Circulation direction in radiator system

[coustanis]

In my boiler fed, household hot water radiator system, is there a way I can determine the direction of circulation? I need to cut, cap and isolate a room to find a leak.

Thanks.

[Clark]

coustanis wrote in news:1181740730.804298.204890 @n15g2000prd.googlegroups.com:

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.

[Edwin Pawlowski]

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?

[Doug Miller]

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 is which?

[coustanis]

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.

[coustanis]

I need to install the snifter valve in the correct section. That is to say into the suspect room loop, not the still connected to the furnace loop.-

[Jeff Wisnia]

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.

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 doing.

"You can only succeed as far as you dare to fail."

Jeff

[coustanis]

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 right there?' 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.

[Larry W]

In the winter when the heat is running you "may" be able to detect a difference in temperature between the supply and return pipes at a radiator. The best way would be to visually inspect the piping and trace back to the circulator pump. BTW, there will be pressure on both lines, I'm not understanding what you are trying to do to find the leak. How will capping of a line help?

[Don Young]

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.

Don Young

[coustanis]

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 furnace. 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.

[Edwin Pawlowski]

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.

[Pat]

Any reason you can't just turn down the thermostates until the system goes cold (or at least cool), then turn up a thermostat so the system comes on and feel which pipe gets hotter before the other.

It's rather low tech but that's the way it's been done for generations.

[coustanis]

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?

[coustanis]

I would have done that but once I located the proper pipes to the room in question, it became obvious. Plus, the valves all have arrows on them.

[Jeff Wisnia]

At the risk of asking a really dumb question.....Is something akin to an automotive cooling system "stop leak" product ever put into a hydronic heating system to plug a small leak (maybe as just a stopgap "fix") without screwing up something else in the system?

I thought about that because I know its not uncommon to use an antifreeze mixture in hydronic heating systems at places like vacation homes where the temperature may deliberately or accidentally get down to freezing when the place is unoccupied.

Jeff

[coustanis]

I don't know if there is or not but I did think about that. Then I decided that I should just fix it properly because I don't know how long something like that would be effective. I'd end up having to fix it sometime anyway.

[Doug Miller]

No. Stuff like that can prevent valves from seating properly.

[Jeff Wisnia]

Y'know I thought about that but then said to myself that I'd never heard of it causing problems with the valves which control the flow of water through the heater core in most cars, so maybe that "stop leak" stuff only "clogs" small holes between the fluid side and the "outside".

But, I'll take your woid for it...

Jeff

[Edwin Pawlowski]

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?