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the phase shift is always 90 degrees. there are some parasitic things that happen that shift it a little, but theoretically it is always 90 degrees. the capacitor acts as a resistor with ac current so it limits the current to the start winding by dropping the voltage.

@ChrisJ

"In a capacitor, the current leads the voltage by 90 degrees. When an AC voltage is applied, the capacitor charges and discharges in response to the changing voltage. As the voltage rises, the capacitor begins to charge, allowing current to flow immediately. However, the voltage across the capacitor builds up more slowly, reaching its peak after the current has already started flowing. Conversely, when the voltage decreases, the capacitor discharges, pushing current out before the voltage drops fully. This creates a phase shift where the current waveform precedes the voltage waveform by a quarter cycle (90 degrees) in an ideal capacitor."

The angle of the phase shift is determined by the interaction of the winding resistance, capacitance, and hertz. This allows the start cap to dump current into the start winding until the voltage reaches the preset level on the start relay. The start relay then drops out the start cap and leaves the run cap in the circuit.

So if the the start cap is to large, it will dump more current than the start winding is rated for before the voltage reaches the required drop out level.

Hard starts are fine-ish. As long as you compare the actual specs on the capacitor and relay to what the manufacture has designed for. That's all they are, a start cap and pot relay in 1 container. The ratings they give them, like 1-5 tons, ect. are garbage.

The compressors are not borderline. The HVAC manufacturer puts them in a borderline envirnment. The Copeland data sheet will tell you exactly what components to use dependant on application.

I recently had to replace a 3 ton compressor out of a York HP. It was an electrical burnout out. As I did my research to determine cause, I found the generic hardstart kit on it had over twice the capacitance allowed by copeland for that compressor. Unit was only like 5 yrs old.

@hot_rod in what world does SIM need a 20* delta? Twelve 1/2" loops at .8 GPM with a 50* delta is 240k. I'm not here to argue or complain, but let's be realistic here. 130* SWT w/ 80* RWT is still going to melt the same amount of snow as 100-80 with a 2.5x flow rate. If I'm not mistaken, I believe I've seen you mention more than once the superior European method of a high delta system. We've adopted 20* as a baseline (mostly because it's easy to calculate), but from a practicality perspective, it serves no purpose in a snowmelt system.

The Kiturami HX has some weird aluminum diverter plates in the SS fire tubes that tend to plug up with scale when running low temp and are just about impossible to clean. I installed a crap load of UFT and Laars Mascot FT from about 2016 to 2020 (hated HTP customer service and switched to Laars, then started seeing these issues come up) and have been kicking my own butt for it on a regular basis. High temp systems and low temp w/ indirect seem to be doing okay, but low temp only have been a nightmare. @Ironman and I have talked about this, I believe he's replaced a few HX as well that were not salvageable

Whether or not it was dumb depends on how the boilers arrive! Certainly if you get 2 new boilers for that price then you got a great deal. Personally I think I would install one and just save the second one in storage. I think the system would be overall more efficient with a single right sized boiler, slightly simpler piping requirements as well so less that can be messed up. Also 2 vents means twice the chances to recirculate flue gas, keep those intakes far away from the exhaust