AccuServ Heating and Air Conditioning

Why You Should Clean Your Boiler System Before a Boiler Install

January 30, 2020

Your New Boiler: Not a Standalone Appliance

When you install a boiler, you’re not adding a standalone appliance to your home. Instead, you’re hooking a new appliance onto the existing heating system. Because the heating system is one you’ve used before, a sparkling new boiler is essentially being paired with a used device, which can damage your new boiler.

Why? Your home radiator builds up sludge deposits with use. And as your radiator is now hooked up to your new boiler, that sludge can easily flow from the radiator to your boiler, dirtying it on its first use. For boilers, dirty equals inefficient, which in turn equals higher energy bills and colder homes.

Clearly, this is something you want to avoid, which is why we – and most other HVAC companies – recommend you thoroughly flush your heating system before a new boiler install. Doing so can extend the lifespan of your boiler.

There is an extra thing to note: When a HVAC company recommends you flush your boiler, they are doing so in line with the boiler manufacturer’s expectations. That is, boiler companies assume that you are installing a new boiler onto a clean system. By not cleaning your system before a new installation, you are not following the instructions of the boiler manufacturer and can end up with a boiler that does not perform as advertised.

If so, the blame is on whoever failed to clean the system, not the manufacturer. If you want the best possible efficiency out of your new boiler – which can be up to a 40% increase when making the switch to a modern boiler[1] – be prepared clean your system properly. Trust your HVAC guy on this one – he’s not trying to upsell you.

 Sludge Buildup Is Normal

Sludge buildup is normal, especially in older heating systems. If you are installing a new boiler, it’s a safe bet to say that you previously owned an old boiler. Your old boiler was likely inefficient compared to your new boiler, and this is a problem because inefficiency implies more corrosion.

It is the corrosion process that produces sludge. That sludge is in fact black iron oxide. This chemical compound contaminates the water and can clog many components of the heating system, including the radiator, the boiler, and the pipes that connect the two.

More importantly for the home owner is the fact that sludge spurs a loss in efficiency to the tune of 6%.[2] This is especially important for homeowners who buy new boilers hoping for more efficient, less costly heating. The sludge clogs the system, straining the water flow and ultimately causing the home owner to turn the thermostat to a temperature higher than actually needed.

Heat Exchanger and Radiator Clogs

You definitely do not want your new boiler’s heat exchanger to become clogged with sludge. The heat exchanger’s main role is transferring heat from the boiler to the water that runs through your heating system’s pipes. When your heat exchanger is layered with sludge, that heat transfer occurs at an inefficient rate.

With Ontario’s electricity and gas prices on the rise, sludge buildup can cost you hundreds of dollars. This is why installing a new boiler is not a cure-all. However, installing a new boiler after a thorough system flushing can drastically reduce your heating bill.

How do you know if sludge has built up in your radiator? Barring looking inside, your best bet is to feel the radiator. Place one hand over the bottom and another over the top, gauging whether a temperature differential is present.

If the bottom is cooler than the top, sludge is likely preventing an even flow of heat throughout the radiator. This problem is fixable with a thorough cleaning. But even if you don’t feel much difference between the top and bottom of the radiator, you still should clean the radiator just in case.

Another method is to simply check the thermostat temperature, comparing the displayed number to how you actually feel. If you think your thermostat is displaying a higher number than what the room is really heated to, you might have a sludge problem. This is correlated to high energy costs because most homeowners simply raise the thermostat temperature, causing the boiler to expend extra energy.

A third sign of a sludge problem is noisy pipes. Pipes should be free of obstructions, allowing water to flow freely. But if your pipes are noisy, it could be the result of sludge being bombarded with water.

Cleaning Your System with a Power Flush

Cleaning your system requires pressure to force water throughout the system, purging your system of the built up sludge. Realize that this task necessarily includes some risks. If you have a weak spot in your system, it might burst, causing property-damaging leaks.

Hence, ensuring your system is strong and stable before cleaning is important. Ask your HVAC company’s technician to give your system a checkup for any possible damage. You can reduce this risk for future cleanings by properly maintaining your heating system and by scheduling annual checkups.

One type of cleaning method is the power flush. In a power flush, your HVAC technician will identify problematic radiators, such as by the “feeling” method previously described. This is not because he only plans to clean a few but to check the effectiveness after the cleaning. He will also make note of your heating system’s settings (e.g., the thermostatic radiator valves) so that he can restore them after the flush.

Other pre-cleaning preparation tasks include testing your system’s water, investigating whether the system is sealed, turning off the power to the system, opening diverter valves, and removing radiator valves. Once prepared, the technician will connect a power flushing machine to your heating system as per the manufacturer’s settings. All of this is performed without the new boiler attached to the system.

The power flushing machine will be filled with water from your mains. This water is then pumped through your entire system for ten to twenty minutes. A cleaning chemical is typically added as a catalyst for breaking up sludge. During the flushing process, the water flow should be reversed a few times so as to ensure all the sludge has been removed.

Following this, each radiator is separately cleaned with the same process. This ensures that both your radiator and your pipes are free of sludge. At the end of the cleaning for each radiator, the contaminated water is flushed out until the water running out is clear, indicating cleanliness.

The entire system is then flushed once again, and the water is checked for clarity. The water is often tested at this point for purity. Afterward, your technician should return the entire system to its original settings so that he can begin installing the boiler.

A Cheaper Cleaning Solution

In spite of its effectiveness, the power flush method is expensive. A cheaper solution is applying a magnetic dirt separator to your system. This filter is attached to the return line of your boiler and acts as an automatic method of cleaning the boiler water.

The dirt separator traps the sludge before it enters your new boiler, thereby reducing the vicious cycle of contamination. Still, regular maintenance is necessary with this solution, as the sludge and debris from the filter must be emptied. Otherwise, the filter could become completely clogged, causing inefficiencies with the heat exchanger and water flow (which tends to occur in narrower pipes with newer boilers).

Now that your boiler system is clean, keep it clean! Doing so can extend the lifespan of your boiler and heating system. Ensure you schedule annual maintenance with an HVAC company for your heating system.