How to Drain the Sediment Out of Your Steam Boiler

There isn’t a lot of regular maintenance that you need to do for your steam heating system. One thing is essential, though — draining the sediment out of your boiler.

Depending on the condition of your water and your heating system, you should do this once a month or as often as once a week. Keeping the boiler clean and sediment free will improve the overall operation of your system — heating effectiveness and heating efficiency.

How Does Sediment Get In the Boiler?

Over time, particles of dirt, grease, and all around gunk find their way into the boiler.

Some of this particulate is dirt and grease that’s lodged in the radiators. As the steam circulates throughout the system, it turns into water and that condensed water brings the sediment back to the boiler.

Another culprit is the water coming into the system. As steam leaks out of the system, new water is pumped in — bringing with it dissolved particles of dirt and sediment. This will settle in the bottom of the boiler as well.

Don’t be alarmed, though, as this is all normal! It only becomes a problem if you don’t take care of it.

How Do I Drain the Sediment Out of the Boiler?

To drain the sediment, you’re going to need a bucket (or a hose) and a drain.

First, locate the drain valve on your boiler. It should be near the bottom. Often-times it’s located below the sight glass that indicates the water level in the boiler.

Place the bucket under the drain or attach a hose to drain water directly into a basement floor drain.

For routine maintenance, open the valve and let the water drain for a few seconds until it turns clear. If you do this regularly, there should be a limited amount of sediment — and you won’t have to drain the water very long. If you have a manual water feed for the boiler, open it to allow a little water back into the system.

Once the water is clear, you’re good to go. Just remember to come back in a few weeks and drain the sediment again.

There’s a Lot of Sediment. What Do I Do?

If you (or the previous owner) rarely cleaned out the boiler, there may be a lot of sediment built up. In that case, you probably want to drain the entire boiler and run some water through it.

Before you start, turn down the thermostat and allow the boiler to cool down. You never want to introduce cold water into an empty and hot boiler. It could lead to disastrous results for you and/or your boiler.

After the boiler has cooled, set up your bucket or hose and open the drain. If you’re using a bucket, you’ll probably have to empty a couple of buckets before the boiler is dry.

Once the boiler is near empty, manually open the water feed to allow new water into the boiler. The incoming water will help stir up the sediment and carry it out the drain.

When you’re satisfied that you’ve flushed out as much sediment as you can, fill the boiler up to its normal operating level and turn the heat back on.

Keep It Clean, Keep It Efficient

Once you’ve got your boiler working efficiently, don’t forget to drain the sediment regularly. If you do so, it will only take a few minutes — and it will keep your boiler running in tip top shape.

Invest a little time in maintenance, and you’ll reap the benefits of more efficient, more effective heating!