Storage Heater Education Unit advice needed for design.

kondormid

Hello fellow money savers, sorry if this goes on a bit.
My newish hobby is electronics, it is something I know a bit about but due to the fact I am no longer very mobile I have decided to get deeper into it. People who like electronics as a hobby are constantly looking for problems they can throw circuits at in the hope of solving them. My parents have storage heaters in their house. They are using them wrong. I found this out last night when I read about how you should turn the output off during the night. I helped them set them up and I thought I knew how, but apparently not. There must be thousands of houses and flats using these things that are using them wrongly.

So I have set myself a little project. To make a box that tells the owner what last nights lowest room temperature was, this should help them get the input temperture right. Also to tell the user if they need to turn their output up or down.

At the moment, this is the design I am thinking of creating...

Basically, it is a room thermostat that gives you informaton. The unit will have a number display, showing last nights low, because we are only after the lowest reading a simple photocell to sense light will do to indicate night.

It will have three LED lamps. Red, green and blue...
If temp is lower than 19 degrees light a blue LED.
If temp is higher than 22 degrees light a red LED.
If temp is between 19 and 22 then light a green LED.

The reason I have choosen to use three leds rather than an actual temperature reading for the daytime is because I know storage heaters can be a pain to set an exact room temperature, so rather than someone aim for 21 degrees I thought a range would be better. You can drive yourself mad trying to get an exact temperature with them, but I feel that most people would just end up giving up and settling for too warm and then opening doors/windows to cool the place down when needed. So that is the reason I choose a range over exact temperature.

I need some feedback,
do you like this idea?
would you be willing to try and make one or get someone to make one for you if the instructions were simple enough?
Do you agree with a temperature range of 19 to 22 ?

If you can think of any simple improvements let me know.

For those a bit more techy, this will most likely be a PIC based project using an LM35 as a temperature sensor. If you are techy and think this is a good/bad direction let me know.

Thanks to all those that read this far, lets try and save some people some money.

rogerblack

Several issues.
Firstly - most people shouldn't operate storage heaters like this - it implies that they are still producing heat overnight - and for economy reasons the temperature should be allowed to fall when the occupants are asleep.

Secondly - there are many thermometers with a 'max/min' feature, that reset daily.

kondormid

Thanks for the speedy reply rogerblack.

Just for clarification the idea of the min temp reading for the night time was so the user could confirm that the temperature was dropping during the night, the goal being to get it as low as possible whilst still having a medium daytime/evening temperature Sorry if I made it sound like the objective was to keep the room warm during sleeping hours. It is not. It is just my own experience at my parents house that they tend to have the outputs closed all day (when they are in) and then at night the things get even hotter and so the rooms get even hotter.

Agreed about the min/max feature available on many thermometers, the idea of this is slightly different. The display will just show the min night (when a button is pressed as not to misslead) and there will be three leds of differing colours to indicate if the current room temp is low/medium/high.

Do you use storage heaters yourself? I am interested how you get on with your min/max thermometer and how you use it to get the best value out of your heaters.

grahamc2003

Just a few immediate thoughts .... imo .. you need a 24 hour strategy indicating both the input and the output settings. The input setting is a function of the next day and night's temperature, not yesterday's! The output is a function of the current room temperature. Also, on some heaters, the output is more 'intelligent' i.e. it responds to room temperature. So eg if the room temp is 26C, then setting the output to 3 from 0 will likely result in the dampers not opening at all, whereas if the room temp is 12C, then setting to 3 from 0 may result in the dampers openng (the control is via a simple mechanical linkage).

Mostly, if the forecast is for temps below 5C min, then the living room SH input typically wants to be on max, as a very rough and ready guide. Similarly, if above 20C max, then off, with probably a linear setting between the two, as a first approximation until some experience is gained on the particular setup. I can't see any reason for the output even being above 0 after the occupants have gone to bed (the heaters will give out quite a bit of heat even on 0 - the output only control the convective heat, not the radiant which is uncontrollable).

Obviously, being based on forecasts, the strategy will fail sometimes, but, imo, there is no better way of driving storage heaters efficiently.

kondormid

grahamc2003, I really need to pay more attention to how much the temperature can jump during the day from one to the next.

Do you think this would be a better idea?
User enters tommorows forcast using a toggle, as they do this the unit calculates what percentage the input should be at. <5C = 100%, >20C = 0%. Dropping 6.67% for every degree that is forcast above 5C.

Suppose it couldn't hurt me to build one and throw it up at my parents to see if they like it. Bring back coal, all is forgiven.

grahamc2003

kondormid wrote: »

grahamc2003, I really need to pay more attention to how much the temperature can jump during the day from one to the next.

Do you think this would be a better idea?
User enters tommorows forcast using a toggle, as they do this the unit calculates what percentage the input should be at. <5C = 100%, >20C = 0%. Dropping 6.67% for every degree that is forcast above 5C.

Suppose it couldn't hurt me to build one and throw it up at my parents to see if they like it. Bring back coal, all is forgiven.

alternatively, you could have

0<= %input setting <=100 = -(6.67xForecast temp) + 133

kondormid

Thanks grahamc2003, all works good. Gonna take a few weeks to bundle together due to a new programmer on the way ect. Will post a vid of it working when done.
(-(6.67 x 20)) + 133 = -0.4
(-(6.67 x 15)) + 133 = 32.95
(-(6.67 x 5)) + 133 = 99.65