Should I clean the piping?

bruce_21

I must replace the steam boiler in a two-pipe system for an old client.



The McDonnell-Miller low water float switch failed and the old boiler cooked and cracked. When I took the float switch apart the little bellows around the switch end of the float was clogged with rusty sludge so it wouldn't move so the float didn't fall to open the feeder and stop the burner.

The HO said the low water had been replaced 10 years before when she purchased the house.

My question is: where is all this crud coming from and how can I make sure there is not a repeat of this movie?

Is there a way to effectively clean the supply and return piping? Will that help or just remove more metal from the lines?

What will happen to the new low water cut-off, its an electric immersion type on the new Weil SGO's, in this situation?

Rod

Piping

Hi Bruce-

Since a residential steam system is a open system, air and dampness are present in the pipes.  Air is going in and out of the radiators, and over time flakes of rust and dirt build up inside the piping and mostly collects in the lower portions of the system. If the system hasn't been cleaned regularly (annually) you will probably find a build up of sludge in the bottom of the boiler and in the lower return piping and the wet return. The rest of the piping should be reasonably clear as normally the steam and condensate are moving through them and this has a flushing action which flushes the dirt etc. into the lower sections where it collects.

The float style Low Water Cut Off needs to  be blow off regularly to remove dirt from the system, everyday for the first several days when the system is new and then weekly after that. I would guess in the case of this boiler that the weekly blow off was not done nor probably the yearly maintenance.

You need to inform your client that annual maintenance needs to be done whether the Low Water Cut Off is the float type or the probe type. It and the boiler controls need to be inspected and the boiler cleaned and the burner tested and adjusted if necessary.

   As you're tearing out the old piping you'll be able to inspect the condition of the piping and see how clogged up it is. You may want to replace the wet return as quite often they (and probably in this case it probably is) are sludged up. If Wet Return is black pipe, it generally pays to just replace it than try to clean it. Since these aren't steam pipes you can use copper pipe for the wet return which works well as it is less likely to corrode nd collect sludge.

- Rod

Michaelynn

Dirty piping

Rod is correct. We just replaced the original black wet return piping with copper. They were plugged. Pro-Press works well. In addition, you may want to add some water treatment or baking soda, etc. If applicable, make certain y-strainers are installed before end of main F&T's.  Good luck!