Thermostat + Timer
in [Design]
|
From: Charlie E. on 15 Oct 2009 14:44 On Thu, 15 Oct 2009 09:31:35 -0700, Jim Thompson <To-Email-Use-The-Envelope-Icon(a)My-Web-Site.com> wrote: >>I would imagine the losses could be quite large unless the pipes are >>well insulated. > >They're not insulated at all :-( > >At some point in time I should re-tile the house and, in the process, >re-pipe will suitable insulation and containment (for easier repair). > > ...Jim Thompson \ Well, in our new house, they ran all the supply plumbing overhead, but it is that flexible plastic pipe, like small, high pressure hose. I 'think' that the house insulation surrounds it, but it isn't really well insulated. Of course, in the summer, our 'cold' water is more like 100 degrees, since the water filter out in the garage gets to that temperature, as well as the water in the overhead. We don't use much hot water for showers in the summer, just the washer and dishwasher... Charlie
From: Jim Thompson on 15 Oct 2009 14:48 On Thu, 15 Oct 2009 11:44:59 -0700, Charlie E. <edmondson(a)ieee.org> wrote: >On Thu, 15 Oct 2009 09:31:35 -0700, Jim Thompson ><To-Email-Use-The-Envelope-Icon(a)My-Web-Site.com> wrote: > > >>>I would imagine the losses could be quite large unless the pipes are >>>well insulated. >> >>They're not insulated at all :-( >> >>At some point in time I should re-tile the house and, in the process, >>re-pipe will suitable insulation and containment (for easier repair). >> >> ...Jim Thompson >\ >Well, in our new house, they ran all the supply plumbing overhead, but >it is that flexible plastic pipe, like small, high pressure hose. I >'think' that the house insulation surrounds it, but it isn't really >well insulated. > >Of course, in the summer, our 'cold' water is more like 100 degrees, >since the water filter out in the garage gets to that temperature, as >well as the water in the overhead. We don't use much hot water for >showers in the summer, just the washer and dishwasher... > >Charlie Same here, but it's all under-slab (and copper :-( ...Jim Thompson -- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.
From: Baron on 15 Oct 2009 15:13 Jim Thompson wrote: > On Thu, 15 Oct 2009 16:59:41 +0100, baron > <baron.nospam(a)linuxmaniac.nospam.net> wrote: > >>Jim Thompson Inscribed thus: >> >>> On Thu, 15 Oct 2009 15:52:50 +0100, baron >>> <baron.nospam(a)linuxmaniac.nospam.net> wrote: >>> >>>>don <don> Inscribed thus: >>>> >>>>> baron wrote: >>>>>> Hi Guys, >>>>>> >>>>>> I'm doing a hobby project to build a timer that can be used to >>>>>> turn on a relay at a pre-determined time and then turn it off >>>>>> after a delay. I also want to use a temperature sensor to >>>>>> override the relay but only during the time period that is >>>>>> programmed. >>>>>> >>>>>> The idea is to turn on a water heater for a pre-determined period >>>>>> but to use a thermostat to control the temperature during this >>>>>> period. >>>>>> >>>>>> I have suggested using a relay because the heater is rated at >>>>>> 3.5Kw 240/250 volts, 50hz AC. Low voltage relays are available >>>>>> that can handle this load with ease. The heater has a safety >>>>>> cutout built in that should prevent boiling dry. >>>>>> >>>>>> I am aware that I can buy programmable motor driven timers very >>>>>> cheaply, however they are limited in contact loading and I would >>>>>> still need a relay for thermostat control. >>>>>> >>>>>> I thought this might make a nice PIC project. (Ducking) :-) >>>>>> >>>>> >>>>> I have built and programmed a battery backed clock chip and a >>>>> PIC16F628, attached to a RS-232 serial port. >>>>> >>>>> I am sure this can be modified to add a relay driver. >>>>> >>>>> Let me get the docs together sometime this weekend. >>>>> >>>>> don >>>> >>>>Thanks. I'll take any help I can get. >>> >>> Doesn't the hot water heater already have its own thermostat? >> >>No ! Just an over temp non reseting cutout. >> >>> Thus all you would need would be ON/OFF. >>> >>> Has anyone tallied up power consumption for such an ON/OFF, >>> COOL-DOWN/WARM-UP type of operation? >>> >>> I have recirculating hot water here... big loop around the house and >>> back to the water heater, pushed by a pump (Bosch). So you get >>> instant on hot water. And also big heat losses in the underground >>> loop. Since the water heater is well-insulated, I'm tempted to >>> simply turn off the pump (with a timer) in off hours. >>> >>> ...Jim Thompson >> >>I would imagine the losses could be quite large unless the pipes are >>well insulated. > > They're not insulated at all :-( > > At some point in time I should re-tile the house and, in the process, > re-pipe will suitable insulation and containment (for easier repair). > > ...Jim Thompson Ouch ! Big losses there. -- Best Regards: Baron.
From: Baron on 15 Oct 2009 15:22 Jan Panteltje wrote: > On a sunny day (Thu, 15 Oct 2009 17:07:29 +0100) it happened baron > <baron.nospam(a)linuxmaniac.nospam.net> wrote in > <hb7hc1$k6i$3(a)news.eternal-september.org>: > >>Jan Panteltje Inscribed thus: >> >>> On a sunny day (Thu, 15 Oct 2009 13:46:48 +0100) it happened baron >>> <baron.nospam(a)linuxmaniac.nospam.net> wrote in >>> <hb75jp$pc8$1(a)news.eternal-september.org>: >>> >>>>Hi Guys, >>>> >>>>I'm doing a hobby project to build a timer that can be used to turn >>>>on a relay at a pre-determined time and then turn it off after a >>>>delay. I also want to use a temperature sensor to override the relay >>>>but only during the time period that is programmed. >>>> >>>>The idea is to turn on a water heater for a pre-determined period >>>>but to use a thermostat to control the temperature during this >>>>period. >>>> >>>>I have suggested using a relay because the heater is rated at 3.5Kw >>>>240/250 volts, 50hz AC. Low voltage relays are available that can >>>>handle this load with ease. The heater has a safety cutout built in >>>>that should prevent boiling dry. >>>> >>>>I am aware that I can buy programmable motor driven timers very >>>>cheaply, however they are limited in contact loading and I would >>>>still need a relay for thermostat control. >>>> >>>>I thought this might make a nice PIC project. (Ducking) :-) >>>> >>>>-- >>>>Best Regards: >>>> Baron. >>> >>> You can make a nice zero crossing power switch for 240 V with a >>> MOC3041, driving a TIC263M triac, that one can do 25 A continuous >>> (use heatink). The MOC3041 needs 15 mA, PIC can drive that, the >>> MOC3042 10mA, and the MOC3043 needs only 5mA. Just did one last >>> week. What sort of temp sensor are planning to use? >>> Immersed in the water? >> >>Hi Jan, >>That heatsink would be live I guess ! I wouldn't want to compromise >>safety at all. The temperature sensor I was just going to clamp to >>the bath lip or I could clamp it to the heater fixing. >> >>-- >>Best Regards: >> Baron. > Well I hope you mount the heatsink in some double isolated housing. > You could use temp_pic: > http://panteltje.com/panteltje/pic/temp_pic/ > as a temprature sensor if you keep it dry, > and drive the opto triac from it. > And you can monitor temperature on the PC if you want. > Only an 8 pin PIC... > You will need a 5 V supply too. > Could all be a very small box. > I use temp_pic as room thermostat at the moment. > > 1 PIC 12F629 > 1 opto triac MOC 3041 > 1 power triac TIC263M > 1 78L05 5V regulator > some resistors, some capacitors, a small met heatsing, and a poly box. > You could even feed it with a series C+R+bridge, > and do optional RS232 out with an optocoupler, no transformer needed. That looks interesting ! Thanks: -- Best Regards: Baron.
From: Baron on 15 Oct 2009 15:37
Martin Brown wrote: > baron wrote: >> don <don> Inscribed thus: >> >>> baron wrote: >>>> Hi Guys, >>>> >>>> I'm doing a hobby project to build a timer that can be used to turn >>>> on a relay at a pre-determined time and then turn it off after a >>>> delay. I also want to use a temperature sensor to override the >>>> relay but only during the time period that is programmed. >>>> >>>> The idea is to turn on a water heater for a pre-determined period >>>> but to use a thermostat to control the temperature during this >>>> period. > > Is this a domestic hot water heater to 60-70C stock or a boiler to > 100C? Most electric immersion heaters usually have some thermostat > built in. > >>>> I have suggested using a relay because the heater is rated at 3.5Kw >>>> 240/250 volts, 50hz AC. Low voltage relays are available that can >>>> handle this load with ease. The heater has a safety cutout built in >>>> that should prevent boiling dry. >>>> >>>> I am aware that I can buy programmable motor driven timers very >>>> cheaply, however they are limited in contact loading and I would >>>> still need a relay for thermostat control. >>>> >>>> I thought this might make a nice PIC project. (Ducking) :-) > > You can buy CH timers that could be easily subverted to doing this job > but check the contact ratings carefully. I had not given a thought to central heating timers... I'll have to investigate those ! > But you would probably be a *lot* better off wrapping 10" of > fibreglass insulation around it (preferably the easy handle stuff in a > plastic tube with a mirror finish on the outside), or the mirror > finish bubble wrap if space is a problem. The water in the low loss > hot tank in our Village Hall is still warm enough to be useful the > next morning. Uninsulated it would go cold overnight. I agree. My hot water tank will stay hot for about 24 hours, certainly enough to have a shower before the off peak comes back on. I've only got 3" of foam insulation around that. > Regards, > Martin Brown -- Best Regards: Baron. |