Tuesday, 26 March 2013 14:04

Maintenance, Maintenance, Maintenance! The key to operational success for your condensing boiler.

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A condensing boiler is a hot water heating system designed to recover energy normally discharged through the chimney as waste. How it works is the water vapor produced by the burning of gas in the boiler condenses back into liquid water releasing the latent heat of vaporization from the water. Because latent heat is a more significant source of energy, condensing boilers have efficiency ratings up to 98%.

Every boiler requires routine maintenance; some more, some less. Condensing boilers have a potential for higher maintenance due to condensate production. So how’s a person to know when maintenance is required?


1. Most boiler manufacturers provide maintenance information in their boiler manuals, detailing suggested daily, weekly, monthly and annual maintenance.

2. Many times site conditions (clean, dirty and extreme) will dictate further requirements. Your installation or service technician will help you make this determination and suggest an appropriate schedule.

3. Last, is a new boiler installation inspection which you should make after the first 3 to 6 months of operation (we highly suggest between 3 to 4 months). Important to remember, many manufacturers note in their literature that warranty may be denied due to improper maintenance!

An area of special concern in a Condensing Boiler is the heat exchanger, located at the top of the combustion chamber.  During normal operation, and especially on a cold start up, condensate will be produced on the tubing coils. The colder the water passing through the coils, the greater the potential for condensate production. Because the burner chamber is fairly small, droplets of condensate can come in contact with the flame as they fall off of the tubing coils. This causes black water and sometimes black residue due to heat from the burner. Some of this residue can be carried into the condensate trap and some may be seen as black liquid flowing out of the boiler’s condensate line.

            This occurrence in condensing boilers creates a couple of maintenance requirements:

1. Checking and cleaning condensate trap and drain system.           

2. Checking and cleaning of the boiler’s combustion chamber.

This later requirement creates a little problem, in that without disassembling the boiler to gain access into the combustion chamber, you cannot tell how dirty it may be.

For this reason, we highly suggest that a new condensing boiler should have its combustion chamber checked at least 3 to 4 months after it has been placed into operation. What does your boiler look like inside?

The actual maintenance schedule for cleaning a boiler will be determined by the condition of the combustion chamber, condensate trap, and other components at the first and each subsequent inspection.  The boiler in the 1 year old picture above is due for cleaning.  The excessive residue prevents good operation, and if left for too long, can result in actual damage to the boiler, as in the picture below where the combustion chamber has cracked.  In addition to loss of efficiency and higher cost of operation, lack of proper maintenance may void the manufacturer’s warranty.  Continued neglect could result in having to prematurely replace the boiler and other components of the heating system.

As with anything, maintenance is a must. Keep in mind that with condensing boilers, they are up to 95 percent efficient, which means that 95 percent of the heat produced by the boiler is transferred to the heating elements in your home and the remaining heat is lost through exhaust. By comparison, a conventional boiler is 75 to 85 percent efficient.

Condensing boilers save money on heating costs, since less fuel is required to heat your home. Condensing boilers also recycle much of the exhaust produced by the system, reducing the amount of pollutants released in the atmosphere. Feel free to contact MacGregor Plumbing & Heating with any questions.

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