Best WiFi Thermostat for Steam Heating?

Ecobee 3 hands down the rest don't compare

Hey Erin! You guys should create a link to a poll on Heating Help for what is the best WiFi thermostat. Happy Holidays everybody!

Ecobee 3 question: how does the multiple temp sensor function? Does it average the temps from various places to keep, say, as close to 70 degrees everywhere? How does it decide which 70 is the one to shoot for, if, say, out of 3 sensors, one is 73, one is 70, and the third is 67? Will it then call for heat until the last 67 is at 70, but the other ones are at 73 and 75 by then, or will it keep 70 average, and let the other 2 temp sensors and rooms in which they are, stay at 67 and 73? How does this exactly work?

We have 1 pipe steam, 3 zone system. I've managed to get the building to have similar temps everywhere as the system fires up in the morning. 66 set back overnight. First firing in the morning is to 69. Takes about 2 hours, and when tstat is at 69, other spaces are at 71 or so. After a few hours, some rooms cool quicker than others. At that point keeping things even becomes a matter of firing the boiler when main tstat still shows temp at 69. I now do it by programming tstat to raise the temp to 71 and then 72 every few hours. By keeping main tstat at 72 from about 3 pm to the evening, building stays at approx same comfort level. In the evening people leave and tstat sets back to 66.

How does ecobee regulate this? Also, with cph, how does setting this help with efficiency? Can it be set to wait 5-10 min between firing?

We now use a few years old Honeywell RTH8500 wifi thermostat with 4 daily settings.

All our mains vent fine (all 3 mains are approx 180 ft long each, 2 are 2.5 inch and 3rd is 2 inch, all have new Hoffman 75 main vents), system is well balanced and all rads get hot evenly, meaning, each zone heats at the same rate, and last rads on each zone heat up at about the same time. I've instaled a few trvs on first 4 rads on the 2 inch loop, and that helped quite a bit to push steam down the run. We have a Weil McLane LGB 7, with a 50 gal condensate tank and feeder pump.

I am mostly interested in economizing fuel use without having to do Tekmar controller, letting the boiler fire when needed and reducing cycling on pressure by delaying firing between pressure rising. Right now I do it with 3 degree setbacks. The system is full and all rads hot before pressure starts to rise, and the vaporstat is sett to cut off the burners at 7oz of pressure. There is of course, a lag between everything getting from 66 to 69 degrees, so what's the best way to delay boiler cycle by 5-10 minutes, and can Ecobee 3 do this?

Thanks!

Thanks @Danscrew . I will contact ecobee.

I have some tight deadlines at work this week - will call Ecobee people as soon as I can and will post the findings here.

Does anyone else knows of any other thermostat that can delay firing steam boiler after the initial pressure build and after burners cut-out? I am aware that some systems that are not balanced will, with this setting possible, keep rooms at the end of zones not heated, so this may not work for everyone. But, for balanced systems, this should work well, no? It would allow for a bit more latent heat to be disposed of into the space, and then the new steam would be introduced to continue, vs. cycling on pressure until the tstat is satisfied.

On a side note, we had 20s here on Saturday. The room with the tstat which is in the office, usually has the door open and air circulating balancing the temp around the tstat. With the door closed on Saturday, the office never got over 69 and tstat was set to 71 (in expectation of colder day after a colder night). The result: the rest of the building was cooking on pressure all day - for 10-12 hours - before I looked at the tstat on my phone app and realized something was wrong and turned off the boiler remotely (by lowering the temp on tstat). 10 min cycle delay would have saved quite bit of fuel, by reducing the number of firing on pressure to 5/hour, vs, god-knows-how-many I had on Saturday.

This would also have made things more comfortable in the building. I had emails waiting in my inbox this morning form people saying the rads were glowing and eyeballs popping (figuratively speaking) from how hot the rads were.

Ugh...

That's my question: which thermostats have the CPH setting? I have Honeywell RTH8500 and it doesn't have the CPH. I'm looking for a wifi one that would have it. Does ecobee have it? Could not find any info online about that.

More precisely, will cph delay restart of boiler burners after the first shut-off due to pressure cut-out on the pressuretrol/vaporstat?

Thank you @SWEI . I looked at the manual prior to placing the tstat into service, and have set function 240 to 1. This did not prevent the boiler from cycling on steam this weekend (per my post above, and I'll explain below)...

My question is if there is a way, other than with Tekmar 279, which I think can do this - although I only am tangentially aware what it does and not all ins and outs of it, - thus, is there a way to set the actual number of cycles to say, 3 or 4 per hour, or better yet, to delay each firing by 5-10 min after first rise to pressure, so that what happened to me this Saturday does not happen again? The following took place: tstat was in a cold room due to various factors that made it so this particular weekend, and it called for heat all day long. Entire building was burning up while tstat room was at 69 and tstat was set to 71. Had there been some kind of timed delay to firing the burners once the max steam pressure was reached, this would have much improved both the comfort of the building and needless waste of fuel. Instead, the building was cooking all day with boiler cycling on pressure.

I'm aware that for systems that are not balanced, this delay would make for cold rads on the end of zones/loops. Our system is well balanced, everything vents well, and everything is nice and hot, including all the last rads on each of the zones, before pressure rises (well, aside from this happened this past weekend with the room where tstat is). We have a one pipe steam, op pressure is set to 8 oz cut out with a 4 oz reset. It really doesn't matter if reset is 1oz, it quickly goes back to 0 after burners shut off. Matter of fact, by the time it fires up again at 4 oz, often if not always the condensate return tank pumps new water into the boiler, and it quickly goes back to 0 psi. I don't have the exact EDR, but we have 29 radiators on 3 zones and EDR was done when new LGB7 replaced the old LGB11 (yeah, I know!).

And yes, that tsat I did purchase online. Not being a pro, I didn't know there were differences, that is, now that I'm on this board I am learning a lot of new things.

So, question is - with this long explanation - how to time-out burners for 5-10 minutes after the first (or each) rise to pressure even if the tstat is still calling for heat? I am aware that this may not be what everyone would want as some systems are not venting well and are not balanced well so some cycling on pressure is needed to get all the rads hot. This is not our case so the ability to delay firing by 5-10 min would allow for enough heat to continue to radiate out of the hot rads before new steam was to be introduced back, In essence, this would both save on fuel and make the building comfortable.

Thanks again to you and everyone else who's taking time to read through my essays...

It sounds to me that you may be looking for a solution to a problem which doesn't exist.. however, a simple way to approach doing what I think I hear you wanting to do would be to add a relay to the pressurestat/vapourstat which would allow for a time delay on reclose. That is, the pressurestat/vapourstat would open on pressure in the normal, simple fashion. It would then reclose rather quickly, as the steam collapsed. However, instead of directly restarting the burner you have a time delay relay in the circuit which would prevent the burner from firing for an additional five to ten minutes.

Mind you, I don't think this would accomplish much. In that time the system would get back to atmospheric and the boiler would cool below a simmer, so you would spend additional time and fuel reheating the boiler and getting the air back out of the system. But... whatever.

Koan said:

@MilanD - In the case of the open door to the room with the tsat, if you have an Ecobee 3 with remote sensors would that work to keep things more even??

@Koan

That's what I'm thinking. But the question is if it will do what I want it - and that's why I need to call ecobee and ask how it averages the temps and which tstat it uses as a bench-mark, if any...

Then, I suppose, second part of this is - how do I get the boiler to delay re-start once it gets to the set max operating pressure? I want to let it give off latent heat for 5-10 minutes, then restart, rather than cycle on pressure for some time.

Perhaps ecobee will in fact solve this if it somehow averages the 3 temps and calls the temp 'satisfied', with one of the tstats still registering below the set temp.

called Ecobee support. on hold for 43 minutes waiting and no one answered. what if I owned one and the heat wouldn't come on?? gotta wonder about that low level of support.

@Jamie Hall

A delay may make sense. I assume this is the effect of a CPH setting being lowered

Here is my take on the the cycling issue with an oversized boiler (as is mine). Boiler fills mains as air vents quickly, then radiators as they vent more slowly. At some point, there is steam in the entire system (hopefully). Then all the traps see steam and close. Adding extra steam then builds pressure because the steam in the radiators cannot condense fast enough to give it's heat into the rooms and has no where to go. Boiler cycles on 8 oz. pressure as radiators try to convert steam back into water by dissipating heat. As they do so and pressure falls to 4 oz. boiler fires up too soon because radiators still cannot dissipate heat into the room fast enough.

1) The amount of reasonable time delay would be base on how fast the radiators cool back down. The amount of delay that would be costly would be in having to reheat the thermal mass of the water to produce steam. You could measure the boiler water temperature to see how fast it cools down, however I recall the heat to produce steam from 212 water is pretty significant, much more so than to raise the temperature of the water.

2) Assuming the water is at 92 degrees, to go to 212 takes 120 BTU per pound. If it were at 112 degrees to start it would take 100 BTU per pound. to get 212 degree water to stem takes 970 BTU per pound. so the losses are not as much in reheating water, but in getting hot water to steam. Once the boiler pressure goes to zero because no water is boiling, this energy has to be put in again.

3) The optimum is probably different for each system. heating water to make steam that cannot be used doesn't make sense

4) Barring an expensive monitoring setup like a Tekmar, the only tool for dialing in a delay would be trial and error monitoring your hardest to heat radiator outlet temperature You could then try different delays and monitor fuel usage, or just see if cycling is avoided. The problem with this approach is that there can be no real control condition to evaluate real fuel efficiency.

5) One idea that might help would be to set the Vaportrol to cut out at 8 oz. and start back at 1oz.?? Is there any reason to not do this?? why are we set to kick back in at 4 oz.? Seems that even if we were cycling at least the the cycle would be longer and allow the radiators to condense a little more... maybe the difference is negligible. I'd love to hear some feedback on this one.

6) Other than that if you are cycling and all rads are hot, through trial and error you could see how long before the radiators cool enough to prevent cycling and set your delay there?

just my 2cents

So really the question is the amount of fuel burned to get that water to steam, in BTUs.

212 degree water can have both 500 BTU and 800 BTU and 1150BTU. If steam is made at 1150, let's say we start with: 70 degree water + 142 BTU/pound to 212 degree water +970 BTU/pound to steam=1112 BTU/pound.

If boiler cycles on pressure, from my novice observations, at 8oz cut out, it doesn't take a whole lot of time to get that steam producing again. This means that BTU input to that water that's already in the boiler sitting with all the 1112 BTUs it can store at 8oz of pressure (actually it's more like 1150BTU if we started from 32 degree water - so let's call it 1150 BTU).

So with 1150 btu in per pound of water, the boiler at 8oz pressure, trol (vapor or pressure, whatever) will turn the burners off. At this same time, the steam in the rads is giving off heat and after it gives off its' 1150 btu - 970 btu, water condensates into 212 degree water with latent 212 btus still in it, and starts slowly making its way back to boiler. (*side note, 32 btus we got for free as it was liquid water at 32 degrees when it came from the water main).

As all this steam collapses back into liquid water, pressure in the system (and thus the boiler) goes back down to 7,6,5,4,3,2,1 oz... At this point we still have water in the boiler that is close to 1150 BTU, but slightly less, and less for the amount of BTUs burners did not put in while they were off.

One can look at the chart on your boiler and see what that max btu rating is, and see the efficiency and then see/calculate what BTU amount goes into water per hour.

Here in which lies the balance: efficiency. IF you are (your boiler, that is), say at 80% efficiency at the boiler, 20 out of 100 btus that are burned up in fuel go up the chimney. At this point, you would look at whether the BTU loss from the hot water sitting in the boiler is greater than 20% (-230 btus/pound/h). If so, cycling on pressure is better. If not, delaying firing is better. I somehow have a hunch delaying firing is better, and better because you also have heat-loss for the building and the fact that even at 212 btu, hot water and hot radiator still gives off BTU energy into the space and there is delay in feeling this BTU energy dissipating into the space.

No?

So, question is how do you look at btu loss in the boiler? I assume each boiler and system will be different (boiler insulation, pipe insulation - to minimize pick-up factor between cycles), draft under the boiler (if no auto draft damper, which I assume 90% of people don't use as they are 1st to break), boiler room temperature (hotter the better??)... But there is also building heat loss to rad btu drop ratio, no?

You would have to time firing cycle-to-steam, and then steam-at-boiler to steam-at-rad time, for each minute off to zero this in, then how it transfers to heated space (BTU in vs heat loss), and this would depend on what the outside temperature is at that time. Sounds complicated, huh?

So maybe, just look at time it takes to make steam after 1, 2, 3, 4 etc minutes off and how it feels upstairs to figure it out that way. I still think delaying firing will save fuel.

Wow, I didn't know I knew all this...

@Jamie Hall my oversized boiler burns gas, and as it is oversized I'm losing a lot up the flue. I don't have those purge cycles like an oil burner. I like the idea of examining the thermal behavior of the radiators, but I don't see any sense in sending heat to them they cannot distribute to the room. It seems then you are just cycling and heating the boiler room.
@MilanD I like the approach of comparing one loss vs another - I also think you are on to something there. My thought is that water producing steam probably loses the latent heat of vaporization (970BTU /lb) quickly, though I do not have any evidence. I guess we could wait different times and see how long it takes to rebuild pressure. It just still seems that if you are cycling you are still making heat but it seems it is not distributed very well.

I am sorry about going into the CPH stuff so far under this thread - that is my fault. We can continue that interesting discussion under a different thread maybe?
Honestly my boiler is rated 750 EDR and I have 399EDR of radiators, so my best bet will be either a normal sized boiler or to try to heat my neighbors house as well!

It is a long standing accepted fact that cycling on pressure diminishes efficiency. For now I am willing to accept that fact, and to get back on track just looking for a good WiFi thermostat that has either CPH settings of a delay that acts to serve this function.

I have read good things about the Ecobee 3, and really want to see if it has a true CPH setting or some proxy that will serve nearly the same function.

If not I have to determine if I can find a Honeywell model that has CPH and remote sensors?

Deriva, intelliSync.....sold by FW Webb....works with two wires and painless set up....Does the job....

What options does it offer for residential steam....that some others may not......Does it require a third wire...Not much one can do with steam except monitor it...adjust it up or down. And program it to your living conditions....

@Koan, I have a 1 pipe steam using a Burnham MegaSteam and a vaporstat. Old stonehouse with open cell insulation (poorly installed, but we didn't know better at the time).

I've used a number of thermostats including the Nest and am now quite happy with the Ecobee. It seems to cycle the boiler less than the Nest but maintain a more level temperature in the house.

The remote sensors will average if you put the system on "Follow me". You can also decide which sensor participate in which mode (Home, Away, Night, Visitor). So there is some flexibility.

It does require a "C" wire but comes with a "PEK" (power extender kit) that lets you "fake" it out. You can see the instructions here: https://www.ecobee.com/installing-your-ecobee3/

I've had good support from Ecobee, but have not needed it often. I would suspect you called during the very busy holiday season...

I know this doesn't answer all your questions, but I hope it helps. All in all, I really like the unit and have recommended it to others who like it as well.

Alex (The Wire Nut)

@stonehouse
All that is left to really upgrade rather than replace the boiler is the thermostat, a Honeywell Chromotherm 8090 from 1969.

I should be able to run a common C wire

Thank you for the input!

We have 11 radiators totaling 399 EDR and a 750 EDR boiler (American Standard circa 1969) on a 2 pipe Hoffman vapor system. It was cycling on pressure most of the time. We had all but the largest rads refinished, flushed them out (got a lot of stuff out of them) and removed the radiator covers (now that they look so good!) Next I re-piped the Hartford loop and some of the near boiler wet returns as there was only about 1/4" diameter passage for the return. Installed valves at the same time to flush out the wet returns every year. Biggest thing was getting the mounds of crud out of the boiler with a 120psi wand. It took and entire day to flush that beast out. Cleaned the clogged pigtails on the gauge and Vaporstat. Replaced every trap cage thanks to @Sailah. Next @Steamhead helped out with an overall inspection, a new gas valve (dialed back a little bit ) and a combustion test to make sure all was well. After that a few house of skimming after using Steamaster and the cycling has completely stopped. All rads get hot - even the 30 section one though it takes a while. Master bedroom gets a bit hotter than all the other rooms (14 section) - i guess that radiator is a bit too big - maybe we put the cover back on that one.

Even though the boiler is massively oversized, it is running great, usually at 2-3 oz pressure and no more even when recovering from a 5 deg setback. Amazing what cleaning the system out can do, and getting good advice for all the kind people here.

I like the Ecobee 3 because of remote sensors. We are adding hi-vel ac in a month or two as well.

Thanks again for the info!

@apraetor

Does it really use the outdoor temperature, or is just for display?

Those are some awesome features. What cycle settings do you use? I wonder if it can factor in wind data.

I have the minimum cycle duration set to 5 minutes; I'm experimenting with giving it the ability to short-cycle, to see what it does. All my radiators are basically balanced, and I can see 5-minute cycles being useful on very cold days where the heat runs for 30 minutes out of the hour on average during the night.

The swing is set to 0.5F, which is actually plenty. With a 1 degree swing the system runs so infrequently (except on very cold days) I wind up burning a bunch of fuel to reheat the boiler. Not sure which approach saves fuel in my case, but:

I'm logging everything to csv and my wife is a data wonk, so I'll have some nice charts after the winter. I promise! It's natural gas, so I have csv log data for daily fuel use, as well. Gonna chart all the data points and we can all pick over it and argue

@nicholas bonham-carter I do think I will be installing a vaporstat for long burns on really cold days. My low psi gauge never shows much pressure on typical burns, but when temps drop to the teens it does run for long enough to start building somewhere around 1 psi.

If you are offering to install the staged burner, then j won't stop you. I'd love one, granularity of control is never a bad thing in itself. But I'm not sure the fuel savings would justify the cost, unless you are sending the Boiler Fairy on over!