Outdoor Reset With Hydrolevel 3250 Target Temperature question

bsimms89

I just had a new Weil Mclain Ultra Oil Series 3 boiler installed in my house and it comes with the hydrolevel 3250 installed from the factory. It was installed by a commercial plumber we use who isn't the best with setting the controls. I am currently looking to add the outdoor reset and warm weather shutdown function to it to save oil and improve the comfort in the house by allowing the circulators to run longer at lower temps instead of at the high limit even in the spring and fall.

Currently the boiler is setup with the high at 180 and the low at 140, but it is a triple pass cast iron boiler and my house is all copper tube baseboard heat. I read in the 3250 manual and the one for it's outdoor reset sensor to set the low to off to activate the warm weather shutdown, but my concern is when using the outdoor reset with the low set to off what would be the lowest target temperature that the aquastat would call for when there is a call for heat? I wouldn't want the target temperature to be too low to the point that it caused condensation.

I cannot find anything in the hydrolevel 3250 manual or the manual for it's outdoor sensor that says what the lowest target temperature would be. I don't think I'd want the target temp to be lower than 145, but with the low limit off to activate the warm weather shutdown I see no way to set a minimum target temp. I even tried emailing hydrolevel a week ago to ask them and I've gotten no response.

Can anyone tell me what the lowest target temp for this aquastat is when using the outdoor reset?

STEVEusaPA

Forget the outdoor reset for oil, unless you have a buffer tank.
Make sure you boiler is piped to protect itself from low return water temperature.
Utilize circulator hold off.
Utilize economy feature.
Hopefully your boiler isn't oversized too much.

bsimms89

I am currently using the economy feature, and circulator hold off and it is piped that way, but wouldn't the outdoor reset make more sense?

Also I am just trying to figure out what the lowest target temperature is when the outdoor reset is used? Also what is the lower target temperature when the economy feature is used?

Jamie Hall

I think you may have missed something @STEVEusaPA just said, or at least the implication of it: you need to make sure that the water coming into the boiler is always above 140, except for startup. If you have a mixing valve controlled by the outdoor reset, and a buffer tank, the outdoor reset isn't going to help at all.

STEVEusaPA

I don't think I missed anything.
Trying to hold the boiler at a minimum 140° and use outdoor reset?
The boiler will target lower temperatures most of the winter and the boiler without a buffer will short cycle 80% of the time. And that's if it isn't massively oversized, otherwise it'll be worse.

With a buffer, off the top of my head, I would use min 120°, probably a 40° delta T. I'd use injection mixing off the buffer to the zones. Then you could use odr to control the injection circ and temperatures out to the emitters. The boiler only knows when the buffer needs to be recharged, the odr controls temperature to the emitters. The boiler never condenses.
But it's copper fin baseboard so you can only go so low anyway.

Jamie Hall

I didn't say you missed it, @STEVEusaPA -- the OP missed the implication.

STEVEusaPA

Jamie Hall said:

I didn't say you missed it, @STEVEusaPA -- the OP missed the implication.

I have to stop reading this on my phone, lol