No difference for non set back savings.. (ME)

JohnNY

I've been taking hydronics courses for about twenty years now and I'll always remember I=B=R's "official" position that daily setback was of NO SIGNIFICANT VALUE toward efficiency. Setback was simply a comfort setting but should never exceed 4 degrees.

In the last 5 years or so I've been hearing different opinions about the topic.

The thing is, opinions really shouldn't matter. It's real-life testing that tells the story.

Thanks for your input, Mr. E.
Happy Holidays.


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[Deleted User]

Annecdotal, yes...

I just got my fuel bill for November to December.

Last year, with the ODR and programmable thermostat, we used 2.6 therms/degree day exposure (average OS daily temp for the month.)

This year, I disabled the programmable set back thermostat AND the ODR and just go on a fixed set point and modulate around that.

Same fuel consumption per adjusted exposure. 2.6 therms /degree day exposure (average OS daily temp for the month.

So, it would appear that the greatest fuel savings is not necessairily from the ODR, nor the programable t-stat, but from the application of the sealed combustion MOD/CON appliance (Munchkin T-50).

I thought so...

ME

Ted_9

Indoor reset

I've been using just indoor reset this year for the first time. It doesn't run that often and the house stays warm, comfortable. We'll see how things go this winter.

I also enable a constant circ feature which I'm loving. I have panel rads with trv's and one radiant loop.


Massachusetts

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Cosmo_3

cool, thanks Mark

I knew the setback wouldn't account for much.

The ODR is interesting however....

Hope you had a great Christmas


Cosmo

Tony_23

I'm glad

I'm glad that YOU have said this. Maybe somebody will now believe me (strictly sarcasm, nothing personal)

Every time this topic comes up, these statements are dismissed as "anecdotal evidence only, with no scientific value"

I live in a "lab", don't you ?

T

Mike T., Swampeast MO

I thought so as well...

Thanks for confirming with your well-measured "anecdote".

Why no difference in the control scheme?

Fixed primary flow!

Uni R_2

It really depends.

On a tight well-insulated home with mass, how can it save unless it is done over many days? On a leaky house with minimal insulation how can it not save money?

[Deleted User]

Agreed....

And I have said publicly more than once, that if your home loses more than a few degrees F over night, then you would be wiser to spend money on weatherization and energy conservation than depending upon a set back thermostat to save you fuel...

You KNOW you're in trouble when you can see the curtains moving and the windows are already tightly closed...

It's a lot less energy intensive to keep the tiger IN then tank then it is to let it out and have to put it back in again....

Thanks for understanding that your mileage may vary.

ME

Mark Hunt

Yah but


the system would be designed around those prameters no?

It doesn't change. Even a leaky house has less heat loss on a mild day compared to an extreme day. The savings would still be there.

Modulate. Design accordingly.

Mark H

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Mike T., Swampeast MO

There's simply no excuse for a leaky house with no or minimal insulation. Most of those were at least minimally improved during the first "energy crisis". BUT the setback studies were based on "leaky homes with no or minimal insulation!"

Uni R_2

BUT the setback studies were based on "leaky homes with no or minimal insulation!"

********************

There is a recent Canadian study that showed savings and it was based on identical R2000 (a very tight modern spec).

********************

We can all agree that all houses leak. Some leak faster than others. The economies of setback scale directly with how badly a house leaks and how long the occupants are out.

Bob Sweet

Ive suspected less benefit from ODR with a modulating boiler by way of its modulation off of water temps. As well as the way some are able to learn the characteristics of a structure and modify the firing to adjust for that.

ODR seems to have its greatest payback when used with a single stage boiler, particularly with a low mass emitter system, in a climate that has wide temp. swings on a daily basis.

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Plumb Bob

Setback saves "up to 1% per degree". Now that "up to" covers all bases. The statement is true even if no one gets 1%. The statement is true even if you get 0%. It's false advertising, but you can't sue any stat manufacturer for it.

zeke

UNDER

> I just got my fuel bill for November to December.

> Last year, with the ODR and programmable

> thermostat, we used 2.6 therms/degree day

> exposure (average OS daily temp for the

> month.)

>

> This year, I disabled the programmable

> set back thermostat AND the ODR and just go on a

> fixed set point and modulate around that.

>

> Same

> fuel consumption per adjusted exposure. 2.6

> therms /degree day exposure (average OS daily

> temp for the month.

>

> So, it would appear that

> the greatest fuel savings is not necessairily

> from the ODR, nor the programable t-stat, but

> from the application of the sealed combustion

> MOD/CON appliance (Munchkin T-50).

>

> I thought

> so...

>

> ME



I doubt that you get 2.6 therms/deg day. For a 30 deg outside temp that would mean your cosumption would be 78 therms, close to my 30 gal of oil which will cost $75. You have a decimal point problem or you will go to the poorhouse soon.
Also, from newtonian heat transfer , which states thes the heat loss is proportional to the temp diference between outside and inside. Even a modest setback temp HAS TO RESULT IN LESS HEAT LOSS. and therefore , refutes your data which cannot see the difference because you have so little setback in your tight house that the measurement cannot be made accurately enough to support any definitive experimental statement.

Darin Cook_6

Setback / Energy savings

Programmable tstats work well with a forced air system (No mass) but very few instances where they work well with a hydronic system (high mass) as far as energy conservation is concerned.






TSGT Darin Cook
Air Expeditionary Forces
Iraq

ScottMP

Heat loss is directly

related to the difference in temperature from out doors to indoors No ?

An ID temp closer to OD would loose less faster, No ?

I agree that the fuel savings between choosing ODR compared to Mod/Con is equal but is it wise to through out night setback alltogether for all customers ?

Scott

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Paul Fredricks_3

I agree

Heat loss is based on indoor/outdoor TD. Your house is set at 70 and you set it back to 65 at night. If it is set to come back up to 70 in the AM, but it only got down to 66, it seems to me you didn't save anything, or possibly an immeasurable amount. But if it gets to 65 at 2 AM, then maybe there's a savings to be had. The longer the setback period, and the faster the space reaches that set back temperature, the greater the possibility of savings. That said, a better insulated home makes the most sense.

Perry_3

It depends..

on how the house was originally constructed.

I have seen many much older houses that it was easier to seal up and insulate than mine as a wall with "no insulation" can easily be insulated by blowing in stuff.

In my case, I have 2" rockwool that only half fill the space in the wall. It's presense prevents blowing in more insulation (effectively).

My attic is minimally insulated as well, In reality - it is nothing more than a crawl space at best. It has no access so there is no good way to get up their and work. Not to mention the ceiling against the roof - which also has 2" Rockwool as this space needs to let air flow under the ceiling to the attic vent system.

Now I figure I can tear down the nice plaster ceiling on the second floor of the house to be able to properely insulate the ceiling and attic (complete with proper air flow channels). Someday I may do that along with tearing out the existing chimney and a few other things. $15,000 - $20,000 is my estimate (especially as I want to restore the plaster).

I have replaced windows on two sides of the house - only another $10,000 or so to replace the other two sides of the house.

While major air leaks can be sealed, how well you can tighten other things up - and how cost effective has a lot to depend with how the house was originally constructed - and its condition. Obviously, if you have a really old house where the walls are deteriorating - and you need to tear them out (down to the studs) it is real easy and cost effective to properely insulatete (and rewire, etc).

All that can be said it that people can plug up the major air leakage relatively cheaply (and very cost effectively). That may not yet be a "tight" house. Improvements beyond that may be major money.

Perry

jp_2

more info?

what was your set back scheme? 2F, 5F, 7F?

for 4hrs, 10hrs, 2 times a day, once?

like to see more data before I start telling people programmables tstats are a waste of money.

what was your supply temp set at?

edit:
other interesting data would be the extent of supply swings with ODR, and how often it maintained a temp 10-15F past the temp you held it at this year?

by the way, i do agree set back has minor savings, if noticeable, but i know lots of people who like it cooler when sleeping, and a little kick-up in the evenings.

Dave Yates (GrandPAH)_1

try this....

Next time you do a M-J load calc with an older R-11 walls/R-19 attic/older D-P clear glass wood sash windows, go back and beef er up to 19 walls/45 attic/D-P L-E wood sash & check out the difference in one year's usage of fuel.

Next: calculate the year's usage with the existing bang-bang unit and no set-back & then again with a moderate set-back and then a deep set-back to gauge potential savings. Set-back can be calc'd using the portion of time and hours that encompases during a 'typical' heating season.

Then: stop, drop & roll it up with a mod-con.

So, where's the best investment consumers can make if they can only afford one major move. A customer of ours decided they'd invest 14-G's into beefing up the insulation and tightening their home following a slick presentation that included infra-red imaging, rather than replacing the cast iron beast gulping nat gas. It's a large home (5k sq ft) with six hydronic zones.

I know where their money would have given them the biggest bang for their bucks.

BTW, when I called the 'specialists' who performed the extreme insulation makeover to inquire about the new heat loss calculations - they had none to share. "We don't do that." From what I saw during my detailed investigation for gathering info for my heat loss/gain M-J calcs, they did a very thorough job of buttoning-up the home and increasing insulation values dramatically.

The HO's aren't feeling very Ho, Ho, Ho this holiday heating season. Once again, we're revisiting the boiler installation & they're kicking themselves.

Do the math. Nuttin wrong with tightening up the envelope & that's a nice-to-have, but if the budget can't cover all bases, it's up to us to advise consumers about ROI. Some won't listen & I've tread lightly because I'm selling (or trying to sell) a product. Time to rachet up the rhetoric a notch.

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Mike T., Swampeast MO

With 2x (by their estimate) oversized, mid-efficiency gas furnaces heating empty houses.

Unknown

Depends. If ODR lowers the temps to condensing range, there is benefit. also, exhaust temps seem to be related to water temperature, so there can be benefit there. and if it allows for consistent modulating operation instead of having to cycle (with the water temp being too high for the emitters, resulting in a loss in heat demand) there would seem to have to be some benefit.

since its not very expensive to add, I'd say it still has benefit. Even more if you take comfort into consideration.

Constantin

True...

If you use a heat loss program, you can start to estimate the benefits of various options... tightening windows, replacing them, etc. It is all reflected in the ACH number that a blower door test produces.

We retrofit a hot roof on this house with zero ventilation. EPDM on the flats, Duraslate on the Mansard sections. Given the research from folk like Buildingscience.com, I saw no reason to add ventilation channels to a roof system that would not benefit from it. The Duraslate still looks great, the EPDM is happy, and our infiltration is quite low.

You might consider insulating your roof from the outside, i.e. tear off the existing roof, put the proper insulation on top, seal all the access holes for ventilation, etc. than to go through the trouble of removing all that rockwool in the attic. If the dewpoint stays inside the insulation on top of your roof, you have nothing to fear. The money you save not having to demo the ceilings can then be invested in a long-life roof cover.

The next time you have a blower-door guy in the house, do the place, then do two rooms: one with and one without the new windows. The impact on ACH of new windows or upgraded storms should then become apparent. Many utilities offer such tests for a nominal sum, we got the whole house checked out via energystar.gov (on oil heat).

Uni R_2

Very True

But nevertheless tight and very well insulated.

Uni R_2

Not quite...

The identical 2400 sq ft test houses have 67K side-wall vented furnaces and a calculated heatload of 44K (they don't say whether this is based on their tests or Manual J calculations). The study merely notes that the furnaces "are overized by about 50% based on monitored results so far." I'm sure many heating systems installed by the pros here end up with a similar degree of headroom.

My point was that this study was based on a tight building spec. The air infiltration factor is only 1.5ach @ 50 Pa (5-8 is tight). While the houses aren't furnished, they do have occupancy simulators.

I'm not sure why you wouldn't consider this a valid study Mike.

http://irc.nrc-cnrc.gc.ca/pubs/rr/rr191/rr191.pdf

John Ruhnke

Please more info.........

Mark,

I imagine ODR is Outdoor Reset. Are you saying you turned off outdoor reset and had no savings difference? I find that hard to beleive unless you switched to something else to reset the temperature, like indoor reset or lowering the water temps based on delta tee or Exquisite Heat. You need to set back the water temps some how or you won't see savings with mod/cons. The lower the water temps the more you save in fuel. What did you use to set back the boiler? When you said fixed water temps, What temp was that?

Day night setback should save money too. Heatloss is based on delta tee of outside and inside temperature. The lower the delta tee the more you save. Naturally if you set back at night you will save. I think the problem is in the thermostats themselves. I set up a Exquisite Heat control on my neighbors house. I did some data logging. They had a setback thermostat. The thermostat short cycled the boiler like crazy. I am sure this cost money in fuel bills that wiped out any savings from setback.

These are all rules that I have learned over the years. Of course, non of those rules matter as much as real time information. I think it is great that you do some data logging and cost comparisons. You need many different sources to compare though. You have to analyse a bunch of different data. It can be a bit dangerous to rely on just one data logging project to learn from. It may cause you to draw improper conclusions. Also always keep your mind open.

Mark, could you please provide me with some more detail on your data? What brand and model was the boiler, thermostat, type of reset in both cases,

JR

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Uni R_2

No dispute with you...

Mark, I totally agree with your claim:

"So, it would appear that the greatest fuel savings is not necessairily from the ODR, nor the programable t-stat, but from the application of the sealed combustion MOD/CON appliance (Munchkin T-50)."

Many others started inferring from your post that setback t-stats don't save at all and that was the point I was trying to address - not dispute the above claim. It's pretty hard in a home situation to find that there is a 2% savings doing something one way and then find out that one of the kids left a window wide open skewing the results, but you really did hit the nail on the head. The Munchie's design is the prime reason for your savings. Even without ODR and setback it is still saving you about the same amount of energy.

Mike T., Swampeast MO

I've read it numerous times. No reason/need to dispute their findings but as they conclude, it's difficult to apply their findings to other structures in other climates.

I certainly agree with both you and Mark that a modulating/condensing boiler [seems] to have an effect that may not be seen with other types of heating appliances.

TK03

What?????????

When I read the above posts what I think I am reading is Mod/con boilers do not save any more fuel when using outdoor reset. I also read ODR will save more on larger water volume on/off boilers. So is it safe to say the savings would be the same if using mod/com without ODR or cast iron with ODR?

[Deleted User]

John...

Yes, ODR = outdoor reset. As I explained, the boiler still modulates, only around a fixed set point of 150 degrees F.

Your presumption about having to have reset or no savings is incorrect John, and this is not the first time I've witnessed it. Actually the third time.

Set back thermostat was Honeywell T8600 series 5, 1, 1 with AIR (active intelligent ramping) capabilites.

The boiler is a Munchkin T-50 with Vision 1 capabilites.

Remember, this is the case in MY SITUATION, and may not be applicable to ALL situations.

ME

[Deleted User]

Bob...

I agree whole heartedly with your statement about ODR and atmospheric Bang Bang boilers.

These new low mass, sealed combustion mod/cons are so efficient, even if they're not doing a reset schedule that there is little to no perceiveable benefit from an ODR control.

In my case, my max temp is 150 degrees F, so I'm always in the condensing mode. If my system were to require 180 degrees F at design, then that statement may not necessarily be true, but in my case, it is true.

ME

[Deleted User]

Heat loss is not as proportionally linear as you would think...

It is heavily influenced by things such as internal mass, infiltration, type of insulation used and internal gains.

But you already knew that, didn't you :-)

ME

[Deleted User]

jp..

Set back was allowed to go back 10 degrees F, two set back periods per day, one during the work day and one during sleeping periods. Typical American profile.

It is not my intent for people to start telling people that programmable thermostats are not a good thing. Depending upon the building and the heating system, there may very well be benefits derived. But in my particular case, which is fairly typical, there was no perceptible benefit over the high efficiency appliance.

The outdoor reset started with 100 degree F water when the OSA was at 65 degrees F and ther was a call for heat from teh house thermostat. When teh OSA got to 5 above zero, the boiler was at its maximum supply temperature of 150 degrees F. With the Vision one boiler controls, there was never any significant temperature overshoot. My system has a buffer tank tied in parallel to it that comes on line at 65 degrees OSA temps, and goes off line when OSA hits 35 degrees F to avoid short cycling. (Thanks Amtrol!)

Even now, with a fixed set point temperature, the highly efficient boiler modulates to a lower input to maintian the set point condition. Amazing to sit there and watch.

I agree, 90% of people polled WANT a cooler sleeping environment. With my system, the bedrooms are ALWAYS kept at a lower temperature (60 degrees F) thanks to my hot bride...


ME

[Deleted User]

Caveats Heatman...

In MY case, ODR and programmable T-stat didn't show any considerable energy savings. If a system were designed to be operated at elevated temperatures, say 180 PLUS degrees F, then there probably WOULD be benefit from ODR. But in my case, designed for low temp operation, the benefits are nil.

In SOME cases, your last statement would be true.

In most cases, the new mod/cons come equipped with an ODR, and to not use it would be really silly. Other than the benefit of sleeping in a cooler environment, there probably would not be a whole lot of benefit to a set back thermostat unless the home leaked like a seive...

I'd try that mode, but why, now I'm comfortable ALL the time:-)

ME

Bob Sweet

Not really

the biggest and most important advantage of a mod/con is it's ability to modulate it's temp.

The boiler is able to adjust its firing rate to match the characteristics of the structure, thats were the biggest savings comes from.

With a single stage boiler ODR limts the supply temps the boiler is allowed to produce, based off a basic preset heating curve that has very little room to manuever, other than the parameters that have been preset.

No matter what when the boiler fires it's 100% or nothing. Short cycling becomes an issue especially when the outdoor temps are moderate, dampers, gas valves, zone valves all work over time.

ODR saves money, but the way these mod/cons are able to adjust firing rates off of watre temps I havent seen the dramatic difference in fuel bills between mod/cons that I have ODR installed on and mod/cons that don't have ODR insatalled on. On the other hand with a typical cast iron boiler, the benefit of ODR can be seen on the fuel bill.




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Darrell

A twist to this arguement:

Here in Alaska alot of homebuilders are having setback stats installed simply for the points that they buy on the "energy audit" done at closing. More points equals lower financing without regard to fuel savings, creature comfort, or system design or functionality...simply because somebody said it was a good idea. In fact, in many systems, radiant for example, the setback stat costs more money to install, throws creature comfort out the window...so to speak, and system functionality is all over the chart.

I actually know one heating contractor who has a box of broken setback stats that he sets in the corner...he'll "put them on after the system settles..." 'Course the general gets the points...and the owner gets normal stats.

Modulation to match the required load...measured inside the living space seems...practically..to be the most comfortable and steady, which should put the least strain or heavy load on a heating plant. Outdoor reset alone gives us fits because our outdoor temps swing 40-50 or more degrees from night to day. Many structures/heating systems cannot respond that quickly and get "over excited" whereas modulating for inside temp dampens the "idiot sine wave".

If I go on a call where the complaint is inconsistent temp control, the first thing I do is override the outdoor reset and the next thing I do is replace the thermostat with a fixed temp stat. This eliminates the two biggest error factors so I can evaluate the system/structure match. Then we can add reset or setback as the situation dictates.

scott w.

tempature overshoot

Mark E.

Could you give an explanation of tempature overshoot. Not sure if you are refering to the boiler or room temp. I would guess room temp such as thermostat set at say 70 but after the boiler quits firing the room or house temp hits seventy five?
I think I may have overshoot as the large 12' CI rad in the living room heats, the stat in entry is set at 69 deg will read 70.
thanks

Scott

John Ruhnke

150 degrees?

Mark,

You said "Your presumption about having to have reset or no savings is incorrect" That is the industry wide presumption based on our modern day science. The boiler isn't supposed to condense until it hits 130 degrees. For every two or three degrees you drop in water temps you are supposed to save 1% in efficiency. Once you hit the condensing temps the efficiency gains double, I have a ASHRAE paper that explains all of this and it is backed up by real data from 20 schools. Everything has been logged proffesionally. This is a before and after comparison.

Are you telling me that you are staying above the condensing point and not losing money over outdoor reset? Something doesn't make sense here. The boiler is supposed to recover the heat from the condensate comming back to the boiler. This is where the fuel savings are supposed to come from. From what you are telling me I think one of two things are happening. One, your gas company didn't read the meter for a while and just coppied data from charts to bill you. In that case you will get hit with a month of very high or low bill when they finnally do read your meter. Or your boiler is not capable of taking advantage of the condensing mode properly. In other words you aren't getting the capabilities you paid for from the Munchkin. Or a third option, that thermostat is costing you a fortune in fuel bills to offset the savings you are supposed to get. Was there condensate comming back at 150? Maybe the boiler can condense at higher temps. Was there condensate comming back when you used ODR? What was the average temps when using ODR? Maybe you have hot water baseboard designed at 180 and the ODR never was in condensing mode.

Maybe the science of efficiency is all wrong. Remember before the Wright Bros came along the physics books on aerodynamics were all wrong too. When they built the plane to there scientific principles at the time, the plane didn't fly. They did a bunch of experiments and rewrote there own physics principles. Then they built a plane that actually flew.


First off I think that AIR is a bunch of junk. All it does is call for heat on and off all the time. This creates short cycling and is very bad for system efficiency. In my neighbors house I data logged the run time of his Honeywell thermostat over night and it never ran for more then 4 minutes at a time. In the early morning while ramping up, it was always on off, on off. During the day, mostly it ran for 4 minutes and was off for a long period and then ran for another 4 minutes. It had something simular to AIR. The Honeywell engineers worry about comfort, not efficiency. They try to reduce wide temp swings. Homeowners only notice comnfort, they don't notice efficiency. Then they use marketing hype based on unrelated studies to give you the sense that you are saving money with there thermostat. They don't actually field test the thermostat for efficiency. So how do they know if it does what it is supposed to do?

JR

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John Ruhnke

Please data log the actual water temps..........

Mark,

The thermostat in my neighbors house never allowed the water temps above 140 durring the day. Mostly the temps were between 110 and 140. This was running below the aquastat setting. Even though your boiler is set at 150, maybe it is running much less then that most of the time. Maybe it is running the same temps that outdoor reset provides. Data Log the water temps with odr for a few nights and without odr for a few nights. Maybe that thermostat is able to accomplish simular water temps as odr.

If that is the case then the science is right. I hope the science is right or all the books have to be rewritten. Keep experimenting with your boiler until you understand why and what is happening. Then let us know what you find out so we can learn. You need to find out why the fuel savings aren't different.

JR

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Kevin_in_Denver_2

Setback in superinsulated home is mandatory...

Just some more real world results to consider: I live in a high mass, low loss, radiant heated home. A programmable thermostat is the only way I can guarantee that I will have a warm bathroom floor in the morning.

This stat only cost $10 more than a basic one (HD prices). It's a comfort, not a financial choice, and an easy one at that.

This logic also applies to any sort of forced air home. When the furnace is on during morning shower times, the bathrooms are usually warmer than the house thermostat setpoint, which is good in this case. (Bathrooms typically get more than than their fair share of the airflow due to ducting realities).

Let's keep pounding the manufacturers to make them easier to use, and those service calls due to programming problems will decrease. There have been improvements made, but most homeowners/tenants still can't cope with setback. Rarely will you find a tenant that will replace batteries in a thermostat even if it means saving $5-$60/month in heat.

Unknown

Well, a couple of things there Mark (and these are definitely questions I don't know the answer to, and am asking in good faith!):

- Aren't there different "degrees" (har har) of condensing? Condensing is better at lower temps that ODR can deliver, yes?

-What about consistent operation at the emitters? Are you taking comfort into account? Is loss of your heat demands lowering your ability to properly modulate?

I understand you see what you see and that's awesome, just curious what you think about those two things.