Setback and Boiler (Outdoor) Reset

Al Corelli_2

I too, enjoy colder sleeping temps. What I did, eas put the bedrooms on their own zone that runs a lower temp all the time. Nobody is in them during the day anyway, so they stay at the lower temp.

I gave up setback for reset some time ago. Never looked back.

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pennron

Setback and Boiler (Outdoor) Reset

On Dec. 20th '06 I had a Taco 702, 2 stage, outdoor reset installed on my oversized Burnham Revolution Boiler. My question has to do with settings and if I should use setback on my stats.

The home is a 2400 sq. ft ranch with slant fin multipak 80 high output fin baseboard. I also have 2 zones and a 3rd zone is an indirect DHW with priority. I have fiddled with the settings of the Taco and I'm trying to get the most efficient settings for my environment. I live in Easton, PA.

Burnham has told me I can go as low as 80 on the boiler min. setting because the Rev. can handle 55 return temps. Others have said that is too low for convection baseboard to be efficient. I have fiddled with the design temp anywhere from 0 to 9 degrees and the min boiler temp from 80 to 115. I have the boiler design at 180.

I really see no difference in all the settings because I'm sure it has to be set at a certain setting over a long period of time. I do note that if I have the outdoor design set to 0 and the boiler min set to 80 then it takes a real long time to get the house up to temp. now its possible this might be the most efficient setting and to use hardly any setback. that remains open to conjecture. So that is one issue.

The other issue is: should I be using setback in conjunction with other settings? I have the overnight set to 66 the day at 68 and the evening at 71. Is this more efficient than just keeping it at a steady temp or using less of a setback?

If anyone can help with the Taco settings in my environment and the setback question I'd be much obliged.

Brad White_9

Generally speaking with any system

outdoor reset will prolong recovery times greatly. Sort of like putting a brick under your accellerator.

This is most noticeable in milder weather when you may normally take an hour to recover six degrees it may take three hours.

The way around it is to have a "boost" mode whereby the OD Reset target is ignored in favor of quick recovery. Once recovery target is reached, the OD Reset resumes to maintain those temperatures. It takes less effort to hold an altitude than to climb there, I guess I would say.

Unknown

it's a hard question to answer, but based on some of the savings I've seen from reset operation, I would tend to favor continuous heating using reset vs. setback. Brad's idea of a boost mode might be the best of both worlds though.

kevin coppinger_4

set your t-stat...

to 68-70 and leave it alone...don't set it back at night or when you are not home...you will not be happy w/ the results...kpc

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ALH_4

agreed

I agree with the three very knowlegable, experienced responses above. The best plan for the average home is to set your reset curve as low as possible to maintain, and skip setback completely. The savings from setback would be very marginal if not negligible in relation to the savings and comfort from outdoor reset. Mark Eatherton showed this in a recent thread.

D107

shame that expensive controls have no boost

For those that seek the comfort --not the savings-- of a good 5-7 degree setback at night for sleeping, the temps have to be jacked up quite a bit higher to reach day temp than they would to maintain the same temp. I think it's a real shame that some high-priced controls do not include a boost which would solve the problem. Does anyone know if it would be possible for a timer to be attached to a control's manual button and t-stat so that every morning the boiler would go full throttle for an hour or whatever until set point is reached then go back to auto?

Unknown

I think Al's solution is best, but many tekmar controls have an "optimum start/stop" feature which will manage setbacks with reset.

Dan_15

Good analagy Brad, but every good pilot knows about the "backside of the power curve"; there are plenty of situations where it actually takes high thrust to maintain altitude, such as high drag configurations, e.g., when flaps and gear deployed in the landing configuration, while flying the pattern or on final approach. Not to get off the topic though.

Uni R_2

No no no...

Think rate of climb... ODR limits the rate of climb. The envelope just means that for any given power setting and configuration of flaps, gear etc. there are typically two speeds - one clean and one dirty depending on the wing's angle of attack.

Boost let's you steepen the climb to get back up to altitude/ temp but it can bring the boiler return temps out of condensing temperatures.

pennron

Taco 702 setting

Thank you for your input re: the setback question. I started using a 2 degree setback and I'm charting my gas usage daily with very minimal settings programmed in the ODR. We keep the house at 71 in the evening and I just can't in all good conscious keep it 71 overnight. so we started using 69 overnight and all day.

Does anyone have any answers about the taco 702 settings? On the blind I have the outside des. at 0, the boiler min at 80 and the boil des. at 175. The house is nice and warm but I'm still trying to get my gas usage down. This cold snap may tell much on that issue.

With the new ODR I have a catch 22 situation. My master bath before ODR only had a kickspace heater. This room has a 15' vault and was always too chilly for showering etc. So I installed 8' of additional baseboard in addtion to the kickspace heater and put it on a separate zone.

Before the ODR install we would close that door overnight with stat set at 60 so it would not go on (it can get as cold as 63) and then have the stat bring it up to 73 at 7am. However with the ODR set at such low water temps I would have to set the stat to reach setpoint at 5am so that at 7am she's at 73.

Do you think I should start keeping the heat on in that bath say at 70 all the time (only overnight?) and then program the stat to 73 so the room is always warm, even when not in use? I guess if that answer is yes then i should still keep the door closed. If open it connects to my master bedroom which is typically set to 69/70 on its separate zone.

Unknown

I'd leave the zone at temp all the time. Especially in the bathroom, your comfort will be noticeably better if you keep the mean radiant temperature of the objects in the room higher (think, not as cold toilet seat!)