@sdspieg
Before anybody starts commenting about the HoneyWell EvoHome system, I'm aware off its existence but I excluded it beause of its proprietary protocol and closed nature. Topic starter wants such a system but with full control and open by design.
I think it's a great idea and I allways like crazy and wild plans. But lets step back and look at a domestic heating system for a while. Several factors must be taken into account before deciding on a heating control strategy. First the isolation level and thermal properties of the house. Second the way of heating. Third the layout. And lastly the way the house is being used.
-1- At one end of the isolation spectrum you'll find the passive houses. Upto 4 layers of glass, 20cm of isolation etc. These buildings hardly need any heating and regulations and energy prices will result in more of these buildings. They don't need such a system, the only use I see for such control is when cooling is taken into account. But that complicates things even further.
On the other end are not isolated buildings. Some of them are very difficult to isolate, for example all kinds of monumental buildings. That market is rather small as well. But as an owner of one these cash drains I do think such control system has it's uses.
-2- Nowadays more and more houses have floor and even wall heating as primary heaters. Only some radiators or convectors below large windows. Such heating system has a long reaction time and are more suited to leave at constant temperature. Houses with a low thermal mass are more suited for such desired control. More thermal mass means longer reaction time don't allow for the much differentiation (within reasonable timespans).
-3- Single level houses allow better thermal segmentation than multi-level houses. Warm air always rises. It's therefore more difficult for example to keep cool bedrooms upstairs and a warm living room downstairs with an open stair case.
-4- You're looking a thermal segmentation, if you can keep certain rooms cooler you'll save energy by not heating them. That's my understanding off your idea. Specific rooms should be at a specific temperature at a specific moment. Why heat a bedroom when nobody is there? (Remember the isolation? If you don't lose energy it doesn't cost anything to keep the room at a certain temperature) This won't work if you don't have doors, in a stair case for example. Or if kids leave doors open all the time. How great your control system is, with such disruptive forces in the house it will never work as good as it in potential can.
Are there other ways of efficiently heating your house and only heat what needs to be heated? Sure many. How about this rather conventional approach:
-fit every radiator with a thermostatic valve
-ensure that the entire system is hydraulic balanced
-install a modern energy efficient pump
-apply the above to the floor heating a well if present.
-buy a modern thermostat and depending on the amount off isolation also an outdoor temperature sensor. (better isolation = no sensor)
-place the thermostat in the warmest room and least isolated! set the thermostat to a nice level.
-adjust the thermostatic valves per room AND KEEP the doors shut!!!
The thermostat will signal the boiler that heat is required. All rooms start heating up. One after another the rooms reach their desired temperature. The thermostatic valves will close and more warm water returns. The boiler (not the thermostat) will lower it's heat output because it senses that heat is no longer being transferred by the radiators because the valves are closed. When the warmest room also reaches it's setpoint the thermostat switches the boiler off. But during this last phase the boiler was delivering a reduced heat output. One should not underestimate the sophistication off modern boilers and thermostats. They are very efficient but only when certain criteria are met.
All off the above off course wont work if the inhabitants leave the doors open and forget to set back the thermostatic valve. For example because teenage daughter think it's her birthright to walk a summer outfit 365 days a year.
For those situations (remote) controllable valves will help. Don't get me wrong I could use a few very well.
Lets look at those future valves a bit more carefully. They need to be reliable. You don't want to leave your house in the winter and upon return discover frozen radiators because the nice gizmo valve executed a 10 goto 10, or the batteries are empty or didn't receive a signal anymore because the neighbor got an RF quadcopter for christmas and jams your thermostatic valves. It might sound far fetched but it isn't. I know two hvac companies which refuse to install RF thermostats. All the interference and empty batteries were costing them so much more than the time saved by screwing one to the wall and not having to run any cable. So the only way to get this reliable is wired, in my opinion. And that's the last thing anybody wants nowadays. Everything should be wireless, the WAF is much lower if it's wired. Perhaps a few diehards here running KNX buses wont object a few more cables but not the general public.
If you do want some domotica and try to safe some energy let me suggest to following project AFTER YOUVE TAKEN CARE OF THE HEATING SYSTEM TUNE-UP described above.
For each room buy a JeeNode. Add a room node, a sensor module reporting temperature and humidity, light and wether somebody is present if you install the power hungry pir.
Next buy two DS18B20 one wire sensors per radiator. You can daisy chain them so only a single thin cable is needed. Fix them preferable just behind the valve and on the outlet. Use care when installing them to minimize errors. Dont install on plastic piping. Only clean metal surfaces and some thermal grease. ISOLATE the sensors!!! The tiniest draft is already recorded. Only some cheap isolation tube around the sensor suffices.
What can you do with all this?
If programmed correctly the JeeNodes can run for months on a couple a AA batteries.
You'll very accurate metric about each room and radiator.
Yes...
With the data you can monitor the performance of each radiator. Ideally each radiator should dissipate that much that the return water is about 20 degrees lower than the inlet. If too much water is flowing through not all energy will be dissipated by the radiator, this will show up as too small delta T's.
You can be alerted that the room temperature is above a threshold because somebody left a valve open. Or better alert your kids that they should close the valves before going to school.
Lots of uses. Not too expensive. No damage if they system fails. Can be removed when you sell the house.
My 2cents:
Would I invest in such a project? Probably not. The development costs are enormous, certification, plastic and electronics are cheap metal is not. The market probably too small. HVAC installers are very conservative.
Still an affordable,OPEN protocol, remote controllable valve... yes I would buy some.
references:
digits's blog
http://blog.hekkers.net/tag/hvac/
JeeLabs
http://jeelabs.org/
PDF met stappenplan voor waterzijdig inregelen
verwarming.danfoss.com/PCMPDF/Inregelgi ... uik_LR.pdf
klimaatregeling.danfoss.nl/Content/4cae ... fcb5b.html
