Click here to Find a Contractor in your area.
Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.

Thoughts on Outdoor reset

13bravo13bravo Member Posts: 18
So I noted in a separate post (about adding a zone) that I was replacing my ~30yr old WM CG-7=SPDN with a new WM CGA-7-PIDN and like with the zones I was also getting conflicting feedback on the outdoor reset from the plumbers quoting. One was adamant that the outdoor resets are still not ready for primetime and don't heat/work to most customer expectations and recommended I not install it (actually they said they would not be willing to install it but would do everything else). Another said it works fantastic and saves a good amount of money (especially with the weird winters we are having now with temp swings we've seen).

Note for reference on weather, I live in NYC.

What are your thoughts on the outdoor reset? Any issues/concerns? Thoughts on the plumbers concerns?

On a related note, is it possible to install the outdoor reset and just deactivate it for the time being? I'm partial (for a few reasons) to the plumber who raised concerns so was thinking maybe I can have him install but not activate...I can go a season with the new boiler (and new ecobee t-stat) and see how it goes and then next season activate the ODR and see what I experience. Is that possible without much difficulty?

Thanks in advance!

13Bravo
U.S.H.A.!

Comments

  • nicholas bonham-carternicholas bonham-carter Member Posts: 8,193
    If you like short term setbacks, you may not find ODR works properly for you.
    Since ODR controls the system by way of water temperature regulation, recovery may take a long time with the lower temperatures of the loop. Even without ODR, a “set it and forget it“ program works best.
    The Ecobee I presume would act mostly as a temperature monitoring device.
    My experience Years ago, with the Ecobee, with its high current draw, (for wireless transmission), and the attenuation of signal due to interior brick walls was not satisfactory, so I went with wired sensors on a Honeywell VisionPro.—NBC
    STEVEusaPA
  • SweatyInTorontoSweatyInToronto Member Posts: 55
    Note that I am not a hydronics pro but aspire to be an amateur one day! I'm Just speaking from personal experience, and don't know your system but can relay our situation.

    Our 2 conventional hydrotherm 300K boilers heat a 21 unit apartment building, in one zone. Individual manual radiator shutoffs are available, however not all people use them and perhaps they shouldn't. We have a Tekmar 261 control which has an outdoor sensor that handles it, as our boilers don't do that natively.

    Obviously, with one zone only that can be controlled from boiler room, outdoor reset is helpful keeping the boiler(s) off when they are not needed, and rooms not overly hot on the shoulder seasons. At one time they were, hence my user name! Ours are now set to 59 degrees. Apartment buildings I've read generally are set to 55-65 and homes would be set somewhat higher. Depends on many factors obviously.

    That said, 59 degrees with full or part sun is different than 59 degrees of overcast or rainy. Also even when on average is fine, it may be too hot in some rooms and too cold in others. Also the comfort is limited by the fact that our water temp minimum is 140 degrees, which still might be too hot on a 58 degree day. Outdoor reset is a blunt instrument but it's better than nothing IMO.

    But personally, if you have the option for indoor (air temperature) thermostatic controls with multiple zones, it will be better as it's immune to the vagaries of the outdoor elements. A mod-con will be able to work at lower temperatures which promote comfort. One thing we are thinking about are setting up individual thermostatic valves on each radiator, with bypasses when closed. That would save also on the operational side as well. Significant $ involved though.

    You could certainly raise the temperature of the ODR to maximum so that it's never going to trigger on a warm day.

    Not sure if this is what you're looking for, but it's about all that I know at this time!

  • 13bravo13bravo Member Posts: 18
    Hey Steve,

    Thanks for the response! That model in the series 2 was discontinued but the same model in the series 3 (with the built-in ODR I believe) is current, at least that was my understanding from my conversation with Weil-McLain.

    The one thing everyone agreed on is I wouldn't get much out of the high efficiency boilers in my set-up...not sure if that is accurate but there are also issues with the venting in my home, etc. It is about 1900 sq ft of livable space, semi-detached and no hydronic floor heating. Currently, there is no zoning but was looking to add a second (hence my other post on adding one), it is a 2 pipe direct return hot water system with 8 convectors.

    Not even sure how to find a hydronics pro, haha...I did a google search and came up with jobs and plumbers...is there an organization or licensing body or something?
  • 13bravo13bravo Member Posts: 18

    If you like short term setbacks, you may not find ODR works properly for you.
    Since ODR controls the system by way of water temperature regulation, recovery may take a long time with the lower temperatures of the loop. Even without ODR, a “set it and forget it“ program works best.
    The Ecobee I presume would act mostly as a temperature monitoring device.
    My experience Years ago, with the Ecobee, with its high current draw, (for wireless transmission), and the attenuation of signal due to interior brick walls was not satisfactory, so I went with wired sensors on a Honeywell VisionPro.—NBC

    Hey NBC, thanks for the response. So yours sounds like a so-so view of ODR, am I reading that right? On the ecobee, if I do end up with a second zone my intention would be to hard wire a t-stat to the bedroom. As I'm not sure if I will be adding that zone my thought was the wireless sensor from Ecobee.
  • 13bravo13bravo Member Posts: 18
    Hey Sweaty, appreciate your response as well! So, I am looking into adding a second zone and would prefer that, just am getting so many conflicting views from the contractors...I was also thinking thermostatic valves on the convectors but would prefer to just put the bedrooms on a second zone if I can.
    SweatyInToronto
  • ZmanZman Member Posts: 6,002
    Outdoor reset performs very well with condensing boilers and radiant floor or cast iron radiation systems.
    In a home with copper fin radiators and a non condensing boiler, I am not sure it is worth the fight.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
    SuperTechSTEVEusaPA
  • Dave H_2Dave H_2 Member Posts: 388
    Not knowing how ODR works and the other half of the story that it wasn't explained to the homeowner on how it works and what is going on. "I don't want the phone call or take a return trip to find nothing wrong" is common.
    What is most often not understood is the response time from a thermostat call to getting that desired temp in the room may take longer.
    We have all been taught in order to save fuel, setback the thermostat. I mean when is a boiler most efficient?
    When it's off, of course. But when you have a weather responsive system and its mild outside, a DEEP setback makes the homeowners think there is something wrong.
    If explained properly, think of it as cruise control....you set it when you are already cruising at that speed (indoor temp) and the injectors and rpm of the engine follow suit to keep it steady. But when you turn it off and slow down quite a bit and then turn it back on to that setting, it takes everything it has to get back up to that speed.
    You can use setback with ODR, just don't set it back too much.
    Take a look here to read up on the potential savings.

    Dave H.
    Dave H
  • HenryHenry Member Posts: 973
    In the city of Montreal we have 10s of thousand of apartment blocks that only use ODR to control the building temperature. We still have some non condensing boileers, but that is a minority. Our winter temperatures can vary from 45F to -30F. When properly installed and adjusted it works very well. Why would one heat water to 140F when it is 45-50F outside? The new boilers with ODR make it even simpleer as one programs the type of radiation.
    SweatyInToronto
  • Steve MinnichSteve Minnich Member Posts: 2,583
    I'm a firm believer in ODR even with a non-condensing boiler so long as you set it up correctly. Adding Indoor Reset to the ODR can alleviate many of the problems associated with a 59 degree sunny day versus a 59 degree rainy windy day.
    Author - Hard Knocks: My Life Inside Boiler Rooms
    PHC News Columnist
    Minnich Hydronic Consulting & Design, LLC
    https://heatinghelp.com/find-a-contractor/detail/minnich-hydronic-consulting-and-design
    SuperTech
  • Alan (California Radiant) ForbesAlan (California Radiant) Forbes Member Posts: 2,485
    edited October 2
    Not even sure how to find a hydronics pro...

    Look up top where it says, "Click here to Find a Contractor in your area." Lots in NYC.
    Often wrong, never in doubt.

    Click here to learn more about this contractor.
    13bravo
  • mattmia2mattmia2 Member Posts: 1,861
    What kind of convectors are they? Are they actual fin tube style convectors in a box or are they cast iron radiators of some form? From your other post it looks like it is a converted gravity system. Depending on the type of emitters and how they are sized compared to the current heat loss of the building you could get efficiency benefits with a mod con.

    Even without the efficiency, the ability to modulate and match the output to the demand may be worth it. If outdoor reset is set up properly it will result on more even heating. As far as setback goes, some controls reset have the ability to increase output if a demand isn't satisfied in a certain period of time.

    This does make the system more complex and less tolerant of bad design. A poorly designed mod con installation is more likely to have a short life and a lot of repairs than a poorly designed conventional high mass boiler.
  • Jamie HallJamie Hall Member Posts: 13,403
    A bit of back to basics. What outdoor reset does is send a signal to the system control which tells it what the outdoor temperature is. The system control then determines what temperature water should be going to the system to meet the heating load; this relationship is the system reset curve, which is put into the controller and adjusted during setup. There are several ways in which the water temperature control can be effected -- with a modulating boiler, for instance, by changing the firing rate. Or a controlled mixing valve. or... lots of options.

    Now. As several have noted, in some ways it's really dumb, as it usually doesn't take into account sun and wind thermal loads. So it is usually necessary to add additional sensors in the building, to tell the system that it needs to boost the output temperatures at times.

    Where it is really at a disadvantage is when trying to recover from a deliberate setback. By design, it will deliver just enough heat to maintain the building temperature. This means that unless there is some sort of indoor temperature sensor to tell it to shift to a higher temperature, it simply won't recover. It may get close, but it will never get there.

    Carefully set up, and driving a modulating boiler in a tight building without too much solar gain and a constant interior temperature, it can deliver very real efficiency advantages. Poorly set up, or in a draughty building or one with lots of glass, or where the users use setbacks, it doesn't work all that well.
    Br. Jamie, osb

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • 13bravo13bravo Member Posts: 18
    Lot's of great insight, thank you!

    Mattmia, yes, they are fin tube style convectors (all but one anyway...one bedroom for some reason has a cast iron radiator).

    I'm assuming that smart thermostat controlled/programmed temp changes do not count as the setbacks you're talking about right, only manual setbacks?

    Jamie, stupid question but when you are talking about an indoor temp sensor...are you talking about something other than a thermostat? Are we talking room sensors that go with it (like the Ecobee)? Something else?
  • mattmia2mattmia2 Member Posts: 1,861
    Do the convectors look like a retrofit? From the piping I would have expected cast iron radiators of some sort. Modcons usually work great with cast iron radiators. Not so much with the convectors unless they are really oversized.

    Smart t-stats count as setbacks. The idea of outdoor reset is that it matches the heat supplied to the load of the building. If it is doing that right the temp doesn't increase, it stays constant, so it takes a long time to recover from lowing the setpoint of the thermostat if the reset curve is well matched to the load of the building. Many mod con boilers have a setting to boost the temp on the reset curve if the heat call lasts over a certain period of time to compensate for this.

  • SweatyInTorontoSweatyInToronto Member Posts: 55
    Henry said:
    IWhy would one heat water to 140F when it is 45-50F outside? The new boilers with ODR make it even simpleer as one programs the type of radiation.
    Not sure if you're referring to my post but 140F is the min boiler temp year round to avoid corrosive condensation of flue gases in a conventional boiler. If it had a copper HX perhaps could get away with lower temps. In fact, why wasnt copper used more often outside of potable applications if It afforded lower temperatures and potentially greater  comfort?

    If we replaced of course we'd upgrade to  modern boiler but cost prohibitive at this time.... 

  • 13bravo13bravo Member Posts: 18
    mattmia2 said:

    Do the convectors look like a retrofit?

    I'm not exactly sure how to tell...what do you normally look for to determine if its a retrofit?

    So with an ODR you wouldn't use a smart t-stat, your ODR basically takes the place of it?
  • Jamie HallJamie Hall Member Posts: 13,403
    13bravo said:

    mattmia2 said:

    Do the convectors look like a retrofit?

    ...
    So with an ODR you wouldn't use a smart t-stat, your ODR basically takes the place of it?
    Exactly.
    Br. Jamie, osb

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • mattmia2mattmia2 Member Posts: 1,861


    Henry said:

    IWhy would one heat water to 140F when it is 45-50F outside? The new boilers with ODR make it even simpleer as one programs the type of radiation.

    Not sure if you're referring to my post but 140F is the min boiler temp year round to avoid corrosive condensation of flue gases in a conventional boiler. If it had a copper HX perhaps could get away with lower temps. In fact, why wasnt copper used more often outside of potable applications if It afforded lower temperatures and potentially greater  comfort?

    If we replaced of course we'd upgrade to  modern boiler but cost prohibitive at this time.... 



    You can add a thermostatic bypass to keep the boiler return water hot enough to prevent sustained condensing on a conventional boiler.

    retrofitted convectors usually look plopped down and out of place. original ones are usually recessed in the wall or at least look like they belong there.

  • Big Ed_4Big Ed_4 Member Posts: 1,433
    You can add a smart stat just make sure the outdoor reset you choose has a boost . This would require an indoor sensor .

    10%-20% saving add up 10-20 years .

    ODR will add comfort . Comfort is the bottom line ,That is what we are paying for .......... ,Your body senses change ,. A outdoor reset flattens the heat curve of temperature change .






    I have enough experience to know , that I dont know it all
    SuperTech
  • 13bravo13bravo Member Posts: 18
    mattmia2 said:


    Henry said:

    IWhy would one heat water to 140F when it is 45-50F outside? The new boilers with ODR make it even simpleer as one programs the type of radiation.

    retrofitted convectors usually look plopped down and out of place. original ones are usually recessed in the wall or at least look like they belong there.

    No, these definitely look like they belong. They are all recessed in the wall.
  • The Steam WhispererThe Steam Whisperer Member Posts: 546
    Low mass systems convector systems can be particularly advantageous to use with outdoor reset. These low mass systems heat up quickly, producing lots of hot air racing to the ceiling and then quickly cool off quickly creating a similar situation to most forced air systems.... a see saw effect on temperatures and comfort. The ODR control, even on a basic non-condensing boiler can hold the water temperature down to 140F most of the winter, smoothing out the up and down swings and providing a quieter system and improved comfort. You should also pick up a little bit of efficiency in the boiler because it will tend to run at lower temperatures while reducing heat stratification ( also saving fuel). However, the one thing to watch out for is if the home can heat with 140F water even in the coldest weather ( which is pretty common even with modern convector systems) than the outdoor reset is useless. If this is the case the boiler temperature limit control can be set at 140F and then your done. With a condensing boiler, you can still use reset ( usually built in) below 140F for improve efficiency and comfort. Just remember, that while saving fuel, you will increasing teh run time of the pumps substancially, so electrical use goes up, increasing your electric bill. For this reason, if you use outdoor reset all the way down to 70F supply water, you want to get the most efficient and properly sized pumps you can get.
    I'd definitely look at what size boiler you really need. A cg -7 boiler can heat about 6000 sq ft of lightly insulated above grade space with an outdoor temperature around 0F. For a well insulated space , that would be more like 12,000 sq ft.
    To learn more about this professional, click here to visit their ad in Find A Contractor.
  • motoguy128motoguy128 Member Posts: 178
    With a high mass system, especially a former gravity system with oversized piping, the system warms up so slow, that it effectively has passive ODR. I was working on a couple recently and the boiler, probably still a little oversized for the heat loss of the house in each case, only raised the system to 110F after running over 30 minutes. IT just takes time to heat up a couple thousands lbs of iron and steel and probably almost 100 gallons of water.

    Even a radiant flor system will have cool return water for 10-15 minutes on startup. Milder weather = cooler slab = lower return water temp.

    My company doesn’t typically install them as it just adds more complexity, one more thing to fail. However, most have a “boost” feature, so it will raise the temp A set amount after a timer.


    Much more critical than ODR is getting the installer to pipe it correctly for Primary Secondary and set the flow rates correctly.

    A system set to 150F with 145F return water temp is less efficient than one set to 160 with 140F return temp.
  • The Steam WhispererThe Steam Whisperer Member Posts: 546
    Moto guy hit the nail right on the head.... High mass systems (especially single zone) inherently have passive reset. Its one of the beauties of high mass systems. The only exception would be multi-zoned high mass systems, then ODR may be useful.
    To learn more about this professional, click here to visit their ad in Find A Contractor.
  • TAGTAG Member Posts: 276
    I redid a big old place in Chestnut Hill PA years back and replaced both of the old boilers with Buderus CI and logmatic ODR controls. I copied Dan's "pumping away" .. they ran on constant circulation with the old thermostats rewired as a limit control in some spots.

    It had old servant areas and a third floor that we reconfigured for an age w/o help. Runtal and mostly panel radiators in those spots. We used the Danfoss heads on the panels and just let the Runtals run.

    After some tweaking -- it worked great and the system basically just ran.
  • JohnNYJohnNY Member Posts: 2,494
    I haven't read any of the comments above so forgive me if this is repeated information. You want the outdoor reset in your home unless you really just don't care about your fuel bill. I have many of those customers to whom it is far more important to feel a piping hot radiator than it is to save a few bucks on fuel usage, so I've been made to disable the feature on many systems in NYC throughout the years.
    What I've learned about it though is that a 160° radiator is indistinguishable to a client from a 180° radiator, so you can still have ODR and just play with how aggressively you set it. Every little bit of rise in efficiency contributes to the common good in my opinion.
    For troubleshooting and private consulting services, find John "JohnNY" Cataneo here at :
    "72°F Mechanical, LLC"
    Or email John at [email protected]
    John is the Boilers and Hydronic Heating Systems Course Instructor at NYC's Mechanics Institute, a professional Master Plumber, licensed by The Department of Buildings of The City of New York, and works extensively in NYC while consulting for clients in and out of state.
    For residential service and installations in New Jersey, please see Toro Plumbing & Mechanical and fill out our contacts page, upload pics, and submit, or call (973-672-1000).
    HVACNUT
Sign In or Register to comment.

Welcome

It looks like you're new here. If you want to get involved, click one of these buttons!