Feeding water in a 2-pipe system

ThermalJake

Fellas and Gals,

I have not posted in a while, but stop by to observe on occasion; as usual, it's the hottest place on the web!

I have a two-pipe "Thermal System" made by the New York Heater and Supply Co in about 1928.

Two years ago, I repiped the header and Hartford loop because there was none there before; I took the whole boiler (oil, Burnham V75) down to the block, dragged it outside, blasted it, cleaned, it and put it back together with new insulation and controls the way I wanted them, including a skim tapping and using both supply tappings instead of just the one that was used before. I added main vents on both legs of the supply mains, and at the end of the dry return. Then I insulated the mains, and the basement got cold! (I can hear you giggling!)

So, I reclaimed a radiator that had been sitting in a corner, built two cement block pillars, raised the monster on top of it (to get it above the water line), and put it into service. Of course, I cracked the boss trying to easyout the plug so I could add a radiator vent... (radiator vent! I thought you said it was a two pipe system!?) Yeah, it is. I had to add a radiator vent because this radiator was below the dry return and drained right into the wet return. Without the vent, there is no vent... Anyway, I isolated the radiator after I repaired it and put 5lb of air pressure on it, but it did not hold for more than... about 30 seconds. However, I decided that I would put it in service anyway, since I run about 8oz/in and maybe, just maybe, the condensing vacuum in the radiator would keep anything from escaping from wherever the leak is. Plus, the basement loved it!

I have found that I am adding water more often than ever before. But before anyone gives me the old "two-plus-two-equals-four" routine... I have had several interesting leaks in the past; for example, most of the valves have had to be repacked with graphite at one time or another. I'm pretty sure I'm doing it right, since after I'm done I don't see nor hear any steam. But I think my senses are unreliable at 8oz/in. Can one really see steam at that low pressure? In addition, I had steam leak out of one of my threaded joints with a union just off the header into one of the legs of the main. The only reason I found it was because I saw a little bit of steam coming out of a seam in the insulation right near that spot. Upon investigation, I found the leak, turned the wrench, and was back in business. Finally, I think the radiator vent fails to "snap" shut, and I don't even think the main vents "snap" shut. I have listened to the radiator one hiss a little bit; I wonder what it does when I'm not listening. I have always wondered if the main vents leak. They are hard to listen to.

This year, in November, I bought an hours meter, and started to keep track of how many hours it took before I had to add water each time. The data is not perfect, but I'll attach the file. I also correlated it to the heating degree days at my nearest weather station. I was expecting to find that with higher heating degree days, it would run longer, and I'd have to add water more often (in a shorter number of days in real time, but in the same number of hours of run time). However this was not the case. There could be a variance because I have no way to tell if I'm adding the same amount of water each time; I just try to hit the same mark on the sight glass.

So before I start taking off all of the insulation just to check for a visual leak, or take the basement radiator out of service, plug the pipe ends and check for an increase in run time, or try to disconnect and soak the radiator vents/main vents, I was thinking there must be some kind of leak test with green smoke or something that I could pump into the system and walk around to see for sure where the leak or leaks are. Does anyone know of anything? Or have any ideas?

vaporvac

Peppermint oil

Someone suggested peppermint oil at one time and I never read of anyone refuting it. Just a drop.

nicholas bonham-carter

Peppermint oil

I wonder if you would ever get the peppermint smell out of the system.

Look for the most likely leaks first, and overfill your boiler with a nipple connected to the pressure relief valve first. Fill it to the very top of the nipple. Leave it this way for several hours, and see if the level in the nipple has dropped at all. At the same time look for any dripping in the firebox.

If the boiler shows no signs of leakage, then examine all the main vents for signs of dripping or steam leaking.--NBC

vaporvac

Don't know1

I don't know the answer to that never having done it myself. I searched The Wall and got 3 pp on peppermint used for this purpose. I didn't read all the posts, but this one specified exactly what to use and how to use it. It's water-based so I suspect it would eventually leave the system.? Plus, all your guests would suddenly want candy!

http://www.heatinghelp.com/forum-thread/146042/Finding-Vacuum-Leaks

This post also has some other tips to check for leaks in addition to NBC's excellent advice.