Directly controlling Boiler

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jpearce
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Directly controlling Boiler

Post by jpearce »

Hi,

I would like to control my boiler from FHEM as the first phase in automating my heating (I currently have a basic timer on the boiler, with no thermostats or TRVs in the house, so phase one is just replacing this basic timer).

My question is: is it possible to directly control the FHT8w boiler relay from FHEM (through either a CUL/CUNO or FHZ1300pc) without the use of any FHT80b devices being involved? Initially, I want to just send 'boiler on', and 'boiler off' commands directly to the boiler. If not, is there another FS20, etc. based device that will do a similar job that I can directly command from a CUL/CUNO/FHZ1300?

Thanks in advance,
John.
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jrkalf
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Re: Directly controlling Boiler

Post by jrkalf »

Hi John,

It's a matter of how you're willing to control your boiler system.
FHT8w is designed as a boiler switch to be implemented when using FHT80b devices. FHT8w doesn't respond to FS20 messages, it responds to FHT actuator messages when a fht80b is paired with the fht8w. So if the fht80b would send a actuator message different then 0% (as in 5% or more) then the FHT8w would turn on the boiler for 15 minutes.

^^ keep this in mind. the FHT8w doesn't do a on or off switch. It does a timed switch for 15 minutes. So it'll only heat for a limited amount of time and will switch off again, unless it receives another message from the system that an actuator is being kept open at the same or different percentage.

The FHT8w can probably be tricked into working with a CUL/CUNO. but for sure it can't with a FHZpc from ELV. But it would require expert knowledge on sending out actuator messages and pairing with the FHT8w.

For the FS20 solution you can use any FS20 device that switches on/off.
If you can't fix it with a hammer, you've got an electrical problem!

Fibaro HC2, various z-wave switching, alerting, detection modules.
ELV FHT80b heating system.
jpearce
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Re: Directly controlling Boiler

Post by jpearce »

jrkalf, thanks for the quick and excellent response!

That's cleared up a few things in my mind. Firstly, I was probably confusingly thinking that FHT uses FS20 'protocol', but it sounds like the FHT stuff is something slightly different. Anyway, it's clear from your description that the FHT8w is not what I want, since I'm looking for direct control of the boiler, where I (FHEM) control the logic, not the room devices. Sure, later I'll want air temperature feedback from different zones, and I'll also no doubt end up with FHT80bs and TRVs, but I will still not want them directly controlling my boiler (which, I appreciate is contrary to the normal design). I'll still want the logic coming through FHEM first.

It looks like I could maybe mimic the messages to the FHT8w with a CUL/CUNO, but it's really designing in work-arounds from the start and, combined with the 15 min function you describe, means it's not really the way to go.

So, since the timer box on my boiler is simply a switched live affair, I guess I could probably just replace it with a normal FS20 switch unit, such as this: conrad.com/Wireless-flush-mounted-switc ... 99_2806020, right?

Thanks,
John.
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jrkalf
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Re: Directly controlling Boiler

Post by jrkalf »

If you're investing in FS20 equipment, you might want to check out http://www.elv.de/
I know it's german, but they're cheaper then conrad and have excellent delivery as well.

the flush mount is an option. Do make sure you install a receiver, not a sender. Those are two opposites :)
If you can't fix it with a hammer, you've got an electrical problem!

Fibaro HC2, various z-wave switching, alerting, detection modules.
ELV FHT80b heating system.
KidE
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Re: Directly controlling Boiler

Post by KidE »

jpearce wrote:jrkalf, thanks for the quick and excellent response!

That's cleared up a few things in my mind. Firstly, I was probably confusingly thinking that FHT uses FS20 'protocol', but it sounds like the FHT stuff is something slightly different. Anyway, it's clear from your description that the FHT8w is not what I want, since I'm looking for direct control of the boiler, where I (FHEM) control the logic, not the room devices. Sure, later I'll want air temperature feedback from different zones, and I'll also no doubt end up with FHT80bs and TRVs, but I will still not want them directly controlling my boiler (which, I appreciate is contrary to the normal design). I'll still want the logic coming through FHEM first.

It looks like I could maybe mimic the messages to the FHT8w with a CUL/CUNO, but it's really designing in work-arounds from the start and, combined with the 15 min function you describe, means it's not really the way to go.

So, since the timer box on my boiler is simply a switched live affair, I guess I could probably just replace it with a normal FS20 switch unit, such as this: conrad.com/Wireless-flush-mounted-switc ... 99_2806020, right?

Thanks,
John.

I wouldndt do that since teh FHT8W has 10 separate channels for comparing actuator opening. The FHT80b 's dont send a "on"command when the boiler needs to heat up but the 8W compares actuator opening v.s. thershold.

For the rest,I have this system (6xFHT8B + FHT8W) runnig now over a year and i'm more than pleased. ;-) and it saves a lot of energy
jpearce
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Re: Directly controlling Boiler

Post by jpearce »

Thanks folks.

I'll look at ELV and, since I'm in Ireland, buying within the Euro zone makes sense (as long as it lasts!).

KidE: When you say "I wouldn't do that", I presume you're referring to mimicking a FHT8B, rather than using a simple FS20 SU?

JOhn.
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Re: Directly controlling Boiler

Post by Kroonen »

John,

Maybe it't possibe what you want without the fht80b

I also workt now without the fht80b.

I use an Oregon device to measure the temperature, and the actuator fht8v is receiving the messages, with ad PID device (see fht8v module in fhem)

As I don't have the fht8w, I understand that it recieves the messages form the fht8v or send to the fht8v? So than it should be possible

see this thread
http://groups.google.com/group/fhem-use ... 9f02c8242d

regards Richard
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jrkalf
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Re: Directly controlling Boiler

Post by jrkalf »

Kroonen wrote:John,

Maybe it't possibe what you want without the fht80b

I also workt now without the fht80b.

I use an Oregon device to measure the temperature, and the actuator fht8v is receiving the messages, with ad PID device (see fht8v module in fhem)

As I don't have the fht8w, I understand that it recieves the messages form the fht8v or send to the fht8v? So than it should be possible

see this thread
http://groups.google.com/group/fhem-use ... 9f02c8242d

regards Richard
Thanks for the addition Richard,; Do keep in mind that it requires a pairing with the FHT8w. The FHT8w does respond to just any FHT8v signal that flies through the air.
If you can't fix it with a hammer, you've got an electrical problem!

Fibaro HC2, various z-wave switching, alerting, detection modules.
ELV FHT80b heating system.
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