Communication method between boiler and wall unit.

I’m interested in home automation and was looking into a way to monitor my boiler and potentially control it via the use of a home server, my problem however is I’m unsure if it’s possible to interface the two.

Almost every search parameter I've used takes me to this site, so I hope you’re the right people to talk to.

I have an ISAR- HE24 Boiler in use with a Honeywell – cm921.

The way I see it, if the wall unit can control my boiler, there must be some kind of "wireless" communication standard that I can tap into?

Thanks.

the wireless room stat / timer runs on radio controlled frequency the receiver picks this up and flicks a relay to 240v and makes the room stat connection in the boiler. am sure some were like maplin will sell some think like that. only other thing i can think off is finding out the frequency the reciver picks up at an getting some thing the pc can send on that frequency

Why in the world would you want to start messing about with hacking wireless thermostats? The CM927 is only the wireless equivalent of a wired timeclock/thermostat - the boiler doesn't communicate any information back whatsoever to the controller on the wall with regard to its status, so going to all the effort of breaking the wireless protocol would be rather pointless.

If you're into home automation, I'm sure you'll know how easy it is to control a set of relay dry contacts, and that's all you really need to call for heat and control the boiler. If you really have your heart set on wireless for whatever reason, it wouldn't be a massive task to convert an X10 switch to control a relay/contactor with 230v coil and the switch contacts wired in place of the existing wireless stat.

If you really must have more detailed information from the boiler, you'd probably have to research the hardwired diagnostic connectors on the boiler and associated protocols. Whether or not it would be worthwhile for a boiler of such questionable quality is another question

crashndie said:

the wireless room stat / timer runs on radio controlled frequency the receiver picks this up and flicks a relay to 240v and makes the room stat connection in the boiler. am sure some were like maplin will sell some think like that. only other thing i can think off is finding out the frequency the receiver picks up at an getting some thing the pc can send on that frequency

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It's not as simple as that. The wireless communication between the two units is at 868MHz, but the signal is encoded so each receiver is unique. The (almost insurmountable) difficulty will be in working out the encoding algorithm used.

You would need to replace the RF Room Stat with another type of control switched by your home automation system rather like a commercial BMS system such as Trend, Tridium or Priva sounds like a huge expense as the Ideal boiler has not outputs that could be used to monitor boiler status such as %load Lock out or Overheat etc so I would personnaly not bother

Do yourself a favour - spend the money on weather copmpensation.

mysteryman said:

Do yourself a favour - spend the money on weather copmpensation.

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the isar is not WC compatible. So you'd need a commercial style system with a mixer, controller and sensor. That only helps room comfort and won't nessarily impact greatly on the boiler efficiency.

Personally if I owned an Isar, I'd be saving ready to replace it.

I don't know what wireless protocols are being used by the HVAC industry, but if you have the time and inclination, it should be relatively (depending on your skills) simple to build your own home automation and monitoring setup using the latest wireless technology in the ISM (Industrial Scientific Medical) portion of the Radio Frequency spectrum. For a quick peek at what is available, Google on "robotics" and I think you'll be very pleased with what you'll find. By the way, the unlicensed ISM spectrum is the same part of the RF spectrum that your wireless routers, etc. run on. Most of the digital microwave radio chipsets have at least 8 input/output (I/O) ports, can be encrypted, and are fully capable of bi-directional monitoring and control. To peek at some resources/sources of this kind of technology, Google "Digi International" or "Motorola ISM" or "ATMEL ISM Radio" or even "IEEE802.15.4" to examine the evolving standard. Hope this helps a bit...

MrTux said:

I’m interested in home automation and was looking into a way to monitor my boiler

I have an ISAR- HE24 Boiler in use with a Honeywell – cm921.

Click to expand...

Perhaps you could link your Isar to the service department at Ideal, via a modem that will auto dial their number.

This will be useful on the numerous occasions that 'MALFUNCTION' flashes up onto your screen, whilst you are monitoring your boiler.