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A complete failure to understand the task at hand

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IanB:

--- Quote from: tooki on December 05, 2021, 02:49:44 pm ---Again, depends on the purpose: if it’s heating water for space heating (or for space heating and hot water), it’s called a boiler. If it’s heating water only to give you got water out of the faucet, it’s typically called a “water heater”.
--- End quote ---

It's generally the same in the UK. The most common form of central heating is with hot water to radiators, and then the boiler is used both for heating and hot water.

Other forms of central heating do exist, including forced air, in which case there would need to be a separate water heater. In this case it would be called a water heater and not a boiler.

Central air conditioning is not typically found in UK homes, so you don't have "HVAC" systems, you just have "heating" systems.

The big advantage I see with furnace hot air systems in the USA is that they are readily combined with central A/C units for cooling. Warm air circulation in winter, cool air circulation in summer.

james_s:

--- Quote from: tom66 on December 05, 2021, 09:48:54 am ---Is it not an AC start/run capacitor?  The charge across the start capacitor should be pretty close to zero once the centrifugal switch re-engages, which would happen reasonably quickly (and the motor wouldn't spin, and the cap wouldn't charge, if the switch was defective.)  The run capacitor (if present) should be discharged nearly immediately.  Both are effectively shorted out by the windings of the motor.

Still, using an insulated screwdriver is pretty special...

--- End quote ---

Furnace blowers typically use PSC motors so the capacitor remains in operation whenever the motor is running, I've never seen one with a motor that had a centrifugal switch. The last couple that I've installed have BLDC motors which are much more efficient, especially at low speeds, although I do have some concerns about reliability. The industry calls them ECM motors.

It's possible that he's bridging the terminals with the (non-insulated) tip of an insulated screwdriver.

james_s:

--- Quote from: IanB on December 05, 2021, 05:35:25 pm ---The big advantage I see with furnace hot air systems in the USA is that they are readily combined with central A/C units for cooling. Warm air circulation in winter, cool air circulation in summer.

--- End quote ---

That is exactly the main advantage, in my case I have both a gas furnace and a heat pump, a so-called "dual fuel" system where the furnace serves as the air handler for the heat pump. Another advantage of forced air is that it can rapidly warm up a cold house, you turn it on and you have nice warm air blowing out of the registers almost immediately whereas with a hydronic system it takes quite a while to get going. On the flip side, the temperature tends to be a lot less even, going above and below the setpoint as the furnace cycles on and off. The thermal mass that makes a hydronic system slow to respond also makes the temperature very consistent and even. The best of both worlds would be hydronic radiant floor heating combined with a forced air heat pump for cooling and supplementary heat.

james_s:

--- Quote from: tooki on December 05, 2021, 02:49:44 pm ---Again, depends on the purpose: if it’s heating water for space heating (or for space heating and hot water), it’s called a boiler. If it’s heating water only to give you got water out of the faucet, it’s typically called a “water heater”.

--- End quote ---

It is a little more complicated than that. It is common to use a conventional tank style hot water heater for dual purpose, supplying hot water to plumbing fixtures and hydronic heating loops using a circulating pump. I've been told it's against code in the UK to use potable water in hydronic heating but it is apparently allowed here. We have boilers here too, very much like the ones that are so common in the UK and other parts of the world, my grandparents house was heated by a boiler supplying radiators but they are rare, theirs was the only house I'd ever seen in this region with such a system until maybe 10 years ago when radiant floor heating started to get popular.

jonovid:
in the video insulated screwdriver tip was NOT used but the insulated stem of the  screwdriver
also you can use the  screwdriver tip on the gap of the two pins before removing any wires or clips

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