Moved into a house with a Weil McLain CGS-4 boiler with baseboard radiators and an indirect DHW. The house has 3 "zones" plus the DHW. The boiler does not have an outdoor reset. The problem is that the zones are just 3/4 ball valves next to the boiler and no actual electric zone valves controlled by a stat or controller, just 1 stat plus the DHW aquastat. I want to make this into a true 4 zones system by adding Taco Sentry zone valves on all 4 zones and control it by a Taco controller with priority for the DHW (model ZVC406-EXP-4). I usually heat with an indoor wood stove and we do not occupy the upstairs except for 1 bedroom, which is directly above the wood stove room and staircase so it gets plenty of hot air so we have the upstairs manual zone valve always off and keep a space heater in that room for when the stove runs low on wood. In the future, I would like to zone that bedroom separately as this is the nursery and I do not want the space heater in there. For now I would like to have the boiler zoned to heat the areas of the house that the wood stove does not reach, which it is already manually zoned that way so adding the zone controller, electric zone valves and stats should help out tremendously. My concern is that if I do not send hot water upstairs, the pipes feeding the baseboards might freeze when it gets in the single digits outside. All of the baseboards are on outside walls. I do not want to have the upstairs stat set to turn on once or twice a night for the upstairs zone because if it is not in the single digits outside, I don't want to waste the propane sending heat up to rooms we do not occupy. As long as the wood stove is running, the temps in the unoccupied upstairs rooms is in the 50s. Is there a way to get a little warm water into zones that have not had that stat call for heat overnight when it is in the single digits outside? Or am I overthinking this? The closest thing I can find is a device that hooks to the thermostat and turns it on once or twice a night but this will do that every night, not just when it is very cold outside. Plumbing a small bypass line around the zone valve has been suggested, but again, this will also send warm water up there when it is not that cold outside and I do not want to have to turn this on and off all the time plus it relies on the boiler getting cycles on by something at night, which it probably would by the zone stat farthest from the wood stove. I was just thinking that there was maybe a product or solution made for this problem. Thanks for any input or telling me I am overthinking this.



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there are many brands of non-toxic antifreeze that are designed for hot water heating systems.
your boiler is pretty small and your system has all 3/4 piping so you shouldn't need more than 3.5 to 4 gallons added to your pipes. you want a minimum 30% and a max of 50%. you are not protecting against below zero temperatures.
it is a pretty simple procedure and i joke with customers that it takes longer to bring in the buckets and the pump and hook them up than it does to pump the antifreeze into the system.
hercules cryotec is one brand readily available..
[www.oatey.com]

I think I'd use a $25 programmable thermostat.

paul, the problem is the primary source of heat is his wood stove.
i would feel better about 50 bucks worth of antifreeze and an hours labor to pump it in.
then his heating system is protected against freezing even if the power goes off.

Thanks for the comments so far guys. As I zone them, I would definitely add programmable stats. My last house had one that I could monitor and control from my phone, even when away from the house. I miss that techy feature and that the app records and shows you when it has a call in for heat so I could track just how long it (they) were calling or the boiler running at night which would help me determine an overnight set temp.

Antifreeze: I have heard that it reduces the heat transfer in the boiler and at the registers. Is this reduction not significant or that the pro (not frozen pipes) beats the con (reduced efficiency)? If i went this route, is is beneficial to drain and flush and refill with just water it in the spring and put antifreeze back in in the fall? I don't mind the work.

Thanks guys

the difference is approx 10% in heat output if you use a 50% mixture..
if you stay down around 30% it is less..
as for draining and refilling.. NO...
just check the PH every year.

Why is it not S.O.P. for contractors to put it in every new install then?