What is condensate in a boiler?

Asked By: Mayda Ostoa | Last Updated: 3rd March, 2020
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The steam/condensate systems are an integral part of the water boiler system. The condensate system includes anywhere that the steam condenses to form liquid water. As the vapor leaves the low-pressure turbine it contains droplets of water.

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Simply so, what is the condensate pipe on a boiler?

The boiler condensate pipe is the pipe that allows this water to be drained from the heating system and disposed of with your household waste water.

Subsequently, question is, is boiler condensate dangerous? Exhaust. The condensate expelled from a condensing boiler is acidic, with a pH between 3 and 4. The acidic nature of the condensate may be corrosive to cast iron plumbing, waste pipes and concrete floors but poses no health risk to occupants.

Correspondingly, what does a boiler condensate trap do?

The job of a condensate trap is to safely collect and release the condensation produced by the boiler, preventing any vapours created during the combustion process from escaping with it. These components vary in design depending on the model of boiler you have, but they are all fairly simple.

How corrosive is boiler condensate?

Carbonic acid is a weak acid, but as the condensate water is pure, this weak acid reduces the pH significantly, often in the range of 5-6. At this low pH, the condensate water is very corrosive to carbon steel piping.

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Why is water coming out of my condensate pipe?

The condensate trap and pipe come straight out of the heat exchanger, which means that if it cracks or pinholes, it will cause system or mains water to drain into the condensate pipe. What may lead to the condensate pipe leaking is if the hot water causes the pipe joints to fail somehow.

Does a system boiler have a condensate pipe?

The boilers fitted to older central heating systems (i.e. those over 10 years old) have a simple heat-exchange system, which can be as low as 70% fuel efficient. The condensate water drains away via an outside pipe, which is the way you tell a condensing boiler apart. Older boilers don't have these pipes.

Should the condensate trap be full of water?

These traps form a seal which prevents poisonous combustion gases passing out of the boiler along the condensate drain pipe. If the trap is removed for cleaning it should always be refilled with water when it is fitted, before running the boiler.

How much water should come out of a boiler condensate pipe?

A general rule of thumb, 3.5 litres of condensate is produced for every 30kw of input providing the boiler is operating in full condensing mode.

What type of pipe is used for condensate?


Condensate Drain: PVC Pipe. Condensate is the water that forms on the exterior of a cooling coil and drips down to be Polyvinyl Chloride (PVC) piping is the most widely used plastic piping material.

What does a boiler condensate pipe look like?

Look under the boiler to see if there is a plastic pipe - It's usually white and around 20mm (about ¾”) wide. The pipe should run to the outside of your home and should always run into a drain. An example of a condensate pipe is shown below. The condensate pipe is the diagonal pipe running along the side of the house.

Is a condensate pump necessary?

If you have an air conditioning system with an indoor unit, or you use a high efficiency furnace, then you definitely need to have a condensate pump to remove the vapor and other condensate that will accumulate when the system runs.

What is the difference between a condensing boiler and a combi boiler?

So, a boiler that takes its water supply directly from the mains and produces heating and hot water for your home from one compact unit is a Combi boiler and with the addition of a Flue Gas Heat Recovery System it becomes a condensing unit too. Thus making it a condensing Combi boiler.

Does boiler condensate need a trap?

Installers should follow the manufacturer's instructions on the use of air breaks in condensate discharge pipes. A visible air break and trap is not required if the boiler condensate trap has a minimum condensate seal of 75 mm incorporated into the boiler.

Can you put a condensate pipe into rainwater?


It is possible to terminate a condensate pipe into a rain water down pipe that terminates into the foul waste system. As with all externally-run condensate pipes, it is recommended to keep the external run to minimum and the pipe diameter to 32mm when exiting the property.

Where should a condensate pipe be installed?

The external pipe work should be kept to a minimum and not more than 3m in length. The pipe may be taken below or above the ground level. Any external condensate pipe work should be insulated to minimise the risk of freezing.

How do I know if I have a condensing boiler?

You could check your boiler manual for reference to condensing or 'HE' in the title. Check the flue terminal which is usually sticking out through an external wall near the boiler. If it is plastic and white steam comes out of it when the boiler is on then it is likely to be a condensing boiler.

Is condensate dangerous?

Like all fossil fuels, condensate contains toxicants which are harmful to the environment, animals and humans. It is generally more flammable and explosive than normal crude oil. Whether escaped condensate causes an oil spill or not depends on whether it has vaporized, burnt off, or escaped in liquid form.

How do I stop my boiler condensate from freezing?

How to prevent your condensate pipe from freezing
  1. Cover your external condensate pipe with foam pipe insulation.
  2. Leave your heating on overnight at a lower temperature to keep the condensate warm.
  3. Set your boiler thermostat to a higher temperature.

Do I need a condensate trap?


The primary purpose of a condensate trap is to prevent air from moving in or out of the coil box or air handler during operation. Traps must be installed in a manner that will stop the air from passing through, but still allow the condensate to drain from the condensate pan. Without a trap, this doesn't happen.

At what temperature does a boiler condensate?

Basically, condensing boilers are designed to take advantage of the latent energy available in the exhaust flue gasses. By allowing the temperature of the return water to go below roughly 130° F this causes moisture to condense out of the flue gas.

What does a condensate neutralizer do?

What is a condensate neutralizer? As its name implies, condensate neutralizers filter and neutralize water by-products, making them safe to dispose of down the drain. With professional help, a condensate neutralizer can be attached to the drainage pipe coming out of your furnace in order to neutralize waste water.