Dunham 9a

AndythePlumber

we have a client with a few different issues

-someone at some point installed a digital water meter

-boiler heat exchanger is failed and leaking

-when operable water will come out of end of main air vent

-I believe the buried condensate line is leaking but unsure at this point. I’m thinking that’s why the meter was installled

-not all radiators get full hot

-it has a Dunham 9a on what I believe is a vapor system and I’m trying to understand it.
-any help much appreciated

-I have lost art and have owned it for years. I’ve read about it in chapter 15 but it’s a lot of information to process.

AndythePlumber

EBEBRATT-Ed

With the Dunham return trap it is a vapor system. The Dunham uses steam pressure to "pump" the water back to the boiler.

Others will comment.

Jamie Hall

As always with vapour systems like this, get the pressure under control! You want a maximum boiler pressure — cutout — of 8 ounces, and 6 is probably better.

I'd almost be surprised if a buried wet return ("condensate line") wasn't leaking. Perhaps a lot. Replace it.

I doubt the end of line main vent belongs there. It might — but it would be more normal for there to be a crossover trap there, with paired drips to the wet return. Since it's there, it will do no harm particularly — if you keep the boiler pressure down. Otherwise it can and will defeat the operation of the return trap.

Water spitting out of it, though — many possible causes. But start with the pressure.

AndythePlumber

I’m going back tomorrow to study the piping more closely. The boiler is in a pit recessed in the floor. Then I believe the previous installer poured a pad about 8” high to put the new boiler on. It was replaced after a devastating area flood in 2011. I’m wondering if I should demo the pad and put the boiler lower. we don’t get a lot of of steam boiler work in our area any more, usually a few a year and none I’ve seen have ever had a return trap like this. The client and homeowners are such that there is no point in rushing anything and I just want to do the dead men proud. I’m going to post more pictures soon and really appreciate the support and community. You guys rock

HeatingHelp.com

This may help:

https://heatinghelp.com/systems-help-center/dunham-general-products-bulletin-of-low-pressure-steam-heating-appliances/ (The Dunham Return Trap 9A is on page 12.)

We have a bunch of Dunham-related literature in the Museum section of our Systems Help Center. Just search for Duhnam.

AndythePlumber

we decided to go forward with the boiler replacement. Keeping the return trap. For me these are new principals-a mechanical condensate pump as Dan puts it. Huge props to the man. I’m posting pictures of the install to see if there is anything I am missing. Kinda nervous about start-up with will be the Monday after thanksgiving. Thank you all for any input. Please note the water line as indicated by red laser level. Also note that at some point, someone removed the crossover traps at the end of mains and screwed air vents into them. There are 4 locations where the crossover traps were originally and only one hadn’t been touched. I have since reinstated the crossover traps. A couple pics illustrate what I mean

Jamie Hall

Nicely done! Keep your pressure where it belongs and enjoy!

AndythePlumber

Thanks Jamie!

Steamhead

I think this is a HeatingHelp.com first- a Dunkirk steamer where they didn't reduce the steam outlets from 2-1/2" to 2". Nice job.

AndythePlumber

thanks a lot guys. In our corner of the heating map we don’t get a lot hole lot of opportunities to mess around with this neat old stuff. A few a year and usually it’s a small counterflow system. Basically self taught here with pretty much just you folks to lean on for advise. Oh sure we get plenty of hot water heat and some pretty intricate systems at that. Not much steam though, and even fewer homeowners still running these systems with the means to maintain them beyond duct tape and bubble gum. It means a lot to have a community. Thanks again