Fibaro Universal Binary Sensor - Underfloor Heating

[davedotnet 0]

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This is my second Fibaro project, this time to monitor the Under Floor Heating (UFH) Flow and Return temperatures, using Home Centre 2. My UFH has 8 water circuits downstairs, through a manifold, and I have the same upstairs, through a manifold. The manifold is rated to 70C, and contains a mechanical trip that cuts off the electricity to the pump and wiring centre to protect itself. Obviously, we need to ensure that the risk of that occuring is minimised.

My first attempt involved epoxy/weld in a plastic box/enclosure (from Maplins) using RJ45 keystone jacks and RJ45 plugs to connect my sensor leads to the Fibaro sensor. Transpired it was overkill for a three-pin Dallas DS18B20 and connection reliability between the plug and socket was poor.

My second attempt involved new boxes (again, from Maplins), and this time reverting to stereo audio jacks. I prepped a CAT5 length of cable, with the Dallas DS18B20 soldered one end, with heat shrink tubing round each leg, and then larger heat shrink tubing round the entire assembly. On the other end I connected a 3.5mm stereo jack. I prepped two of these cables.

Then, the stereo sockets were mounted in the casing. Not satisfactorily I might add in that the socket pushes thru a hole and then you thread on a washer. However, the thread is weak and the washer jumps on the threads. The result is, that pushing the jack into the socket causes the socket to break away from the plastic box and pull the washer off. Now, I could araldite/weld the audio jack on, but if ever I need to get it off that wouldn't be a possibility. So, I'm currently trying to source a good quality (panel mounted) audio jacks (not from Maplins). In the meantime, I've fixed the thermocouples to the 22mm copper pipes using aluminium tape. I've also used a 12v 500ma power supply adapter. Checking on the home automation system seems to indicate we're picking up sensible temperatures (when cold).

I've tested it whilst the heating has been on and I have a scene that runs to check if the temperature exceeds 67C. It's taught me a bit more about scenes in that they only run when the temperature changes (makes sense). But guess what, when the temperature exceeds its limit, the HC2 talks/speaks to us in the house to announce the imminent event! I now need to build a second one for the upstairs manifold.

[Guest Kuuno]

post some pics of the universal sensor box:)

thanks!

[davedotnet 0]

Here we go, nothing stunning. It has a plate which fixes to the top which allows it to be screwed to a wooden facia. The top lead is the power, the bottom two the temperature sensors.

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[Guest MitchellOnline]

How have you powered the universal sensor?

[davedotnet 0]

We have a store here in the UK called

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. I bought the

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.

I also bought a panel mounted 2.1mm power socket from them and mounted that on the box, so it's just plug and play from there.

[pooh 2]

2 questions:

1. how come your "flow" temp is lower than the return?

2. how do you assure that certain temp won't go in the flow? you need to somehow protect the floor in case you have too high temp on your "flow"...

[davedotnet 0]

Ah, you noticed the difference in temperature!

My prognosis is that these temperatures reflect a system that hasn't been on for a while, thus the temperatures are in a cooling down state. For some reason, the Flow cools down more than the returns. Perhaps because there's more water volume on the return side ?? When the heating is on, the temperature difference between the flow and return is about 20C, obviously with the flow higher than the return.

With respect to protecting the floors from overheating, the manifold itself has a trip, which cuts all the power to the pump, the actuators, the wiring centre, etc. It has tripped a couple of times but I've never known when (because when the temperature comes back within tolerance it all switches on again), hence the reason to get some sensors on there to start getting some insight as to what's going on. Do you have any experience in this area ?

I have three different floor constructions, 1) floating floor (22mm board above pipes), 2) 22mm T&G board with embedded pipes, 3) pipes in screed.

[K.Bergmann 2]

davedotnet, nice work with such solutions

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[Guest Kuuno]

20 degrees is too big difference. for underfloor heating the normal difference should be ~7 degrees. in your case you should make the flow faster that so it would be more effective

[Guest Cirion]

Nice project!

I would love to start a similar project with my underfloor heating system. Right now I'm using 2xVariant Waterline system WLM2. 1 for the rental apartment with 4 zones and one for the house with 8 zones (actually 14 zones combined to 8). 18 actuators in total. And a separate system called ETO-2 for the driveway. It has 3 zones.

WLM2 and ETO-2 works good, but they lack remote control. No need to defrost the driveway if I'm on vacation... But I'd like to be able to defrost it before I get back home...

A 2x1,5KW module would make a easy way to switch off the ETO-2...