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Whether to turn home machines on and off or leave on all the time

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  • #16
    Re: Whether to turn home machines on and off or leave on all the time

    Hi Paulo,

    last SSR I brought was from Radio Parts in Melbourne but I am fairly sure Jaycar carry them as well.

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    • #17
      Re: Whether to turn home machines on and off or leave on all the time

      Thanks BF,
      Was hoping that someone could point me towards a thread. Looked at Jaycar but cant find a 25 amp jobby....which I think I will need for a 15amp machine.

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      • #18
        Re: Whether to turn home machines on and off or leave on all the time

        Gosh you want all the work done   At the risk of incurring the mod squad link to an 40A SSR http://www.radioparts.com.au/ProdVie...ID+STATE+RELAY  

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        • #19
          Re: Whether to turn home machines on and off or leave on all the time

          how does it work? I know what a relay does in a car for example for headlights/spotlights but how is it going to save contacts here...I cant think of it.

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          • #20
            Re: Whether to turn home machines on and off or leave on all the time

            Originally posted by 54414858544F4F3B0 link=1244161210/18#18 date=1244285109
            how does it work?  I know what a relay does in a car for example for headlights/spotlights but how is it going to save contacts here...I cant think of it.
            Gday Oz,

            Its a question of current mate. Each time the p/stat opens its contacts, an arc forms for a short time and this vaporises a small amount of the parent copper/silver from the contacts each and every time. Eventually, the contacts are eroded to a point that they no longer make very good contact when closed such that the current flowing through them causes them to heat significantly. This rapidly escalates to a situation where enough heat is generated that the contacts can autogenously weld together, causing the runaway boiler syndrome and the eventual operation of the Boiler Safety Valve.

            Since the SSR has no moving contacts but solid state switches, the current flow is simply turned On and Off via the application/removal of a very small control current. In essence, these devices do not wear out and if properly rated for the job, will last the lifetime of the machine. The contacts on the p/stat are only used to switch the control current On and Off which is so small and at such a low voltage, no erosion of the main contacts occurs. The weak point of the p/stat then becomes the mechanical levers (which shouldnt wear if properly lubricated) and the diaphragm which are very easy and cheap to replace.

            Thats it in a nutshell Oz.... Hope that is as clear as mud

            Mal.

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            • #21
              Re: Whether to turn home machines on and off or leave on all the time

              Originally posted by 786D6474786363170 link=1244161210/18#18 date=1244285109
              how does it work?  I know what a relay does in a car for example for headlights/spotlights but how is it going to save contacts here...I cant think of it.
              Opps! Mal types faster then me! Anyway;

              It basically works like a transistor. Well it is a bit more complicated.
              http://en.wikipedia.org/wiki/Solid_state_relay

              So instead of moving a piece of metal to touch another (relay or pressurestat) you are turning on and off a transistor (MOSfet to be more accurate).
              They a very useful for turn on and off high currents like an element in a coffee machine.

              Other than Radio Parts you could try Farnell (expensive).
              This place doesnt sound too bad:
              http://www.oceancontrols.com.au/relays/relays_relaycards.htm
              Could always do the Evilbay thing.

              Do forget you will also need to get a heat sink. SSRs usually drop 2 volts across them. Doesnt sound a lot but if your element takes 15 amp the SSR needs to dissipate 30Watts (15amp x 2 Volts).

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              • #22
                Re: Whether to turn home machines on and off or leave on all the time

                Thanks Gents. I appreciate it. Before i asked I could see that you would have to trigger the relay with a trip wire - small diameter low current and have the relay send normal high current to the boiler...but I couldnt see how that would help the switching of the pressurestat reduce. Now, thanks to your assistance I see that the switching of the pressurestat is the same but because the current used is much smaller it doesnt eat the contact points anywhere near the same...CHEERS

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                • #23
                  Re: Whether to turn home machines on and off or leave on all the time

                  My machine is a 95 model. I have had it for a while running pretty much all the time and before that it ran for 6-8 hours a day but didnt pull more than a couple of doubles a day save for the odd occasion when it pulled coffees for 50 or so....so mine has obviously lasted 14 years....and counting. So the question is how much are the pressurstat contacts or box (the diaphragms being very cheap and easy to replace) to replace. For example if you have to do one every 20 years in a big commercial machine and they cost $200 say (guessing because i dont know whether the whole box gets replaced and if so the cost) isnt that pretty good value and doesnt it mean that a $100 odd relay may not make sense? Also i know if motor vehicle applications relays burn out (even good ones) eventually....(so would it last longer than 14-20 years say?

                  Cheers

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                  • #24
                    Re: Whether to turn home machines on and off or leave on all the time

                    Hi again Oz,

                    Commercial machines in a commercial situation would benefit from such a simple mod as it it reduces the list of components that are likely to fail in service. With your particular machines history, the p/stats contacts may still be quite OK but the diaphragm could be another matter and might benefit from replacement.

                    The cost of acquiring and fitting SSRs though mate would come in at much less than $200. It is an easy matter to purchase 40A Industrial Grade units for less than $30 each and providing you can identify a clean metal location to mount them, separate heatsinks wont be required either. Im sure that someone like "AngerManagement" wouldnt mind doing the job for you, for the cost of a couple of great brews ;D ....

                    Anyway mate, let me know if you think you want to go ahead with something like this and I can point you in the right direction for parts acquisition at the right price.... 8-)

                    Cheers,
                    Mal.

                    Comment


                    • #25
                      Re: Whether to turn home machines on and off or leave on all the time

                      Originally posted by 466B6F636E020 link=1244161210/23#23 date=1244291056
                      and providing you can identify a clean metal location to mount them, separate heatsinks wont be required either.
                      Cheers,
                      Mal.
                      Whats wrong with me? Dont answer. ;D
                      Thats what I did when I PIDed my Silvia.

                      Also over rating the SSR will probably help in this matter.

                      Comment


                      • #26
                        Re: Whether to turn home machines on and off or leave on all the time

                        There is only a small cost increase to go to a 40A SSR from a 25A one so dont scrimp Also grab a tube of heatsink compound when mounting it to the chassis to help with heat transfer to the chassis (pick a cool spot away from the boiler and group/s)

                        Back on topic a little the other main part in the equation here is the element they also have a cycle life so less cycles here is a good thing. Insulation and if you are fitting up an SSR then grab an electronic timer and fit it up to the SSR as well and have it turn off just the element for times you dont need it. Fitted with a manual overide this will drop the on time by heaps for not much money.

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                        • #27
                          Re: Whether to turn home machines on and off or leave on all the time

                          Thanks Mal - yep I understand because the commercial ones would have the pressure stat contacts clicking in and out much more often.

                          I changed the diaphragm about 6 months ago I guess - I posted up photos on my FAEMA Value thread if your interested. It didnt make a whole lot of difference but it did close the on and off gap a little. I actually kept the old one because frankly it looked better built (thicker and better material I suspect) than the new one and was still pliable).


                          I see Coffeeparts has the complete pressurestat www.coffeeparts.com/faema/faema24.html for $89 so I think when it wears out that will do me. I appreciate the offer though mate.

                          Cheers

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                          • #28
                            Re: Whether to turn home machines on and off or leave on all the time

                            Originally posted by 25222629212B3E2E2920470 link=1244161210/25#25 date=1244329144
                            There is only a small cost increase to go to a 40A SSR from a 25A one so dont scrimp
                            Theres no real need to use a 40A unit in 99% of domestic situations and with some devices, over-rating by too high a percentage causes its own problems with reliable switching. I think a 25A unit is more than enough for the average 1,200-2,000W element.

                            Originally posted by 25222629212B3E2E2920470 link=1244161210/25#25 date=1244329144
                            Also grab a tube of heatsink compound when mounting it to the chassis to help with heat transfer to the chassis (pick a cool spot away from the boiler and group/s)
                            Absolutely, forgot to mention that one.... :-[

                            Mal.

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                            • #29
                              Re: Whether to turn home machines on and off or leave on all the time

                              Originally posted by 4F5A53434F5454200 link=1244161210/26#26 date=1244336191
                              I see Coffeeparts has the complete pressurestat www.coffeeparts.com/faema/faema24.html for $89 so I think when it wears out that will do me.  I appreciate the offer though mate.
                              Yeah, fair enough Oz. Theyre not very expensive and its probably not price alone that most owners would opt for the SSR option with these.

                              Cheers mate
                              Mal.

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                              • #30
                                Re: Whether to turn home machines on and off or leave on all the time

                                Originally posted by 1934303C315D0 link=1244161210/27#27 date=1244363431
                                Theres no real need to use a 40A unit in 99% of domestic situations and with some devices, over-rating by too high a percentage causes its own problems with reliable switching. I think a 25A unit is more than enough for the average 1,200-2,000W element.

                                Hi Mal,

                                private chat going on behind the scenes Paulo has a 2GR aas well

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