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Steam Radiators? Here’s How to Improve Your Boiler’s Efficiency.

Our heat cut out last weekend, which prompted some overdue maintenance on our boiler. It turns out that the transparent tube that shows the water level (called the sight glass or water gauge) had gotten plugged with sediment, and we accidentally added too much water. In addition to the lack of heat, this led to horrible clanging in the pipes and radiators as the steam hit water that shouldn’t have been there.

Our landlord cleaned out the tube and Jason flushed 8 buckets (!) of water from the system before it got back to normal. And the water was disgusting! It ran red with rust and sediment and stank up the basement.

Here’s how he fixed it:

1) He turned down the thermostat, flipped the main shutoff switch on the boiler, and let it cool down. (Very important to prevent burns, as well as damage to the boiler.)

2) He closed the valves at the top and bottom of the sight glass, removed it, and cleaned it with a pipe cleaner. Then he replaced the sight glass and opened both valves.

3) He used the valve at the bottom of the boiler (below and slightly to the left of the sight glass) to empty water into a bucket until it ran clear and the sight glass was below 3/4 full.

4) Then he opened the valve at the top of the boiler and added water slowly until the sight glass was 3/4 full.

(House in Progress has some good photos of the process.)



Ideally this sort of maintenance should be done once a year by a trained professional, but since we’re just renters, we don’t have much say about that. Now that we know an easy way to keep the system running efficiently, we can do it ourselves, without having to rely on our landlord.

A well-running system shouldn’t make any noise. When we moved in, the radiators were so loud that they terrified the cats and woke us up in the middle of the night. Since then we’ve checked the water level every other week (it should always be 1/2 to 3/4 full), made sure that the radiators tip slightly towards the in-flow pipes, and cleaned or replaced any hissing or spitting pressure release valves. (Check out this This Old House video or for how.) It’s made a huge difference in the noise level, and I hope we’ll see a difference in our gas bill this year because of it.


Comment from Brian B
Time November 13, 2009 at 2:33 am

When we moved into our house we quickly discovered that our old boiler had a constant leak that proved extremely inefficient if not dangerous. Our boiler was less than ten years old and apparently these things are designed not to last long. If your boiler is feeding a hot water tank I would recommend adjusting the temperature down to 120, but no lower. This would also help save cash. We have since replaced our boiler with an efficient biomass pellet boiler that saved tons of cash and feeds the local economy. Obviously not a renter’s upgrade, but I still thought you would appreciate. For renters who have oil delivery there are companies that deliver biodiesel at competitive rates to oil. Our boiler doesn’t have a glass so I don’t know what the levels are at, but we have it inspected every 6 months to ensure efficiency. I love your blog, by the way.

Comment from Brenda Pike
Time November 13, 2009 at 11:50 pm

Thanks! I’ve read that you can crack old boilers if you add cold water while it’s still hot. Maybe that’s what had happened to yours? Then again, apparently that tends to happen more with older cast-iron boilers, not newer ones.

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Time November 17, 2009 at 11:49 pm

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Pingback from Health is Easy » Uncategorized » Festival of Frugality #204: The iPod Playlist Edition
Time November 23, 2009 at 11:28 pm

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Pingback from Looking Back at 2009 « Pragmatic Environmentalism
Time January 4, 2010 at 9:08 pm

[…] Boiler maintenance – We replaced some of the valves, un-leveled the radiators, and are monitoring the water levels. We still have to clean or replace a couple more valves, but the noisiest are done. […]

Comment from Gas Heaters
Time October 29, 2010 at 4:02 am

Oh what a messy job! I am pleased it was your partner and not me! Though, I will say it might be worth while asking for the service of a professional to ensure that you do not have the same problem again.

Comment from Designer Radiator Store
Time November 22, 2010 at 10:56 pm

I recommend an annual audit of your entire home equipment. There is nothing worse than a breakdown just when you really need it, such as heating in winter.

Pingback from Pragmatic Environmentalism
Time January 18, 2011 at 2:43 pm

[…] Steam Radiators? Here's How to Improve Your Boiler's Efficiency […]

Comment from John S. Heat
Time December 20, 2011 at 3:29 am

We rented a place in Seattle and were stunned to find our boiler faulty too. Now thanks to your handy guide, we can fix it up ourselves without having to go to war with our landlord to get our heating.

Comment from Sarah Carmicheal
Time March 18, 2012 at 10:17 pm

A lot of people talk about proper waste management to reduce their footprint on the environment, but fail to realize that there is a lot more they could do if they were aware of all these maintenance that they should do on their household appliances. Thanks for sharing!

Pingback from Festival of Frugality #204: The iPod Playlist Edition | Health Safety Program
Time January 25, 2015 at 11:13 pm

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