Will my design work?

Mike_D

I need to add this baseboard to my one pipe system. I will cut in the 1.25" to 1" reducing tee to feed it where a 1.25" elbow (riser to 2nd floor) feeds 29 EDR. I will drip it back into an existing wet return. I am afraid to let the condensate flow back against the incoming steam and I'm not sure if one section of my return can hold condensate without causing trouble. Thanks

JStar

How low will that return be in the crawlspace? What pressure are you operating at?

Mike_D

I'm operating at 1 psi. There is less than 3' to the bottom of the floor joists. I can run the 1st portion of return at any level below the joists. The return off the 2nd baseboard has to remain higher than the foundation base plate (between the joists) to cross over into the basement and join with the existing wet return.

Gordo

That's a nice, clear drawing!

If you could, I would suggest you run each drip sloping separately back to your wet return and do not try to join them above the water line as you depict.

Perhaps run those dry returns as high as possible before turning down into the drip

I would suggest to vent each piece of BB at the opposite the valve. Basically, you should try to re-create a "one-pipe, two-pipe air vent system".

Yes, keep the pressure very low.

Mike_D

Thanks. Space is very limited though. Is it not exceptable to join return lines above the water line? Even if I could run separately, can I still upturn the one return to exit the crawl space? The other thought I had was to let the 1st BB counter-flow (no return), but afraid I'll get hammering.

JStar

I would either run both returns separately into a wet return near the floor, or drop the first BB return as low as possible in the crawlspace before coming back up into the bottom of the common return.

Gordo

It is possible, if you join the lines above the water line as you depict, that steam can, after a long burner run during a very cold day, find it's way into those dry returns and play roughly with the water there. Generally a shallow water pocket in a return is problematic unless you run the system on oz/in2 and even then I would not advise it.

Best keep 'em separate and steam-free.

The second option you mention above might be better for you. A big enough supply for both as you show, that counter-flow main only has to handle the condensate from that one unit and the start-up flow from the run-out to the next, and then drip that other unit back to the boiler.

You might have to experiment with various venting arrangements, but generally vent the mains well and esp. the unit on the counter-flow, vent that slowly.

And pay attention to pitch, certainly.

Mike_D

Thanks for the advice guys, - and the explanation Gman, I understand it now. That main is not vent anyhow because it is only about 8' to the boiler from the 1.25" tee and it only feeds that one 2nd floor radiator before my addition.