Why use deaerators such as a Tigerloop® or GOK®?

The Tigerloop completely removes the gas from the oil so that the oil going to the burner is 100% pure this is known as deaeration.  The downside to this is that any air that has been removed from the oil must be expelled into the atmosphere.  This is smelly and can be inflammable.

The GOK removes the gas from the oil and then fragments this into small particles before feeding this back into the oil at a size that will not interfere with the combustion of the burner.

Because the Tigerloop expels gas into the atmosphere, traditionally these have had to be fitted externally so that the odour does not impregnate the home or become a fire risk.   Because the GOK does not expel the gas it has been the deaeration device of choice for fitting indoors next to the burner.  The downside being that these are less tolerant of air links in the system and have to be manually primed when they are installed or when the oil has run out.  The installer will require a priming pump for this – see image right/below.

Tigerholme have now introduced the Tigerloop Bio that can be fitted internally so long as a vent pipe is attached to take the gas outside. The downside being that not everyone wishes to have a vent pipe showing.


Frequently asked questions

The two main products are the Tigerloop® and GOK®.  Whilst they both deaerate the oil they do this in different ways.

When oil is drawn up from the oil tank to the burner large amounts of gas bubbles can be released from the oil.

These gas bubbles are released when there is a negative pressure (vacuum) in the suction line. This occurs to some degree in almost every installation, however, even more so when the oil must be lifted up to a higher level; drawn through long suction lines; or when the suction line is too large for the required oil flow.

This is a natural phenomenon; gas will automatically be released from the oil when pressure in the oil line falls below the atmospheric pressure resulting in a vacuum.

When oil must be drawn up from a tank lying below the level of the oil pump gas will be released.  The higher the oil is lifted the more gas that is released.

Gas is also released when friction in long oil lines causes a vacuum to build in the oil line, i.e. the higher the friction then the more gas that will be released.

If the size of the feed line is too large, i.e. too coarse for the required oil flow, gas pockets will develop as the siphon effect is lost.

The quality, temperature and viscosity of the oil will also play a determining role in the amount of gas released.

Gas can also enter the suction line if any connections are not 100% tight or if the tank is allowed to run empty. The gas bubbles flow with the oil into the oil pump and are the leading cause of burner fluctuations; breakdowns; increased build up of soot; unnecessary wear and tear on the oil pump; and higher oil consumption.

An oil pump delivers the same amount of oil regardless of what is actually needed for combustion.  In the case of a normal domestic burner, only about 5% of the delivered oil is actually burnt in combustion.

Two pipe system:

With a two-pipe system, the remaining 95% is then transported by a secondary pipe back to the oil tank.  There is a risk that the return pipe could be ruptured allowing oil to spill out leading to large scale pollution (large fines are imposed by the Environment Agency and these are even more severe where this is in close proximity to a stream or water course).  For this reason both OFTEC and the Environment Agency strongly advise against the use of a two-pipe system.

It is a fact that the two-pipe system was developed to try and overcome the problem of the gas bubbles from the oil pump. A return line pumps the separated gas bubbles together with the unburned oil from the oil pump back to the oil tank. This, however, does not reduce the amount of gas bubbles that flow to the nozzle for combustion, which leads to a gas pocket forming between the oil pump and the nozzle. This gas pocket causes dripping from the nozzle each time the oil burner is stopped resulting in increased soot build up and poor fuel efficiency. The high flow of oil in the two-pipe system can be up to 20 times more than what is actually used for combustion, which leads to increased dirt/sludge being released from the oil tank in turn leading to clogged oil filters and nozzles. The pressurised return line in a two-pipe system is the primary cause of leak damages, where even the smallest leak can lead to terrible environmental damages and expensive clean up.

One-pipe system:

Alternatively, a one-pipe system without deaerators is not recommended.  This is due to the increased risk of breakdowns as gas bubbles cannot be removed from the oil pump during operation. Such a system will only work as long as the oil is continuously 100% free of gas bubbles. Moreover, it is impossible to automatically deaerate the system during start up or after running the tank empty since a tool is necessary.

One-pipe system with deaerators:

The best solution is a one-pipe system using deaerators where no oil needs to be transported back to the tank.  The deaerators removes the unwanted large particles of gas from the oil before feeding this purer oil through to the burner.  The oil that is not burnt in combustion is fed back to the deaerators, where it is deaerated again and again automatically. For this reason only the exact amount of oil to be burnt in combustion is sucked from the oil tank.  The net effect is a significant decrease in the risk of pollution with only a fraction of the amount of oil being taken from the tank to the burner and also there is no return pipe that could be ruptured allowing oil to spill out and cause pollution.

The oil flow in a one-pipe system with deaerators is minimal due to the fact that only the amount of oil burned needs to be drawn up from the tank. For this reason very little dirt/sludge is transported from the oil tank. This reduces the risk for clogged oil filters and burner nozzles. Filtration is more effective, soot build up is reduced and filter life is extended.

Whilst a one-pipe system with a de-aerator increases the oil pump capacity, moreover, the oil is actually preheated to at least room temperature as friction in the oil pump generates heat. This eliminates problems with cold oil thus giving cleaner combustion and reduced oil consumption.

Advantages of a de-aerator

  • Gas-free oil supplied to the burner;
  • Reliable heating operation;
  • No dripping from the nozzle;
  • Less soot build up;
  • Higher efficiency / cleaner combustion;
  • Reduced oil consumption;
  • Only the amount of oil that is actually burned will be drawn from the tank (i.e. Lower flow of oil);
  • Less sludge in the system, reducing risk of nozzle and filter clogging;
  • Better oil filtration;
  • Extends life of filter elemen

The complete range of de-aerators can be purchased from

The individual deaeration products are as follows:

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