Low-tech ways to adjust outdoor temp sensor based on wind

sreja

we have a steam boiler that heats a large building, and i've been thinking about the problem where wind has a

HUGE effect on the heat needs on any given day -- and the fact that the

outdoor temperature sensor doesn't reflect this.







it got me thinking about possible low-tech solutions..







can't we set up the "outdoor" sensor in a way that it mirrors the cooling effect of wind, at least in a gross way?







for example, if we have the sensor in an indoor unheated area like a

garage where wind infiltration could affect temperature.. or something

like that..







or maybe someone else can come up with a clever way to trick an outdoor sensor to read lower in high winds?



any thoughts?

Big Ed_4

North West

You seem to have problems with your sensor ? The sensor should be located in the North-West outside location and high enough to avoid obstructions to sense the winter whether ... And not above and high heat loss locations like windows ....

sreja

outdoor temp vs wind

Sorry if i wasn't being clear.



What I'm suggesting is that when it comes to regulating the heating boiler, knowing the TRUE outdoor temperature is much less useful in a building like ours where there is so much wind infiltration.



And that what would be more useful would be to come up with a clever way to use an outdoor temperature sensor such that it read a lower value when there was high wind.

landmobile

The idea of sheltering the sensor

is good, but an unheated garage would only work if there was sufficient heat infiltration from the heated portion of the building into the garage to raise it's temperature slightly.  Then there would be some reduction in temperature on windy days (assuming the garage was drafty) to produce a change that the sensor could 'see" based on the wind. 



If the garage doesn't meet these requirements you might be able to build a small semi-permiable shelter around the sensor and install it in a place that receives a small amount of heat from inside the building, such as near a louver.  It would then read a little high on normal days, but would drop down to the actual outdoor temperature in the wind.



If the sensor is electronic, it might be possible to defeat by installing a switch that is activated when the wind blows above a certain level for a period of time.  This could be accomplished with a wind vane or anemometer and a few components, but it would require a little engineering and knowledge of how the boiler's control circuit is designed.  Of course, that isn't very low tech, is it

sreja

semiheated sensor room.

landmobile thanks for the great reply.



here's my new plan -- there is a tiny room with a window on the ground floor (it's an unused bathroom), that has a radiator.



my plan is to put the indoor sensor in that room and set the radiator to heat the room a little bit.



normally we keep the window in that room completely covered with insulation but my plan is to remove some of the insulation to in effect allow heatloss in that room through the window, in a manner similar to heat loss in the normal units.



so if all goes as plans, that tiny room should in effect be a microcosm reflection of the average unit in the building which is receiving heat. on high wind days it should lose more heat through the window than on low wind days, and it should reflect the building wall heat retention and loss.



any thoughts?

landmobile

It sounds like that would work

Since your goal is to reduce the temperature "seen" by the sensor on windy days, you need an environment that has a slight supply of heat which is removed by the wind.   Your prospective room has a radiator, so you can control the amount of heat the room receives, and by adjusting the window insulation you can contol the effect of the wind. It might take a little time to tweak it just right but it sounds good. 

Keep in mind that if the window to receives a lot of solar radiation it might throw things off, so a Northern exposure would probably be best.

sreja

re: Low-tech ways to adjust outdoor temp sensor based on wind

sounds like we are on the same page and thinking alike -- hopefully the weather will stay cold for a couple more weeks so i can test the theory, otherwise it will have to wait until next season.  thanks for the feedback.

Techman

Wind and Sensor

I was not aware that a steam boiler operated off of an outdoor sensor as some hot water systems do.And I was not aware that an outdoor sensor was sensitive to wind chill,like humans.

Randy Baerg

alternate method of solving heat loss from wind.

srega:

 I agree that the wind can have a huge effect on heat loss of a building re: your very first post - "i've been thinking about the problem where wind has a



HUGE effect on the heat needs on any given day -- and the fact that the



outdoor temperature sensor doesn't reflect this."



I guess you could try to use some wind factoring device to compensate but another easier way I think would be to look at the net result of the wind problem which is the underheating inside the building.

If your Outdoor Reset steam control has the option for adding an' Indoor Sensor'  then any underheating in the building caused by the wind would be addressed by the 'Indoor Feedback' shifting the outdoor reset curve higher. This should solve the problem of extra heat loss due to wind.

sreja

incorporating wind affect on heat loss

Randy,



This is exactly what I am now doing -- I've set up an indoor sensor near a "leaky" window in a very small heated room.



So the indoor sensor used by the boiler controller (tekmar 279) now "feels" the heat loss due to wind quite severely.



I think this should do the job.

michael_43

Some thoughts

The only way OD reset works on steam or hot water heating systems is with a combination of an OD sensor located on the north side of the building, supply/return sensors and space averaging sensors. The industry standard calls for approximately 10% of the the apts in an apartment building. A building will under heat on a cold windy day and overheat on a sunny day due to the passive solar gain.

MaMa

Northwest for ODR sensor?

I know this is a few months old now, but curious why you recommend northwest as sensor mounting location.  Looking at installing a Logamatic 2107, and they suggest north/northeast:



http://www.buderus.us/files/201006231702550.Logamatic_2107_Controls_applications_manual_06%202010.pdf (p. 18)



Thanks, if you're still reading.

sreja

re: Low-tech ways to adjust outdoor temp sensor based on wind

After about a year in use i can report that this technique is working quite well for us, and i think significantly better than if the sensor was actually in a lived-in unit.



Essentially, i have the sensor set up in a room that receives some heat, but also suffers from some wind-dependent heatloss because the sensor is near a single paned window.



The result is that the sensor does a good job of reflecting the different amounts of heat loss that is suffered on a very windy day.

lchmb

alway's

follow manufacturer recommendations.

ecletrical

changing the resistance of the sensor

Since most (??) sensors used for outdoor reset have the resistance inversely proportional to the temp - temp drops and resistance goes up. Then a simple potentiometer, hooked to a vertical hanging wind paddle. wired in series with the outdoor sensor should increase the resistance when the wind blows - effectively lowering the temp the sensor reads.

njwebdevguy

Arduino, anerometer, or moisture

You could stick the sensor on an arduino, ( http://arduino.cc ) or similar microprocessor along with an anerometer and have a lookup table that mapped the two input values to an output value.



Alternatively, if your temps dont go below freezing you could simply allow the wind to strike a wick/temp sensor combination.. The wick could keep the temp sensor wet.. I think its called "wet bulb temperature"...

then measure the wet bulb temperature - wind + water = evaporation which lowers temp..



Google "wind chill" AND arduino, or "wet bulb"

I am sure lots of people have already done this one way or another..