Radiant Heat System Leak?
I have a home with a 5-zones of radiant heat, 2-zones of baseboard, and a water heater. Nothing but problems due to incompetent plumber. Last week I came in to find two out of three air vents spiting large amounts of glycol.
Incomptent plumber showed up, thought that the expansion tank was discharged, changed two of the air vents, recharged expansion tank and system to 14psi and left.
I have an external pressure gauge. Gauge on boiler stuck.
System will run and pump up to 20psi. If I turn off system, drops down to zero in a couple of hours. I can turn on Cold Fill and hear the system fill.
Now the mystery. I shutoff all of the system valves. I install pressure gauge so that I only measure Boiler, Pressure Relief Valve, Expansion Tank, Cold Fill (shutoff). Pressure drops. I can shut valve between Expansion Tank/Cold Fill and Boiler/Relief Valve. Pressure drops on Boiler/Relief Valve.
No visible leaks from Boiler/Relief Valve.
How could I have a leak in the Boiler with no visible evidence?
What could have caused the original spitting?
Any troubleshooting ideas?
Did your plumber pressure test the system with air before he/she filled with water? Is this a retrofit or new construction? Which method of radiant floors did you use?
New Construction / 3 years ago / Pressure Tested Tubing at Manifolds / Tubing in Concrete Slab
Whole system held pressure for three years.
Ace plumber, on a two loop zone, had one loop hooked up to two supplies, the other hooked up to tthe two returns. For over a month he was scratching his head trying to figure out why zone didn't heat up!
The only place that I can think of where the water can virtually disappear is the expansion tank.
When your system was recharged, was a mixture of glycol used to fill it? Or was it city water. Expansion tanks dont normaly need to be recharged. If the schreader valve on the air side of the diaphram was leaking, a new one can be easily installed, however, if the diaphram itself has been compromised, and the tank became waterlogged, it would need to be replaced.
If the expansion tank has been compromised and is waterlogged, your system pressure will increase, because the heated water will have nowhere to go as it expands. It is possible that the expansion tank can be absorbing the mixture your adding, but at some point, if it has failed it will not be able to recieve any more liquid, and your system pressure will go up
I am assuming that when you say cold fill, your refering to a storage tank and pump that adds premixed glycol to the system, if the system pressure drops below a preset setpoint. There should be a check valve in this line to isolate the storage from the system.
Bleeders will spew fluid if your system pressure is too high, or they get debris in the schreader valve and wont seat after bleeding off the air. It would be helpful if you had noticed the system pressure at that time.
Glycol or water just doesnt disappear. I am scratching my head when you say the pressure drops to zero when the boiler and pressure relief are isolated and dont see any leakage.
When the pressure drops to zero, does the level in the storage tank increase?
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