I’m hoping for some help on the following series of problems I’ve been having. I am NOT looking for a DIY fix, but need some guidance on which professional option to choose here.
1) I have a Utica gas boiler, forced hot water with two zones. It’s at least ten years old, and was in the house when I bought it.
2) Three weeks ago I had the gas valve replaced. The valve had been buzzing at startup and the boiler would cycle on and off intermittently. When it was tested by the technician, the gas pressure was low.
3) The unit worked fine for several days, then the intermittent on/off cycling returned. I tried to wait to call back the repairman until I could reproduce the problem. Before I could reproduce it reliably, the pilot light stopped staying lit.
4) Long story short, the technician returned. After several minutes, he sheepishly admitted that he had not properly tightened the new thermocouple when he did the gas valve replacement. The boiler (which had been off for over a day) fired right back up, and we were both satisfied that both zones were getting heat.
5) About 20 minutes after the tech left, and once the boiler heated up to working temperature, a tea-kettle whistling noise began to come from inside the boiler unit. This noise had never appeared before, and it now occurs each and every time the boiler fires—but only when the gas jets are firing. It does NOT occur only when the circulating pumps are active, and there is no leak, no evidence of steam escaping, and no loss of pressure (steady at about 20psi). It takes a minute or two for the whistling to start (seems temperature dependent)), and sounds almost as if there is a now pin-sized hole allowing air to be forced through somewhere within the block. When the unit fires down, the pressurized noise also dies down and goes away. This noise never occurred before the technician’s visit to fix the thermocouple.
6) The tech returned today and was stumped. Re-tested for gas pressure, circulating pressure, and operating temperature—all are fine. He removed the side and back jacket panels and looked internally at the unit with a hand mirror, and could see no leaks. According to his diagnostics, the unit runs at 78 percent efficiency.
7) After consulting with his boss via phone, the tech offered me two options. The first was to try and “skim” the system with a chemical flush. He said it was coincidental that the unit just started making this noise right after his last visit, and that a sludge buildup might be causing a blockage, and thus the noise. He said it was a 50/50 shot at making the noise go away, and offered go guarantee on the work.
8) The second option was to replace the boiler with an entire new unit. The tech offered me several pricing options, and although I don’t doubt that this unit is old, I think it is a radical step to spend a lot of money on an entire new unit without knowing the cause of the current problem. I was also a bit scared away by his hard sell—i.e. “If you commit to buying a new boiler from us TODAY, we’ll refund the cost of the work you’ve already had performed, but you must make this decision TODAY to get the refund.”
Right now I’m leaning toward getting a second opinion, but would appreciate any feedback to help me make my decision.
Thanks in advance for your help,