outdoor reset control

[Deleted User]

Which reset ratio (1:1, 1:1 1/2 or 1 1/2:1) do you recommend installing to control a system in the New York City area and how is it determined? (Building heat loss, system design such as baseboard as opposed to CI Rads, or other factors.

hr

Two ways

A heat loss calc would tell you the supply temperature you need at design day. The control could be set based on the numbers.

Often the installation manual will have recommended start point settings.

Or start with a low reset and adjust, if necessary, when the weather hits it's coldest swing.

Your building and personal comfort level will tell you as temperatures drop Ideally on the coldest day, heat the space with the lowest supply temperature for best fuel use efficiency.

hot rod

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ken wickre

Heating Curve Equation

Heating curve equation is:
HC = (DWT - WWSD)/(WWSD - OAT);
Where: DWT = Design water temp on coldest day;
WWSD = warm weather shut down (usually same as design indoor air - 70 deg F perhaps);

OAT = Design outside air temp on coldest day

Because different terminal units require different design temps, the equation accounts for any terminal unit - fintube, cast iron, radiant slab, etc. - when you plug in the required design water temp.

[Deleted User]

I put outdoor reset controls on my boiler in the past and like the results. Very even temptures but, the pay back is having the circulator pump run almost non-stop. I have a B&G Series 100 installed and it does well. But, the utility rate in this area has increased almost 50% in the last 2 years. Should I think about putting in a differant pump to save on the electric cost, and if so, which one would you recommend to do the same job?