reset control

C.M.

I have to install reset control on two hydronic boilers,not sure if I should reset the boilers or the main loop.Loking for some response on the adventage and desadventages on both methods and whats the reight way to do-it.Thank you.

Brad White_185

Assuming these are on the same system

and depending on what type of boiler they are (conventional or condensing), I would start with the boiler especially if it is condensing and most of all, modulating. Either way, if the boiler is fired to it's maximum efficiency, the system will follow.

If there are two boilers, firing them in parallel while injecting into the common loop would be my first choice. (Fire them in series and the one that may not be running becomes a reverse heat exchanger to an extent.)

There are staging controls (Tekmar among them and similar ones by Taco) which monitor the main loop and in doing so set up the timing between stages, the temperature difference before firing subsequent stages, maybe even get you your horoscope if you are good.

If the boilers are conventional (non-condensing) a definite primary-secondary arrangement will be advisable with a distinct boiler loop and monitoring of the return water temperature to each. When HWR temperature drops, supply water is bypassed to protect it. The remainder is injected into the radiation loop for control and tracking outdoor temperature requirements.