banging steam pipes

stevetheplumber

I have a steam pipe that is pitched away from the main. It feeds 4 radiators . The steam and condensate run counter to each other. I would like to install a drip in the line. Just don't know the best location for it. Also what size is appropriate for the drip? I will be attaching the drip to a wet return. Do you have to have a steam trap? Would like to stop all the banging!!!

Jamie Hall

If the steam pipe is pitched away from the main, are you sure the steam and condensate run counter to each other?

In any event, the drip should be at the lowest point of the steam pipe. It doesn't have to be that large -- 1 1/4 to 1 1/2 is ample. And if it goes to a wet return which you are quite sure is wet, you don't need a trap. Don't want one, in fact.

stevetheplumber

The pipe is pitched back to the main, so all the condensate runs back counter to the steam. In addition this pipe is installed in a very cold garage. I asked the homeowner to weatherize.
Thanks for your response Jamie.

Fred

stevetheplumber said:

The pipe is pitched back to the main, so all the condensate runs back counter to the steam. In addition this pipe is installed in a very cold garage. I asked the homeowner to weatherize.
Thanks for your response Jamie.

Radiator run-outs do pitch back towards the main and the condensate does run counter flow to the steam in those run-outs. That is normal. What size is that run-out? As I see it, there could be one of two issues or a combination; 1) the run-out may not be large enough to feed steam to four radiators and allow condensate to flow back to the main or 2) the steam is condensing in that very cold garage creating a lot more condensate than typical. Are those pipes well insulated?
A third possibility is pressure. What pressure does your system run at? If it is high enough, that may prevent condensate from flowing like it should. Make sure the pressure is no more than 1 PSI to 1.5PSI. Put a 0-3 PSI gauge on the boiler if you don't already have one.

Jamie Hall

Ah. Sorry, I misinterpreted. If it pitches back to the main -- the two issues @Fred mentioned are very likely culprits. A third -- related to his first one -- is that there may not be enough pitch.

A drip won't help much in that situation. As I see it, there is a lot of condensation due to the cold garage, particularly at the beginning of a cycle, and it just can't cope. You should put a minimum of 1 inch of insulation on the pipe, as well as checking size and pitch.