OpenTherm protocol PDF document

Post by **phil_in_china** » Tue Feb 03, 2009 1:26 pm

Then seriously buy an OpenTherm thermostat that will display the information that you want to see. But I fail to really see "why" that info: temperature of the water, speed of the fan, Water pressure etc is needed. The only ones that could be useful is the temperature drop across the flow and return from the boiler and the CH flow rate as these could then could be used to calculate a total load figure for the boiler. Anything else to me is just uninteresting numbers.
With the temperatures (flow and return) you could fit a pair of temperature pipe sensors and for the flow rate you could use a flow meter.

What good is it to know the fan speed is 58Hz and 10 minutes later its 62Hz, does it tell you anything useful? Will knowing that the CH water pressure is 3 bar make your home anymore energy efficient?

Phil

Post by **Snelvuur** » Tue Feb 03, 2009 1:41 pm

Phil, we are home automation geeks, it doesn't really matter i mean most of us has a temperature reader in every room. Or has a website which shows the speed of the fan of the pc, neither of those you really need to have a normal life/house. But still its just fun to have. We know its possible thats why we want it, not because we want to screw up the intelligent factor behind most heating devices, we just want data. we like data..

// Erik (binkey.nl)

Post by **phil_in_china** » Tue Feb 03, 2009 1:58 pm

Hehe OK I understand, I know person who collects stamps is called a philatelist, not sure what a person who collects any numbers is called?
Anyway here is some more data to add to your collection 0,25,1,14,0,25,1,17,0,25,1,16,0,25,1,24.

Phil

Post by **RDNZL** » Tue Feb 03, 2009 2:28 pm

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by phil_in_china
0,25,1,14,0,25,1,17,0,25,1,16,0,25,1,24.
<hr height="1" noshade id="quote"></blockquote id="quote">

They are no good for me, I have those already [8D]

My point above was, being able to control the heating when I'm away (by the use of the picbasic potmeter trick), and still have the possibility to control it manually and see the temp setting, and heating on symbol when i'm at home. Later when I have more confidence in my HA app, I can settle with only the potmeter control trick I guess.
Note I have a Nefit, so no open-therm, hence the picbasic idea.

Regards,
Ron.

Post by **phil_in_china** » Tue Feb 03, 2009 3:54 pm

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by RDNZL
 <blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by phil_in_china
0,25,1,14,0,25,1,17,0,25,1,16,0,25,1,24.
<hr height="1" noshade id="quote"></blockquote id="quote">

They are no good for me, I have those already [8D]

<hr height="1" noshade id="quote"></blockquote id="quote">
But I thought you do not have Opentherm?
So how come you already have them?
They are only meaningful anyway to anyone who has OpenTherm

But to answer your point, so you want two heating controls, one for remote control and one for home use?
Either you will need two thermostats, one for each situation (remote and home)and have a method of switching them in or out of the heating circuit.
Or you could design the PIC mod so that you can switch it in or out
of the thermostat dependent on the need.

Phil

Post by **amelia** » Sat May 09, 2009 11:38 am

I followed the discussion with attention.
I have an HVAC with Opentherm.
I am building my own integrated home-control:
1- every room as it own system that controls all the local events (light, power, temperature, alarm, ...), sending requests directly to another room or to the central system.
2- every room has it direct hot water supply for cooling, controlled by a modulated-motorized valve, all sited into the central-heating-room.
3- my wish is to be able to modulate the maximum temperature of HVAC depending on the actual requests of all rooms, in the range of 40-55 C, for example; also the temperature of sanitary water can be modulate during the day, using historic consumption-habits tables.
4- depending on the point 3-, I need to communicate with the HVAC, but here I stop my development.

I have on my hands a QAA73 but it does not speak.

Post by **RDNZL** » Fri Mar 26, 2010 11:37 am

I moved to another home a few months ago, so I don't have a Nefit boiler anymore, but these links may interest people having one...

wiki.neo-soft.org/index.php/Heizungssch ... ServiceKey

A lot more info and other links are to be found is this long thread...
http://www.mikrocontroller.net/topic/141831

The protocol is called "EMS-bus", eBus seems to be similar...
http://www.mikrocontroller.net/topic/75698#new

Disclaimer:
I cannot be held responsible for any injury, loss, expense or damage of any
kind whatsoever suffered or incurred by any person who uses this information!

Post by **Bwired** » Fri Mar 26, 2010 2:48 pm

Thanks for the info
The Germans are way ahead of us!

Post by **phoenixb** » Fri Mar 26, 2010 10:35 pm

while originally it's a Dutch invention, right?

Post by **Rene** » Fri Mar 26, 2010 10:47 pm

Pieter,

When you build the electronics and get it up and running in combination with some software, I can just copy it over to my place;-)

Post by **Bwired** » Fri Mar 26, 2010 11:17 pm

I have the original service key (tool) from Nefit, with rs232, IR and even bluetooth.
http://www.nefit.nl/SiteCollectionDocum ... cetool.pdf
These links will help me a bit more, but hack, the servicetool is number 23 on my todo list

: nefit.jpg (13.07 KiB) Viewed 20219 times

Post by **Rene** » Sat Mar 27, 2010 12:13 am

You do not have a second set do you?

Post by **RDNZL** » Sat Mar 27, 2010 9:21 am

@Rene
I have ServiceKey hw and sw laying around here useless, it's a version without Bluetooth, but has IR and serial cable support.
Mail me your address and I will sent it to you.

Post by **Bwired** » Sat Mar 27, 2010 1:02 pm

solved

Post by **gjniewenhuijse** » Wed Nov 10, 2010 12:45 pm

Bwired wrote:I have the original service key (tool) from Nefit, with rs232, IR and even bluetooth.
http://www.nefit.nl/SiteCollectionDocum ... cetool.pdf
These links will help me a bit more, but hack, the servicetool is number 23 on my todo list
nefit.jpg

Is it already posible to monitor my Nefit with this tool. I have already a service key from nefit.

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