Heating Control

I have been thinking for some years now that I would like to have finer control over my central heating.

The problem
Now we are older we feel the cold more so in winter the heating is on all the time. This means that we have to keep altering the thermostat on each radiator at different times of the day or just leave them and so waste energy. One method means wasting energy but the other means rooms will be colder than we want initially.
The system and what i have
We have a combination boiler which has a digital timer and also on the panel are temperature controls for hot water and radiator temperature. Each radiator has a thermostatic valve so each room can have it's temperature set independently. I have a computer which runs 24/7 and also a bit whacker which I can control via python code and electronics has been a hobby for over 50 years

My idea
I would like to have some system which would allow me to adjust each room temperature via computer control.
Possible solutions
Solution 1
Fit a stepper motor to each thermostatic valve to adjust it at different times of the day/night.
This would allow precise control but would be quite expensive to set up.
Solution 2
Fit a small structure round each valve with a filament bulb or resistance wire in the bottom so that when power is applied to it then the temperature around the valve will rise and so the valve will close or, at least partially close.
I think this would be much cheaper to implement but would have the small on-going cost of using power to the bulbs whenever the room temperature needs to be cooler that it would normally be.

My initial plan
Build a small structure around one of the valves with a low voltage bulb in it. It would have vents at top and bottom and so air would circulate. I have a portable digital thermometer so i could gather information and try different bulbs to see how much power would be needed and therefore what the on-going cost would be. Also try various shapes of structure to see what the effect would be.

So guys what do you think?

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Roxer8 years ago
Have you considered a CM Zone system? It uses wireless signals to an HR80 wireless controller on each radiator. It also aggregates demand from radiators to optimise boiler firing. You can switch radiators between zones at any time in the future.  See www.cm-zone.com
buteman (author)  Roxer8 years ago
Hi Roxer,
No, I had not even heard of them. So I have had a look and as far as I can see I would need 3 controllers and 9 valves costing £873.57 plus delivery.
I think that I can do it the way I propose way cheaper than that.
Sure each will need wiring but there will be no plumbing to do.
Thanks for the thought though.

lemonie8 years ago
If you're not leaving the house empty for long periods I suggest this instead:

Turn the radiator water temperature right down, around body temperature. Leave the heating on continuously 24/7. Yes I've done it, and it works.
The boiler trickles heat in through intermittent burns, the place stays the same temperature all the time.
Hot/cold cycling will only save you energy with long off-times. See how much fuel the boiler burns up in the morning - think about that keeping the place topped-up overnight instead.

buteman (author)  lemonie8 years ago
I can see where you are going with this but I do not feel this would work as you describe.
Let's say I want to keep the bedroom warm from 22:00 to 09:00 = 11 hours.Then it can cool down over the next 13 hours. Similarly our living room would be kept warm from 08:00 to 22:00 = 14 hours. Then it can cool for 10 hours. and so on for the other rooms. Even with just those 2 it means that energy only needs to be used for part of the day. Having the water temperature low in the radiators only means the room will heat up more slowly it will not save energy. So having the unused rooms cooling down for a while will save some.
lemonie buteman8 years ago
The rooms will not heat up or cool down, they maintain their temperatures. If you're both not out of the house for half the day why let it cool down? You have to pump a lot of heat in to get it up, then it dissipates through the walls, windows, roof and the cycle starts again.
The view is: how much energy does it take to "thaw something out" against keeping it warm. You're losing heat continuously until the building is stone-cold (then you start saving). I'm thinking that one/both of you are in more than you're out, but I may be wrong there?

buteman (author)  lemonie8 years ago
If the room starts cooling down at say 22:00 the it will cool fastest during the 1st hour. As time goes by it will cool more slowly. It depends on the difference in temperature between the room and the outside as to how fast cooling occurs. the rate is not linear. In the 1st 4 hours the temperature will have dropped by a greater amount than the next 4. Similarly when it starts to warm up it will warm up faster during the 1st 4 hours than during the next 4. While the heating is not on you are saving heat. I do not think it would take more heat in all that time to heat it back up as leaving it at a steady temperature as the steady temperature would be at the level of the highest difference between outside and inside. Of course the way to find out the actual values would be for me to build a little interface to my Bit Whacker which I can use to monitor the temp in a room overnight if I turn the heating off.  I have not built one before but i think it would be pretty easy to do.

I think I could feed a diode with a constant current and use one of the Bit Whacker pins as an analogue input and read off the voltage values and log them to a file. I will try to find time during the next week to do that and then report back.
If anyone has any other thoughts in the meantime please let me know.
I was going to say I don't want to build something for nothing but a thermometer like this would be useful for other things - like monitoring our greenhouse temp.

Great another use for the Bit Whacker!!!!!!

lemonie buteman8 years ago
All the heat that goes out has to be put back in. While the boiler is not burning you are not using fuel, but this doesn't necessarily equate to saving heat, as it will still burn heavily when it turns back on. And one has to consider comfort levels as well.

buteman (author)  lemonie8 years ago
it is true that you need to put heat/energy back in the bring the room back up to temp. If you maintain an even temp all night then you are maintaining equilibrium so what goes out is balanced by what you put in. If the outside temp drops you get more heat going out so you have to put more in to keep the temp the same.
If you, instead, stop putting heat in the the temp in the room goes down. The greater difference between the inside and outside the faster the transfer of heat so as time goes by the rate of loss of heat goes down as the temp difference is getting less. While you are not maintaining the temp you are using no heat/energy.
When you want to bring the temp back up you do indeed need to add more heat. Imagine you want to just put exactly the same amount of heat back in per minute as you were doing to maintain the temp. Now your room temp will still rise until what you put in is balanced by what goes out. In practice the thermostats put more heat in per minute initially but and it's a big BUT only for a shorter period of time.
therefore you do save heat.

buteman (author)  buteman8 years ago
Just to point out that I am trying to regulate the temperature of each room independently so that each room is at a comfortable temp at any time we are using it. We tend to be in a room for the same periods of time each day but by controlling it via a computer program I would be able to have a virtually infinite range of control day to day and hour to hour.
lemonie buteman8 years ago
What about plumbing-in solenoid valves? Thermostatic valve one end, electrically-operated the other (of radiator)

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