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Roomnodes a slightly different concept

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17 October, 2012 - 18:08
ian7
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Joined: 1 Oct 2012

I thought I would post this and see if anybody has any ideas. I have followed a few good sites on decoding the Conrad FHT8V radiator valve system, the idea is to intrograte control of the valves into XAP. A friend and I are trying to control a number of valves and I initially looked at using a HAH Central node modified for 868Mhz OOK. It soon became apparent that it may be troublesum having to sync up a number of valves to one central node and so we decided to look at intergrating the control into the roomnodes instead. We are intending to have one roomnode per valve / room where control is needed and have successfully produced a roomnode that still sends the data back to HAH central as usual, but also sends OOK signals to the valve, It is working well so far, but the problem is that of current drawn from the batteries of the modified airwick, due to timing inaccuracy's associated with sleep mode, I have had to remove the sleep function from the roomnode sketch. The problem is the valve only wakes up about every two minuites to recieve data and due to the timing issues the valve soon dropped out of sync. I am thinking mabe adding a real time clock to handle the timing and wondered if any one has any further ideas. For now we may temporary power the roomnodes with small mains adapter and move on, but it would be nice to get the portability of the roomnodes back at some stage.

 

Ian Blackman (G4OCQ)

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17 October, 2012 - 18:25
#1
g7pkf
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United Kingdom
Joined: 11 Jan 2011
Strange

I was looking at the same or similar product in B&Q and wondered what if?

 

trouble is in total i have 25 radiators, albeit 3 towel radiators and at £30 a pop thats £££ but i would only put them on probarly 10.

 

can you get just the radiator part and not the thermostat rf bit?

 

Dean

 

P.S if you get it going may but 3 to test.

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18 October, 2012 - 07:08
#2
ian7
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Joined: 1 Oct 2012
Hi Dean,    The FHT 8V on its

Hi Dean,

    The FHT 8V on its own from Conrad is £30, there is another manufacture type which is £25 but as we now have the FHT8V working thats what we are running with. I do not think all radiators will get one, just the critical radiators in the house, the rest can stay with normal TRVs for now I guess. We plan to control the boiler with a relay driven jeenode so all in all we should have a resonable control of the house heating.

Regards Ian

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13 January, 2013 - 14:23
#3
aanten
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Joined: 13 Jan 2013
fht 8v

I've been trying a similar idea, but using a nanode (similar to jeenode, but has rtc).

So far, I've tried a few of the fs20 based sketches, but so far no luck in establishing a link to fht 8v's, or receiving data from fht 8r (i've been buying fht 8 set's in uk for ~ £38)

The second part of the plan is to control the boiler based on radiator demand, using a wireless remote socket in place of the existing boiler time switch.

I'd be very interested in your progress to date, and also in the sketch that your using to control the fht8v's. Is your sketch also able to receive and decode (eg. from fht 8r) ?

andy

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21 January, 2013 - 11:26
#4
ian7
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Joined: 1 Oct 2012
fht 8v

Hi Andy,

 

     Our little project here is to control the valves by modifying the code in the roomnodes. We are just purchasing the valves and saving costs by not purchasing the thermostats. The transfer of data betwwen the room node and the valve is all based on acuate timings. The reciever in the valve is asleep most of the time, so we can only transmit within the 500ms approx window when the valve reciever is awake.

  We have had problems with the timings as the original room node itself goes to sleep and timings have not been acuate enough. Now we use a different sleep mode to save on batteries in the room node , but its not as efficeint as the original HAH roomnode and had to introduce a little error correction as the maths do not seem to be spot on for the timings somehow(In desperation I think its safe to say we have cut the original sketch to shreads and it does not resemble much of the original code now). The room nodes control the valves by themselves with out any user interaction by using a bit of PID code and the temperature senser in the room node, unfortunately we took a break at the point where we were introducing a different way to correct the error and need to test the new method on a few of the valves before we can be sure we solved the timing issue.

The project has taken a break over Christmas so appoligies for not replying sooner, we are in the process of using a room node to switch the boiler on and off. We are hoping also to use the temperature reports from the room nodes to decide when to turn the boiler on and off. you are welcome to check over what we have been doing, maybe you might come up with something better than us which would be good.

 

Regards Ian

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26 January, 2013 - 21:46
#5
aanten
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Joined: 13 Jan 2013
Hi Ian,Thanks for your

Hi Ian,

Thanks for your update. Yes, I would be very interested in taking a look at your much modified sketch -It may provide some hints as to why my code does not work. Is it available on-line ?

 

For the boiler interlock, are you connecting relays directly to a roomnode ? I understand the conrad interlock (FHT 8W) is configurable to switch on the boiler when any of the radiator valves reach > n% open - is this also the approach you will take ?

 

regards,

 

andy

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