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outdoor reset?
Andy_14
Member Posts: 121
When using an outdoor reset, do you always have a circ pump constantly running?
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Comments
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Not to my knowledge...
...but why wouldn't you?
One of the main benefits of outdoor reset is to modulate the heating-water temperature down to the lowest temperature at which the heat emitters in a home still satisfy the indoor demand. Thus, any time the house anticipates the need for heating, the pumps ought to be running. Whenever the outdoor reset controller dictates that no heating is required, the pumps could be turned off, I suppose.
The constantly circulating water serves several purposes I can think of:- It evens out the temperature throughout the house, as floor radiant systems are (to a certain extent) self-limiting.
- The smaller temperature swings in turn reduce the creaking, groaning, and squeaking from attempts to quickly heat a space.
- It gives the control system a constant update on heat loss in various zones that may or may not be tied to a thermostat.
- Plus many more that the local heating demigods can add, no doubt.
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Thanks, That definatley helps me understand it better now.
I am planning a new install-1 room-bare concrete slab-1 zone and am trying to decide weather or not it would be worth using an outdoor reset for this application. Just not sure if it is needed.0 -
Outdoor reset is really neat...
...whether you have radiant or not. Honeywell did a study where they showed a 16-24% fuel savings per annum due to outdoor reset alone. Your choice of heat emitter is pretty much immaterial, IIRC.
OR has the biggest impact with high-mass, slow-response systems like radiant floor heat or cast iron boilers, for example. A good control strategy is also important. Have a look at the Tekmar literature on the subject, they have a lot online.
Outdoor reset costs so little to add these days, I don't know why not more folks insist on it.0 -
outdoor reset
I have heard so much about outdoor reset on the wall and since this thread pertains to it I (HO) would like to know if I can use it with my system in order to make it more efficient.
I have a series 2 Gas burnham boiler with 4 Taco circulaters tied into a Taco SR 504 exp. There are Flo-checks above each circulator and I have CI Baseray on all 4 zones. Digital programable t-stats also.
Would an outdoor reset "install" require more plumping work in my case and would it help my system be more efficient?
Thanks Jim.0 -
some homeowner perspective
Greetings,
I installed a Honeywell outdoor reset controller on my 3 zone baseboard system last season and saw about a 10% reduction in gas usage. Jim, you should not need to change any pipes from what you have said so far. What you will find with outdoor reset is more consistent indoor temps, longer run times for the circulator with a greater temperature differential between burner on and off cycles. You will need to consider your return water temps to prevent condensation of flue gases and associated problems. All in all, I think controlling the boiler temps based on the prevailing conditions outside is a good idea. Lots of people here tend to agree.
With regard to setback with programmable t-stats, there has been a lot of discussion about the benefits. I have reduced my level of setback to only about 4 degrees and without any hard evidence, I tend to think that there is a diminishing return with larger setbacks. It seems to be about the energy needed to bring the mass of the stuff in the building up to the non-setback temp. Having cold furniture and floors and walls will make you less comfortable even if the air temp is up to the t-stat setting. (There are people much better qualified than myself here on the Wall that can offer a more reasoned discussion. I am merely a homeowner.)
Larry0 -
I can't help you there...
... haven't seen your system, and more importantly, am a mere homeowner myself. However, there are plenty of professionals you may be able to find by clicking on "find a professional" in your area. They'll be able to give you a great perspective on what the low-hanging fruit are in your particular house.0 -
Reset and Setback
Another homeowner here. I had a new boiler installed on a gravity hot water system a few years back. The contractor sold me outdoor reset and a setback thermostat. In practice, the two did not work well together. The reset kept the water temps too low to recover from setback. If I turned up the setting on the reset the burner ended up being controlled primarily by the t-stat so why bother with reset?
The current experiment is a two stage thermostat where the second stage bypasses the reset. Eliminates reset during recovery only (or other higher than usual heat needs, like a really cold windy day.). Have been tracking efficiency by degree day since before new boiler install. This will be the first heating season on the two stage setup.
Brian Macdonald0 -
Set set and Reback, I mean Setback and Set re,,,,,,,,no
Setback and Reset.
First, Reset. I have never met a system that wouldn't or didn't benefit from outdoor reset. It provides a marked increase in system efficiency. Viessmann says 1% increase in system efficiency for every 3* less than 140 boiler temp and I would have to agree. It has to be done with boiler protection in mind for non condensing type boilers. (Except the Vitola) Installing a new system without it is not an option IMHO.
Setback is debatable in my book. It obviously doesn't work well in tandem with a reset system that is tuned right down to the last degree of excess water temp. Setback on a high mass system,(slab,gyp,standing iron) should be done with care as the flywheel effect can really mess you up. I had one customer with a slab install who insisted on using it. He wound up scrapping it after it got to the point where he was running his heat on at night and off during the day when the building was occupied. Also bear in mind that the lowest temps are at night which causes the system temp to ramp up anyhow.
Long story(s) short. I have seen little benefit with setback and a lot with reset. Especially if you have a boiler that can take full advantage of the low temps.0 -
Hey Scott,
I have been trying to e-mail you re: my cousin. However, my e-mails get bounced back with the reply that your e-mail account is over its quota. Can you mail me when you're account is happy again?0 -
Interesting setup! That's a problem I've long suggested could happen with a really tight curve--particularly with an old standing iron system. Without some "headroom" your recovery from setback will be extremely delayed.
Another thing to experiment with will be the level of setback. IMHO you should get two calls for heat at the REDUCED (setback) temperature to truly save energy. If there is no call for heat during setback, use less setback. If only one call, I'd still reduce setback a bit...
It's all about maintenance and mean radiant temperature. The better your insulation and the less your infiltration the less daily setback you want to use.0 -
If you are trying to do setback and reset, you need indoor feedback as well. your alternative setup may work, but this is funky way to do something tekmars can do already. they use outdoor reset and indoor feedback together to raise or lower system water temperatures based on both heat load and actual performance in the room. that is it's minimized whenever possible, but raised if it's not keeping up.
To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"0 -
If you are doing a small room, it may not be worth adding reset controls. You could use a tekmar thermostat (51* series) which instead of real reset modulates the zone by cycling the zone pump on and off as it gets closer to its target room setpoint. Kind of a poor man's indoor feedback.
the larger the system, the more important reset becomes and the faster it can pay itself back. we use it on all but the smallest heat loads.
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Jim, the SR504-EXP accepts an outdoor reset "Add on power control" model #PC700. It plugs right into the SR504-EXP and accepts an outdoor sensor as well as a boiler sensor.
I'm fairly certain it's not as sophisticated as the Tekmar curve, but it looks like it'd be a real easy add-on for your setup. Just be certain you do in fact have the 'EXP' model.
http://www.taco-hvac.com/uploads/Product_Install/7.pdf0 -
a bit of a misconception here
Brian,
You say "If I turned up the setting on the reset the burner ended up being controlled primarily by the t-stat so why bother with reset?"
This is a common misunderstanding about outdoor reset. Outdoor reset is not for controlling the temperature in a room, it is for optimizing the boiler/heating system for improved efficiency and comfort. So if you want improved efficiency and comfort, reset will almost always make sense.
You found out one problem with a reset curve too tight (low,) poor recovery. Another can be a situation where a poorly sealed house will not heat on a windy day.
IMO, the temperature on the outdoor reset curve should be high enough that the primary controls (thermostats/TRVs) can easily go 20% over the target demand. This guarantees that the primary control has the autority to make changes to cover a higher than expected demand, adding maybe 10-20% more if you're doing setback.
Now there is another subtler question here. If you have both reset and setback, what combination saves more money and provide the most comfort? Without a detailed examination, I would bet on a tigher reset curve and less setback.
jerry
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Second that Motion!
>>If you have both reset and setback, what combination saves more money and provide the most comfort? Without a detailed examination, I would bet on a tigher reset curve and less setback.
WELL SAID!0 -
pc 700 reset control
Thanks for the info Bucky. Do you know how the boiler sensor on the pc 700 reset control is hooked up? Is it something that attaches to the outside of the supply pipe of the boiler or does it need direct contact with the water which would involve plumbing work. thanks Jim
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his statement was correct
> You say "If I turned up the setting on
> the reset the burner ended up being controlled
> primarily by the t-stat so why bother with
> reset?"
>
> This is a common misunderstanding
> about outdoor reset. Outdoor reset is not for
> controlling the temperature in a room, it is for
> optimizing the boiler/heating system for improved
> efficiency and comfort.
I think he understood more than you think. Read the statement you quoted. If you turn the reset setting UP, then the boiler will get turned off by the thermostat BEFORE it gets to the reset setting, because the room will get hot. The water will only get as hot as is necessary to heat the house, but it will not reach the reset temperature. So a reset controller is unnecessary. Controlling the water temperature in this way, with the tstat, is called "poor man's reset".0 -
Exactly!
Exactly, Jim. However, after three years of comparing gas consumption (in CCF) to Degree Days, I would also agree with Jerry that reset is preferable, particularly on a high mass system such as mine. I was (am) curious to see if I could utilize both setback and reset effectivly.
Also, it is all about comfort. I like to sleep at night at a little cooler temperature than my wife likes in the day.
Enjoying the thread and the forum.
Brian Macdonald0 -
It's a tape-on to the boiler supply pipe.0 -
> > You say "If I turned up the setting on
> _BR_ > the reset the burner ended up being
> controlled _BR_ > primarily by the t-stat so
> why bother with _BR_ > reset?"_BR_ >
> _BR_ > This is a common misunderstanding
> _BR_ > about outdoor reset. Outdoor reset is
> not for _BR_ > controlling the temperature in
> a room, it is for _BR_ > optimizing the
> boiler/heating system for improved _BR_ >
> efficiency and comfort._BR_
>
> I think he
> understood more than you think. Read the
> statement you quoted. If you turn the reset
> setting UP, then the boiler will get turned off
> by the thermostat BEFORE it gets to the reset
> setting, because the room will get hot. The water
> will only get as hot as is necessary to heat the
> house, but it will not reach the reset
> temperature. So a reset controller is
> unnecessary. Controlling the water temperature
> in this way, with the tstat, is called "poor
> man's reset".
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> > You say "If I turned up the setting on
> _BR_ > the reset the burner ended up being
> controlled _BR_ > primarily by the t-stat so
> why bother with _BR_ > reset?"_BR_ >
> _BR_ > This is a common misunderstanding
> _BR_ > about outdoor reset. Outdoor reset is
> not for _BR_ > controlling the temperature in
> a room, it is for _BR_ > optimizing the
> boiler/heating system for improved _BR_ >
> efficiency and comfort._BR_
>
> I think he
> understood more than you think. Read the
> statement you quoted. If you turn the reset
> setting UP, then the boiler will get turned off
> by the thermostat BEFORE it gets to the reset
> setting, because the room will get hot. The water
> will only get as hot as is necessary to heat the
> house, but it will not reach the reset
> temperature. So a reset controller is
> unnecessary. Controlling the water temperature
> in this way, with the tstat, is called "poor
> man's reset".
0
This discussion has been closed.
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