It's better to have a balanced tank of water, most everyone pulls from the bottom. Returning the cold water to the top helps to balance the tank. It's also aids in circulation of heat in the water inside the tank, it helps eliminate "cold spots" in the tank, all are thinks you don't want.
If your only worried about having the top portion of water hot, then why do we need the water at the bottom? I think in thinking of it in that matter would be like saying I have a 100 gallon boiler, but only use 60 of the gallons
I have helped a couple home made guys who were pulling from the top fix circulation issues by switching that around, some of those problems included boiling in the front part of the stove and 140 in the back.
Also, if your boiler was set at 170 and that's what the water was at the top, you sure would t want cooler water surrounding the firebox at the bottom, that would cause moisture in the wood to possibly gather on the cooler firebox walls vs going out the stack
That's a good explanation. Thank you!
Keeping all that in mind, where is the best location to install the aquastat? And what are the advantages and/or disadvantages of a dry well versus a wet style aquastat? Maybe there's only one kind available now, I'm remembering my short 'career' as an oil burner tech in the early 80's!
I'm still on the fence regarding buying or building a unit. Being a welder/fabricator by trade, I'm sure I could put one together. Whether or not it would operate with any degree of success is what's holding me back. Firebox size in relation to waterjacket size is another point of question for me. All I can do is try and copy a unit from a manufacturer that's given me a quote on a specific unit that he says will work for my application.
I'd like to do grates with air under fire as well, but a lot of people have told me that the grates, no matter how heavily built, will just deteriorate over time and not to waste my energy building them.
I thought I had an 'ace in the hole' so to speak. I found a guy locally that built quite a few boilers for friends and family. He has been successful I guess, but in talking to him, he told me of some problems he had early on with them. He pulled his water off the bottom and returned it to the top but couldn't get more than 150 degree water at the house. In checking his water jacket with an infrared temp finder, he found a vast difference in water temp from the top of his boiler to the bottom, so much so that the water was boiling at the top and 150 degrees at the bottom. So he reversed his lines and started pulling the water from the top and it solved his problem. THEN he showed me pics... His firebox was half as long as the waterjacket and the firebox was within 3" from the top of the waterjacket as well. He had to build a little 'tower' on top of the water jacket and he fills it to the top of that tower. This makes the waterjacket FULL all the time and expansion of evaporation takes place in that little tower. To me, what he has done is NOT a solution. He has to add water about once a week to keep the waterjacket full and the firebox completely submerged.
I want to do this right if I'm going to do it, and I only want to do it ONCE. Any suggestions or advice anyone can throw my way will make me eternally grateful to you!