ODR Tuning

dgoldstein

I've been using ODR on my Munchin 80M that powers 3 zones, all HWBB tube/fin emitters in series on each zone.

We keep the t-stat set usually between 66-68*F. Typically we're running 66* for the 12 hours we're not home, then we go up to 68*F for the 4 hours before bed, then back down to 66* at night so we're not sweating in bed - we also have an electric blanket and duvet.

Lately, after a frozen water meter supply pipe issue, we've been running the heat at 68*F day and night. I notice that the boiler does cycle on/off maybe 1-2 times an hour. Our house is far from tight, but am slowly improving.

I'm looking for figure out whether or not I need to refine my ODR curve to keep the boiler on longer and hopefully reduce the cycling and maybe lower my gas bill a bit.

My current curve:
Warm Water Shut-off: 66*F
Min Outside Design Temp: 5*F
Design Supply Water Temp @ Min Design Outside Temp: 180*F
Max Outside Design Temp: 66*F
Design Supply Water Temp @ Max Outside Temp: 120*F
Lowest Temp for Central Heating: 120*F

Most of the HWBB tube/fin is SlantFin 30 type and their ratings start with a water supply temp of 110*F.

It's been stupid cold here in NJ this winter, regularly staying below 20*F, and going into the single digits to minus-0 with wind at night. I don't know if this is the new norm.

With the current situation, we're relatively comfortable, but some days we just feel kinda cold all the time - like it's hard to shake off the chill - not entirely sure why, heat is at 68* and we sometimes bump it up to 72*.

I'm presuming that in order to lengthen the boiler cycles I need to lower the water temp output and lower the Min Outside Design Temp?

I was thinking of dropping the Design Supply Water Temp @ Min Outside Temp to maybe 170*F, and taking the Design Supply Water Temp @ Max Outside Temp and reducing that and the Lowest Temp for Centeral Heating to 110* (the lowest advertised temp output rating on SlantFin's tech specs). Maybe go to 0* on the Min Outside Temp?

FYI - This boiler is dedicated to heating the interior, so no potable hot water heating is involved. I have a Rheem PowerVent 2 50gal for that.

Another monkey to throw into the future equation is that I'm planning to change the heat emitter type in my 268.75 sq. ft. living room (6710 Total BTUs heating per rough ManJ estimate) to either a radiant floor (like Uponor/Roth) or to a Hydronic Alternatives steel panel radiator - with mixing valves, etc.

Any insight is appreciated!

SWEI

dgoldstein said:

With the current situation, we're relatively comfortable, but some days we just feel kinda cold all the time - like it's hard to shake off the chill - not entirely sure why, heat is at 68*

I'm guessing that happens when the thermostat shuts down the boiler as it reaches setpoint. The best way to tune your ODR curve in my experience is to crank the thermostat up (like 80°-85°F up) and leave it there for a week or so. Adjust the ODR parameters until the space is staying the same temp regardless of the outside temps. Your stat is now just a high limit controller. Set it 2°-3°F higher than you want the space to be and leave it alone.

Setbacks and tightly-tuned ODR are not a good match. If the boiler has a supply temp setback option, that can work OK. If not, recovery can take hours depending on the particular system dynamics. Consider adding TRVs to rooms you want cooler.

wogpa67

What control does your boiler have?
Finned tube only length per zone?
The minimum input for that boiler is 27K.

dgoldstein

SWEI - So you're suggesting to essentially turn the t-stat into just a master on/off switch for the boiler, set it to ON 24/7 since I double it'll ever get to 80-85 in the house with it leakiness, and then adjust the ODR curve to obtain the temp/comfort level we desire?

wogpa67 - I'm not sure I understand your questions about the control. My boiler is using the Vision 1 ODR.

I'll get back to you on a finned tube only length per zone. We only use two of the zones. The 3rd is in the utility room where the boiler and hot water heater live. It stays at a relatively steady 68*F in there from the heat loss of the boiler/hwh and copper manifold piping. I sometimes wonder if it makes sense to eliminate the zone entirely, or ditch the tube/fin and stick a smaller panel radiator in there instead - that's obviously for another discussion.

bmwpowere36m3

wogpa67 is eluding to the fact, if you have insufficient baseboard.... You might not be able to lower supply temps or cycling.

Cycling to a degree is normal, given boiler sizes and modulation levels.

wogpa67

That control has a 6 minute step modulation that is set on from the factory.(parameter 18=1) This slows the boiler from going to high fire to try and help with short- cycling.
Maybe this was turned off when installed.
You need in the 40" range of finned element per zone to keep it from short cycling.
What Tstats do you have?

dgoldstein

wogpa67, I will check to make sure that parameter 18 is set to 1. I certainly didn't set it to off, but maybe the previous owner - who was the installer did.

I certainly have well over 40" of elements for each zone. I'm only actively using one zone for my 1st floor. The 2nd zone is my second floor and I seldom ever turn that tstat on and it stays in the 65-68*F range. The 3rd zone is my utility room, never turn it on and it stays around 68*F in the room from the heat generated by the boiler/hwh and pipes.

All of my tstats are Honeywell. I can get back to you with model #'s in a little while. I did change some settings in them a few months ago to play more nicely with the ODR/boiler - I just can't remember what they were off the top of my head, but I think I got the recommendation from some users on here. Maybe it was something like limiting the max cycles per hour or something along those lines, and making sure they were set to Heat Only mode. I'll check and get back to you.

Thanks again to you all for the guidance!

SWEI

dgoldstein said:

SWEI - So you're suggesting to essentially turn the t-stat into just a master on/off switch for the boiler, set it to ON 24/7

Basically, yes -- at least while you tune the ODR parameters. If the tstat is turning things on and off, you'll never know when you have the curve set right. If you want to use the stat(s) to control room temp, you can add a few degrees to each end of the curve after that's all done.

Some boilers (it's been a looong time since I played with a Munchie) have a boost feature that will increase the water temp if a call has not been satisfied in some amount of time. If you intend to use the stat(s) to manage temps, and the boiler offers that feature, be sure to enable it.

dgoldstein

Tstats:

All Honeywell.

Main zone for first floor: 4110D1007-1035

2nd floor zone: TH5110D1022-0447

Utility room (never on): TH8110U1003-0613

Parameter 18 is set to 1 for ON.

wogpa67

The best Tstat is in the utility room?

wogpa67

That control doesn't have the boost function. Which is usually not good to turn on for small zoned systems. It depends on the maker of the boiler. Most continually raise the target by 10 degrees up to the design temp and on the next call it will target that temperature.

wogpa67

They don't have a remote sensor on the 8000 do they?

dgoldstein

No remote sensor is installed on the 8000. I didn't install these, but yeah the 8000 is in the room we never turn the zone on.

Is there any advantage of putting it in the primary zone? It seems like all its going to do is provide an upper temp shut-off off provided I get the ODR curve dialed in to provide adequate comfort without the tstat calling.

wogpa67

Do you have central air?
It does have some more functionality then the others.

dgoldstein

We use window and portable ACs. No central or forced air.

dgoldstein

I dropped my curve 10*F on the min and max supply temps. Running the tstat at 85*F, the indoor temp was peaking at 70 - nearly right. 66-68 is usually where we feel most comfortable. Outdoor temps were in the low to mid-30s.

SWEI

You're getting close. Now see how the indoor temp does as the outdoor rises and falls.

dgoldstein

SWEI, I intend to change my HWBB radiator in my living room to a steel panel radiator with TRV, but it will still be in series with the rest of the HWBB. I can't install TRVs elsewhere since the zones are series loops.

There are 8 rooms on the main zone. Two large rooms on the 2nd zone and 1 room on the third zone (utility room).

bmwpowere36m3

If you install a TRV on a series loop, than the radiator with the TRV needs a bypass fitting…

Don_197

I would add to SWEI's post NOT to necessarily use the temperature at your stats to gauge how comfortable you are. depending on how much radiant heat you get out of your emitters, if you totally IGNORE the air temp (what the thermostats are measuring) you might be surprised at how comfortable you are regardless of the air temp. I purposely set my last radiant system so it would set back EACH AND EVERY CYCLE...........forcing my son or I to go "oohh.....its getting a little uncomfortable here....I better go turn the zone stat up" and the savings was incredible......cut our fuel bill AT LEAST in half. Radiant is a different animal.........our bodies are the determining "comfort factor". We now live in a home with forced air heat......we both HATE it!

dgoldstein

My emitters are all currently SlantFin or similar baseboard. They emit very little in the way of radiant heat.

Despite that, after dialing down my ODR curve's high/low water temps to the point where leaving the t-stat calling for heat 24/7, the interior temps now read at 70*F. We're typically comfortable at an indoor temp of 68*F.

I think I still need to move my Min Outdoor Temp for 5*F to the Manual J temp for the city climatically closest to my town, at 13*F and then readjust the curve accordingly so at least the MOT is using a common reference. I went with 5*F initially because this particular winter was extremely cold, but I guess it doesn't really matter since it's really more about the curve of the water temps. Now I'm running between 110*F - 160* F (or might be 165*F).

I just got my gas bill and I'm using the same amount of fuel (155 therms) to keep the house more comfortable during a colder month as I was the same time last year when the month was several degrees warmer and I was using no ODR and setbacks.

Stuff left to sort out...

• Figure out how or if I need to dial it (ODR curve, Differential) in further.
  
• Have a heat loss done for the whole house to make sure the boiler is actually properly sized and if not, adjusting it accordingly so it doesn't short-cycle.
  
• Determine whether or not my boiler piping is optimal (it was installed by the prior home owner who had his own HVAC biz).
  
• Make sure my t-stats are indeed set properly (cycles per hour, etc.)
  
• Figure how how to leave room in the system without re-plumbing the whole house to allow for integrating a steel radiator panel in my living room and the viability of changing the HWBB in my two small bathrooms (less than 100 sq. ft. each with 7' 2" ceilings) to panel radiators, towel warmers or radiant flooring.
  

So, still a bit of learning and tweaking to do...all thanks to your educational help

bmwpowere36m3

If you have the t-stats turned all the way up and the interior temp has been steady at 70* through various outdoor temps/conditions... then your spot on with a very small buffer of 2*.

The temps on the ODR curve aren't really that critical, other than the slope of the curve and your MAX and min supply temps. I think you did good, set the stats to 68* and enjoy the comfort. Not much more to adjust on the boiler if is over-sized beyond the "tight" ODR, barring more emitters, bigger zones, buffer tank or smaller boiler.

icesailor

ODR is a wonderful thing. It can tell if the outside temperature goes down, or up, and can make adjustments accordingly. One thing it CAN'T do is figure out that set back thermostats manipulate the outside temperatures. When you turn a thermostat down, you are making the outside warmer, When you turn it up, the outside is colder.

Everyone has their theories. Mine is all about comfort. I find with many years of experience, your set back range to be too close. When it is 23 degrees outside in NJ, you aren't wearing your Seashore Park clothes. You're wearing your Warmies. My Polartec insulated pants went on around the end of October and didn't come off until June. You need a wider set back range. If you are sleeping in a room with beds with all you describe, you could be in 58 degree room and never know it. And if the T-Stat sets back at 9:00 PM, before you go to bed, if it is a tight house, the house is still warm. If the T-stat kicks back on at say 5:00 AM, the room still hasn't dropped to the lower set point. And if it has, it just ran for a short time. Sleeping in a cold room is comfortable. Sleeping in a hot room isn't. Getting up to a warm house is nice. But what makes houses feel warmer is higher system temperatures in the emitters. Or why people LOVE steam heat radiators. They get hot and radiate warmth.

My minority observation. The higher the system water temperature, the lower the human will set the thermostat. The cooler the system temperature, the higher the human will set the Thermostat. If it is 70 degrees OAT, and a human goes outside, they will sit in the sun rather than the shade. Even though both places are 70 degrees. Sitting in the sun feels warmer. Same applies to a house temperature. If the human is busy burning calories, they don't care what the temperature is. When munching chips, slurping suds while watching TV, they want to feel those changes of air. Why people continue to live with scorched air.

dgoldstein

I ran the t-stat to 80*F the other day (was in the low 40s outside), and the system brought the indoor temp in my hallway (where the stat is) to 71*, my master bedroom is across from the hallway stat and my alarm clock has a temp gauge in it that read 69.3F. My wife noticed that our guest bedroom, down the hall was a bit too warm.

I'm contemplating dropping the Min Supply Water Temp down from 110*F to 105*.

Should the ODR curve be tuned so that if the t-stat was calling for heat 24/7, that the boiler would just run continuously and produce a comfortable interior space?

I'm thinking the point is essentially eliminate setting the temp with the t-stat, no setbacks and just let the ODR curve control the level of comfort based on the outside temps and eventually do some micro-zoning with in-series panel radiators with TRVs (unless there is a way to put TRVs on the HWBB emitters) - so I could have the house "comfortable" at 68*, and have the master bedroom at 66* for cozy sleeping under the bedding.

Paul48

I remember someone posting a TRV with a bypass that could be used with baseboards.

dgoldstein

I will look into the options for a TRV maybe with a mono-flow T since the HWBB are all in series.

I'm still trying to figure out whather or not the ODR curve be tuned so that if the t-stat was calling for heat 24/7, that the boiler would just run continuously and produce a comfortable interior space?

Paul48

Are you maintain the same indoor temp across all outdoor temps?

dgoldstein

I'm still running tests.

Yesterday I lowered my Max Supply Temp to 160, and lowered the Min Supply Temp to 105, lowered the temp for Central Heating to 90.

So far with the t-stat set to 85*, the indoor temp is holding at 68-69*F, outdoor temps are in the high 20's at night, and 40-50 during the day.

Rich_49

Suggesting 2 panel rads for a room of that size .

dgoldstein

@ Paul,

So far the house is keeping at 68*F. The boiler is cycling on and off periodically through the day & night. My concern about dropping the Min/Max supply temps further is negating the ability of the system to warm the home beyond the t-stat set temp when we want to bump the heat up on a particularly cold or chilly day.

When I run the t-stat at 85*F (calling 24/7), the temp seems to peak around 71*F. Comfort is good, but again, the bedroom gets too warm at night - we may need to adjust our lines since we're using a sheet, an electric blanket and a duvet.

We're coming towards the end of the heating season here and I've noticed that despite the outdoor temps in the 50s and 60s, there are times where the inside of the house feels chilly and the t-stat is still reading a steady 68*F. We generally keep the plastic shades and curtains drawn unless it's a particularly sunny day.

@ Rich,

Yes, I'd love to put in panel radiators into the master bedroom and have the ability to micro-zone via the TRV(s), but the current "main" zone (and the other 2 zones) are series loops with HWBB. I'm leery of the effectiveness of changing more than one room over to the panel rads without re-plumbing the whole system to send supply/return to each micro-zone/room. I already intend to plumb in a steel panel radiator for my living room remodel using a H-bypass on the radiator and I think a mono-flow tee.

I see you service my area. I might be interested in a consultation, but I am a competent DIY'er and have done heat load calcs through RadiantWorks and LoadCalc for most of the rooms, but haven't built up a total solution for the best comfort in the house given the components installed. We can talk privately if necessary.

Rich_49

My number is in the haeder on every comment . feel free to use it . You would not be the first competent DIYer whom we designed for and supported through completion .

Jean-David Beyer

"So far the house is keeping at 68*F. The boiler is cycling on and off periodically through the day & night. My concern about dropping the Min/Max supply temps further is negating the ability of the system to warm the home beyond the t-stat set temp when we want to bump the heat up on a particularly cold or chilly day."

I have a mod-con with outdoor reset and I set the curves almost as tight as they will go. I set the thermostat at 69F, that is the temperature I want my house for comfort. There is no reason to increase the temperature inside the house on a particularly cold or chilly day. If the system can maintain the desired setting from 0F outside to 70F outside, why would I wish to change it?

dgoldstein

Hi Jean-David,

Part of the issue with my tightening the ODR curve further is that while my hallway has stayed relatively consistent at 68*F, other rooms vary by a degree or two, and since my house isn't tight (a work in progress, but will never be 100%), some rooms get drafts that the t-stat never sees, but us humans feel cold and want to bump the heat up more to compensate.

I think the other issue is that my heat emitters rely on convection and have minimal radiation. The convection in and of itself creates a draft. Jean-David, if I remember correctly, you have radiant floors - so the experience of warmth is different than my baseboard emitters.

Basically, I'm trying to dial in a compromise since I can't afford to tighten the house to a modern standard, nor afford to micro-zone every room with panel rads/TRVs. I'm trying to find more info on TRV installs for HWBB for our master bedroom.

Need to read through this article.

Overall, I started this whole journey a year ago without ODR and the boiler running at High Supply of 180*F and a Low Supply of 159*F. I've installed the ODR sensor and brought the curve down to 160*/105*.

SWEI

Tune the ODR so the coldest room is comfortable, then throttle back the other rooms until they balance.

Jean-David Beyer

"if I remember correctly, you have radiant floors - so the experience of warmth is different than my baseboard emitters."

True downstairs. Upstairs is Slant/Fin BaseLine 2000. It is oversize (14 feet in each of two rooms) so I need only 150F when it is 0F outside. Design temp is 14F outside.
At 14F outside, supply temperature is 142F.
The downstairs needs only 130F when it is 0F outside, and 116F when it is 14F outside.

(Indirect gets 190F whenever it runs; it ignores outside temperature. I had to raise it to this when I raised the indirect temperature to 140F minimum -- goes up to 160F sometimes. There is a Caleffi automatic mixing valve to deliver 120F water to domestic hot water taps, dishwasher, and washing machine.)