Attacking My Landlord's Boiler
blog.videah.net
blog.videah.net
If your goal is saving energy/money, you don’t want a system capable of going from cool to toasty in 20 minutes.
Instead, you want a system that runs (much) lower water circulation temperatures (giving lower losses in the unconditioned spaces and more even room heating). That can be done to any condensing boiler by just turning down the flow target temperature.
A second layer of optimization on top of this is the addition of outdoor reset/weather compensation which will adjust that flow temperature based on the outside temperature, giving a flow temperature than can just barely restore the building to the desired setpoint temp.
With mine properly tuned, I was targeting having the thermostat act more like a high-limit and for it to call for heat between 22 and 24 hours per day while not overheating the house. That often meant flow temps in the 110°F (warm day) to 135°F (below freezing day) range. Compared to the prior winter (at a constant 160°F flow), the house used 8-15% less gas and was wildly more comfortable. (This setup does preclude using deep setback settings, which also can save money, because recovery times are necessarily long in such a scheme, unless you have an even smarter control system that can run perfectly tuned water most times but hotter water during recovery from setbacks.)
I target the long run time to maximize efficiency. A 160°F pipe will lose more heat to the part of the building that I don’t want to heat as well as more heat to the wall right behind the radiators. It also results in the house going micro too-hot, too-cold, too-hot, too-cold as it cycles. Mine is constantly trickling in just enough heat to replace the heat lost instead of cycling between adding way more than needed then none for a while.
Another large effect is that low return water temperatures into the boiler allow for greater condensation of exhaust gas energy to be used in the building instead of sent outside. Walking by my house on a cold day, you’ll see minimal steam plume during operation. All that steam I see my neighbors emitting is energy they paid for and delivered to the outside… (They paid a lot for a boiler with a 95% or 98% sticker and run it at 80% efficiency.)
https://kw-engineering.com/how-to-optimize-condensing-boiler...
You’ve got the first part of that backwards, it’s the walls near your radiators that are your problem and need more insulation.
Correct.
> Walking by my house on a cold day, you’ll see minimal steam plume during operation. All that steam I see my neighbors emitting is energy they paid for and delivered to the outside… (They paid a lot for a boiler with a 95% or 98% sticker and run it at 80% efficiency.)
Please check your assumptions.
A boiler operating in condensing mode will produce a trickle of liquid condensate (that may well be drained somewhere that you can’t see [0]), teeny tiny drops of condensate suspended in gas (colloquially “steam”, but it’s more like fog), and some residual water vapor mixed with the exhaust gasses. You can see the “steam”, but you cannot see that residual vapor except to the extent that it condenses further as the exhaust stream cools after it exits, much as you can see some of your own exhaled water vapor on a cold day as it condenses outside your nose or mouth. The exhaust gas is saturated: it has maximum humidity and is at its own dewpoint, so there is a lot of visible fog. The droplets that form inside the boiler and escape with the flue gas do not represent wasted heat: their heat of fusion has been captured.
A boiler operating in non-condensing mode will produce no liquid condensate, and its exhaust will be well above its own dewpoint. It will contain far more water vapor than a condensing boiler, but you cannot see that vapor except insofar as the flue gas has a different index of refraction than the surrounding air and distorts the background a bit. Depending on weather, a bit of it may condense later. All of it is wasted energy.
[0] This liquid condensate is nasty stuff: it’s basically carbonated distilled water plus some impurities but not usefully buffered, and it’s rather acidic. It will quickly corrode many metals, including copper and many common copper alloys, non-stainless steel, galvanized steel, etc. Non-condensing furnaces and boilers are generally carefully engineered to avoid condensation, because the condensation would damage them. If your plumber is unaware of the degree to which boiler condensate is corrosive and uses copper pipes or metallic fittings (push-to-fit in the style commonly sold as “Sharkbite”), the system will fail. Use plastic pipes (PVC or PEX) and plastic (or maybe stainless steel) fittings such as ordinary solvent-cement PVC fittings, “engineered plastic” PEX fittings, or push-to-connect fittings with plastic wetted surfaces. John Guest makes these, and there is also the somewhat bizarre ProLock brand, which seems to be some sort of joint offering from John Guest and Sharkbite.
I can see a clear difference between running my own boiler at 25°F OAT (lots of “steam”) versus 40°F OAT (almost none) while I see my cross-street neighbor showing large plumes on both. I’m not sure if I mistyped above or I’m actually thinking about it wrong, but I don’t think my observations are incorrect.
Having that water condense outside the building (giving up heat to the neighborhood) is less efficient than having that water give up its heat into the incoming (return) water.
The other variable is how well controlled your heating is. A lower flow temperature means less overshoot of the target set point - and as losses scale linearly with temperature delta, that can mean higher energy losses (depending on the characteristics of the controller of course).
Whether or not you care about losses in unheated spaces depends on your system topology. Personally, all my heating pipes are within the thermal envelope of my house, so flow temperature has no bearing on those losses at all.
If you had a resistive electric boiler, flow temperature would have absolutely no effect on efficiency. You'd be completely right, that running heating only when you needed it would be more energy efficient.
50 years ago this was _always_ the case, but condensing boilers and especially heat pumps muddy the waters a little. Condensing boilers can be close to 100% efficient (vs ~70-80% for ye olde gas boilers), but generally only at a fairly specific operating temperature, which may be lower than you'd need to get a rapid rise in temperature. Heatpumps are >100% efficient (that is for every joule of electricity you put in they move more than one joule), but are even more fussy about operating temperature.
The answer now is going to be a solid 'it depends', based on behaviour of the heating system, outside temp, desired inside temp, insulation...
So you save up to 30% of the gas while heating your home nearly 24 hours a day, instead of saving 67% of the gas by using it only for the ~8 hours that you're home and not under a duvet?
The math might work out for those who work from home, but I mean in the standard case with an hour's commute (round-trip), an 8-hour work day, and a 30-minute lunch break (9.5h gone, 7h sleep -> 7.5h during which the apartment should be warm if you run no errands). Of course, you'd schedule it to start before you get home, but it can also stop a bit before going to bed
I've been hearing both arguments for years and while it's exceedingly convenient to believe the condensing boiler story and just heat 24/7 to always come home in luxurious warmth, nobody ever does the math. You're one of the few people who even mention what the alleged savings are in the first place
We have a condensing boiler, chosen by my landlord so I'm no expert but I looked into it because we pay the bills in the end. The device's manual lists the efficiency as 88% ƞ4 at 60°C return water temperature, called high-temperature operation, and 98% ƞ4 at 30°C return temperature. It also gets tested yearly by a professional (Schornsteinfeger I think they call it here) and produces two efficiency measurements. Just looked up the record again: the mechanic handwrote "min" and "max" with them, so I presume that the "max" one is where the system operates at maximum capacity (minimum efficiency, then?), where the efficiency is 98%. At the "min" setting, the efficiency is shown as 106% (iirc some older measurement techniques don't include the condensation efficiency gain in the percentage, that's how it goes above 100%, or so I read when I looked it up a few years ago). For that difference, please correct me if I'm overlooking something but using a low heat for 24h/day makes no mathematical sense to me
Energy moves from hot to cold linearly with temperature differences. Hypothetically, if the pipe was the same temperatures as the inside of your home all the heat transferred would be outside the envelope. The hotter the pipe the better this ratio becomes. This is true regardless of what percentage of the pipe is inside the envelope.
However, heating along the exterior of the home under windows and such then you’ll heat the exterior walls to higher temperatures than the interior thermostat thus losing more heat to the outside. Radiant heating on the other hand largely avoids this effect.
https://www.earth.org.uk/MHRV-mechanical-heat-recovery-venti...
(not a native speaker here)
Eg: https://www.earth.org.uk/note-on-superinsulating-bedroom.htm...
In New York, at least - the standards were never changed to accomodate for closed windows in 1920. Snopes has a rundown. https://www.snopes.com/fact-check/apartment-radiator-pandemi...
These are statements of neutral fact, and the whole process is described in some detail on my site, for each room that we retrofitted.
I don't understand if I have caused offense or something: apologies if somehow so!
By placing the radiator near the place that is likely the coldest place in the room, you ensure that the room is an even in temperature as possible. Rather than to counteract 'cool draughts'. I think.
So perhaps people thought that your initial comment was wrong/misleading.
But if you have triple glazing and this mitigates the heat loss, then the coldest wall of your room may no longer be the one with a window, so you may well be doing the right thing for your room(s).
That said, heat loss is through exterior surfaces so you really want to avoid spot heating of poorly insulated exterior walls. Thus the design of baseboard heaters can make a larger impact than you’d think.
For a furnace you’re talking fractions of a percent difference in efficiency across a wide temperature range so by far the most critical issue is total heat losses to the outside. A heat pump’s efficiency is far more variable making total losses to the outside less important.
Redundancy is critical in areas that get really cold. That may eventually mean turning to hydrogen, but a backup gas furnace for a well insulated home really isn’t a major CO2 contributor. More relevant to the discussion it further reduces the impact of minor changes in efficiency or comfort.
Wood stoves require you to physically be home and are kind of a pain to use thus make a poor backup on their own, though a solid 2nd backup.
PS: Most areas are better off with solar thermal + heat pumps. Solar thermal however requires sunlight which not everyone gets in the depth of winter.
Work out the amount of solar + batteries you need in the winter when the power goes out and your COP is less than 2 because it’s very cold and you need more BTU’s than normal because it’s very cold. Solar thermal is just significantly cheaper on a large home in a cold climate.
Particularly in temperatures where the heat pump is at/under 2.0 COP for a few dozen hours per year, an electric boiler makes a great deal of sense. It's almost as clean as the heat pump in the extremely rare times when it's needed for supplementation due to extreme cold temps, can allow for a more suitably sized heat pump to cover the 99% of heating hours [meaning greater efficiency there], is extremely reliable due to its simplicity, is fully automatable with existing controls, doesn't require local gas supply network, and is a pretty good match for a heat pump.
Therefore, 1st: Heating/cooling cycles from your HVAC are fighting these objects because they don't mix at the same speed as other objects (e.g., the air itself), so you end up with gradients across objects; people rate this feels unpleasant.
2nd: Mechanical equipment tends to operate more efficiently under constant load compared to constant start and stop cycles.
With #1 and #2, you can just heat constantly to increase both the uniformity of heating across objects and also the efficiency of the mechanical equipment's energy conversion.
There's a 3rd point, which, really, is just a sneaky way of reframing #1 and #2, and that is that you can also lower your setpoint and still have a subjectively superior comfort perception compared to a cyclic system. It drives home the point to say "constant 68F feels more comfortable than intermittent 72F." But it also invites the complaint about constant versus intermittent energy use, right? So I think just detailing #1 and #2 is better.
One thing I missed in summary is the concept of general radiant temperature gradient. It's not only about the gradient for conduction, but for radiation (and convection). So you could probably improve my summary by talking about any gradient between different objects in the environment and their EM, which feels unpleasant (but I think it had value in its reduction of the problem, too).
Depends. As explained in a sibling comments, I have some rooms that have combined UFH and radiators, and if the desired temp is more than 1 celsius away from the current temp, then both are driven, otherwise it's just the UFH.
So long as you can get the boiler return water temps low enough, you can operate the boiler in its high efficiency range.
Most dual-temp setups are set for the highest temp and mixed-down to provide the lower temp for under-floor. That’s cheapest in terms of equipment and install but cannot be as efficient as a system that mixes down when both loads call but also lowers flow temp (thereby lowering return temp) when no high-temp rads are calling.
Most home boilers lack an outdoor air reference temp sensor but all commercial boilers have them.
Also, condensing boilers are amazing, the size difference alone vs an old tube boiler is wild, very small in comparison.
I used to divide my time between a concrete hulk of a NYC apartment building, and a California home insulated to notoriously poor California standards. I was plenty warm in New York winters just from my neighbors' heat nearly all of the time. In California, there was a narrow window (think "Apollo 13 re-entry") between too cold and too warm.
Then we modernized ceiling fans, and I hit on running them in "winter mode" drawing hot air up to flow back down the walls. Bingo! I love that ISO 7730 confirms this.
A well-designed system would have good insulation, can dump 10000W watts of heat out and bring the room from cool to toasty in 5 minutes, and then scale back and maintain the temperature after that by putting out 500W after that.
This also tends to be more efficient in practice because if you know it only takes 5 minutes to heat up you are less likely to want to leave it on when you're not around.
Specifically, setting a fixed temp vs turning things up/down/off when you are leaving and reversing it before you get home. There was little difference either way. The amount of electricity consumed was similar to both.
I wish I had a link, they even tested cases where efficiency was lost heating things up. This includes “emergency heating”.
It seems like the easier hack would be to put a peltier heater/cooler under the thermostat then control that remotely to assume control over what temperature the thermostat sees.
The link to the exact model of thermostat isn't working, so I don't know how amenable its design is to this approach, but the thermostats I've used are generally wall-mounted and putting a heat/cool source under them wouldn't be too hard. You'd need to make sure that you didn't send both the heat and cool into the thermostat, but that's a simple positioning problem.
That said, if he has access to the interior of the thermostat, I'm sure it won't be difficult to replace the temperature sensor with a circuit to cause it to read either really high or really low on demand.
Ice pack and desiccant?
Probably a 30 minute job if you’ve never done it before and easily reversible with a little bit of double sided sticky tape, which all Brits should be familiar with if they ever made a Tracy Island. There is a real risk of electrocution which could be completely militated against by turning off the power to the boiler.
Still, a fun hack, and nicely executed!
The one in my apartment has a “feature” a lot of US thermostats now have, where you set four ordered times called wake, leave, return, and sleep and the temperature you want the space in each interval. I know very few people who actually live in a household where everyone wakes, leaves, returns, and sleeps on the same schedule every day.
I work from home and personally just want to set a temperature and have the space stay at that temperature indefinitely but this system requires that I tap through and enter the desired temperature four times, while confirming the four intervals.
I guess I’d be happier with a more programmable thermostat that I could set to behave like an old school dial thermostat.
Your use case is possible with that. Just set the standard program to 15°C, and activate the holiday set to whatever you need whenever you want. Configure it to go to 15°C at some sensible time in the evening, so it won't go on even if you forget it.
Nope! The smart learning feature was the biggest pain in the ass. You’d be sleeping during the day for a night shift, only to find yourself freezing because it decided no one was home.
Everyone leaves, and the thermostat adjusts.
Someone comes home (or walks in front of it), and it goes back to the normal setpoint.
Sounds easy. Isn't always easy.
The reliability of this seems to be highly dependent on the phone(s) themselves simply succeeding at not killing useful processes.
Overall, I'm not entirely displeased with it. I procured it very inexpensively by buying it from one of my energy provider's online store in conjunction with a substantial rebate from my other energy provider. I'm confident that it paid for itself very quickly, and it's nice to be able to set the thermostat remotely.
My lament is that there seems to be approximately nothing I can do to improve the presence detection function without gymnastics or spending real money. What I want is a local API that I can enable and do stuff with; what I get is "Good luck! Have you tried buying Nest Protect subscription motion detectors? (Oh lol, we stopped selling those.)"
(I'm OK with the privacy and security aspects of what I'm trying to do. I'm not OK with having a connected device that I can't bend to my will. I'm even less OK with more recurring expenses. The next thermostat I buy will have local control over the LAN, but it probably won't pay for itself quite as quickly as this one did.)
[note: I've never played with the auto-schedule "learning" function at all. It always seemed like a complete waste of time, since I for one do not have a regular schedule.]
Anyway, my ideal setup would be to install 'smart' thermostat taps on every radiator in the house, either manually turn them down when you're not in the room or have them automatically detect activity or open windows and adjust accordingly. But each one has the authority to trigger the central boiler if needs be, instead of only the master thermostat in the living room.
Regarding "what is better" from energy efficiency, I would prefer a system that "check it" because my guess is that it depends a lot based on the individual situation. I mean everybody is going crazy over "IA" but a couple of sensors and a system smart enough to adjust your usage based on your particular situation and preferences (like "eco", etc.) is an exception.
But of course, not really feasible in Atlanta or Phoenix. Nighttime temps are too warm.
In general, you should either run the heater or have your window open. Both at the same time is bad news for your energy bill.
I've heard this theory a lot too, but it doesn't match with physics. A warm house loses more energy than a cold house, due to a higher temperature difference allowing easier heat transfer. So in most homes, with radiators and high temperature CV, it's way more efficient to just turn it off when you gone.
One exception is when you have a very well insulated house, combined with floor heating and a very efficient, low temperature heat pump. In this case, it takes a lot of time for temperature to move in the house and it's already incredibly efficient.
The reasoning: when you heat up the house, then your boiler needs to produce constant high-temperature water. When you keep the house at the same temperature, then the boiler produces much lower temp water and it is more efficient.
Insulation also matters because if your house has outer insulation then it means that heat transfer from the house to the environment is mostly blocked, but cross-room heat transfer is likely not (through the walls). Therefore it is better to heat the whole house than heating just a couple of rooms because if you do the latter then you'll end up heating the whole house anyway but you're using less surface area (meaning you need higher flow temperatures, meaning less efficiency).
How does your boiler produce heat for your water in your scenario?
> Therefore it is better to heat the whole house than heating just a couple of rooms because if you do the latter then you'll end up heating the whole house anyway but you're using less surface area (meaning you need higher flow temperatures, meaning less efficiency).
Just model the other rooms as very weird wall to the outside.
This is only true if the heating happens quickly and the system is less efficient when heating quickly. Otherwise, this doesn't make sense from a physics standpoint. A temporarily lower temperature differential means less kWh of heat lost.
FWIW I run my heat pump intermittently and with locally-smart TRVs that get to call for heat centrally, and a weather compensation only flow temperature curve, and it WORKSFORME!
Certainly feels like I'd need PhD from it to successfully install, modify, calibrate and run the installation until its fully adjusted, for the peak comfort and minimum cost/dirty energy use.
The obsessives amongst us can continue to tweak if we wish...
The losses are proportional to the temperature differential between outside and inside.
So you should have somewhat higher losses from the hotter air streams from the radiators passing the windows.
Dunno about magnitude though.
This topic comes up anytime thermostats and heating are mentioned. The physics arguments only makes sense if you don't care about comfort. Most people would rather optimize for comfort with some energy/cost savings if possible and the physics folks seem to not care about comfort at all.
That's true if you completely stop heating. However if you lower the temperature by roughly 3.5C when you're not home, you'll be saving energy.
So you can for example program it to be 16C when you're out and 19C when you're in. You don't completely turn off heating indeed.
https://www.honeywellhome.com/us/en/products/air/thermostats...
As you go on to describe, there probably isn't one.
Unless you have a crazy random schedule, or you want the temp the same whether you are asleep, awake, or not at home, or i guess if you have different temp preferences every day. Otherwise you can program in a basic schedule and just adjust manually as needed. Nothing stops you from changing the temp manually if you wake up an hour early, but if you wake up on time, then you don’t even have to think about it.
The round Honeywell electromechanical thermostat with a bimetallic strip, invented in 1953: https://www.honeywellstore.com/store/products/honeywell-roun...
24VAC, dead simple, and reliable. My family’s lake house has 50+ year old Honeywell round thermostats still in service.
I honestly prefer the older type. Ours is programable, but we just don't program it and always just set it to the temp we want. If we are feeling a little chilly on a cold day, we'll bump it up a degree, or down a degree when it's particularly sunny and everyone is feeling warm.
The original product understandably arrives with heavily-restricted firmware (I imagine to reduce the amount of flak the company receives). However, it is incredibly easy to install Flipper Unleashed or similar, which removes all said restrictions and adds a lot of additional functionality.
Possessing the tools that could be used to commit a crime is not necessarily a crime in and of itself! Just be careful with what you do or, depending on what country you’re in, you might find some men in suits knocking at your door.
Personally, I wanted to replay “encrypted” 433MHz signals for my own devices (electric gate, roller door, roller shutters, …) and this was disabled with the Flipper’s region set to Australia.
While I do agree 1000%, I also want people to be careful with this thinking since I have gotten in some minor trouble in the past. Always assume the authority questioning you can and will create whatever narrative they wish, that it will be accepted, and that your own reasoning will likely be used against you.
I will always encourage exploration and curiosity in tech, but if we stick with the Flipper Zero example, there's a few things one should keep in mind, regardless of the jurisdiction they're in:
* Don't carry it around unless you intend to use it.
* Read all documentation before you start practicing, then practice being subtle.
* Taking a note from my outdoorsy side, adopt the "leave no trace" ethos.
* Pay attention to the effect your presence and actions have on the environment and your target and how that might be interpreted by an outside observer, then take action to mitigate suspicion.
These apply to lots of devices, everything from your disposable smartphone to a cheap RFID card copier from Temu.
Our eagerness sometimes gets the best of us, especially new-comers, and we want to jump to the part where we can be like the hackers we see in tv and video games. There's a reason those guys are fictional characters. Innocuous actions or not, the perception of the authority questioning you is all that will matter, in the end.
Smoking pot in a dark parking lot with friends at night gives more cover, but smoking pot walking down your city's main street in the middle of the day gives you the cover of just smoking an innocuous "rollie," like any other person could be.
(The underlying point is completely valid, though. Audacity is a powerful thing.)
My job requires me to wear hi-vis (as well as other PPE) and it is crazy how little security pays attention to me in some of the very-big-name plants I visit, often with a laptop bag full of flash drives and a bunch of other tools that allow me to get into the machines.
Early in this part of my career, I found myself in a very large plant for the first time, and my escort got pulled away on some other task (I now expect this to happen since it's such a common occurrence), leaving me to fix the machine I was working on. The place was the size of a small town, and I needed to use the restroom, but nobody was in the vicinity to ask, so I did my best to follow the floor markings and signs. Found it, but took a wrong turn coming back and found myself in a completely different area. Since I was new, I tried to find my way back without asking anyone I saw because I did not want to look stupid, but nobody stopped me, questioned me, etc.
Probably one of the best lessons in social engineering is looking like you're supposed to be there.
And with that, I give you:
Don't Talk To the Police:
Do heed what's mentioned in the video, it's mostly true I presume and probably doubly so for their country of origin, but also consider there exists a balance
But then I build thermal control devices for fun so maybe it just seems like a much easier method to me.
[0]: https://thex10shop.com/products/x10-powerhouse-th2807-thermo...
Good luck with your future apartment customizations!
Though in reality many landlords don't mind as long as you know what you're doing and return it to how it was. Just a problem if you get a jerk landlord.
Penalties would depend on the adjudicator's opinion of the damages and risk.
Usually it's just acting as a simple relay (on-off switch) so there's two physical wires.
I've got my Hive thermostat running great with various Bosch and Vaillant boilers. And it works great with HA.
Some newer boilers have 12V "smart" controls but still expose 230V "dumb" call for heating pins.
Vaillant has a proportional signal as well, and that thing in my old home was 30 years old... [1]
[1] https://www.mikrocontroller.net/topic/126250?page=single
Also, if you read this far, are you German or something? you can just do things. which OP seems to know. And even if the landlord came and saw the apartment as long as the new thermostat isn’t neon orange, he isn’t going to notice and even if he somehow noticed you would just gaslight him and say no that’s how it’s always been and how the hell is he gonna escalate past that? And why would he if the new thermostat is more expensive and has better features?
Speaking of newish natural gas (CH4) heaters, they all should have modulating thermostat capability with OpenTherm/eBus or other protocol. Combined with a thermostat with outdoor temperature sensor system efficiency is increased a few percent and that should help offset thermostat and installation costs. In the end you have more efficient modern heating system.
Same should apply for heat pump systems.
In particular: stable and individually adjustable temperatures for bedrooms and living rooms; underfloor heating in some rooms (bedrooms), radiator-based heating in some others (living room), and combined UFH+radiators in some others (where UFH might not be enough during extreme colds).
I thought I can just pay someone some money and they'll set up the controls for me. It must be a simple exercise, right?
I could not have been more wrong. After spending a few hours of understanding the setups that "experts" have recommended, I figured out edge cases where they would be either wasteful or uncomfortable (meaning: unnecessary and inavoidable temperature overshoots or undershoots, etc.). I had many-many rounds with Honeywell, Tado, Siemens, etc. and every single one of them had _major_ issues.
The renovation got a bit stuck because of this, but the plumbing was ready so I wanted to see whether the pluming and pumps are working, at least. So I connected the pumps and valves to "smart plugs", i.e. Zigbee-controlled plugs, so that I can see that they turn on. They did, which got me thinking...
Right now I have $20 Zigbee temp sensors sprinkled across the house, $30 smart plugs and relays driving valves, pumps and the boiler, and Home Assistant is controlling the whole thing. Everything works perfectly and I could implement some features that simply no system would have done out of the box, for example in rooms where there's combined UFH and radiators I can drive both heating systems when the target temperature is far from the desired (so that the room heats up quickly) but as the room temp is getting closer to the target, the radiators are turned off so that UFH dominates heating (more comfortable and more energy efficient than radiators). In rooms with radiators, temp is +- 0.4 C within target, in rooms with UFH, it's +-0.1C within target.
Some people are unlucky enough to buy homes where a machine engineer designed the boiler setup and the boiler room have enough valves and manometers to like operate the engine of Titanic.
I guess programmers are the new sinners in this area nowadays.
If I inherit a heating system I want it to be all mechanical except maybe the control system for any heating pump.
(But still more comfortable than 99% of the houses I've been in.)
I haven't mentioned in the parent comment but as a test I've dismantled the HA system and installed the Siemens system and it works well, just not 'perfectly'.
In generall I think all these IoT systems will be a major headache as they age.
My thermostats on the radiators are 45 year old by now. That is kinda the expected service life we are used to.
Contractors today put in over-sized equipment, set flow temps higher than needed, undersize emitters for aesthetics and cost, and run pumps at full speed to avoid callbacks for “it’s too cold”. You can’t afford the windshield time to drive over to tweak the system to extract maximum performance, because homeowners don’t want to pay for it and will go with the lower bidder enough times that your premium AI-powered service will struggle.
I’ve tweaked my reset curve 12 times the first winter and 2 more times since then (counted from my spreadsheet).
Realistically, if I gave up on the last 3% tweaking, we could have lived with it after 2 post-install tweaks, but at least one of those had to wait for seriously cold weather snap to fine-tune the low end.
My spouse would happily agree that the house is finally very comfortable and noticeably more than before. She’d also tell friends who asked that there were a few days the first winter where the house wasn’t warm enough and needed an adjustment. People who heard that story might conclude that their neighbor’s guy who never has a callback for “too cold” is a safer bet.
Over time, I think even the best mechanical contractors will start to lean towards avoiding callbacks and do that by running the system 5-10°C hotter than “correct” engineering requires. That’s still better than today, where flow is set to 80°C, pumps to max, and the thermostat cycles 4 times an hour but the house is never too cold.
My knowledge is that for UFH you run at temps between 40-50C and radiators run at 60-70*C.
Almost everything in engineering is like this, not just heating. It's pretty rare that something is fully optimised.
Btw, you can use $5 LYWSD03MMC thermometers with ble or zigbee.
You calculated wrong, guaranteed. Most likely, you wildly underestimated fuel/electricity costs.
> After spending a few hours of understanding the setups that "experts" have recommended, I figured out edge cases where they would be either wasteful or uncomfortable (meaning: unnecessary and inavoidable temperature overshoots or undershoots, etc.).
Instead of thinking "the entire HVAC/heat industry are idiots who can't do any of this right", maybe you should take a look in the mirror and consider that your assumptions and/or criteria are wrong.
For example: under/over shoots in a modern HVAC or heating system will not cause any "waste" or discomfort. 1-2 degree F in overshoot does not mean the space will lose appreciably more heat than if it had perfectly regulated at the setpoint. You also don't want a system that responds instantly. Let's say you open the door to receive a package, and you're signing paperwork, etc. You close the door. The air in the room is substantially cooler.
Should the heat turn on?
I bet it does in your home...but the correct answer is no, because the air will warm up rapidly from all the objects that were at the temperature of the room. Thousand-plus square feet worth of surface area...
Temperature hysteresis is unavoidable with a conventional thermostat, but you can reduce it with PID controllers. Most commercial building automation systems use PID controllers extensively.
My guess is that the residential options from Honeywell, JCI, Siemens, Trane, Carrier, etc are focused more on one-size-fits-all applications, whereas commercial BAS systems are more or less bespoke designs for a specific building (using commodity sensors and controllers). I work with all five of the aforementioned companies on building automation projects, FWIW.
(use at your own risk of course)
> rpitx is a general radio frequency transmitter for Raspberry Pi which doesn't require any other hardware unless filter to avoid intererence. It can handle frequencies from 5 KHz up to 1500 MHz.
Wait, how does that work?
1.5GHz is a _lot_, I can't imagine this is done with bit-banging an I/O line, nor do I expect the Pi will have a DAC with anything close to a 3GHz+ sample rate.
> Plug a wire on GPIO 4, means Pin 7 of the GPIO header (header P1). This acts as the antenna.
A bit of Googling shows me that on the later Pi board GPIO4 (pin 7) has a bunch of alternative modes, amongst which is a general purpose clock output (GPCLK0), a DPI output bit (DPI_D0) and what I recon is composite analog video in/out (AVEOUT_VID0, AVEIN_VID0), and the TDI JTAG pin. But none of these would get close to 1.5Ghz TRX capabilities, no?
What's the magic here?
A hammerier solution would be to control the temperature seen by the thermostat (ignore the difficult RF protocol).
A heating element and a temperature reading could control the heat seen by the thermostat.
I'm pretty sure you wouldn't need any cooling (Peltier or whatever). Just a heater and ambient cooling! Set the thermostat to a high temperature, and run the heater to make the measured temperature hotter: when you don't want the heating to run.
That said, I think hacking the RF protocol is geekier and far awesomer.
Let's be honest here: the FCC is gonna have to see a helluva lot of problems coming from your transmissions before they bother to send the black Suburbans filled with men in suits to knock on your door. You're going to get a series of letters that basically say "please don't do that" if anything.
In the US you are allowed to tinker around there with home-built RF devices for personal use and prototyping in unlicensed bands, to some extent. Although, using an SDR for this requires a certain interpretation of the rules. In Europe it's basically not allowed, one shall only use pre-certified modules. Or only use the device you've built in an RF anechoic chamber until you've undertaken the certification process (totally impractical for a hobbyist).
All the apartments I lived in had basic thermostats; and I even rewired and replaced one of them.
What was blocking Videah from buying an off-the-shelf thermostat?
Then the boiler is basically controlled by the relay.
```There was a comment section here. It's gone now. As of March 16th, 2025 the United Kingdom's Online Safety Act has gone into full effect. The law presents a lot of challenges for hobbyist websites like this one to present any user-to-user content (like y'know, blog comments) and comes with some pretty serious repercussions for non-compliance.
The odds of Ofcom (the regulator whose job is to enforce this) kicking my door down over this blog are low if we are being honest with ourselves. But the odds are at least somewhere above zero and the punishment is a life ruining £18 million fine(!!) so it's just not worth the risk.
A kind lawyer has written up the implications of this law for self-run blogs like this one and the only way to guarantee that I am not in-scope would be to manually review all comments made before being available to the public. Not to be a big baby about it all but I don't really want to do this! I liked my current setup!
So I guess as a little act of protest and to hedge against any risk I've removed the comment section entirely. Sorry about that!```
The government maintains indoor temperature at 24 degrees from October to May, and the water is heated at the power stations.
That's a level of paranoia I would never have. You can easily conceal them in a way that is almost imperceptible.
People generally don't like you messing with their stuff. They especially don't like it when you add sketchy-looking electronics to things that are expensive and can burn their property down.
If you want to take a swing at it, I'm not stopping you. But after 30 years having landlords, plus having family and friends who are landlords, I think I have a pretty good sense of what can upset a landlord. Maybe yours will be super chill. Me, I'd rather go the radio route.
Our landlord installed a Honeywell home, the cheapest version, and it has no remote or timer capabilities
And especially in winter it would be nice if it would jump on before we wake up!
If you bought such a thermostat in the US (e.g. at walmart or what-do-I-know), that device would probably operate on 433 or 915 MHz. I think you can legally broadcast on these in the US, much like the OP did [in the UK]. Power limits might be a bit different and such. But IANAL and no US person, so do some research before grabbing a HackRF One ;-)
I haven’t done this since 2014 but the google nest API used to (hopefully still does?) let you see and or set the thermostats status with curl commands.
My use case was to run one shell script that got my burglar alarms status, and if it was “armed/away” to simply set my nest thermostat as away, too.
But it can also be hooked up to a dummy load or a relay and just used as an indoor temperature sensor.
And the curl commands OP is relying on can be tied in to indoor and outdoor temperatures , such as scraping local weather with curl/wget and based on that integer, turning the boiler to a minimum when it’s a certain temperature outside.
Or turning it completely off when it’s warm outside.
I’m about to revisit this again just because I have an ancient gas pig of a furnace that uses microvolt and is too cold when it’s cold outside, and too hot when it’s warm outside.
So I need one thermostat in place to turn it on no matter what at 40F, but then some conditional logic to kick that thing on and off on different cycles based on outdoor temps. The whole systems too crude to implement one off the shelf without adding a zone controller, so I just want a Linux box at home to be the zone controller….
where I differ is that I’m not sending an RF signal to the boiler, I just have to close an NO contact to engage mine (and I’m lazily going to use the nest for that.)
If anyone knows of a better thermostat that has its own API I can set, read sensors, turn hvac on and off without using google/nest account or having a dependency on the goodwill of their API existing forever , I’ll come back and glean any responses thanks in advance.
As an afterthought, hm I can just attach temperature probes and a GPIO for a relay and indoor/outdoor temps and do away with google/nest altogether…. Thanks for jogging my brain a bit I might do exactly that.
(The nest was cool , and educational, I guess, 12 years ago when I didn’t know how to really do anything but run and fire off curl commands on someone else’s hardware for temp sense and closing a relay and I don’t have anything bad to say about it as a starting point.)
Where I was going with this , though, was that , you could use an off the shelf nest , and run
1) one command against API to get thermostat status (system thinks it’s on or off , even though it’s factually not directly controlling anything) and then based on that,
2) another command to your RF board to transmit a matching signal.
…
(However you could also do the same with a temperature probe that can be read on board or over WiFi , and then manage your setpoints in the script and or by other means: eg scraping a weather site for the local outdoor temp in your case where the landlord probably wouldn’t let you attach or connect an outdoor probe.)
Bonus with the nest approach is you get a dial, can mount it on anything , doesn’t have to be the wall of your unit… and it “sort of works” like a normal thermostat as well, as soon as the shell script reconciles the two states manually.
Long winded rant but the original use case was an apartment where the thermostat was proprietary and serialized data and I didn’t have any option to integrate a smart thermostat other than turning it to its maximum set point and then using the nest with a massive 220V/50A HVAC relay to just chunk the AC power line on and off on demand.