Another question for Uafitter/Johnlobb

Prawn Farmer · Apr 24, 2015

I have an older Water Furnace (early 90's) that recently started making a cavitation/gurgling type noise from one of the circ pumps after a repairman was here. Both impellers have been replaced separately this past year after waking up to water on the floor. The gurgling/surging noise is especially loud for the first few minutes the unit comes on and eventually fades completely. Repairman said the system's loop was full. Could the loop have air in it and is that something I can purge myself?

El Toro · Apr 24, 2015

When the pump or pumps are running you may be able to bleed any air from the system. There should be a bleeder on your heating equipment such as base board heaters or radiators. You may need to add water at the furnace. Hal

johnlobb · Apr 24, 2015

Usually water by itself (when the system is full) will make little or no noise. Some closed systems have an air scoop which is usually at a high spot in the system. The best place for it is on the return side just before the pump intake. That is the lowest pressure in the system and any entrained air will come out easier. Dan Holohan wrote a book called "Pumping Away" that lays this concept out for the layman. Also check at high spots in the system, air can gather there and sometimes be bled off. Again, heatinghelp.com has a "wall" where questions can be asked about hydronic systems.

Prawn Farmer · Apr 24, 2015

Thanks - it's a forced air, geo-thermo unit that uses alcohol glyco mix in a closed 3 well loop.

Prawn Farmer · Apr 24, 2015

I'll have my wife see if she can find a copy of his book on e-bay or amazon and check out the heatinghelp site. Thanks!

Steve A W · Apr 24, 2015

Prawn Farmer
Maybe You can find something on this site;
Heating Help

woodbutcher · Apr 25, 2015

Our 4-ton system made the same noise recently. The tech said we have a leak in the loop system somewhere underground. So, our options were to replace the whole loop system at a cost of $7K or install a water valve which injects municipal water at 45 psi into the loop. As I recall, it cost around $800 installed. It solved the gurgling noise problem, so far.
Butch

Prawn Farmer · Apr 25, 2015

Hmmm . . . We did notice a small sinkhole east of the house close to where the wells are. Showed it to the tech on his last visit and that is when he shrugged and made the comment that the loop was full. Does seem awful suspicious, though. Has been pretty much trouble free for for more than 20 years up until now.

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