There is usually a flow direction arrow on a pump. Also the inlet on a cast
iron boiler will be higher (further from the burner) than the outlet. The
newer low mass boilers undoubtedly have inlet/outlet labels somewhere.
Look at the pipes/tubing leaving the boiler. There are probably a couple of
valves in the system that will have an arrow on them showing flow. Then
just follow the pipes.
I don't mean this to be nasty, but if you don't know how to find the flow
direction, are you qualified to cut into the system?
I'm wondering why the flow direction even matters for his purposes. In order
to isolate the area from the rest of the system, he needs to cut and cap both
the supply and return pipes anyway... so why does it make any difference which
Doug Miller (alphageek at milmac dot com)
Probably not but I can drain the system, I'm good at sweating copper
and I'm fairly well mechanically inclined.
It'll be a learning experience and money is tight. I need to learn
not to be afraid of the system anyway for future problems.
I have already located the two pipes I want to cut and now that you
mention it, I believe the air purge valve has a direction arrow
cast onto it.
I feel fairly confident (famous last words).
The plan is to install a snifter valve and pump the suspect loop with
about 10 pounds of air.
Hey, thanks for teaching me a new term, "snifter valve". The one time I
needed something like that I carved the brass part out of a tire rim
valve and sweated it into a hole drilled through a brass pipe plug. <G>
Good luck with your project, it sounds like you'll be able to handle it,
and I don't see any major dangers to life and limb from what you plan on
"You can only succeed as far as you dare to fail."
I just learned the term yesterday when I was explaining to the guy at
the plumbing supply place what I wanted to do. The valve cost 1.49,
and is threaded.
That, the other three caps and a sweat-on-able(?) fitting for the
valve to thread into cost all of 6 dollars.
Cheaper than a plumber.
Thanks for the good luck wish. I started last night and found that I
had marked a wrong pipe. It's hard to trace those things sometimes.
In and out of walls, through floors.
I was really pissed off and cursing up a storm about not finding the
proper pipe when my 5 year old points and says 'you mean that pipe
It was the right pipe. My 5 year old is smarter than me. Now that
everything is located it should be a quick job to cut and cap.
It is unclear to me from this thread whether you realize that you must
isolate both the feed and return lines to isolate a part of the system.
Otherwise your pressure will still pressurize the entire system. Your
reference to "a pipe" rather than "those two pipes" made me wonder.
I cut the pipe as close to where it enters the suspect room as I could
and capped both open ends.
Then I cut the pipe again as close as I could to where it exits the
suspect room and capped only the exposed end that returns to the
I then installed a special cap that I made with the snifter valve in
the last exposed end (the one that is exiting the suspect room).
I then refilled / repressured the now sealed furnace loop with water
to 12 psi and verified no leaks.
I then used my air compressor to pressurise the now sealed loop to the
suspect room (via the snifter valve) to about 15 psi.
Now I can see if the boiler pressure holds (it did overnight) and I
can see if the air pressure in the suspect room holds.
I haven't rechecked that yet but I strongly feel that it won't. I
have thought all along that the leak is where the pipe is laid in the
concrete pad of the suspect room.
If the air pressure zeros out then I was right. If it holds then I
was wrong and the boiler pressure would drop.
There is definately a leak somewhere.
Just trying to pinpoint it's location.
What makes you think there is a leak? Do you see water?
Copper in concrete over many years can corrode and leak. Some older homes
with copper radiant heat had problems and the solution was to change over to
baseboard rather than tear up the slab.
It is baseboard.
The reason I think there's a leak is because the boiler pressure drops
to almost zero every couple of days and I can hear the water gurgling
and flowing in the pipes as if the level was low.
It didn't used to do either of those things and it suddenly started to
do so one day.
I see no water. That's why I have thought all along it's in the
concrete pad. Knowing that pipe in concrete will corrode combined
with the fact that except for the concrete pad, the piping in the
house is largely exposed visually. Where it's not visually exposed
it's in walls and such. I see no water anywhere. No puddles on the
floor, no wet walls and no water dripping from ceilings. No water to
be seen anywhere. Deductive reasoning (however faulty mine may be)
dictates that it has to be in the pad and I guess it's flowing down
and going somewhere as opposed to coming up onto the floor. I have
been using my plumber as a sounding board and he seems to agree with
my thoughts. I asked him if it could be a steam leak and he said no.
Bless his heart for talking to me instead if insisting that he do it
for a lot of money.
Anyway, the deed is done. I have isolated and pressurized the room in
question so either it will lose pressure or the boiler will. I'll
find out tonight when I get home.
I'll keep you all posted. Isn't home ownership fun?
If you don't find a leak, get back to us. There are other reasons you can
hear the gurgling sounds, such as faulty expansion tanks, etc. There was a
lengthy thread on this just last week. BTW, do you keep the feed valve open
to the system? If no, did you before you had the problem?
Read this posted by hvacmedic a few days ago. It is part of a thread from
your original ost.
In retrospect, I think you said that you only had problems when the
valve was closed. In that case, what I went over above is why you had
problems before, i.e. with the valve closed. The valve is supposed to
be open, so you didn't do anything special to your system, you only
set it back the way it was supposed to be. Pardon the oversight.
Can I run the circulator pump with a loop capped off? Other rooms
loops are still intact, so probably. Also, I believe I need to make
sure the expansion tank pressure is about equal to the boiler
pressure. That shouldn't be a problem, I guess. Just release or pump
in air to about 12 pounds.
No one has mentioned this possible scenario to me. Have been getting
told it is a leak.
If I leave the feed valve open and there is a leak, won't it just keep
feeding in water and never allow the pressure to drop.
That is why I was told to keep it closed. I also wouldn't know how
far to open the valve (slider lever thingie). I tried that once a few
weeks ago - opened it just a crack and the pressure was headed merrily
up to the high 20's or low 30's. I shut it back off so the safety
valve wouldn't blow.
I may be getting in over my head at this point but I'd like to keep
If you keep talking, I'll keep listening.
So you're telling me that air air in the expansion tank will diffuse
into the water? I thought it was contained in a rubber bladder.
I couldn't measure the amount of water I had to add every few days but
I would estimate around a quart or so. Maybe more. Hard to tell.
Not only do I feel like I've been barking up the wrong tree but I'm in
the wrong damn forest.
I do know that if I run the system with the feed closed, I do get some air
in the system. I had a leak in the packing of hte feed valve and kept it
closed and after time, air was gurgling. Replaced valve, left it open, a
day or so later, noise was gone.
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