I contacted The Boiler Guys recently to come in and assess a few problems I had been having with my boiler--intermittent heat output in certain areas, difficulty maintaining pressure, etc. The responsiveness of the boiler guys was great, came next day, but their repair service was subpar. Based on my experience, The Boiler Guys were overpriced and not thorough, maybe they have better techs but I would not recommend.
The tech came, looked at my boiler and said it could potentially be a leak anywhere so keep an eye on things, and was prepared to charge me $250 with no work done and still problems. He then (as he was about to leave) thought of checking the pressure relief valve which he said he had forgotten to check. He found that the valve had gone bad and said he would replace it for $200; I agreed since I wanted it fixed and didn't know at the time it was only a $20 part... He replaced the valve and left.
Then my boiler pressure started going extremely high so there was obviously another problem. When I called The Boiler Guys back, the head tech told me the issue was probably with the expansion tank. Why did the tech who serviced my boiler fail to check the tank at any point while at my house? He had also noticed that the pressure was too high before leaving and had all of the same info firsthand. On top of that, the tank was very obviously waterlogged (a clear sign the tank has gone bad).
They quoted me another $450 to replace this tank. As $1,000 seemed like a lot for maybe 1 hour of work and $150 worth of parts, I did not get them to do the 2nd job. The tank had indeed gone bad, I ended up researching and replacing it myself for the cost of the part ($100).