Simmer Down! A Guide To Common Boiler And Radiator Noises
In a perfect world, your steam or hot water boiler system would turn on and operate in perfect silence, keeping your home warm without you ever noticing it's there. But the world is not perfect, and most boiler heating systems do make noises from time to time. Some of these noises are rather normal, while others can be a sign that something is wrong with your system. Knowing the difference is important, so here's a look at some common boiler noises and what they mean.
Clanging Noises
If you hear clanging, banging noises when the boiler first kicks on and starts heating, this is usually caused by a buildup of minerals in the bottom of the boiler tank. Experts often refer to this problem as "kettling" since it can sound similar to the noises made when a water kettle warms up. This problem is most often seen in steam boiler systems rather than water boiler systems.
You can try to eliminate kettling yourself by turning the boiler off, allowing it to cool down, and then draining it completely. (Turn the water supply valve off before you do this). Connect a hose to the boiler's drainage valve and run it outside for easy draining. If the mineral deposits are really stuck to the bottom of the boiler, however, draining the boiler won't work and you'll need to arrange to have it professionally cleaned.
Whistling Noises
If the whistling noises are coming from your steam radiators, then you probably just need to loosen the pressure relief valves on the noisy radiators just a little bit. This will allow the air to escape more freely.
If you have a hot water boiler system and the radiators are whistling, it might be because the bleed valve is open a little and air built up in the system is gradually working its way out. This is really a good thing since you want your water radiators to be free of air. However, you need to make some adjustments so water does not start coming out of the valves. Use your bleed key to open the valve a little, wait until some water drips out, and then close the valve as tightly as it will go.
Gurgling Noises
If it's below freezing outside, check your condensate drain line. Frozen condensate drain lines often lead to gurgling noises in a boiler. If the line is frozen, you can thaw it out with a blow dryer or by wrapping rags soaked in hot water around it. Once the line thaws, make sure you apply some insulation to it so that it does not freeze again.
Gurgling could be caused by sediment buildup in the tank. You can drain the boiler as recommended in the section entitled "Clanging Noises," which should hopefully eliminate this issue. Ultimately, having a water softener installed will help keep additional sediment from building up in the tank and causing noises.
Hissing Noises
If you hear a noise like hissing coming from the boiler itself, this could be due to overheating. The thermostat itself may not be functioning, or you may have a jammed circulator pump. The jammed pump will not move water through the tank correctly, and so the tank will get "hot spots"where the water produces too much steam and sends it though the release valve.
Hissing usually needs to be addressed by an HVAC professional since replacing a broken pump is pretty involved. Don't wait to address this problem as it makes a boiler very inefficient and is probably driving up your energy bills.
If your boiler is making any strange noise that is not addressed above, your best bet is typically to have an HVAC contractor, like one from Rickett Industrial Environmental Systems, take a look.