kenc_zymurgy
Well-Known Member
Here's my 3rd, and last question on the subject (until I do more research!) on my Electric Brewing plans:
I assumed I'd be using SSRS to control a 1650 ~2250W element, like most brewers. I have some experience with SSRs on other projects, and I know that heat-sinking is critical when you get up to tens of amps. And that many of the cheap ebay/ali-express units are counterfeit (seems mostly authentic units, but a 10 Amp unit is relabeled as a 40 Amp?). So for > 20 Amp SSR, I'd want to buy from a major US distributor, and those aren't cheap. Plus heat sinks.
Then it occurred to me that the relay/contactor for a home A/C unit ( 20 ~ 40 A @ 240V) cycles a few times an hour for several months for years. I did some research, and for < $15 these are rated for 100,000 cycles. And they are dual pole, so could be used on 240 V as well, and I could parallel the contacts for 120V, which should further prolong life.
https://www.arrow.com/en/products/t92p7d22-12/te-connectivity ( 3 minimum, < $40 with shipping to me)
Some math - per brewing session, 1 cycle to heat the strike water, 1 cycle to heat the sparge water, and 1 cycle to get to a boil. Not sure how many cycles to control a 60 minute boil, but I'd guess that a 10 second period ( X seconds ON, 10-X seconds OFF) would be more than fast enough to maintain a consistent boil. So that is 6 cycles per minute, and 360 + 3 cycles per brew session. round up to 400, is100,000/400 = 250 brews. That's beyond my lifetime (I'm a geezer).
So I'm thinking the mech relay has advantages for this sort of set-up (not for a RIMS/HERMs though, I think those need faster switching and/or true PWM?). Other advantages are fully OFF (no leakage current from SSR). And typical failure is OFF rather than ON for an SSR?
I'm competent enough with Arduino programming, that I could easily set up a $4 Pro-Micro for 0~100% duty cycle on one pot, and the time period on another. I'd include some safety start ups, and a safety time out (I have his nightmare that I get locked out of the house with my pots on!).
About the only con I can think of is hearing the relays clunk on/off every 10 seconds for an hour, but I usually wander in/out during the boil, so I don't think that will bug me too much.
Anything else I'm missing?
I assumed I'd be using SSRS to control a 1650 ~2250W element, like most brewers. I have some experience with SSRs on other projects, and I know that heat-sinking is critical when you get up to tens of amps. And that many of the cheap ebay/ali-express units are counterfeit (seems mostly authentic units, but a 10 Amp unit is relabeled as a 40 Amp?). So for > 20 Amp SSR, I'd want to buy from a major US distributor, and those aren't cheap. Plus heat sinks.
Then it occurred to me that the relay/contactor for a home A/C unit ( 20 ~ 40 A @ 240V) cycles a few times an hour for several months for years. I did some research, and for < $15 these are rated for 100,000 cycles. And they are dual pole, so could be used on 240 V as well, and I could parallel the contacts for 120V, which should further prolong life.
https://www.arrow.com/en/products/t92p7d22-12/te-connectivity ( 3 minimum, < $40 with shipping to me)
Some math - per brewing session, 1 cycle to heat the strike water, 1 cycle to heat the sparge water, and 1 cycle to get to a boil. Not sure how many cycles to control a 60 minute boil, but I'd guess that a 10 second period ( X seconds ON, 10-X seconds OFF) would be more than fast enough to maintain a consistent boil. So that is 6 cycles per minute, and 360 + 3 cycles per brew session. round up to 400, is100,000/400 = 250 brews. That's beyond my lifetime (I'm a geezer).
So I'm thinking the mech relay has advantages for this sort of set-up (not for a RIMS/HERMs though, I think those need faster switching and/or true PWM?). Other advantages are fully OFF (no leakage current from SSR). And typical failure is OFF rather than ON for an SSR?
I'm competent enough with Arduino programming, that I could easily set up a $4 Pro-Micro for 0~100% duty cycle on one pot, and the time period on another. I'd include some safety start ups, and a safety time out (I have his nightmare that I get locked out of the house with my pots on!).
About the only con I can think of is hearing the relays clunk on/off every 10 seconds for an hour, but I usually wander in/out during the boil, so I don't think that will bug me too much.
Anything else I'm missing?