possible clogged heat zone? how to troubleshoot

DanJ

Hi,

   I have an oil fueled hot water heating system that is fairly new. it is on the verge of being three years old in a newly constructed home at the time. the system is uses three zones one zone for the bedrooms and master bath, one zone for living room, kitchen and laundry room, and third for hot water tank. zone one in the system just stopped working the yesterday, zone 2 and hot water work without issue. I have done the following:

thermostat- checked and switched with thermostat from working zone- no issue

taco SR 503 switch board- ensure zone one light is on, checked fuses, pulled relay noticed motor turned off when I did so.

Grundfos UPS 15-58 FRC circulation pump- I removed pump from system, while doing so I notice very little water coming into the pump itself. I drained this zone, pulled pump to check for damaged or clogged impellar all checked out ok. turned pump on while housing was to confirm impellar was spinning.

I reinstalled pump, but when I tried to purge the air from the system by opening the cold water valve and leaving the drain valve open after the pump no water at all is coming out from the return side. I am thinking some how debris or something built up and clogged the system somewhere. Would I be correct with this thought?

I also tried to increase system pressure to about 20psi, more than that I was getting water coming out of the furnace overflow, in hopes the pressure would force the water through the line. however, this didn't work either. I am kind of lost at what to do next.

My thought was to pressurize the system with air from a compressor to see if the air would blow through the line. how would I go out about doing this properly? there is no place on the intake side of the system for me to open up as it all soldered or sealed with what seems like high quality heat shrink type of clamp for the plastic style lines.

Tom_133

Dan

If you KNOW its not frozen, and you definitely have the correct supply and returns, then isolate the loop from the boiler remove the pump as you did and try pushing water or air thru the return side and see if there is something stuck. I'm not suggestion you put 125PSI to it to test, I am saying you bump it a few times. Sounds like a frozen pipe

DanJ

thanks

I don't believe it was a frozen pipe because the house is always about 68-70f and the heat has been running constantly due to very cold weather over the past week. however, it may of been. Too tough to try and figure out as 90% of all the pipe is behind drywall. 





 The issue is fixed as of late last night. I ended up closing all three zones and opening the drain on the zone with no water coming out. I then force filled the system to about 25 psi, just enough to prevent the pressure valve from opening up. I let the pressure sit in the system for about 10-15 minutes. then I drained, refilled, and re-pressurized the system. I did this about four or five times then finally water began to slowly flow through the zone I suspected to be clogged. then last time I did it the water came through at full force. all in all the water was pretty clean. there was some dirt, but not much.





Once I got that zone flushed I then proceeded to drain and flush the entire system from the lowest point just in case whatever caused the issue was still somewhere in the pipes or furnace.

Tom_133

classic

Dan



It sounds like a frozen pipe, by chance do you have a woodstove or another heat source you use? Typically people try to keep the boiler off and run an alternate heat source that keeps the tstat satisfied, then without circulation a pipe thats near an outside wall gets cold and freezes. You say it's been really cold, I assume frozen pipe, since you didn't get any other culprit back when you purged.