I agree with Paul. If the main loop off the boiler is hot in and out, and
you can determine that the pump is actually pumping,(not just circulating by
convection). This sounds like a "venturi" system, as he described and the
most likely scenario is that the boiler was drained to do some work and not
properly bled.




"Paul Franklin" wrote in message
...
On 20 Oct 2005 22:34:33 -0700, wrote:
snip

Anyway.. The "trunk lines" leading in/out of the boiler are getting
REAL hot.. No problem there. The gage on the front of the boiler reads
approx. 25 lbs. and 190-200 degrees F. This is probably above the
intended maximums of the system, as the relief valve is dripping. The
pump motor is turning, and presumably functional. I'm assuming all the
pipes are hooked up properly, but that can't be taken for granted as
there is some construction going on in the house and much of the copper
tubing does look to be new. Further complicating the problem is the
fact that this guy, nor his family, speaks much English! Unfortunately
I don't speak Bengali (the language spoken in Bangladesh) so I'm pretty
much on my own trying to figure out the situation..

I tried tracing the path the water travels in, but I got a bit
confused.. There are brass "Tees" in the main pipes that upon further
examination may not actually be a Tee like I'm used to.. It looks like
one leg of the Tee might actually be closed or atleast greatly
restricted?!

The main symptom is that the pipes that branch off the "trunk" and go
to the baseboard radiators upstairs are cold. It doesn't appear that
there is any circulation through the plumbing above the basement. I've
googled a few older threads on baseboard heat and think that air must
have entered the system somehow, and must be bled out before he'll get
any heat. Am I on the right track with this?
snip

All right, I'll take a quick crack..I'm sure Heatman and some of the
others will chip in too.

It sounds like you have a main loop from boiler outlet to inlet, and
several branch loops that are tee'd off the main loop, run up to some
radiators, and rejoin the main loop farther down. It also sounds like
the system uses diverter tees, which, as you describe, are like
standard tees but have a partial obstruction or scoop in the main
path. This forces, or attempts to force, water to flow through the
branch part of the circuit. But you have no flow through the branch
circuits, otherwise they would be hot. As you surmize, a common
reason for this is for the branch to be air locked.

There is usually one or more air bleed valves for each branch. They
are often small, maybe an inch high, and have a small spout. They
often have a recessed hex shaped shaft that requires a little radiator
"key" to turn, although some just require a screwdriver.

The general idea is to open the bleed valve and leave it open until
water comes out steadily with no sputtering. You can do it with the
system off or on, I usually do it first with the system off. If the
bleeds are rusty, soak them with a bit of WD-40 or the like before you
attempt to open them. If one breaks, you are in for a bit of a job.
Bleed all the branch circuits, and try it out. It's a good idea to
bleed them several times over a few days as more trapped air makes it
way to the high points. If you can't get water out of the branches,
you may have thermostatic valves or zone valves that are off..

And since it sounds like the system has been neglected, I would
strongly urge you to urge your friend to call a pro to inspect it.
They can make sure the temp and pressures are right and that the
burner is adjusted properly and burning safely, and that all the
components are working properly, especially the safety systems. I
realize from your description that money may be a problem, but urge
them to get a pro as soon as they can.

HTH,

Paul