Invisible Leak?

watercress

Home owner here. I have a closed loop water boiler heating system. The kind commonly used in cold climates. One boiler, a tank that holds hot water from the boiler, and 4 zones. 1 zone for hot water, 3 zones for baseboard heaters.

2 of the baseboard zones where closed in order to save on heating. But the zones where only closed at the return, but still open on the supply side. This means there was still water in the lines. Well it got very cold, and a door was blown open making it even colder. The 2 zones that where turned off on the return side got bursted pipes once it warmed back up. The zone to the basement had one burst in the laundry room. The living room/kitchen/dining room zone, has several bursts in the pipe. I've counted 5 so far. Thankfully no water damage, as the pipes bursted in a small crawl space by the garage where it got the coldest, and all the leaking water leaked onto the ground, and the basement leaked into the laundry room drain.

I turned off both supply lines to those zones to stop the leaks. And began fixing the basement zone, since it only had one visible leak.
After patching that leak, I turn on the basement zone. I still have not patched the other zone with broken pipes, so it remains off.

Now begins my confusion. When turning on the supply and return for basement zone, it seems the return never gets hot. The supply gets hot but only half the baseboards heat up, as if there is a block somewhere. I can hear a trickling sound coming from the pipes, and it doesn't seem to go away. What further worries me is the water pump (well supplied) continues to pump more water in every 5 or 10 minutes I would say. But there is no sign of any leak. No water anywhere, no steam from hot water. If there was a leak, the water would certainly be visible I would think? Or is it possible that the leak is going down the side of the foundation somehow and being absorbed into the ground the house is on? That worries me the most because it would in essence be eroding the ground underneath the house, as the house in on a slight incline.

When I turn on only the return line to the basement zone, I can feel some of the other pipes get warm that before were staying cold. It seems the water will go into the return side if there is no pressure pushing against it. But once I turn on the supply side, the return side goes cold.

I've purged the air from the good zones in the house without issue, and there was a good amount of air in the lines. But when I try to purge the air from the basement zone, the water never returns, like its blocked, or simply never making it back. It also seems that whenever I open the basement zone, air enters into the 2 good zones as well.

I figure I'll just keep the basement zone closed for now, and move onto patching all the leaks from the zone that has 5 bursts.

Any instruction someone with more experience has for me is greatly appreciate.

Another idea I had is the water is getting past the backflow preventer and the water is tricking back into the well.

Thanks,
David

EdTheHeaterMan

Did you get all the air out?

Another idea I had is the water is getting past the backflow preventer and the water is tricking back into the well.

Not possible.

But when I try to purge the air from the basement zone, the water never returns, like its blocked, or simply never making it back.

then there is a blockage. That blockage could be air or something solid in the pipe. Is there a valve closed? As long as you put house pressure into the boiler to purge the basement loop at one end, you should get water to run out the other end. If your purging valves are not set up that way then you won't get all the air out.

Here is a typical purging set up. If you put water in from the supply from your home, and you turn off the valves so the water can only go one way, then the only way out must have water and air exit thru the hose. there is no other option. If there is nothing coming out the hose, then there is a blockage or design flaw.

watercress

I think I got all the air out of the zones Im not having problems with.

what do you mean is there a valve closed? I have the other zone that still has broken pipes closed, so theres two valves (supply and return) closed.

To purge air from the zones, I closed the supply and return for all zones. I shut the boiler off. I closed the return pipe that goes to boiler (all zones go into one pipe that can then be closed to stop water flowing back into boiler and supply side). Then I open up the purge valve for releasing water and let it do its thing until no bubbles in bucket. But when I do it with basement zone, no water come out the purge valve... well theres a few cups that come out and then it stops.

EdTheHeaterMan

Your description is a little ambiguous,

I closed the return pipe that goes to boiler

hard for me to visualize

Can you look at my diagram and tell me where you have a "Return pipe that goes to the boiler"?


In this diagram the water pressure from the house enters at the fill valve location and enters the boiler system at location B. Since valve valve M is closed the water from location B can not go into the boiler after it is full. The water pressure must go to position C and into the only open valve D. Since the only outlet is purge valve J then the water pressure must go thru Baseboard Radiator loop G in order to exit with air and water at purge valve J.

This may not be exactly your design, but you see that by having the house water pressure forcing the water thru the only open loop which I have called Basement, the water and Air MUST purge.

I hope I have made my self clear and I hope you can answer my query about your "Return pipe that goes to the boiler"

watercress

mine is a little different. I have a valve at P, and right before P is the purge valve. That being said I dont know what A is. I also have shut off valves and the beginning and end of each zone, but only one discharge valve for the whole system.

I think mine is basically the same as your diagram except my purge valve is after the shut off valves, since there is only one for the whole system, and after that purge valve is a valve that shuts off anywater getting past into the boiler.

here is a video:
http://f.ob7.us/f/boiler.mov
in the video I have everything running normal, boiler is on and everything, except bad zone and basement zone are closed, and I have purge valve open draining into bathtub. I think proper was is to turn everything off but is there any harm doing this as well? There is plenty of air coming out, actually quite a bit of sediment came out as well. But this is all still with basement zone closed, which is currently the one with suspected blockage.

EdTheHeaterMan

A is the Boiler

Here is an illustration of your boiler (not perfect).

Fill valve goes in to the tee just under the circulator pump
If all the valves are closed on all the zones and the water heater zone to start with including the valve marked E.
Open the Valve for the basement zone only. Valve B, C and zone valve D, then when you open the purge valve the you can get water out of the purge valve is by opening feed valve to full house pressure. the only path for water pressure is thru the Basement zone loop because E is closed so the water and air is forced thru the basement loop.

Does that make sense?

My guess is that the zone valve may be closed on the basement zone.

watercress

This makes sense. I believe I did exactly this before and no water would come out. Perhaps there is still frozen water somewhere in the pipes. I'm going to try again tomorrow as its getting late here.

watercress

I'm getting ready to try again.

I read that after turning the boiler off it should be cooled down before starting the flush.

How long should I wait between turning the boiler off and flushing it? I've read anywhere from 20 minute s to 2 hours.

The temperature gauge on the side currently reads 170f.

EdTheHeaterMan

The cold water from the house pressure will reduce the boiler water temperature in short order. You do not want to force cold water into a 250° boiler that has overheated and may flash into steam. The thermal shock could crack the boiler. Putting 40° water into your 170° boiler slowly will not hurt anything. As the cold water enters the return, the 170° water will raise the temperature of the 40° water. The 40° water will lower the 170° water in the same way. Use your head and take your time. By the time you get the boiler pressure up to 25 PSI you may have added only 1 or 2 gallons of cold water to the boiler that holds 9 to 15 gallons.

...And what do you think happens when the circulator pump puts cold radiator water into the 180° boiler, If this was such a problem ,there would be a lot more boiler failures every time the thermostat calls for heat. But it doesn't!

hot_rod

Sounds like you still have a frozen line.

watercress

I tried to purge air from the zone once again. Same thing. No water comes out from the return. Worse yet, the water pressure goes to zero, you can hear the sound of water moving, and the well water pump keeps engaging, pumping water somewhere... but there is no sign of leak anywhere.

Possible a broken pipe I cannot see leaking into the ground somewhere...

neilc

yeah, you need to find that leak,
have you looked outside ?

watercress

no, its winter... but leak is somewhere in basement... I just got done tracing the entire zone, and I have reason to believe there is a busted pipe behind a bath tub.

The zone goes cold at this point depending on which side is open. Return side open leaves baseboards to the right of the tub hot, but ones to the left cold, closing the return and opening the supply leaves pipes hot to the left but cold on the right. Getting ready to pull the tub.

watercress

pulled the tub, wait until you guys see this



invisible leak detected!
a side note, the insulation possibly failed due to shrews, either eating the insulation or pushing it away from walking across the pipes. Lesson learned: keep zone valves on even if you dont need to for heat, as it will atleast keep shrews from using them to transport around the house, removing the insulation from the pipe.

by the looks of these pictures, how long would you guys say there was a leak there? It could have been drizzling for years and I would have never known until I had the full burst take place recently.

Dave Carpentier

Yikes ! Thats pretty cool that you found it though.
Water can do an incredible amount of damage in a short time.
Probably good idea to protect against mold for that wetted area. I used glycol to kill off mold in a travel trailer that got water under the flooring once. Ripped out the lino floor and painted glycol on all wood surfaces. Its an old wooden boat trick, apparently. 5 years later, trailer still smells nice and no mold visible.

watercress

yes it definitely smells terrible right now. I've got a space heater in there with the door closed and the fan on trying to dry it out. Then I'm going to rip all the insulation out... and I guess use glycol like you say. Do I just paint all wooden surfaces with it once they are dry?

Dave Carpentier

After I ripped out the flooring, I soaked up the remaining water, then I used a pretty thick brush (like 1" thick by 4" wide) and really glopped it on, then left it for a coupla days. Ran an electric heater until everything appeared dry after that. It took a coupla weeks for the smell to completely disappear (cushions, curtains etc maybe).

There are many different types of molds, some quite dangerous to breath in.
Mask for sure, goggles for the glycol for sure so you dont flick into eyes, keep animals away from the glycol (kills), a temporary vapour barrier wall would help to prevent spread of the molds as things dry and they can become airborne when disturbed.

Keep in mind, Im not an expert at that stuff.. thats just the procedure I used after doing some research.