Waste Oil Heater /Multi Oil Fired Heater – Automatic Ignition

Waste Oil Heater Output range – 26kW to 347kW

SZ Automatic Fired Stationary Heaterswaste oil heater – A waste oil heater is the best way to get free heat! Recycle your waste oil with our range of Kroll waste oil heaters. We can offer a full range of Kroll waste oil heaters and waste oil heater spares. Your investment in a Kroll waste oil heater will quickly pay for itself.

  • High efficiency – Over 91%
  • Minimum service and maintenance – Our Stainless Steel Combustion Chamber ensures the best combustion with longer maintenance intervals
  • Clean, soot free combustion
  • Fast and simple installation
  • Room thermostat for economical operation (optional extra)
  • Automatic burner with pre heating
  • Can be connected to a bulk tank if required

Our stationary warm air waste oil heaters are the most economical way to heat your commercial building, warehouse or garage. Available with adjustable side vents or ducted version to get the most use of the heat produced. They can be fully automated and thermostatically controlled. All of our multi oil heaters have a stainless steel combustion chamber as standard and we often get asked why we construct our waste oil heaters this way,the answer is simple , it’s a better engineering solution as stainless steel is a superior heat conductor allowing our waste oil heaters to get warmer , faster ! as well as being able to withstand higher temperatures than standard steel, ensuring our waste oil heaters have an extremley long service life.  Our 25kW to 110Kw units also have stainless steel heat exchangers (for long product life) fitted as standard to ( this is an optional extra for our larger units). All of our waste oil heaters have –

  • An access panel to the heat exchanger – which allows easy access for cleaning the unit
  • Our waste oil burners have a swing arm – which allows easy removal of the burner from combustion chamber, making cleaning the nozzle and diffuser plate of the waste oil burner a breeze !

Multi Fuel Capability of our Multi Oil Heater

    • 35 or 28 second Heating Oil/Diesel
    • Processed Fuel Oil ( PFO )
    • Rapeseed Oil
    • Linseed Oil
    • Certain Vegetable Oils
    • Used Engine Oil (subject to licensing control)  
    • Hydraulic Oil
    • Bio Diesel

Waste Oil Heater – Showing Internal Configuration

Waste Oil Heater Clear Panel

Features of our Waste Oil Heater / Multi Oil Heater


The burner is equipped with a photocell that continuously monitors the flame.

In case of ignition failure or poor combustion, lack of a flame or partly blocked nozzle, the photocell stops the burner.


This multi functional thermostat ensures that the main fan only starts after the combustion chamber has been sufficiently heated. Therefore, there is no cold air blown before the heater has warmed up.


Electrical overload is protected by a trip system for both the main fan and the burner.

Heating overload is protected by a limit thermostat built into the heater control thermostat. This has an automatic reset.

Any obstruction of the main fan or its air stream is secured by a manually reset overload protection.


In summertime the heater can be used for ventilation only

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NEW for 2017

At Flexiheat UK we are always striving to satisfy the requirements of our customers. Due to the increasing demand we can now offer a range of multi oil heater cabinets which are supplied with movable rotating distribution heads.   The FMOH range offers the same level of design and build quality of the Kroll units but are an advantageous alternative as the rotating heads  enable you to easily  direct warm air into any area within your environment.

Multi Oil – Waste Oil Tank – 100 Litre Storage 

We highly recommend that you use our oil tank with our multi / waste oil burners, which are fitted to our automatic waste oil warm air heaters or our multi / waste oil boiler packages.

The purpose of this tank is twofold –

  1. It can be used as your oil tank for your fuel, negating the need for an external oil tank, depending on the size of your waste oil burner, it may need topping up every couple of days or may be every week dependant on your usage.
  2. You can also use this as in intermediate oil tank , from your external oil tank and there are numerous advantages for this –
  • You have a quantity of oil, which is stored internally within the building, which should mean that the oil is warmer than the oil in the external oil tank. This helps the burner , as the oil does not have to be heated as high
  • The tank has a “floating oil suction line “(see picture), with a filter attached. This takes the cleanest oil as it floats on top of the oil

  • The oil is then pumped , and controlled by the burner , via a filter , ensuring you have the cleanest possible oil to the burner
  • It is a fully automatic operation , the burner controls the pump on demand

Coupling the 100 litre tank to a bulk external oil tank –

This is an easy thing to do –

We supply a kit, that consists of a solenoid valve, and two float switches. These are to be installed to suit site conditions i.e. where ever your incoming pipework dictates

You need to make a tapping / tank connection on one of the walls of the 100-litre oil tank, for the oil supply that will be controlled with a solenoid valve.

You also need to make one tapping below the incoming oil line, which will have the solenoid valve attached to it, this is for the “control float switch “, which opens or closes the solenoid valve – for safety, the oil solenoid valve we supply is a normally closed valve, which means that the control float switch, energises the solenoid valve when more oil is required, and cuts the power to it, when the float switch is satisfied

The second float switch, which we call the “safety or alarm float switch” needs to be positioned at the top of the tank. This float switch can activate an alarm bell (supplied by others) and also be wired to kill the electric supply to the waste oil heater or burner. It is in effect an alarm system to notify you should the solenoid valve ever fail

Waste Oil Tank Schematic

Waste Oil Heater

We believe we have the best  waste oil heater for sale on the market ,German manufactured, these units are engineered to the highest standards , giving years of trouble free operation, and paying back their initial cost in a short time period.

You may call these warm air heaters  – used oil heater , waste oil workshop heaters , engine oil heaters , waste oil space heater, waste oil burning heaters,waste oil burner heater, garage waste oil heater , whatever you call them , (they should really be called a ” Universal Oil Heater “) , then we have the solution for your requirements.

Universal Oil Heater 

Please be aware  that whilst “waste oil heaters” is a market term used by many , our heaters are actually universal or multi oil heaters. They burn a variety of oils that are of much higher viscosity than fuel oils. This includes used hydraulic oils , engine oils and also vegetable oils such as rapeseed , sunflower etc. However, they also burn red diesel,  diesel , 35 second oil, and kerosene fuel oils extremely well

If you require any further assistance with our Waste Oil Heaters or any of our products, please click here to contact us via email or call us direct on 01202 822221