outdoor reset help...

Timco

So I have a p/s setup with a crown CI boiler. I want to add outdoor reset, but do not have a 4-wy mixing valve piped in. What are my options? I was told the tekmar 260 will not 'govorn' the aquastat, but wants to control a 4-wy mix valve or injection setup. Any opinions are very appreciated. We get 40* to 0* days here all winter long so I would think an outdoor reset would save a bit of $$. Thanks a bunch!

Tim

Uni R_2

Reset

In really simple terms it should just intercept the t-stat signal that would normally go to the burner. If it gets to the reset point it will shut off the boiler and/or if the t-stat gets satisfied it shuts off the boiler.

Timco

Shouldn't the t-stat have ultimate say? If I want it 71* inside, I don't want the outdoor reset telling the boiler to only go to 69* on a warm day...I just want to use cooler water to get to 71*. Looks like I need to accompish this with a mororized mixing valve? No other way?

Thanks again, Tim

Dave_4

Depends...

If the reset is too low, the house will never catch up heatwise, so that t-stat will never be satisfied, however that would also mean that you need to raise that setting. You want the lowest setting possible that allows normal recovery from your typical day to day activities (minor set-back, doors opening and closing). You set it to a number that will work. Once you dial it in, you leave it alone for all temps. Have you priced a motorized mixing valve?

Timco

I have not priced a 11/4 motorized valve, but I am SURE it is pricey, and I am already piped. If this is the only way, I will research it and give the cust a quote, but I would like to control the water temp without the extra piping...and cost.

Tim

Bob Sweet

The 260

is a nice and simple ODR control that can do what your looking for.

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Dave_4

No changes needed

You don't need any piping changes to use it.

Mark Wolff_2

Tekmar 260

The 260 can be wired several different ways. Based on your requirements, you could wire the 260 into the TT connections on your triple aquastat, wire the circ pump to the 260 and wire the thermostat to the 260. Any time the thermostat calls for heat, the 260 will turn the circ pump on. When the boiler temp falls below what the 260 has calculated as the required temperature based upon outdoor reset, the 260 will make a heat demand. With the triple aquastat high and low limits set above the design high limit (say 210* and 220*) the boiler will fire. When the temp of the boiler reaches the calculated temp (plus a few degrees) it will remove the heat demand to the TT's, thus shutting the burner off, while leaving the circ pump on. This gives you the cooler water to reach your desired temp. without truly overriding the t-stat.

Timco

Mark,

Thanks a million, that is exactly what I was looking for. I thought that was the solution, but my supplier who shall remain nameless said 260 only controled 4-wy and injection, not boiler temp...Just wondering why soo high on the upper limits? (200*+) Does that ensure the system will be able to hit 180*?

Tim

Timco

Also,

Do my secondary circs (3) stay with the taco 4-zn controller, and just the pri circ goes with the 260?? Will the 260 allow full temp for DHW calls?

Tim

Unknown

Tim,,,,,,,,,

I looked-up the 260 and like Uni & Bob said, it will do what your looking for. And yes, it does provide for DHW priority. From what I see, you don`t need the mixing-valve to do this as it just controls the primary-pump and the burner.

Mark Wolff_2

high settings

I usually set my triple aquastat low and high limit above the design maximum I program into the Tekmar, so that any time the Tekmar determines additional heat is required, the burner will fire. If you don't do that, the Tekmar will show a call for heat and try to fire the burner but the triple aquastat will see boiler temp that is acceptable and interupt that command.

It makes the aquastat a relatively dumb control at that point, but then again, with a Tekmar in the system, who needs it to be smart?

Additionally, you are correct that the secondary circ pumps would remain tied to your Taco SR control, but the circ pump for the DHW tank would be tied into the 260. The 260 has a DHW priority option and does ramp the boiler to whatever you program for the DHW setpoint requirement.

Leo G_99

First off

What emitters are you using? infloor? convection? panel rads/ you get the picture....

Leo G

Timco

CI rads...converted gravity system.

Tim