Relative Merits of Outdoor Reset

Chris Maderia

Norm,

The high limit on that boiler was set at 165 from the factory. If you did not change that to 180 and the baseboard was sized based on 180 than there is not enough board in the rooms. Here are the typical ratings for baseboard:

@4gpm

180 Degrees 590btu per foot
170 Degrees 550btu per foot
160 Degrees 480btu per foot
150 Degrees 410btu per foot

@1gpm

180 Degrees 560btu per foot
170 Degrees 500btu per foot
160 Degrees 430btu per foot
150 Degrees 370btu per foot

Maybe this will help you out. Take care and Merry Christmas.

Chris Maderia

Dana Zaichkin

Is it really for everyone?

Okay, Okay...I know that this may be a nearly blasphemous question, but is reset/const circ really the "preferred" design for all applications?

Specifically, I'm thinking about my territory - mild climate western Washington State: Design temp 22-23*, most of heating season in the 40's, usually about 20* day/night variation (add: new construction, gyp suspended slab).

Do we really attain remarkable comfort benefits in this setting compared to a good setpoint with slab sensor? Especially when we consider the additional energy requirements of CC, potential velocity wear to the copper components, etc?

Or...am I just thinking about this too much?

Paul....Alan...?


Best Regards
DZ

Alan(CaliforniaRadiant)Forbes

Setpoint w/ slab sensor

cannot compete with the way an outdoor reset system can anticipate weather changes.

Setpoint will give you spikey indoor temperatures which can be uncomfortable.

The outdoor reset jobs we do are nothing short of remarkable in that the owners do not have to touch the thermostat. At first, it is very disconcerting for them; some of them are alarmed that they will not be able to raise the temperature to 75* if they want to, but they settle down after awhile and get used to it.

As far as energy efficiency and wear on components, I'm sure it costs a bit more, but the wear component is negligible.

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Dana Zaichkin

Had to ask...

Alan,

As always, I truly value your expertise (and in this case - mild climate experience)

Best Regards

Dana

Boilerpro

No it isn't....

Outdoor reset should ony be used when you are maintaining a constant temp. in the structure. If you use setbacks, you should either add indoor feedback or upgreade to a control that can boost water temperatures during recovery periods. If the heating curve of an outdoor reset control is tightly programmed and a thermostat is set back and set up again, recovery times become very long because the system does not produce enough heat to recover in a reasonable amount of time. I've seen this problem in several situations. Also if you have large, variable internal gains, like in offices, schools, and passive solar, outdoor reset really helps, but internal feedback is really a good idea. For the homeowner that never changes their thermostat setting, it is really nice, but otherwise be careful in its application. Just some of my experiences.


Boilerpro

Alan(CaliforniaRadiant)Forbes

Excellent point

tekmar and Viessmann reset controllers have setback options, but I think they have the ability to ramp up water temperatures to come out of setback.

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Steve Levine

I think otherwise

If you have the heating curve tightly programmed, and use setback, you will be in for a very long (if ever) recovery. If you loosen up the programming, (as I do in my own home)it will accomodate reasonable setbacks. Yes, you will have periods when a zone is off for a short period, but is off far less than without reset, and this really adds to comfort with the much longer ON cycles.

Steve Low

Outdoor Setback

We used a Taco Mastermind for outdoor setback for many years until it failed and had excellent experience with it until it failed. Taco no longer supports this product.

The system had tankless hotwater and thermostats were programmed for 10 degree nighttime setbacks. The Mastermind device had a built-in timer that overrode the outdoor setback. That permitted max boiler temp for morning recovery from the thermostat setbacks plus access to domestic hot water for showers. The unit was particularly valuable in the summer months when the only reason to run the boiler was for DHW.

Can anyone suggest an economical replacement for that Mastermind device (it was also sold under Enertrol the brand name)?

Steve Low

Outdoor Setback

We used a Taco Mastermind for outdoor setback for many years until it failed and had excellent experience with it. Taco no longer supports this product.

The system had tankless hotwater and thermostats were programmed for 10 degree nighttime setbacks. The Mastermind device had a built-in timer that overrode the outdoor setback. That permitted max boiler temp for morning recovery from the thermostat setbacks plus access to domestic hot water for showers. The unit was particularly valuable in the summer months when the only reason to run the boiler was for DHW.

Can anyone suggest an economical replacement for that Mastermind device (it was also sold under Enertrol the brand name)?

Dana Zaichkin

Injection & Reset

So it seems that reset/cc really is preferred for most applications, regardless of climate.

Pondering the other thread discussing injection vs mix valves gets me wondering about "how much" of the system you like to have running on constant circ when injection is used? primary AND secondary circuits or just the heating panel circuit(s) and leave the primary boiler loop on demand? Now this means that the injection circ might need to run a bit longer if the boiler has to ramp up the temp, but I dont think it should be that much? This would abate the majority of my concerns about energy use and system "wear". I don't really have enough experience with control options to know what is possible.

Questions, Questions....

Thanks & Best Regards

DZ

George Peteya

Agreed ...

... two of my six zones are on programmable tstats. They are Honeywell (10-15 yrs old) with Adaptive Intelligent Recovery. The A.I.R. feature does compensate for the low water temperatures. The only zone where I have a "problem" is a sunroom which I keep at 55, but crank up for breakfast on weekends. In mild weather it's the worst. I installed an Intermatic timer (2 hrs max) that drops out the outdoor sensor and substitutes a 100KOhm resistor ... simulates -4 degrees F. So on the weekend, I turn up the tstat and crank the timer for an hour or so. For me, great. Do not try this on your customers.

Mark Chaffee

Taco can fix your Mastermind

If you want the Mastermind fixed we can do it for you. Contact George Taber at Taco. Phone number 401-942-8000.

- Mark at Taco

Norm Brulotte

Constant Circ.

I think cc has its benefits depending on its application for instance I live in a moderate sized home with a single zone split series loop HW baseboard system 1" S&R a Viesman Viatola-Biferal oil boiler with a EKR control with out door reset installed by me installed 6 yr. ago and have not been able to tune the heating curve in yet to where its comfortable in mild temps on cld days the house heats fine but on milder days when the boiler temp drops BB dosent put out.any input.

Ernie

EKR Control

Are you sure that you have an EKR control, I thought this was the manual version and did not have reset capability. I too have a Veissmann Vitola Biferrel with EKR control package, with largest zone on cc as the controlling unit (Living Room, Dinning Room/Kitchen). Baseboard wraps exterior walls full length. Bedrooms are also wrapped by BB on exterior walls and are individually controlled by t-stats. Highest temperature I run is 150*F. Also have Indirect piped parallel to system. Have more than enough heat, always nice and warm.

Bill NTSG

EKR

Ernie, there were two versions of the EKR the second generation had simple reset,kind of like the basic tekmar. Norm , maybe I will stop by and check you out if I see your truck.