Waste oil boiler or multi oil boilers from Flexiheat UKFlexiheat UK

Waste Oil Boilers – Multi oil Boilers From 25kW to 176 kW Output

Waste oil boiler or multi oil boilers from Flexiheat UK

Waste oil boilers deliver an efficient way to recycle waste oils as a free fuel source to generate heat and hot water, which can be used to heat garages, workshops, warehouses, greenhouses to name but a few, within the broad range of applications it can be used for. Our German made waste oil boilers are designed for the unique demands of providing water heating systems run on waste engine oils, hydraulic oil, vegetable oils, bio-diesel and a range of other fuels. Convert all these free or low cost fuels into clean, usable heat and virtually eliminate your fuel costs!

At a time of rising fuel costs, the universal/waste oil boiler, which can burn nearly all vegetable, animal, conventional and waste oil, will save you money and provides you with flexibility in choosing your preferred fuel source.

The Flexiheat series of waste oil boilers are designed for perfect compatibility with our waste oil burners, providing a complete and proven solution and can be use to produce domestic hot water with an indirect hot water cylinder. These waste oil boilers are made in the EU and exported worldwide. They combine exceptional prices with excellent quality for unbeatable value.

In more recent times we have seen a large increase of people using vegetable oils as a fuel, this is a very green option as its renewable and also is CO2 neutral. Our multi oil burner was one of the first, of the very few to gain the DIN standard for use on rapeseed oil, which is used extensively as fuel in countries such as Denmark and Sweden due to the high relative prices of energy within those regions and more and more popular in the UK.

Did you know that you could significantly reduce or even eliminate your heating costs by utilizing waste oil boilers or heaters for your heating needs?  Waste oil boilers and heaters fuelled with used oils such as used vegetable oils, recycled oil, used motor oils and hydraulic oils –

What can the Multifuel / Waste Oil Burner use as a fuel-

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

No Gasoline or petroleum though !!! as this as not an oil.

The Waste Oil Boiler, is a steel pressurized boiler for operation of water temperatures above 50C, and benefits from the following features –

Reversed flame combustion chamber for high efficiency, efficient combustion, low emissions and lower flue gas temperature
Highly resistant to condensate thanks to:
– Furnace misalignment against the outer shell
– Patented fin effect on the welding seams of pipes onto the rear tube plate
• Anti-condensing helicoidal turbolators
• Fully insulated design prevents heat loss, due to the extensive insulation (60 mm) of rock wool surrounding the boiler body and the ceramic fibre insulation on the door
• Adjustable door with double opening (left or right)-with easy access through the front door to all parts of the boiler chamber for quick, easy cleaning and ash removal
• Separate control panel with simple and clear information and controls
• Maximum working pressure: 3 bar; it is possible, under specific request, to provide a maximum working pressure of 6 Bar

Steps should be included in the design of the hot water heating system to ensure the return water temperature is always above 50C such as a low loss header or plate heat exchanger, otherwise condensation will form in the heat exchanger and combustion chamber, which is very acidic and can eat through the boiler in a very short time.

Kroll waste oil boilers - multi oil boiler from Flexiheat UK


Download the brochure for Multi Oil Boilers

These multi oil boilers are often used in commercial and industrial wet central heating system, using water fed industrial unit heaters for warm air heating.

Leo hot water unit heaters EPP plastic cased for space heating Flexiheat UK

Leo unit heaters EPP Plastic cased from Flexiheat UK


Waste Oil Boilers / Multi Oil Boilers – Thing’s you need to know

General Waste Oil Boiler Info –

1. When burning correctly, these units burn as clean as a standard oil boiler, with no plumes of black smoke etc
2. These waste oil boilers are not suitable for installation in a house, as the pre-heating of the oil, can sometimes cause a smell. They should be sited in a separate building, such as a boiler house / garage etc, and the warm water is brought via pipes into the house or premises.
3. These waste oil boilers are not room sealed / balanced flue thus shouldn’t be fitted in within residence, as they require a combustion air source i.e. ventilation

Fuels – Waste Oil or Standard Oil – these Multi Oil Boilers will burn both

1. The burner attached to the waste oil boiler, is in reality a multi oil burner, which means it will burn gas oil (sometimes referred to 35 second oil or as red diesel), kerosene ( 28 second oil), waste engine oil (with some conditions – see point 2 ), transmission oil, vegetable oil, and used vegetable oils ( with some conditions – see point 3 )
2. If you are using waste engine oil, then if you have over 50% synthetic oil, and by this we mean any oil that has the word synthetic in it , to mineral oil , then you need to add 15% gas oil or kerosene to the waste engine oil. This needs to be agitated, so it mixes with the engine oil (normally done, by dropping a compressed air line into tank, for approximately ½ hr after introducing the gas oil into the waste engine oil). This needs to be done on a monthly basis in the heating season, as the diesel will settle to the top of waste oil over this period and needs to be remixed
3. If you are using waste vegetable oil, then the fats have to be removed, via settling out, the oil should also be filtered down to 5 micron – please see separate data sheet on this subject

Maintenance of your waste oil boiler –

1. “You get nothing, for nothing” as the saying goes, and if you are burn waste oil, then they are not made to a definite BS / EN standards, which specifies their filtration level, their calorific value etc. Waste engine oil often has small metal particles suspended in the oil, which should lie as a fine white dust if the boiler is burning correctly. This builds up over a period of time, how quickly this does depends on how “dirty” the oil is (remember it’s your oil, not mine – I can’t tell you ! ) thus we recommend opening up an inspecting the boiler every 300 burning hours ( roughly 6 weeks in the winter ) and cleaning the combustion chamber , and boiler tubes – this should take approximately ½ to ¾ of an hour of your time – if so required- if it isn’t close the boiler back up and check again in another 6 weeks . If you are not prepared to do this, to ensure the correct operation of the boiler, please buy a standard oil or gas boiler of us, and don’t moan to us regarding how much your fuel bills are !!! , you get free heat via your waste oil, it needs your time!!

2. These waste oil / multi oil boilers are an “oil burner “not a miracle worker, and things like brake fluid and clutch fluid, should not be burnt as they cause problems to the burner ( they destroy the rubber seals, that we use in our nozzles, and crystallize up, causing blockages in the nozzles and pipes of the burner – they are fluids not oils !!!!!

3. Also no petrol (also known as gasoline or petroleum) or paint thinners either!!! We use a pre-heater to heat the oil up to 75 C “ish” for waste engine oil , or up to 140 C for vegetable oil . This will ignite the fluids and cause a fire!!! also no transformer oil or capacitor oil is to be burnt.

If you are not prepared to do this, to ensure the correct operation of the waste oil boiler, please buy a standard oil or gas boiler from us, and don’t moan to us regarding how much your fuel bills are !!! , you get free heat via your waste oil, it needs your time!!

The basis of this information, is to let you know the pro’s and con’s of burning waste oil, and the fuel bill savings you can achieve, please remember that you could be saving thousands of pounds per year and to let you, the customer, decide if a waste / multi oil boiler is right for you.

Multi Oil – Waste Oil Tank – 59 or 109 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.

waste oil boiler day tank; waste oil boilers

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 dependent 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 59 or 109 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 59 or 109 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 Boiler – The range extend to 1,200kW ( External Compressed air source required for all Boiler Packages  )

Here at Flexiheat , we are always moving our product development forward , and due to many requests , we now have a waste oil boiler and burner combination , that has an output range of up to 176 kW   . These Flexiheat Multi Oil Boiler Packages are now designated the “FMOB” range , The full range of multi/waste oil boiler goes up to 1,200 kW output , and you require a compressed air supply , with a 2.5 Bar pressure and the volume of air require varies with regards to the waste oil burner output ( up to our 163 kW waste oil boiler requires 63 litres a minute of compressed air , after this size and until our 400 kW waste oil boilers , they require 130 Litres a minute of compressed air ).The waste oil boiler should be installed in an appropriate room with ventilation openings, according to requirements of provisions in force, ensuring a sufficient supply of combustion air, as these are not balanced flue or room sealed waste oil boilers or multi oil boilers.

These boilers that we use are steel, high efficiency boilers , that are CE marked and are ideal for heating medium to large size facilities. The unique construction of a combustion chamber and heat exchanger guarantee high efficiency of the waste oil boiler, which results in lower fuel consumption. These waste oil boilers also have low heat losses due to the high level of insulation used to cover the heat exchanger and boiler, and thanks to the turbulators installed in the heat exchanger , which lower the flue gas temperatures and ensure the flue gas speed is optimized, they extract the maximum energy from the oil being burnt.

A brief overview of the most common waste oil boilers are listed below – Please note -The heating capacity and oil consumption depend on the calorific value of the fuel used and this data is based on rapeseed oil.

Download – Waste Oil or Multi Oil Boilers Brochure – Flexiheat UK

Best Waste Oil Boilers / Multi Oil Boilers for sale in the UK & Ireland 

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