Would someone explain outdoor reset?

Jamie_6

I have put in many Wirsbo promix's which have outdoor reset and I understand how they work! The problem is, I do not understand how you put outdoor reset on a normal hot-water system. Do you just reset the main house and keep that on constant circ? Then let the boiler and primary loop just operate off of the 180 degrees when ever the main house calls off of a primary loop??????????????

Jamie

Dana

The reset controller has an outdoor sensor and a supply main sensor. You wire the reset controller in so it controls, (resets), the main temp. coming from the boiler based on its curve setting and the outdoor temp. When theres a call for heat the boiler operates to the temp. the controler and its curve is set for. The boiler aquastat becomes a high limit, your actually controlling supply temp. with the strap on sensor on the upply main. Tekmars work nice. Make sure your minimum temp. is set correctly based on the boiler and equipment.

Aidan (UK)

outdoor reset

You can re-set the boiler flow temperature, or install a mixing device and re-set the reduced flow temperature from it.

See;

http://www.pmengineer.com/pme/cda/articleinformation/features/bnp__features__item/0,2732,21624,00.html

for a detailed description. Also try searching the archives at PM Engineer for other Siegenthaller articles on other aspects of outdoor re-set.

Mark J Strawcutter

It depends

I always wanted to say that :-)

In it's simplest form with the boiler and system on the same pumping loop, the reset controller just changes the high limit based on OAT.

With P/S pumping, boiler on primary loop system on secondary you can use a conventional boiler control on the primary. Run the secondary constant circ (subject to warm weather shutdown) with it's temp monitored and controlled by the reset controller. The "burner" contacts of the reset controller are connected to the "thermostat" contacts of the boiler control so the reset controller can call for heat.

There are many, many variations. Room thermostat connected to reset controller instead of constant circ. System on primary, boiler on secondary. And so on.

Mark

jack_4

More Basic question

What is an outdoor reset? What is the concept? or What does it do?

[Deleted User]

It is variable water temperature in a heating system

Check this page, and on the left, it says click here.

http://www.tekmarcontrols.com/cspages/csmain.html

Good explanation in there.

Noel

jack_4

Oh

So if I understand it correctly, they are only used on hot water systems and never steam, as steam will not be developed at say, 150 degrees.

Yet in a hot water system, the water is warmed to some delta above the outside temp to keep heat cost down.

Correct?

BTW I looked off the Wall and what I found did not help.

[Deleted User]

Correct

And here's a curve for you.....


You CAN do it with steam, too. Check this system out, from decades ago, and still used.

http://www.mepcollc.com/VV.htm#mepco2

Noel

Terry

cruise control

think of outdoor reset like cruise control in your car & doing the speed limit is like matching the btu load of the space with the output of the system.

you need x amount of throttle to roll down the road. the inclination of the road is the outdoor temp (uphill = getting colder, downhill = getting warmer).

as the road starts going uphill, the reset control (cruise control) will increase boiler temp to compensate for higher load. vice versa for going down hill.

If more btu'sd required, more btus are delivered. & Bob's your Uncle.

Regards,
Terry

Caselli

Bob's your uncle ??

I could tell what this saying meant, but looked it up :
(I'm quoting from somewhere; I wish I had kept the reference to give them credit.)

"Bob's your uncle" is a way of saying "you're all set" or "you've got it made." It's a catch phrase dating back to 1887, when British Prime Minister Robert Cecil (a.k.a. Lord Salisbury) decided to appoint a certain Arthur Balfour to the prestigious and sensitive post of Chief Secretary for Ireland. Not lost on the British public was the fact that Lord Salisbury just happened to be better known to Arthur Balfour as "Uncle Bob." In the resulting furor over what was seen as an act of blatant nepotism, "Bob's your uncle" became a popular sarcastic comment applied to any situation where the outcome was preordained by favoritism. As the scandal faded in public memory, the phrase lost its edge and became just a synonym for "no problem."

Chris Maderia

Used the ProMix

quite a few times. You will need to pipe in a boiler by-pass if your using a standard boiler for starters. I have attached a piping diagram to give you an idea on the piping. You will need to add the by-pass though.

Jamie_6

So it would be possible to run the main house on costant circ. w/ outdoor reset? BUT, how do you protect the space from over heating?

Jamie

[Deleted User]

You only add heat when needed

The water in the loop circulates constantly, and only enough heat is added to maintain the temperature. That makes for a really comfortable, quiet system.

Noel

Jamie_6

What type of "products" do you use to do this? A three way valve or some kind of injection control?

Jamie

Unknown

both work well

it depends on the application.

Look at tekmar.com for both.

Noel

Bill NTSG

Jamie

I think you are over complicating this. Constant circulation or "near constant" is just as good. You can zone the house with T-stats or thermostatic radiator valves. You only need one zone or even one large radiatior to "run wild" so you have constant movement past the supply sensor. A pressure differential valve would work too. Also you could have indoor sensors, Viessmann and I am quite sure tekmar have indoor sensors that turn the curve back if the house is overheating. I have a viessmann and a trimatic [their od rest control] in my house in it's third yr of operation and I have not hooked up the indoor sensor yet. I have no t-stat for the system and the house has only overheated once or twice. 74°-76° or so because of extreme od temp change or if my wife uses the oven. I like constant circ. the best but like I said using a thermostat is not the worst thing you can do. The first job I ever did was a 200 yr old farm house with CI rads. My brother and I put TRV's on all but two radiators. I used a simple tekmar control. I could hardly believe how simple the wiring was. It was all low voltage. Outdoor sensor, indoor sensor,a supply sensor and a wire to tt on the boiler. Took less than an hour to wire and the house was never more comfortable .