Zoning a hot water radiator system

[balboni]

I would like to zone my basement hot water radiators separately from the rest of the house since it doesn't seem to get warm enough there before the thermostat upstairs turns the system off. I would like to install a zone valve that controls the water to the upstairs. I would also install a thermostat downstairs. I have a Honeywell Aquastat relay type L8148A on the system (hooked up to the upstairs thermostat). I believe I need to wire the upstairs thermostat to the zone valve and then to the Aquastat and that I need to wire the downstairs theromostat to the Aquastat as well. Is this the proper way to wire the system? Can you wire to thermostats to the same screws on the Aquastat?

[Edwin Pawlowski]

Zoning is more that just adding thermostats. The loops in the system must be independent. You also need either a single circulator and two zone valves, or you need two independent circulators, one on each zone.

What you really need is a good book on hydronic heating systems.

[m Ransley]

Have you thought about just adding more radiators in the basement, a cheaper and easier solution then another pump and the controls. Opening up old pipes to make a zone may have bad suprises

[balboni]

The upstairs loop is independent of the basement loop. Unfortunatley, there is no good place to put a zone valve on the downstairs loop without redoing a lot of the plumbing. (All of the plumbing is less than 3 years old, but the downstairs was done afterwards by a contractor finishing the basement, and they did not do a very tidy plumbing job). But there is a good spot to put the zone valve on the upstairs loop. There are two scenarios that I want the circulator on:

1. Upstairs and downstairs need heat so the upstairs zone valve is open and the circulator is on.
2. Only downstairs needs heat (it's always cooler in the basement and we use it very much, so we would never just want the upstairs heated) so the upstairs zone valve is closed and the circulator is on.

The third scenario is the circulator is off.

So can I hook two thermostats up to the Aquastat? If my understanding of a thermostat is correct, all it does is close a circuit, so it would be like hooking up two regular light switches to the same light.

[Edwin Pawlowski]

Sure, but I doubt it is going to turn the heat on. The aquastat will control the water temperature by turning the burner off and on. You have to activate the circulator. See my note about getting a book.

[RBM]

If you have a triple aquastat on the boiler, it will maintain temperature in the boiler. You need to separate the two zones, as Ed said, by either two circulators, or one circulator and two zone valves. Zone valves would be easier as you don't have to add switching relays. Each thermostat controls its respective zone valve and each zone valve has an end line switch that turns on the boiler by connecting to the "tt" on the aquastat relay that you currently have