains exactly when the bypass opens, the purge modes available, and how to configure the summer bypass settings on the LCD controller.
Key takeaways
- The bypass opens only when all three temperature conditions are met at once.
- It manages temperature and comfort – it is not a dehumidifier or air conditioner.
- Evening Purge and Night-Time Purge force the fans to boost for faster cooling.
- Set your indoor target 2–3°C above your heating thermostat so the systems don’t fight each other.
Table of Contents
What the Vent-Axia summer bypass does
In winter your MVHR recovers heat from the stale extract air and uses it to warm the incoming fresh air – exactly what you want. In summer that same heat recovery can make a warm house warmer. The Vent-Axia summer bypass solves this by opening an internal damper that routes the supply air past the heat exchanger, giving you free cooling whenever the outside air is cooler than inside.
One important point up front: the bypass changes temperature, not moisture. It does not dry the air and it will not behave like an air conditioner. Continuous ventilation still handles indoor air quality and humidity spikes from showers, cooking and laundry.
When does the bypass open? The three conditions
The Sentinel Kinetic will only open the bypass when all three of the following are true at the same time. If any single condition fails, the unit keeps recovering heat as normal.
- Condition A – indoor temperature: Indoor temp is above your target comfort temperature (it’s too warm inside).
- Condition B – free cooling available: Outdoor temp is below indoor temp (outside air can actually cool the house).
- Condition C – draught protection: Outdoor temp is above the minimum threshold (e.g. 14°C) so you don’t pull in cold, uncomfortable draughts.
Worked example: Indoor 26°C > Target 23°C, and Outdoor 18°C < Indoor 26°C, and Outdoor 18°C > Minimum 14°C. All three conditions are satisfied, so the bypass opens and the home gets free cooling.
Summer bypass operating modes
The bypass can work passively or actively force higher ventilation rates (a purge) to cool rooms much faster. Choose the mode that suits how quickly you need the house to cool down.
| Operating mode | What it does |
|---|---|
| Normal (Passive) | Opens the bypass based on the temperature conditions. Fans keep running at their normal scheduled speeds. |
| Evening Purge (5 hours) | Bypass opens and the fans are forced to maximum speed (Boost) for exactly 5 hours for rapid cooling. |
| Night-Time Purge (Continuous) | Fans run in Boost for the whole night. The purge only stops once the indoor temperature has dropped enough. |
| Off (Disabled) | The bypass stays permanently closed regardless of temperatures. |
How to configure the summer bypass (LCD controller)
Use the arrow keys and the SET button on the unit’s controller to set the correct summer parameters. There are three quick steps.
Step 1 – Select the mode
- Use the Down button to navigate to Summer Bypass in the main menu.
- Press SET.
- Select the mode you want (e.g. Normal or Evening Purge) with the arrows and press SET to save.
Step 2 – Set the indoor target temperature
- Navigate to the Indoor Temp tab and press SET.
- Adjust the value with the arrows (default is 25°C), then press SET.
Pro tip: set this 2–3°C higher than your central-heating thermostat. This stops the ventilation and heating systems “fighting” each other across the shoulder seasons.
Step 3 – Set the minimum outdoor temperature
- Navigate to the Outdoor Temp tab and press SET.
- Change the safety threshold that protects against cold draughts (default 14°C) and press SET to save.
- Leave the panel for 2 minutes and it will automatically return to the home screen.
Recommended settings for Irish homes
The factory defaults are a sensible starting point for the Irish climate, but a few tweaks help in NZEB-level and highly airtight dwellings where summer overheating is the real risk:
- Keep the 14°C minimum outdoor threshold. Irish summer nights are often cool, so a lower threshold would let the fans pull in genuinely cold air and create draughts.
- Use Night-Time Purge during heatwaves. Our cool nights are ideal for flushing accumulated daytime heat out of the fabric before the next day.
- Set indoor target around 23–24°C. Low enough to trigger useful cooling, high enough to avoid the bypass chasing minor fluctuations.
- Don’t rely on the bypass alone. Control solar gain with blinds and shading first – overheating is far easier to prevent than to remove.
Under TGD Part F your system must provide adequate fresh air and control moisture, while Part L looks at energy use and the growing focus on limiting overheating in new dwellings. A correctly configured summer bypass supports both.
Summer bypass not opening? Troubleshooting
If your Vent-Axia summer bypass doesn’t seem to open, work through the three conditions before assuming a fault:
- Outdoor air isn’t cooler than indoors. On a hot, humid day Condition B fails and the bypass correctly stays shut.
- Outdoor air is below the minimum threshold. Early morning temperatures under 14°C block the bypass by design (draught protection).
- Indoor target set too high. If your target is 27°C, the room rarely exceeds it, so Condition A never triggers.
- Mode set to Off. Check the bypass hasn’t been disabled in the menu.
- Sensor or damper fault. If all conditions are clearly met and it still won’t open, the temperature sensor or bypass damper may need checking by a technician.
FAQ
Does the Vent-Axia summer bypass cool the house like air conditioning?
No. It provides free cooling only when the outdoor air is already cooler than indoors. It moves cooler air in without recovering heat, but it cannot chill air below outdoor temperature or remove humidity.
What indoor temperature should I set for the summer bypass?
Around 23–24°C works well in Irish homes, and 2–3°C above your heating thermostat. That’s low enough to trigger useful cooling without the system reacting to minor swings.
What is the difference between Evening Purge and Night-Time Purge?
Evening Purge boosts the fans for a fixed 5 hours. Night-Time Purge boosts continuously through the night and only stops once the indoor temperature has dropped enough.
Why won’t my summer bypass open?
Most often one of the three conditions isn’t met – usually the outdoor air isn’t cooler than indoors, or it’s below the 14°C minimum threshold. Check the mode isn’t set to Off, and that your indoor target isn’t set too high.
Need your summer bypass set up correctly?
Eco Vent can commission and configure your Vent-Axia Sentinel Kinetic – verifying airflow, checking the bypass damper and sensors, and optimising both winter and summer settings for your specific home.
Related guides
- Seasonal settings overview: MVHR summer bypass – winter vs summer HRV settings.
- New to the system? Start with how to use your ventilation system.
- Using boost correctly: HRV boost mode explained.
- How MVHR works: heat recovery ventilation (MVHR) systems in Ireland.
- Keep it running efficiently: ventilation cleaning and servicing.