Steam traps

Matthias

What causes banging noises in a 2-pipe steam system? Bad traps? Dan has writing about getting a 10° difference across traps to see if they're working. Is that the only way to check them? If it's less then 10°, replace the guts of the traps?

Jamie Hall

Bad traps do do evil things. Banging noises -- if it's water hammer and not expansion -- isn't one of them. That's not to say you shouldn't check the traps -- although I'd be quite happy with 5 degrees difference rather than Dan's.

What you do need to do is start looking at is the pitch of every single bit of pipe, particularly the steam mains and runouts, but also the dry returns. What happens is that condensate -- particularly at the start of a cycle -- will pool in the pipe if it isn't adequately pitched, or has a low spot (it's surprising how much iron pipe can sag) and then the steam pushes the puddle along to where it hits and obstacle and... bang.

EBEBRATT-Ed

@Matthias

when a trap fails open the radiator heats fine, why wouldn't it the steam is blasting straight through.

but the steam blasting straight through puts steam in the return line this cause back pressure on the returns of other radiators (whose traps may be fine) holding up condensate and causing the ones with (maybe) good traps not to heat

jumper

Sometimes returns go too far horizontally.

Matthias

@EBEBRATT-Ed, @jumper and @Jamie Hall , thanks for you feedback. We are still negotiating with the homeowner about doing this project. Fairly complicated as he wants to convert to gas but the current oil steam boiler as a DHW coil that does 2 hot water loops. Most has boilers don't come with a DHW coil. My solution was to install a oil boiler that we can throw a Carlin EZ-Gas burner on instead of installing 2 boilers - one steam, one hot water. The homeowners seem to like that solution. We are waiting to see.

mattmia2

you could use the condensate in the steam boiler to heat an indirect water heater if you size everything right.

Jamie Hall

You can also just pipe the boiler water itself through a pump to the indirect -- or your hot water loops directly. It's done quite frequently. Gets a little tricky if the hot water loops are above the boiler's water line, but even then it's quite possible. You don't need a DHW coil to do it. Pump, thermostat, aquastat, and off you go.

mattmia2

that's what i meant.