outdoor reset

nitwouttgrict2118451

Hi All,
About this time last year, I converted from a 50 year old oil fired boiler to a Burnham PVG-4 gas fired unit. The heating contractor was of the old-school variety, no heat -loss calculation to speak of, just added up the existing radiation and VOY LA ! Magically the new boiler has the same output as the old fire-breather.

Not being as savy as I am now, I went with his choice. Well, a year of reading and asking lots of questions on this forum has schooled me in what NOT to do when changing equipment. The Slant-Fin heat-loss program should be required reading when signing up for this forum, you will all be tested at the end of the semester.

As it turns out, my boiler is 2X+ what the heat-loss calculation indicated. What's that they say about hind sight?

Anyway, I installed a Tekmar 256 outdoor reset and monitored it closely last winter. It was at least entertaining to see how it shifted the water temperature with the out door temp. Did I save a bucket of money? I really don't know as I have no before and after gas meter readings. What did change was that the burner-on cycles got longer. I guess this is good.

k

how important is an outdoor reset

met with a very large oil company friday, and he told me that an outdoor reset is not needed, and they do not install them on houses. comercial building yes.
Looking for this company to install a new boiler for me, and now im second guessing them doing this work, and Ive been told that i will save $ if an outdoor reset is instlaled. any help out there ?? thanks !

Robert O'Brien

I'd

look for someone else.
http://www.tekmarcontrols.com/literature/acrobat/p022.pdf

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Uni R_2

Conflict of Interests

I'll bet they don't do heatloss calculations on replacement boilers either. You should.

Brad White_198

There are few things better

than outdoor reset to save energy.

There are few things better than avoiding outdoor reset to help sell more oil. I would give them the benefit of ignorance on one hand but if it works for commercial interests, why not on residential where cash costs cannot be passed on to a customer base?

One has to set up ODR intelligently though- limit it on the boiler to keep the flue gas from condensing, but go as deeply as you can on the radiation side to maximize savings. The boiler has one circuit and the radiation is another. Hotter boiler water is injected into the radiation loop to maintain whatever temperature is needed at that moment. How cool.

Think about it: When your outdoor temperature is in the 60's say 65F, you have essentially no heat loss and thus need no heat. Your radiator output is directly related to the average water temperature inside it at a given air temperature. When the room temperature, radiator surface temperature and yes, the outside temperature converge, you have no heat transfer to speak of. No heat needed.

A few degrees colder outside, say it goes into the low 50's, you will only then begin to cave in and start heating. Do you REALLY need 180 degree water then? Nope. Maybe 15-20 degrees water temperature above space temperature.

Your entire heating curve can be set on the radiation side from say, 80 degree water when it is oh, 60 degrees outside (your lights, appliances, the sun and your bodies make up the difference to comfort setpoint). The slope will increase the supply water temperature from that minimal on-point up to say, 180 degrees or even less, when it is at the minimum design outside temperature.

Save the hottest water for the coldest weather which when you figure it out, is a ridiculously short time compared to the entire winter heating hours. Unless you live in Alaska of course, and even then, you have summer

Leo_16

A lot of companies

A lot of companies do not want to take the time for the learning curve involved with high tech controls. They need to train their staff many who are older and too stubborn to learn something new. Even some smaller companies are afraid of what they feel is the unknown. I am not making excuses just speaking the real world.

Leo

narcaparbebra

Does the value of ODR exclude EK systems? I've talked to 2 EK installers and both said not to use ODR. One couldn't give me a reason and the other noted the low water volume (2.5 gallons) makes the ODR less of an issue.

Robert O'Brien

EK

takes a different approach,the system manager purges the residual heat from the boiler after each cycle,basically eliminating idle loss.Conventional ODR is really not applicable to single EK's.
The Honeywell AQ2000 is a full featured ODR with the ability to purge for up to 30 minutes,I've installed a few on both Viessmann and Biasi with excellent results

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Glenn Sossin_2

How

Did you figure that one out? I recently ran across an oil company telling a customer they would save 30% + on their fuel consumption by putting in a Riello burner for X $.

Its unfortunate that there are a few "name brand" oil companies out there pulling these stunts. Homeowners, desperate to get out from under the upcoming fuel crisis are predisposed to believe these guys.

I told my customer to always consider the motivation of someone when they ask advise. I told him Riello is a great product, commonly acknowledged as the best burner, but he'd be lucky to see 3-4% difference. I came up with a couple of questions to ask.

I told him to ask for a few recent installs in his neighborhood this same time last year, with a phone # and name so he could call to confirm savings. Would you believe it he didn't give him anyone???

I also told him to ask for a savings guaranty in writing - He said it would save 30% or more, tell him you'll go along with it as long as he credits you back the savings as if it were only 15% savings. huminahhuminah ah ha

My $.02

Glenn

Robert O'Brien

Glenn

I agree that some people will misrepresent the truth,but it's not just oil co's.How about the claim that converting to gas will save energy? With a mod/con that's absolutely true.With the "low cost" National Grid standing pilot promotional boiler it's very likely energy consumption on a BTU basis will increase depending on the oil boiler it's replacing.

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Robert O'Brien

\"how important is an outdoor reset \"

I forgot about this,As of 11/2015 every boiler sold in the USA will require some type of reset control

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Unknown

the oil company might be right.

most baseboard could be run at boiler minimum all winter, right now, with no additional control added.

At least, that's what I keep finding.

if you add a mixing system, that's another story. but you still have to run to boiler minimum in that case so I don't think the mixing is as much of a cost savings there. If 90 would do the job it simply won't call for heat again very soon... right?

now, talk comfort, and I'm right there with you. but ODR is not a magic bullet when your boiler can't run cold.

Jim_67

Concept Question

Homeowner here.
If a person has enough baseboard radiation, why not run the aquastat/high limit at 160 or 150 degrees instead of 180?

Robert O'Brien

Jim

Absolutely,and if you have a enough baseboard to operate at 160 on a design day,what temp would be required on a day 30 degrees above design?

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Brad White_194

In general and in principle

everything about ODR holds true.

Sure, if the boiler needs protection and cannot run cold itself, is not a reason not to do it. Obviously a Modcon can handle that with ease and love you for it. This is why I mentioned the mixing system (or injection, whichever is chosen). That is a given when using normally high temperature non-condensing boilers.

In mild weather, the radiation loop will 'sip' that hotter boiler water which means less demand. If the boiler is allowed reset from 180 to say 140, that too is saving fuel, even if not as much as going to near room temperature. You too made that point but it supports ODR, not counters it. It all saves fuel to a proportional degree. Certainly the higher your starting point, the more dramatic, but cutting your fuel bill by 25-30%, even if smaller to begin with, is something I would do.

That some if not many houses have surplus radiation is a bonus which really just lowers your highest operating temperature. That is beside the point. Nothing says that you cannot go down from there. Maybe your range to save is less because you start lower to begin with, but that to me is not a reason to forgo ODR.