what thermostat will deal best with boiler recovery times and outdoor reset

luckyguy

now that i solved my C wire issue and have one, been looking at stats that can assist me in my issue. i have a luxpro stat now set to turn on 4 am for a 5am wake up. that may not be the best time to have it turn on and it could be much longer or shorter. id like a stat that figures that out for me .if it's wifi thats great. but if a standard one will do it, thats ok too. but for ease of programming wifi is probably best. the tekmar outdoor reset only has the outdoor sensor, never got the indoor one installed. wiring in the house is difficult due to crawlspace issues.

been reading reviews about ecobee and honeywell having some kind of smart recovery. then of course you read 'bad' reviews about something not running correctly but i do wonder if they are user error or not. also i know ecobee can have an indoor sensor to make sure a certain room will be warm and i assume honeywell has that too.

boiler is solaia 110 btu installed approx 2008 with gas. also there's a 30 second delay relay my guy had to install on it. unsure if that really affects anything as far a programming a new stat. but what was happening was the pipes above the boiler werent purging well enough so the unit would turn off right away when it went to fire up again because hot water was still in those pipes. with the delay the cooler water gets to the pipes and the unit runs how it's supposed to. (at least this is what i remember)

i do have the timer set back 2 degrees starting at 9pm. im good with 66 over night but want 68 in the day. hoping to save money of course like everyone but my old gas contract just ran out and my new price is double what i was paying on the 3 year contract. current stat waits till its 2 degrees below set point to kick on and rarely overshoots, perhaps 1 degree maybe.

Zman

What type of radiators? Baseboard? Infloor slab? Staple up? Do you plan on deep setbacks daily?

luckyguy

also forgot to say i have triangle indirect HW if that matters.

i have 190 ft of cast iron baseboard. current schedule is weekdays 4 am to 68 then 9pm to 66. weekend has 6 am for 68 degree.

i learned when i moved in NEVER to set it by more than 2 or 3 degrees difference. would take way too long to recover. right now im pretty sure my current stat waits till its about 2 degrees lower than set temp to turn on. but im not 100% sure. is that how it should be operating?

ive read so many ecobee reviews my head is spinning. some curse it, then i read a positive reviews. also my gas company has a huge discount on the ecobee which is why im interested in that particular one at this time. but if it's really not good i'm ok going with honeywell or something else. but i def want some kind of smart recovery thermostat, wifi or not.

Ironman

ODR and setback stats don’t play well together.
If you have a modulating boiler with ODR, the best thing you can do is set the stat at one temperature and leave it there.
You’ll have less efficiency and comfort using setback.

luckyguy

i dont know what a modulating boiler is. are you saying with ODR thats what i have?

i just feel that for 7 to 9 hours at nite with 2 degrees cooler there can be some savings there. also is it normal for a stat to wait 2 degrees until it kicks on? plus if i had the same temp during the day in the bedroom as nite i think i'd not like that extra heat in there.

http://boyertownfurnace.com/residential/solaia-boilers

Jamie Hall

First off, the Ecobee is good. For some heating systems, like hot air, it's fine. For hot water radiators, it's OK. For steam the best that can be said is it's better than a Nest. For anything with radiant floors, no smart thermostat or one with setbacks should be used at all. Your application, with two degree setback, probably not too bad. It will fight with the boiler and the outdoor reset when using setbacks, resulting in you not getting the savings promised by either one, but it won't be too bad.

luckyguy

any opinions on ecobee vs any honeywell. obviously HW has been around a long time but is that a reason to trust it more? was looking at this one possibly and they use 'smart response' . the eco premium thru my gas company is 99 but the honeywell below id have to pay 99 regular price. no biggie of course. more expensive doesnt always mean better. and no matter what i'm keeping my old stat for a backup of course.

gas company also has the T5 for 20 bucks but that seems like an older model if i'm correct

https://www.honeywellhome.com/us/en/products/air/thermostats/wifi-thermostats/wifi-color-touchscreen-thermostat-rth9585wf1004-u/

luckyguy

did a test at 6pm. stat was reading at the normal 68 daytime temp. baseboards were cold but my living room remote thermometer was 66.6. i then cranked up to 69. 50 minutes later the boiler turned off. LR remote thermometer was 67.8.

20 minutes later the LR was up to 68.2. love the radiant heat!

luckyguy

i got tired of research. ordered ecobee premium for 99 bucks thru my utility. will report back after using it a while

PEvans

Boy is this topic confusing and frustrating!

My sense is the modern "smart thermostat" is really designed around deep, frequent setbacks, for when you are asleep or out of the house. So maybe their most highlighted features don't match up that well with the requirements for very slow-responding steam and hot water radiant systems. Maybe Jamie Hall is right, you should use low or no setbacks and you just don't need this stuff.

There are threads on this board talking about direct configuration of maximum cycles per hour and temperature deadband which would be great, but I don't see any non-discontinued thermostats with those features.

Everyone (including Nest) has some variant of "learning" your cycles so the thermostat knows when to come on to reach the desired temperature by the desired time. Who knows if one's works better than another's. Notably the Honeywell color touchscreen linked in Luckyguy's post above does allow you to tell it that you have hot water or steam heating.

The ability to add remote temperature sensors is really limited to the most expensive thermostats. In Luckyguy's post above I think the Ecobee premium has it but the Honeywell color touchscreen does not. So if you want this make sure you are getting it.

If you are a data geek (likely on this board) possibly the Ecobee offers better access to downloadable logs; I don't personally know.

I'm still researching. No one is offering me an Ecobee at more than half off. :-\

Jamie Hall

It is fascinating. The fundamental problem, of course, is that we are dealing with a very complex system -- heating a house or other occupancy -- and the nature of the system varies over an extraordinary range -- from systems which respond very rapidly (many well designed forced air systems, for instance) to systems which respond very slowly indeed (such as a high mass radiant floor). Further, the parameter we are trying to control -- indoor temperature -- is actually very subjective. Then the equipment we are controlling has widely varying characteristics. The end result of this is that some types of thermostats are well suited to one type of system, and remarkably poorly suited to other types.

The Nest and Ecobee fraternity -- and others in that group -- are actually excellent control devices, but only for systems which respond rapidly to changes in the settings. They were, after all, designed by coastal Californians for coastal Californians for coastal California -- and forced air heat and conditioning is what is in the vast majority of those buildings. They do a very good job at it. They do no better, even if tweaked as far as they can go (Ecobee seems more tweakable), than a 60 year old mercury T87 for a slow responding steam system, never mind a high mass radiant.

Another thing to consider is remote sensors. They sometimes make a good deal of sense, but there is no point in having more than one -- unless each one controls its own heating zone. Where they do make a lot of sense is where one wants the actual control device to be remote and possibly inaccessible from where the sensor is -- such as many multi-family applications, or other applications inhabited by fidgety fingers.

A third consideration is off-premises monitoring and, possibly, control. There are a number of applications where this is quite desirable, but it does mean additional complexity in the control device -- and it implies good communication to the rest of the world, which must be considered.

PEvans

I'm learning...

Here is an article by Paul Kuehnel that I found helpful in addition to the info posted here.

He ends up with a Honeywell RTH6500 which he says did a great job keeping the temperature constant, which was his goal. That is an interesting choice because the documentation actually describes settings for heating system type and cycle rate. The article is now 5 yrs old, and I'm not even sure that thermostat is available. The RTH9585 linked above does not give the complete settings list in the manual, but maybe it is worth a try given its family history, with a schedule with very small or no setbacks.

I have history with Nest in my prior home and professionally as well. For where I was using them -- a house with three independent forced-air heating systems handling spaces more or less open to each other, the Nests were great. No so much savings but way more comfortable for the same fuel use.

luckyguy

installed 2 days ago. old unit was set 66 over night then 68 during the day. did the same for ecobee. the overshoot on ecobee was insane the first morning. i have temp sensors in 4 rooms of my house so i know those historical temps very accurately. the living room was almost 71 (rarely got above 68) ! even in the room where i have poor baseboards, temps normally reach maybe 64, the temp was 67! bathroom was super nice and toasty though. 71.

i set back the day time to 67 and ensured it was manual .5 differential. another thing that worried me is that it was well over 68 and still running but then i did research and i wasnt aware of that differential. so it was really shooting for 68.5

next morning was fine thankfully and set it to automatic threshold just to see what it would do. i really dont understand exactly if i did something good or not but ill watch the temps to see what is what. normal regular temps are thankfully back. however over night is too hot. so put that back to 65.

PEvans

I purchased and installed a Honeywell RTH9585, same as linked by luckyguy above.

The good news so far is you can tell it the system is, in my case hot water/steam and then specifically steam, during the on-screen setup. So I can't directly set the CPH or specify a deadband, but at least in theory the thermostat knows it is running a slow-responding system. It is going to have to learn for a while, I'm sure. (To illustrate, at installation I set the program temperature to the ambient temperature at that time. The system called for heat and ran for probably 3h without really moving the ambient temperature. Then it shut off and over the next hour the temperature increased by 5*F. So yes, the thermostat will have to figure it out if it is able.)

This thermostat has a simple time-based schedule scheme; no proximity or occupancy sensing. Based on advice here I'm going to stay away from big setbacks, maybe a degree or two at the most. And the base temps are going to be pretty low; we're using space heaters in the occupied rooms rather than making the whole place tropical. FWIW there is no support for external temperature sensors.

You have access to the thermostat via the internet and a smart phone app. But the functionality is really just the schedules and alerts. You don't have access to the device settings and there is no historical run time data that I can see. So that is lame IMO.

PEvans

I am going to return the Honeywell RTH9585. My system operates with reversible valve actuators and the thermostat is not energizing the valve "close" circuit properly, even though Honeywell says it should.

During troubleshooting I learned from Honeywell that the trade thermostats (TH models rather than RTH models) are more configurable; that is where you have options to set CPH directly among other things. So I'm going to try a TH8321WF if I can get one.

SteamBoiler

@luckyguy @Jamie Hall

I have my Nest set to 68F during the day and and 64F at 10pm on my 2 pipe steam system. Recovers in 1F hourly increments from 3am to 6am. Never cycles on pressure with this gentle of a recovery (set to about 0.75psi cutin and 1.5psi additive differential). The normal temperature maintenance heat call is about 20 minutes and the recovery heat call is about 27 minutes and the needle on the pressure gauge doesn't move. Since about 10 minutes of heat call is required to get steam to the earliest radiators, I figured I would take one 27 minute recovery heat call over two 20 minute maintenance heat calls and come out ahead, additionally we prefer a cooler home at night.

PEvans

@SteamBoiler

Is your 1F/hour recovery in the Nest program? That is, do you set the programmed temperature to 64F, then 65F, 66F, 67F, and 68F in successive hours between 3am and 6am? Do you feel this keeps the Nest from over-shooting the set temperature?

Also this sounds like it is entirely time-based. You are not using any of the Nest's occupancy-based setback features (or the Nest's learning features). Is that correct?

Do you have a guess as to the time of heat call to get steam to the last radiators on your system?

Aside: one nice thing about the Nest is you can see in the history in the app or online when it came on and how long it ran, so it is great for tuning. Unfortunately the data only go back a week and does not include the inside and outside temperature.

luckyguy

unsure if leaving it on automatic for the differential is a good idea. it was on 3 hours this AM to get from 65 to 67 and it was 50 outside. so certainly didnt need to run 3 hours. i dont know the true setpoint since it's on automatic. could have wanted to get 67.9 or even 68. all i know is even hours later i had an increasing temp in my LR to over 71. the room temp may not really be 71 but for comparison sake to PRE ecobee time i had to leave it where it was. its on a table sitting about 18 inches from the baseboard. so it's def warmer there but relatively speaking its still a major overshoot.

i wanted to wait a month to deploy the sensor that came with it but maybe it would be a good way to help with this overshoot. or maybe just turn it to manual and .5 like i had it before. but it's just week 1. hate to make toooooo many changes.

SteamBoiler

PEvans said:

@SteamBoiler Is your 1F/hour recovery in the Nest program? That is, do you set the programmed temperature to 64F, then 65F, 66F, 67F, and 68F in successive hours between 3am and 6am? Do you feel this keeps the Nest from over-shooting the set temperature? Also this sounds like it is entirely time-based. You are not using any of the Nest's occupancy-based setback features (or the Nest's learning features). Is that correct? Do you have a guess as to the time of heat call to get steam to the last radiators on your system? Aside: one nice thing about the Nest is you can see in the history in the app or online when it came on and how long it ran, so it is great for tuning. Unfortunately the data only go back a week and does not include the inside and outside temperature.

My setback and recovery are entirely time based and do not use the Nest's learning or occupancy based features at all. My program is: 3am 65F, 4am 66F, 5am 67F, 6am 68F and 10pm 64F. In general Nest will stop at slightly below the setpoint and will allow the home to coast to maybe 0.5F above setpoint, max of 1F above. 1F above is rare. I am not sure if Nest overshoots during this recovery period but honestly I don't really care too much, typically it does seem to run every hour as programmed for about 25 minutes. I do use the pre-heat time of 1 hour so it can start slightly earlier if needed and it seems to start about 10 minutes ahead.

Under normal conditions when heat may have been called a couple hours ago and water is still warm in the boiler, it takes about 10-12 minutes for steam to reach the earliest radiator and about 15 to reach the latest and the typical heat call is about 20 minutes long. First run after a long time may be 5 minutes longer on all durations but I haven't really paid too much attention to this, just to the general heat call duration. Setback recovery where you have to recover the 1F increment, is also slightly longer than the maintenance heat call.

Overall as you point out one can look at the heat call start and stop times and monitor system health. I had an extra long 2 hour heat call early in the season and it turns out I needed to add water as LWCO was cutting off but Nest was still calling. Start of season, water was surging and I added then removed too much water, so not needing to babysit the system and use heat call duration as proxy for system health is liberating. I was coming off a mercury thermostat which I am pretty sure now, was keeping the heat calls too short and the home was cold and basement warm and the late radiators rarely got hot.

Looking at the Home app I have practically the entire history log available not just a week. As you point out it doesn't include outside and inside temperatures though. Overall I am very happy with Nest, compared to our mercury thermostat we have used 25% less energy this month and the home living area is warmer.

How exactly do you use these data to tune the system? I take a cursory look at the heating history daily just to make sure everything is kosher. The only thing right now I would like to improve is the 10-12 minutes for first heat but looking at some of the half-hour and 1 hour times posted by some, that doesn't look too bad. 

luckyguy

geez the eco is set for 67 and just came on even though it says it's 67 on the device..what gives! turned it back to manual threshold at .5 and hope that helps. no clue why it would turn on, wasnt DHW either. i checked the tekmar screen.

SteamBoiler

@PEvans

I just read and absorbed your posts on this thread; I was previously more focused on OP. Either Nest or Ecobee will allow you fine control of your temperature on a half-hourly basis and are well capable of dealing with "slow moving steam systems", caveat being I don't know how they would deal with systems that may take an hour to move. Between the 2 I would recommend Ecobee as it provides control of deadband (the delta below setpoint at which thermostat calls for heat) and minimum heat call duration. Nest is defaulted to 0.5F below setpoint for heat call on, and I can't control minimum heat call duration. Sometimes it calls only for 13 minutes and given it takes 10 minutes best case for the earliest radiator I would like some bang for the buck and overshoot if necessary to really use the energy sunk cost.

luckyguy

i saw the post about min heat duration. i never thought to change it but with my hot water system that seems to make sense actually. how do you figure out what it should be? default is 5 min

SteamBoiler

luckyguy said:

i saw the post about min heat duration. i never thought to change it but with my hot water system that seems to make sense actually. how do you figure out what it should be? default is 5 min

I have steam heat and what I would do, if I had control of minimum heat call duration, would be to set it so that the latest radiators to heat up got a chance to saturate. I don't know about the thermodynamics of hot water heat though.

If it were a warm day outside and the system would have run for 15 minutes but ran for 20 minutes instead, that might overshoot a little but I would probably live with it. Since I don't have control of this parameter with Nest I haven't thought about it much.

PEvans

I may have explained above that I am coming to this topic needing to replace an old Chronotherm thermostat that was short-cycling on my 2-pipe steam system. This thread has turned out to be a good resource for my use case. As it happens my system uses the thermostat to drive reversible zone valve actuators, so that adds its own complications.

Anyway thanks to Jamie Hall and other guidance on the Wall I have installed a low-pressure gauge and a Vaportstat, so I have a pretty good idea of how my system should work and how long it takes to recover and get steam distributed. Maybe more importantly, I now understand that a steam heating system in the Northeast is not the type of system you set back to 55F when you go out for an hour, which is where the Nest is really great.

I think @SteamBoiler overcame one complaint about the Nest overshooting with his "gentle recovery" program. I'm going to guess one could do the same thing by cranking the pressure down and limiting the CPH on the thermostat if you can. This way the system would take a good long time (hours) to recover say 4F. I actually like just programming it better.

I ordered a tradeline Honeywell thermostat as much as anything because I know Nests and I figured this would be something new. More configurable, and I have no idea what it all means.

I was a very early adopter of Nests, had three in my last house, and worked with the company professionally. I am glad to hear they have improved Nest Home. This was one of my gentle suggestions years ago. If you think you know how your system should work, you can use the Nest run data to determine if it is working that way, instead of just relying on your ears when you are awake. If you have multiple zones the run time data from the Nests will tell you if one zone is trying to heat another.

I think for a steam system, if it ever runs less clock time than it takes to saturate the furthest radiator, it's not right (unless it is just running to maintain some boiler temperature).

SteamBoiler

PEvans said:

I may have explained above that I am coming to this topic needing to replace an old Chronotherm thermostat that was short-cycling on my 2-pipe steam system. This thread has turned out to be a good resource for my use case. As it happens my system uses the thermostat to drive reversible zone valve actuators, so that adds its own complications. Anyway thanks to Jamie Hall and other guidance on the Wall I have installed a low-pressure gauge and a Vaportstat, so I have a pretty good idea of how my system should work and how long it takes to recover and get steam distributed. Maybe more importantly, I now understand that a steam heating system in the Northeast is not the type of system you set back to 55F when you go out for an hour, which is where the Nest is really great. I think @SteamBoiler overcame one complaint about the Nest overshooting with his "gentle recovery" program. I'm going to guess one could do the same thing by cranking the pressure down and limiting the CPH on the thermostat if you can. This way the system would take a good long time (hours) to recover say 4F. I actually like just programming it better. I ordered a tradeline Honeywell thermostat as much as anything because I know Nests and I figured this would be something new. More configurable, and I have no idea what it all means. I was a very early adopter of Nests, had three in my last house, and worked with the company professionally. I am glad to hear they have improved Nest Home. This was one of my gentle suggestions years ago. If you think you know how your system should work, you can use the Nest run data to determine if it is working that way, instead of just relying on your ears when you are awake. If you have multiple zones the run time data from the Nests will tell you if one zone is trying to heat another. I think for a steam system, if it ever runs less clock time than it takes to saturate the furthest radiator, it's not right (unless it is just running to maintain some boiler temperature).

Looks like you have a good handle on your system. How long does it take for steam to get to your earliest and latest radiators after the boiler fires?

Please see my comments on this almost parallel thread if interested.

https://forum.heatinghelp.com/discussion/190324/ecobee-thermostat-with-weil-mclain-boiler

I think the knock on the Nest re: setback recovery isn't temperature overshoot. It is pressure buildup from deep setback and subsequent steep recovery which isn't possible to do with steam systems. Nest has been really good with temperature overshoot for me.

User dabrakeman has an even better recovery than I, takes care of some corner cases. If interested you should search in his posts but ATM I am happy with mine.

I also am coming from a Honeywell Chronotherm and as I have said on this thread it was definitely short cycling my boiler and not heating the late radiators at all. It was set to the appropriate anticipator setting. I thought the steam traps weren't working on those radiators. So very glad I switched to Nest. Nest has been really reliable with an external 24V 40VA transformer and White Rodgers isolation relay. As I said already I do recommend Ecobee if only for the control over minimum heat call duration. 

PEvans

Right now I'm running my system (this zone anyway) without a thermostat, just a jumper from R to B to open and to W to close the zone control valve. So I'm getting to know it better. It is probably a little under 40 min to get steam everywhere. That is also the time the pressure sits in the 0.1-0.2 psi range before it begins rising on the low-pressure 3 psi gauge. After about 50 min more the pressure gets up to its cutout point of 0.7 psi. That's pretty hot and the space will keep warming up for several hours afterward, so I'm considering reducing the cutout some more.

So when I'm running it by hand I turn it on for an hour, then shut it off for several hours. That is pretty comfortable. If I had a Nest I would check the data to see if that is how it is working -- it should never run for less than 40 min and never more often than once an hour, really once every two hours if it is not super cold.

I have some baseboards that take f o r e v e r to heat up. Those need to be trouble-shot; that is a different topic.

Once I get a working thermostat on this zone I think I will start with no setback or your gentle recovery. Based on what I see, if the heat isn't satisfied in 60-90 minutes because it is recovering from a deep setback, it is going to overshoot.

luckyguy

actually id love to hear how to fix bad baseboards. i had brand new cast iron ones put in my bathroom this summer and my contractor discovered i have i think it's called manifold valve. basically the guy said it splits some water flow to bypass the baseboard and some goes to the baseboard. something must be wrong in my one bedroom because it's 3 degrees colder in there usually and ive use a laser on the baseboard and it could be 30 degrees cooler than all other. bleeding doesnt help

SteamBoiler

PEvans said:

Right now I'm running my system (this zone anyway) without a thermostat, just a jumper from R to B to open and to W to close the zone control valve. So I'm getting to know it better. It is probably a little under 40 min to get steam everywhere.

40 minutes to get heat everywhere, ugh. I am sitting at 15 and thinking that's not great. Admittedly it is a relatively small home and we have 14 radiators and at least one return vent is working. One doesn't seem to be, and have to get that looked at.

PEvans

@SteamBoiler

It's a pretty big house and a lot of metal to heat up. Also I'm running at quite a bit lower pressure than you are. I think it vents alright other than those baseboards and a couple of radiators remaining that need their steam trap innards replaced.

luckyguy

i just realized i can download the data and ecobee does get down to the tenths with historical data. just would have to analyze it . thought i'm confused as to what the difference is between heatStage1On
and then that with smart recovery next to it.

PEvans

To finish off my thought, I did install a Honeywell TH8321WF, and it does have directly-settable max CPH in the installer settings. So for my steam system I selected system type = radiant and CPH = 1 (to start). The CPH choices are 1-12.

I think that CPH flexibility is probably useful. As I understand it, if the system takes a long time to distribute steam everywhere or it is recovering from a deep setback, or the CPH is set low (say 1) so the thermostat tries to do it all in one cycle, the boiler capacity may outrun the condensation rate with the usual heat load and the system will begin to cycle on the pressuretrol high pressure setting. If you moderate the setback and/or sort out the venting so steam distributes evenly and quickly throughout, you might get more even heating with a CPH setting of 2 or even 3.