3rd zone after problems with leakage

Old 11-25-08, 07:31 AM
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3rd zone after problems with leakage

recent problem. i've had 2 zone baseboard heat in my house 4 18 years. Just recently I added a 3rd zone for a new enclosed back porch. After abt a week of installation I noticed a quite large wet spot on the flr, abt a 1/4 of a bucket full. Wasn't sure where it came from. Then I happened to see it was coming frm the bkflow preventor vent. 9d-me watts. I ran all 3 zones at once no discharge psi built to 29psi but nothing from relief valve.

Putting together a theory, wife mentioned that the dishwasher, washing machine where on at same time, so I ran the two and at start up that is when discharge happened.

But never had a problem until the 3rd zone was installed. ?????

After some investagating on the bkflow prev. I saw in the diagram that the bkflow prev, should be in front of the water reducer which it is not an has not for 18 years.

Is this due to the lost of street pressure, which in return is calling for water ?? from the boiler but then has no where to go but out the vent..

Is the expansion tank also bad., but then it should release thru the relief valve not the bkflow vent..

doesn't the bkflow prev. need a minimum of 25 psi on the inlet side to work properly??

any help.

just weird after 18 years, doesn't work.

these are not electric zone valves, manual on the original two, but the newer one has a zone valve built into the taco cir. pump. so I'm told.

Old 11-25-08, 08:27 PM
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I'd guess that when you installed the new heat loop, and went to fill up the system, some 'crud' got dislodged from the water line and is interfering with the 9D's innards ... probably first time that much water went through that pipe in lots of years !

the newer one has a zone valve built into the taco cir.
Maybe not a 'zone valve', but a CHECK valve ... if the model number of that Taco circ ends in " I F C ", that means Internal Flow Check .

Is the expansion tank also bad.
Probably not at this time ... do you have the convential type ? a large tank in the joists above the boiler ? or the bladder type that looks like a propane tank for a gas grille ?

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