Control for Constant circulation.

jjheat

i just took over the servicing of 6 apartment buildings that all have constant circulation with honeywell zone valves in each apartment with individual thermostats wired to the zone valves. The only way the boilers and circulators are currently operating is by a manual switch(turned on as heat is needed) and high limit boiler control. What outdoor reset control would be the best option for this scenario?

STEVEusaPA

I this all one system, one boiler, one circulator, 6 zone valves? Or 6 separate systems utilizing constant circulation and zone valves.
What type of circulator do you currently have, Delta P or are you piped for a bypass?
What type of boiler and is it oil/gas/propane.
Any reset control will work with the following caveats:
You most likely need to protect the boiler from low return water temperature (unless its a mod/con)
You need either a bypass for the circulator or a delta p circulator, capable of handling when all 6 zones are calling or none are calling (none are calling can be handled with the boiler control).

jjheat

6 different buildings with the same system. Each building has 20 apartments each with individual zone valves and thermostats in each apartment feeding baseboard loop throughout the apartment with no end switch or thermostat operating the boiler or circulator. There is a bypass piped in at the end of the supply and return loops with no valves. The single circulator is a B&G 2" pump.

ratio

Sounds like all you need to do is to add outdoor reset & everything will just work. I use one of these on a boiler of mine, a five section Peerless 211A.