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tim2255 01-03-2012 01:07 PM

Using Two Thermostats Question
I live in a one story house with a basement. The house is heated using a hot water boiler located in the basement. The house doesn't have AC. I recently installed a wood burring fireplace on the first story. The fireplace keeps the house nice and warm without having to use the boiler. However the basement is freezing and we still use the basement for the kids to play. I turned off all the zones I don't need and just left the basement zone on. The thermostat is located on the first floor. I want to install a thermostat in the basement to regulate the heat for the basement. However I want to leave the original thermostat on the first floor in case there is a problem with the fireplace, I run out of wood for the season or something else that will not allow me to use the fireplace. So basically I want to have two thermostats in the house. The upstairs would be left in the off position because that would not be used. Again I would still like it wired where I can just turn the zones back on and turn the thermostats back on and everything works. At that time I would just turn the basement one to the off position. So basically One thermostats would always be in the off position.

Is this something that can be done?
Is so, do I run a separate line to the furnace for the downstairs thermostats and a separate line for the upstairs thermostats (Tie them in at the boil)? Or do I just splice into the line that is all ready running to the upstairs and branch off for the down stairs thermostats.

Bondo 01-03-2012 01:12 PM


Is this something that can be done?
Ayuh,... It depends entirely on How yer zones are controlled, 'n how the boiler is wired up...

Yes, it can be done, But.......

tim2255 01-03-2012 01:32 PM

The boiler is a 1967 peerless. In regards to the zones, they are just valves on the return pipes. I have four loops that go througout the house. To shut down a zone, I manually turn the valve off. So currently three are shut off and one is open.

TarheelTerp 01-03-2012 02:13 PM

If it were me... I'd be looking into adding a relay to the "call for heat" wire.
So that the thermostat doesn't go directly to the boiler... it instead energizes the relay.
Then add ANOTHER thermostat (in the basement) that can also energize that relay.
(beware of backfeeding power)

You'll still have issues of the upstairs getting hot water pumped up there if there aren't solenoids on those lines. But if it were me... *that* would have been done twenty years ago.


beenthere 01-03-2012 04:03 PM

Ah, its not zoned then. Those are probably either balancing valve, or the shut off valves for a purge set up.

What you want to do can be done.

tim2255 01-03-2012 04:43 PM

Cool Thanks. So I can wire either method that I mentioned? Regarding the zone, is it bad to leave the valves off? I was told that if I want to control and not have hot water in a certain area of the house, I can turn off the valve which seems to be working. Just want to make sure I am not hurting the system by having a couple of the valves shut off.

beenthere 01-03-2012 04:52 PM

No real harm done. Just makes the boiler grossly over sized for just the basement zone.

1 pit fall though. is if you have a very cold night, it is possible for the water to freeze in the zones that are turned off. probably best to leave just a little flow go through. Not enough to heat those areas, but enough to make the baseboard elements warms.

tim2255 01-03-2012 08:51 PM

OK Thanks. So would it be better to run two seprate lines, one set of wires to each thermostat or can I just splice into the main thermostat and run one to the basement.

beenthere 01-03-2012 09:41 PM

Probably better separate. No worry about a bad connection from wire nuts in the middle of the wire run that way.

TarheelTerp 01-03-2012 10:13 PM


Originally Posted by tim2255 (Post 811722)
OK Thanks. So would it be better to run two seprate lines, one set of wires to each thermostat or can I just splice into the main thermostat and run one to the basement.

get a relay <---like that one

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