Steam radiator with identity crisis (noisy, spitting water)
Hi all We came back from a couple of weeks away to find out that a couple of our one-pipe steam radiators are having an identity crisis. They are making a loud sound, almost like a washing machine (water churning). Difficult to pinpoint exactly where it’s coming from within the radiator or pipes. Also, they have “spat” some of the lovely, brown radiator water out of the air vent. We recently had the boiler converted from oil to gas, but can’t see how this would be the cause. Any thoughts? Am I totally wrong on that? Could it be an obstruction stopping the condensate draining? (Is it normal for the water to be brown) Or pitch issues? Something else entirely? Thanks AussieBen
aussieben
in Radiators 10 years and 4 months ago
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24 replies
kensny | 10 years and 4 months ago
Aside from too much water in the system as a whole, another possible cause is radiators that are not pitched adequately to let the water drain back out. Note: radiators are constructed with internal pitch in the bottom, so that a radiator the top of which is level is OK. But a radiator the top of which is pitched away from the steam pipe may need to be adjusted so it’s level. Excess water collecting in a radiator or steam pipe will often make noise – including the loud “bangs” that are sometimes heard – definitely wrong – the bang is the sound it makes when steam hits a pocket of water that’s blocking it such as in a pipe that has moved over time to lose its pitch and collect water. Another thing to check for – the radiator hand-valves (for shutting them off or on) must be either fully opened or fully closed. No partial closing !! – this doesn’t really work to regulate heat, and may block water from draining out. Finally, it may be that the air valves are not functioning right – although when that happens and they are stuck “open” you’ll get steam coming out, but the steam shouldn’t be too wet. If they are stuck closed then the radiator won’t heat up (since the air can’t come out). Given the noise and water, it does sound to me like a case of too much water in the system. I once had this problem, something possibly the automatic filler, I can’t recall, but my steam pipes (I mean the ones in my house; my own personal steam pipes are OK so far) actually filled up with water, right up to the 3rd floor! I had to drain a ton of water out of the boiler….
kensny | 10 years and 4 months ago
Your radiators should not be “spitting” out water, clean or rusty. When the system is working correctly, when the thermostat calls for heat, the boiler produces steam under a small amount of pressure. As the steam rises through the system it forces air out of the radiator air vents. Hence the normal “hiss” one hears. If the air wasn’t forced out this way, the steam couldn’t come in. When the radiator air vents get hot from the steam reaching them, they shut off – often with an audible “click”. Then no steam should get out. When they cool off again, they let air back in. The steam in the radiator condenses to water and the water drains back down to the boiler (the radiators are pitched internally to allow this to happen, and any horizontal pipes in the system should have a moderate pitch (slope) back towards the boiler. The water enters the boiler and the cycle repeats. Some water is gradually lost, so most boilers have automatic “feeds’ to keep their water at the right level. It sounds to me that your boiler is making “wet steam” — is it too full? Check the gauge glass.
slopefarm | 10 years and 4 months ago
I should add, you are doing the draining job on the boiler not the radiators. Someone more knowledgeable will correct me if i’m wrong, but I believe what happens is that after the boiler stops, the steam cools in the radiators back to water and drains back down into the boiler, carrying rust from the pipes with it. then, next time the boiler fires up, the steam carries bits of rust back up. So you want to periodically cleanse the boiler water of rust by draining so it can refill with fresh water.
slopefarm | 10 years and 4 months ago
Do you drain the rusty water periodically? Crank up the thermostat, get a decent bucket, and open the spigot to drain out the rusty water until the thermostat shuts off. Then close the spigot. The boiler should automatically draw new water and then fire up again automatically. Also, make sure the valves leading to each radiator are fully open, not partially. If those two DIY steps don’t work, then consider a plumber.