Smart TRV

madapan

Hey Everyone!

I'm at the very early stages of developing a smart one-pipe TRV to reduce overheating. What do people think? Is there demand? Issues / Challenges?

JUGHNE

Can you define "smart"?

Sailah

"Hey Alexa..."

nicholas bonham-carter

If your system is balanced properly, with good main venting, and low pressure, all the radiators will heat at the same time.
As a result, there should be no localized overheating.
Often TRV’s are used as a bandaid for dealing with bad venting, and thermostat placement. In the end, the solution defaults to getting the system back in balance, and that’s where the “smart” comes in-not from a mechanical add-on, but from diagnosing any system faults, and then performing subsequent remediation.—NBC

madapan

Thanks Nicholas. Totally understand the bandaid issue, but wonder if a better bandaid has any merit.

To address the "smart" question above. Yes, we are thinking of including all of the things that make smart home tech cool and user friendly - app based interface, connectivity, compatibility with other smart home integrations (ie. Alexa, Google Home, IFTTT). But the main "smarts" come from the ability to learn and optimize based on how the room is responding to the heat - taking in indoor and outdoor environmental data to change home much air needs to be kept in the radiator

ChrisJ

I'm using 5 TRVs on my single pipe system in a single family house.

I don't use them for overheating issues, as much as allowing the system to compensate for changes in the environment. Like, the sun warming rooms up during the day, or the oven going in the kitchen etc.

That said, my wishes would be a digital thermometer along with a digital set point with a remote sensor rather than a simple wax motor right by the wall. The sensor being right by a cold wall and sometimes hot radiator is the biggest issue IMO.


Your TRV needs a decent vacuum breaker and the ability to change it's venting capacity either through a variable vent like the Vent Rite 1, or being able to change vents via an 1/8" NPT port.

madapan

Thanks @ChrisJ! I think you've hit on a few of the critical needs for this type of product - remote sensor and changes in the environment.

Eastman

Will these smart TRV's be able to call for heat?

ddunn

How would it distinguish from existing https://www.amazon.co.uk/Electronic-Radiator-Thermostat-Programmable-Thermostatic-x/dp/B01N35O95F

Compare with other similar options shows four items that seem similar to your proposal.

gennady

Bad idea. In steam systems boiler works on thermostat or outdoor reset. Radiators act as accumulators of heat. They are charging and discharging. It is cyclical process. With “smart” trv system will fall out of cync with boiler.

mikeg2015

If you had a totally sealed system you could use an EEV to control boiling rate, control a modulating burner off superheat, then use zone valves to control radiator output. Would work better on a 2 pipe system.

Eastman

The TRV's shouldn't rely on a thermostat. Collectively, they should be deciding when to fire the boiler and for how long.

ChrisJ

> @gennady said:
> Bad idea. In steam systems boiler works on thermostat or outdoor reset. Radiators act as accumulators of heat. They are charging and discharging. It is cyclical process. With “smart” trv system will fall out of cync with boiler.

Eh?

hvacfreak2

Eastman said:

The TRV's shouldn't rely on a thermostat. Collectively, they should be deciding when to fire the boiler and for how long.

Yeah a networked system of these would be fantastic. Back to a main controller to allow group assignment and logic. It would be nice to be able to force the positions ( close upstairs zones to x percent until first floor zones are at x degrees if the outdoor temperature is less than x ). And floor plan graphics since I'm dreaming , lol.

Eastman

@hvacfreak2

Like you said, the TRVs should have a main controller for group assignments, etc. But it is my hope that this main controller would also be in charge of CPH and pressure. I also think temperature sensors on the end of each main would be helpful.

Jamie Hall

Keep in mind -- firmly -- that steam heat (any heat, for that matter) is a system, and all the bits must work together in some sort of harmony.

I think that there is some merit -- in fact, probably a good bit of merit -- in having thermostatically controlled valves for the individual radiators in a two pipe steam system (not in one pipe -- condensate problems, unless the valves are really tight) -- but only as part of a complete control system. Think of it this way: the boiler is in charge of supplying the heat transfer medium (steam at some temperature) and must also be controlled to provide that medium in the right amounts at the right temperature.

So... if we are going to leave the ultra simple and reliable world we usually work in, where do we go? Well, the TRVs control the individual radiation, but they are expecting to have the transfer medium always available. So the boiler is controlled, within a narrow but adequate pressure range, by a pressure controller. If we really want to get fancy, we can seal the system and provide an induced vacuum, controlled by an outdoor reset, to vary the temperature of the steam which we are supplying (note that this also implies that the target pressure for the pressure controller is also controlled by the outdoor reset. The TRVs can have very narrow deadbands, to maintain steady temperatures in the space -- or could even be proportional if the valves can do that. The pressure control system can have a much wider dead band, to minimize boiler cycling (and could be tied into the burner control, if the burner can modulate).

There are some rather interesting potential feedback loops here, which would make programming the controller for such a system much more interesting and would require considerable expertise in setting the system up, but that's doable.

It would also be possible, with a few additional controls, to make the whole thing fail operational (like the limp home mode on a modern car).

Is it worth it? A resounding maybe... unless you can operate much of the time at a high enough vacuum to make the boiler condense -- and the boiler is designed to do so -- the gain in thermal efficiency will be small. The gain in comfort in a relatively small building will also be small. But in a bigger building it might be worth it. There would be, of course, a real increase in maintenance involved, and the person in charge of keeping it running would have to be well paid for their training and knowledge -- not a trivial item.

Random thoughts of a Wednesday morning...

hvacfreak2

I guess what I would want is just a proportional ( or pulse ) motor for an actuator. I would connect it with that small chrome armored cable like door contractors use to a controller like this one ,

https://easyio.eu/benefits-of-the-new-ft-04/

This controller would need a wired 24 volt power supply as well as a wired stat ( or a wireless with a receiver unit ). It is only 2 x 3 inches so it could be incorporated onto the actuator or maybe placed in a wall with an antenna extension for the wireless comm. After that it could be as simple or as complicated as needed , controlled from a phone or integrated into a BACnet / ip network.

twix

I might start my own thread (once I have done more research), but I myself am planning on adding smart TRVs to my single-pipe steam system.

I've already done a test in one room and it seems to work great. I'm not a heating pro, just a smart home geek.

I'm using the Shelly TRV, which is Zigbee-based and linked with my Home Assistant custom smart home hub. The smart home has average temperature and real-feel readings for every room of our 1700 sqft house (as well as true occupancy sensors) and I'd like to use that info to throttle down the steam in rooms we are not using.

The smart TRV is able to receive remote temp readings to use for valve regulation, or be set remotely based on any criteria (ie, shut valve if window is open). The valve can be moved incrementally from 0 -100% quite smoothly. It works up to multiple PSI of pressure.

https://www.shelly.cloud/en/products/shop/shelly-trv

The motivation is the extremely high oil prices where we live right now, and trying to conserve/save heat wherever possible.

I believe that we can save a bunch, but maybe not enough to offset the high cost of parts (each TRV is a whopping $85 USD, not including the Danfoss adapters and straight vents).

I'll cross link to my thread once it's opened, but I'm glad I found this one

JakeCK

That TRV is an EU product. How are you using it in the US? I'd imagine there are many of the same issues with ZigBee as there is with z-wave when bringing over products from across the pond. Namely that they use slightly different frequencies and aren't exactly legal to use in the US per FCC spectrum licensing...

Granted z-wave does use the 900mhz bands and ZigBee the 2.4ghz if I'm not mistaken.

Chris_L

@twix, Is the link you provided for your TRV? That link says it uses wifi without a hub. Yet you describe it as using ZigBee.
@JakeCK, my understanding is that ZigBee is an international standard. It is used on many products in the US. What issue do you see with this one? Is it not FCC certified?

JakeCK

Chris_L said:

@twix, Is the link you provided for your TRV? That link says it uses wifi without a hub. Yet you describe it as using ZigBee. @JakeCK, my understanding is that ZigBee is an international standard. It is used on many products in the US. What issue do you see with this one? Is it not FCC certified?

I apologize, I'm not that familiar with ZigBee. I had to actually look but apparently there are no issues using ZigBee in other countries like there is with z wave.

EdTheHeaterMan

A real SMART device will "do what I Mean not what I say!"
But I can't even get my kids to listen!

Chris_L

JakeCK said:

Chris_L said:

@twix, Is the link you provided for your TRV? That link says it uses wifi without a hub. Yet you describe it as using ZigBee.
@JakeCK, my understanding is that ZigBee is an international standard. It is used on many products in the US. What issue do you see with this one? Is it not FCC certified?

I apologize, I'm not that familiar with ZigBee. I had to actually look but apparently there are no issues using ZigBee in other countries like there is with z wave.

@JakeCK, your comments caught my eye because I have an older Zwave thermostat (Radio Thermostat CT-100) that was given to me as part of an energy audit in MA.

I found this FCC search tool: https://www.fcc.gov/oet/ea/fccid and am happy to report both the thermostat and Building36 Zwave hub it connects to are approved by the FCC.

So while there certainly may be unapproved Zwave devices being sold in the US, not all of them are.

JakeCK

You misunderstood what I was saying. There are z wave devices in the US that are approved for our market. But a z wave device for the European market will not work with our devices. I have a lot of z wave devices I use in my house. And I spent a lot of time looking for z wave trv's in the US, but there are none.

ZWave devices in Europe will not work with US hubs because in the eu they use 868-869mhz and the us uses 908-916mhz. I had mistakenly thought ZigBee might suffer from the same issue of using a slightly different frq. 

random12345

@madapan The TRV must not be too heavy or after a while it will bend, and not only will it become useless, but it could also damage the radiator vent tapping itself.

See 2:14 in this video: https://youtube.com/watch?v=hjS5slMqtuA

Plastic and steam don't play well together though. Most plastics will not tolerate being in contact with or even close to metal at 215 F.

ChrisJ

random12345 said:

@madapan The TRV must not be too heavy or after a while it will bend, and not only will it become useless, but it could also damage the radiator vent tapping itself. See 2:14 in this video: https://youtube.com/watch?v=hjS5slMqtuA Plastic and steam don't play well together though. Most plastics will not tolerate being in contact with or even close to metal at 215 F.

Most plastics are 3d printed at 392f to 572f.
Peek as high as 752f.

Plastic being by a steam radiator isn't an issue.

pedmec

i think the "smart " idea has some merit. i have plenty of apartment buildings and condo's that use non-electric trv's to control heat output for both steam and water. AS simple as they are i find the issue with the trv's is that most tenants or condo owners don't even know how to operate them. if you could get a led screen on it so they can see it visually. most if not all trv's are label in numbers which confuse the occupants so they wont touch them.

I think the issue would be finding a price point that would get people to buy. I have building with 5 and 6 per unit for a two pipe steam. after getting 125 thermostatic traps replaced I couldn't get them to pull the trigger on the trv's with direct mount actuators.

twix

I mistakenly said the Shelly TRV was Zigbee -- it's not. It's Wifi and joins the home network like most other devices (can be operated locally, without a cloud/internet connection).

This is actually a US official model -- until recently you were right, there were only EU products. I'm happy they finally brought some to the US market!

The TRV is plastic, but it's also specifically made to be attached to radiators. Beyond that, I have it on a stand-off adapter that adds another inch or two away from the fins.

The drooping is a concern for sure, but our vent taps are already loose and I just put a bunch of plumbers tape on them anyway. Most are stiff enough to hold straight though, w/o extra help.

Here's a pic of my test setup:

random12345

From the website, it looks like it's made to attach to hot water radiators, not steam. The higher temperatures may be a problem. I would not be comfortable putting a battery next to a steam radiator like that.

Also that reflector you have behind the rad was designed for hot water not steam. I spoke with a company that makes those, and they never tested it for that application. Aluminum foil is just as effective.

Sorry to be such a downer.

ChrisJ

random12345 said:

From the website, it looks like it's made to attach to hot water radiators, not steam. The higher temperatures may be a problem. I would not be comfortable putting a battery next to a steam radiator like that. Also that reflector you have behind the rad was designed for hot water not steam. I spoke with a company that makes those, and they never tested it for that application. Aluminum foil is just as effective. Sorry to be such a downer.

How close is your car battery to the engine and exhaust manifold that runs 800-1200F?



That battery is a good 4 inches away from the coolest part of that radiator and it's off to the side of it not over it.

KC_Jones

ChrisJ said:

random12345 said:

From the website, it looks like it's made to attach to hot water radiators, not steam. The higher temperatures may be a problem. I would not be comfortable putting a battery next to a steam radiator like that. Also that reflector you have behind the rad was designed for hot water not steam. I spoke with a company that makes those, and they never tested it for that application. Aluminum foil is just as effective. Sorry to be such a downer.

How close is your car battery to the engine and exhaust manifold that runs 800-1200F?



That battery is a good 4 inches away from the coolest part of that radiator and it's off to the side of it not over it.

Yeah, I can put my bare hand within 1/4” of my steam radiator and it’s warm, but certainly not hurting me and I could leave it there forever and not have an issue.  My body is way more heat sensitive than anything in that picture. That battery, the TRV, the bubble wrap are all more than fine.

ChrisJ

I sure am glad I'm not scared of my steam radiators like it seems like so many are.

They hurt if you touch them too long.  That's about the extent I've found.

Or if you fall and hit your head on them you could get badly hurt... Of course the came can be said for coffee tables too.

ChrisJ

@random12345

I find it interesting you disagree with my post regarding what plastics are printed at etc.

Jamie Hall

A few miscellaneous comments, inspired by various remarks above.

First, steam radiators are only slightly more dangerous that hot water radiators, particularly in older systems. Hot water radiators often run at between 180 and 190. Steam at 212. There's almost no difference in terms of hazard touching them, or heating materials near them. Neither is hot enough to set fire to anything. Both of them will give you a nasty burn if you hold onto them. Your reflexes --even as an unsupervised toddler -- will not allow you to do that. So don't worry about them.

Second, on plastics. Depending on the particular formulation, there are many plastics which will maintain their shape and most of their properties at those temperatures. There are, of course, some which won't. One hopes the manufacturers are smart enough to avoid those. However, almost all plastics -- there are a very small number of exceptions -- eventually become brittle, and the length of time it takes depends on the formulation and the temperature. This may take 10 or 20 years, even at steam temperatures, but... it will happen, and I wonder about some of these plastic fantastics and their actual longevity. Curiously, the more rigid they are the more this is a problem, in general. It also depends on exposure to light, particularly UV -- even polyethylene, which is pretty good about that, will degrade in time if exposed to UV light.

ChrisJ

Jamie Hall said:

A few miscellaneous comments, inspired by various remarks above.

First, steam radiators are only slightly more dangerous that hot water radiators, particularly in older systems. Hot water radiators often run at between 180 and 190. Steam at 212. There's almost no difference in terms of hazard touching them, or heating materials near them. Neither is hot enough to set fire to anything. Both of them will give you a nasty burn if you hold onto them. Your reflexes --even as an unsupervised toddler -- will not allow you to do that. So don't worry about them.

Second, on plastics. Depending on the particular formulation, there are many plastics which will maintain their shape and most of their properties at those temperatures. There are, of course, some which won't. One hopes the manufacturers are smart enough to avoid those. However, almost all plastics -- there are a very small number of exceptions -- eventually become brittle, and the length of time it takes depends on the formulation and the temperature. This may take 10 or 20 years, even at steam temperatures, but... it will happen, and I wonder about some of these plastic fantastics and their actual longevity. Curiously, the more rigid they are the more this is a problem, in general. It also depends on exposure to light, particularly UV -- even polyethylene, which is pretty good about that, will degrade in time if exposed to UV light.

I'm printing some nylon as we speak, at 285C, or 545F. Specifically, PA12.
The bed temp is 80C or 176F.

Nylon may be one of my favorite materials actually.

rwebb010

I used PA12 for the adapters I needed to attach the Tado smart radiator thermostats to my older cast iron radiators.  Granted my use case is hot water vs steam.  

random12345

And if the valve or device fails and steam gets into the battery compartment? That TRV looks cheap. Shelly specializes in making IoT products. This is their one and only hydronic heating product. Maybe it's good quality, but I wouldn't know and wouldn't risk it. I wouldn't want any battery operated TRV on a steam radiator unless I knew it was designed and tested for that application. At least with something from Macon or Honeywell I know it was.

Lots of plastics have a max service temperature well below 215 F. For example, PVC. https://omnexus.specialchem.com/polymer-properties/properties/max-continuous-service-temperature A plastic that can withstand being close to a hot water radiator may not hold up as well close to a steam radiator. No indication on their website what kind of plastic they're using.

Specs say working temperature tops out at 30 C (86 F). Will the temperature be that high next to a steam radiator? I don't know. It uses a Li-ion battery too. Too many potential problems in my mind. Not trying to cast aspersion on the manufacturer. Might be a good product.

ChrisJ

random12345 said:

And if the valve or device fails and steam gets into the battery compartment? That TRV looks cheap. Shelly specializes in making IoT products. This is their one and only hydronic heating product. Maybe it's good quality, but I wouldn't know and wouldn't risk it. I wouldn't want any battery operated TRV on a steam radiator unless I knew it was designed and tested for that application. At least with something from Macon or Honeywell I know it was.

Lots of plastics have a max service temperature well below 215 F. For example, PVC. https://omnexus.specialchem.com/polymer-properties/properties/max-continuous-service-temperature A plastic that can withstand being close to a hot water radiator may not hold up as well close to a steam radiator. No indication on their website what kind of plastic they're using.

Specs say working temperature tops out at 30 C (86 F). Will the temperature be that high next to a steam radiator? I don't know. It uses a Li-ion battery too. Too many potential problems in my mind. Not trying to cast aspersion on the manufacturer. Might be a good product.

All of my TRV's, both Danfoss and Macon have plastic all over their actuators. And a wax motor inside!

You must realize if that area got "steam hot" the TRV's thermostat literally would be useless? It's a thermostat designed to detect the approximate temperature of the space.

What if the TRV leaks steam. What if a meteorite crashes through the house and hits you?

JakeCK

Dude give it up. Residential hot water and steam radiators just do not get hot enough to damage anything not in direct contact with them... And even most items in direct contact.

random12345

I think you missed the point I was making. OP is using a TRV made for a hot water radiator on a steam rad by a company with apparently zero hydronic experience, product is much cheaper than other products on the market for what it does, and has a li ion battery which can explode if heated. Is it likely to happen? Probably not, but I wouldn’t try it. I have no problem with something made by Danfoss or Macon.

ChrisJ

random12345 said:

I think you missed the point I was making. OP is using a TRV made for a hot water radiator on a steam rad by a company with apparently zero hydronic experience, product is much cheaper than other products on the market for what it does, and has a li ion battery which can explode if heated. Is it likely to happen? Probably not, but I wouldn’t try it. I have no problem with something made by Danfoss or Macon.

I try a lot of things other's haven't.
It's my job.