A common dilemma arises on construction projects: the designer specifies LPHW air curtains for their lower operating costs, whilst the contractor proposes electric units – simpler to install and less expensive at the outset.
Who is right? Both – but over entirely different time horizons. In this article we analyse when it is worth investing in the hydraulic solution, and when a supply cable will be the only sensible choice. We draw on hard data for a typical 4.0 x 4.0 m logistics gate.
Key conclusions
- An electric air curtain costs more to purchase than an LPHW unit (difference in device price alone), but installation is simpler – only an electrical supply is needed, with no requirement to construct a pipework installation.
- Despite the lower cost of the LPHW unit itself, the complete installation (pipework) is more expensive at the outset, but pays for itself through the lower cost of heat (gas/district heating). Gas heating is significantly cheaper than grid electricity (the difference depends on current energy carrier prices).
- The higher cost of the LPHW installation pays for itself within a few heating seasons (the timeframe depends on the intensity of use).
- Electric air curtains are unrivalled in buildings with photovoltaic installations or where no heating system connection is available.
- An LPHW air curtain requires anti-freeze protection and appropriate valving. An electric air curtain requires sufficient connected power capacity.
- An air curtain is not a heater – its primary purpose is zone separation, and air heating is a function that supports comfort.
What determines the choice of air curtain type?
When selecting a unit, the question to ask is not “what is cheaper in the catalogue” but “what infrastructure is available on site”. The decision should be based on three pillars:
Availability of utilities
Is heat from a pipework installation or gas available at the gates? If not, the cost of making the connection may eliminate the financial case for the LPHW option.
Electrical power balance
An industrial air curtain for a 4 x 4 m gate has a heating capacity in the region of 35–40 kW in practice. For the electric version, this means securing a substantial power allocation (high amperage, consumption of up to 40 kW). In older buildings, the available connected power may be insufficient.
Building operating characteristics
Does the gate open cyclically, or does it remain permanently open?
In large-volume buildings with their own boiler room, an LPHW air curtain is the most common choice.
If you are refurbishing a leased hall and cannot alter the existing pipework installation, an electric air curtain is often the only option.
Where does the money go – LPHW vs. electricity in figures?
Let us compare costs for a typical dock leveller gate (4 x 4 m).
Case study assumptions (January 2025):
- Electricity price: 0.90 – 1.20 PLN/kWh
- Gas price (for water heating): 0.30 – 0.40 PLN/kWh
Scenario A: Air curtain with LPHW heat exchanger
- Advantages: low operating costs due to inexpensive heating water. Reliable construction – the LPHW heat exchanger is a simple component with no control electronics.
- Disadvantages: complex installation. Pipework must be routed and valves, actuators, and a pump must be fitted. Risk of the heating medium freezing if the control system fails (anti-freeze protection required).
Summary: higher initial cost, but with intensive use the investment can pay for itself within the first season.
Scenario B: Air curtain with electric heating element
- Advantages: hang the unit, connect to the electrical installation, and it works. No risk of leaks or freezing.
- Disadvantages: very high electricity bills. With intensive winter operation, the monthly energy cost for a single gate can be significantly higher than for the LPHW version.
Verdict: ideal where pipework installation is technically impossible or not cost-effective (e.g. a gate that opens once a day).
Cost comparison (Indicative market values)
| Parameter | LPHW air curtains | Electric air curtains |
| Unit cost | Lower (standard heat exchanger) | Higher (costly high-power heating elements) |
| Installation cost | High (pipework installation, valves, pressure testing) | Medium (cable run only, but large cross-sections required) |
| Energy source | Boiler water (e.g. gas boiler) | Grid electricity (Tariff C) |
| Estimated cost per 1 kWh of heat | approx. 0.30 – 0.40 PLN (Gas) | approx. 0.90 – 1.20 PLN (Electricity) |
When does the investment pay for itself?
Although the overall investment in an LPHW system is higher at the outset, an LPHW air curtain typically begins generating savings within a few heating seasons (depending on intensity of use and the difference in energy carrier prices).
HOWEVER! An electric air curtain wins when:
- The building owner has a photovoltaic installation
- No heating medium connection is available
- Gate opening cycles are infrequent
Does photovoltaics change the rules of the game?
Yes, and dramatically so. In this case, the electric air curtain wins on TCO.
If the building owner has a photovoltaic installation that generates surplus energy, the cost of powering an electric air curtain falls to almost zero (excluding distribution charges). In such an arrangement:
- We eliminate costly pipework (CAPEX reduced).
- We have “free” fuel (OPEX reduced).
In such cases it is worth considering integration of the air curtains with the BMS – the heating then activates only when the gate is open, reducing energy consumption.
Comparison of HUMMER industrial series solutions
| Parameter | LPHW air curtain (e.g. HUMMER W) | Electric air curtain (e.g. HUMMER E) |
| Heating capacity | 20 – 70 kW (dependent on medium temperature) | 6 – 24 kW (fixed, dependent on model) |
| Power supply | 230 V (fan only) | 400 V (3-phase for heating elements) |
| Current consumption | Low (e.g. 2.5 A) | Very high (e.g. 35 A) |
| Unit weight | Higher (heat exchanger + water) | Lower (PTC heating elements) |
| IP rating | IP 54 | IP 54 |
| Max. jet reach | Up to 7–8 metres | Up to 7–8 metres |
In addition, for up-and-over gates, installation above the opening is not possible – the open gate would obstruct the air curtain.
Why does vertical installation often win in logistics applications?
The jet reach problem
The key factor is air velocity at floor level (minimum 2–3 m/s required). If an air curtain mounted 5 metres above the floor is too weak, heat will escape at floor level. Money wasted.
The vertical solution
For wide gates, column installation at the sides is preferable. Gates frequently open upwards, making it impossible to mount air curtains above the gate.
In such cases an electric air curtain is the better choice. Running a cable to a vertical column is simpler than a pipework installation – there is no issue with air bleeding, and the overall appearance is aesthetically clean.
Technical constraints – what must the designer bear in mind?
- Available electrical power (Electric air curtains)
- Anti-freeze protection (LPHW air curtains)
Installation and servicing – the contractor’s perspective
Challenges with an LPHW air curtain:
- Weight
- Pipework installation
Challenges with an electric air curtain:
- Cabling
- Electrical installation
How does an air curtain pay for itself outside the heating season?
We dispel the myth that an air curtain only works in winter. In summer, an air curtain acts as a barrier against insects, dust, and exhaust fumes (which is critical in the food industry).
In addition, the air curtain retains air-conditioned air inside the building. In fan-only mode, LPHW and electric air curtains consume the same amount of electricity (fan only), so cost differences disappear.
Summary
The debate of “LPHW or electric” has no single winner – everything comes down to available infrastructure and TCO. The decision should be based on a considered calculation, not on the price of the unit alone:
- Choose an LPHW air curtain if the building has its own gas boiler room and the gates operate intensively. The higher cost of the complex pipework installation and valving will be offset by lower heating bills within a few seasons.
- Choose an electric air curtain if the building owner has a photovoltaic installation (a “game changer” that reduces operating costs to a minimum), if no heating medium connection is available, or if you are refurbishing a leased hall. It is also the unrivalled option for vertical installation and in locations where routing pipework is technically impossible.
Bear in mind that an air curtain is a year-round investment – in summer it protects against heat, insects, and dust just as effectively, regardless of the heat source. The final choice should therefore be guided by the balance of available power and utilities, because that is where the real savings are to be found – not in the purchase price.
FAQ – Technical questions
1. How do I protect an LPHW air curtain against freezing?
This is a frequent question. Two solutions are used:
- Automatic control: A frost protection thermostat that, when the temperature in the vicinity of the gate drops, forces the valve to open and maintains minimum flow of hot water.
- Glycol: Filling the installation with a glycol solution (the most reliable method, but reduces heat exchange efficiency by several percentage points).
2. Can an LPHW air curtain work in conjunction with a heat pump?
It can; a heat pump is a heat source in the same way as a gas boiler, for example. It should be noted, however, that it is a low-temperature source, which means lower heating capacity of the LPHW air curtain.
3. Does a “cold” air curtain (without heating) make sense in a heated warehouse?
Yes. An air curtain without heating creates an air barrier that reduces heat losses through the gate opening.
4. How should an air curtain be controlled to avoid generating costs when the gate is closed?
The best approach is to use a magnetic contact sensor on the gate or to integrate the air curtain with the BMS. The air curtain then activates automatically only when the gate is open.
