In 1994 I installed a brand new New Yorker boiler. Well, I did not install it, Ultramar did. I was quite good at having it serviced annually but probably missed a year or two. After 10 years and at my annual service the service guy called me down stairs. In great seriousness he informed me my boiler was rusted out and I needed a new one. $4,600 would solve my problem.
As it just did not feel right I asked good friend Tom to have a look as he is much more handy at stuff like this. He confirmed rust, showing me where it was and suggesting a quick trip to Belmont Sheet Metal might solve the problem. I spent $23 to have them make the part, installed it myself and the furnace is still just fine.
Since new I have been dissatisfied with the domestic hot water. Like most, my furnace has tankless hot water and just does not keep up. It is just a nuisance. For instance when showering the hot water will gradually get cool, thus causing us to step out of the water for a couple of minutes to allow the hot water to catch up. A series of plumbers have done my annual service and I always mention. When they leave I am told that it should be fine now. It is not.
Enter 2017 and I asked the Internet. The aquastat controls this stuff and I always thought the high setting on the aquastat was the maximum water temperature setting and the low setting was the lowest temperature the water temp would go to. Simple. I was wrong. The Internet told me most plumbers do not understand this and just leave settings at default. I checked mine. Set at default.
An aquastat has at least 4 settings. High setting and high setting differential and low setting and low setting differential. It is the low setting and differential that controls domestic hot water. In fact if you don’t have a tankless hot water system the low setting should be disabled.
The Internet told me how to properly set and after 23 years the nuisance is gone. There is a lot to understand so I am not going to repeat what I did, but if you have a similar issue, ask the Internet. Smart rascal.