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Author Topic: I want good Temperature Monitoring / Control  (Read 4524 times)
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« on: July 27, 2018, 12:12:35 PM »

High time I did something about this. I'm mostly a SQL database programmer by trade, plus HTML and Basic, and a long time ago lots of C, and a bit of C++.

Some time ago, when we installed Thermal Store etc., I got a large number of 1-wire sensors and dotted them around pipes and up the thermal store etc. They were connected serially/Bus, and had some sort of serial-to-USB connector and were plugged into a particular PC which was easily reachable by the cables that trailed around the place ...

Time has moved on. I now have star-wired CAT5 to every room, so if I could plug something into one of the CAT5 sockets in every room I'd be ale to monitor temperature everywhere ... and then take some control decisions. I could dedicated a CAT5 cable [from each room] to non-network use for this purpose, but my recollection was that 1-wire would not be happy with star-wire and long cable runs?

I know nothing useful about Unix, but lots about Windows. I'm very time-poor at present, so having to learn / experiment / rinse-and-repeat is not really an option.  So I favour a Windows PC and Ethernet devices ... but they are mostly not cheap.

A quick start that got me logged data would help, so I would have some data history to then play with (even the current heat wave data would be useful)

I fear that Raspberry PI, Python (something else I've never used) and 1-wire, and a soldering iron for the resistors etc., is Not Going To Happen. I haven't had to use a compiler in years, and would prefer not to have to use a DEV environment, these days all my stuff is interpreted; I use a fancy programmers editor that I know like the back of my hand, so working in that will be far more efficient than a brand new, unfamiliar, DEV environment.

Suggestions on my options would be appreciated.


I have two heating sub-systems in the house.  (Its a big house)

1. The old part has a single circuit with skirting radiators and no individual rad controls at all (nor possible, AFAIK).  There is one riser pipe that we have found (there are more, but assumed to be buried in walls, and despite employing people with clever equipment to find them, we've failed), so there are two bedrooms that I can isolate with mechanised valve, but its a big house and that isn't really going to make any tangible difference.

We have a log burner fire in one room and tend to use that to reduce boiler-use in shoulder months. But I have no idea (currently) if it burns more wood, inefficiently, compared to the boiler/accumulator/radiator equivalent

2. the new part, built to Passive House standards, has UFH downstairs and a "rad" in the MVHR upstairs (we've rarely used it because the plumbing would benefit from changing [long story])

New part has Heatmiser controller, fancy thermostats in all rooms, but normally we only "demand heat" in the kitchen and adjacent dinning / snug areas. In cold weather also the hall. There are other circuits, such as Loo and Utility, which we have never install Stats for and are presumably never [currently] used. Also some Rads in Conservatory that we don't use in Winter (but needs frost protection)

After attempting to get logging data from Heat Miser (waste of time, format was utterly useless, although with effort I could have made something of it; Stats show 0.1C but logged was all whole-degrees; no indication of when demand-for-heat, so would have to use temperature-rise. By the time the UFH has moved the temperature a degree we are in trouble, the buffered heat in the slab is going to continue to radiate, and given the insulation levels, raise the temperature unbearably ...). We installed an Automation system over the top of heatmiser.  Don't like that much either (but it does a great job for Home Entertainment distribution around the house, and interfaces to the HA for Lights and Alarm, so does some stuff with them ...). The HA has zero data export <sigh>, pretty graphs of history of temperature in each room ... but I can't be ar$ed to scroll through them all, so something parasitic coming on at night is not a simple "SQL Query" to find outliers ...

So I thought:

Put a temperature sensor in every room. Cheap would help, as would using existing CAT5 (rather than wireless). If they can run PoE and not have batteries so much the better.

Find a way to open/close the (heated wax) Heatmiser valves on the UFH. (Perhaps switchable so can fall back to heatmiser if necessary / during DEV)

Do some programming to decide how much heat to pump into the building, and which UFH zones to activate.

That would involve checking the weather forecast rather than the room temperatures, per se. Smiley

We burn logs and heat an accumulator.  In shoulder Spring / Autumn that's perhaps twice a week. In depths of cold winter once a day. For once-a-decade cold twice a day.

Temperature of thermal store, and weather forecast, determines a) when next a Burn will be required and b) how best to use the available heat - either dump heat into house, and overheat it (and then a longer period before heat demand on store is required), or use the available stored heat (at an increasingly lower temperature). When boiler is alight we run CH - aim is to get house to ideal temperature and Accumulator to max temperature just as boiler goes out, and at the time we go to bed Smiley The system is well sized, so we do achieve that most of the time.

I know how to do that "manually", based on 10 years experience, but its a bit hit and miss and no doubt I could improve both comfort and "time and effort" fiddling with things manually.  AND I could get rid of any parasitic use by the existing thermostats (e.g. "Might be cold tonight, I'll run the RAD in the Conservatory at 1Am just in case we get down to 5C overnight" - which is very different to what I thought Frost Protection would be "Crikey: We are AT 5C, turn the thing on" ...

Summary: I want good logging so that I can then consider better control.  If kit exists for control I'll consider it, but the people I use(who are good) tell me not, so my expectation is that it will be DIY.

Would like to also log: PV generation, Solar Thermal, Electricity Usage, etc. - lower priority than Heating ... but if its just "get another sensor and plug it in" I could do that on day one too.
« Last Edit: July 27, 2018, 12:19:13 PM by kristen » Logged
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« Reply #1 on: August 01, 2018, 10:58:06 PM »

As a basis for protocol, have a look at mqtt. It's rapidly become the standard. Using say openhab and rednode (not sure if they both run on windows) you can use pretty much any hardware as inputs and outputs if they speak mqtt. IIRC openhab uses SQL.
To control things have a look at sonoff. At 5 you get a wifi controlled mqtt relay unit. Sensors are less readily available , or quite expensive (50) so you may have to get your hands dirty. If you are a bit handy, you'll be up and running with arduino using the esp8266 in no time. As for editor, you can point the arduino at any editor.
1 wire does not like star, but you can wire out on 1 pair of cat 5 and back on another, giving the correct non-star arrangement. Cat 5 is quite capacitive - IIRC there is a maxim app note on the subject. You could then rig them into your usb thingy and hopefully openhab can make sense . If not, arduino will.
I'm in the process of going to mqtt and openhab/rednode, although I'll be using a Pi.

1.1kWp PV & SB1700. 7kW log burner.
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« Reply #2 on: August 02, 2018, 06:29:38 AM »

Very helpful, thanks.

you can wire out on 1 pair of cat 5 and back on another, giving the correct non-star arrangement
[SlapsForehead] Never thought of that! The distances would be fairly big, but might be within bounds, definitely worth a look, thanks.

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