Gas and Oil Home Heating Furnaces - Parallel themorstats

On an Smith oil furnace circulated water heating system is there any reason I cannot hook up parallel thermostats on the same heating circuit? I realize efficiency and uneven heating will suffer however, for this heating season it would solve a problem.

This sound like you have two thermostats and you want the home to controlled by one thermostat. Is that correct?

No. I want to hook up two thermostats to one heating circuit. Therefore the pump will be turned on if either of the parallel thermostat circuits are closed. My heating repairman (a high school buddy) says no you can't. I'm a mechanical engineer (a drawback I know) and I can't understand why. Since the thermostat wiring is simply an open or closed circuit a second parallel thermostat is no different than puttin a jumper across to closed the circuit.

If you have only 1 zone(1 circulator or 1 zone valve)1 tstat will heat area.Need more info.Is this an apartment complex?or was building added onto?More input please!!Can probably be done with DPDT relays.PDF

Hello: walshmp53

The critical point in your question is solving a problem.
The question is what problem????

Having two thermostats connected to any single heating unit will not work under any conditions. One T-Stat would just be countering the other.

It would be like having two independently operated accelerators in the same car. One on the drivers side as normal and one for the passenger. Unless both were at the same setting, the engine would not know at what speed to run at. Get the point here?

Therefore, you'll have to explain in detail exactly what the problem is your attempting to overcome.

If you want to operate one heater from another location from where the existing thermostat is currently located, you'll have to relocate it by adding more wiring to the new location, not add another thermostat.

Thank You all for your input. This is an incredible opportunity for professional dialogue.
I apologise for not clearly stating the problem. I have a small apartment in a house that is on the same heating zone as two rooms in the main part of the house. A second heating system is planned in the future for the apartment on its own, however until then I want to give independant thermostatic control for the same zone for both the apartment and the two rooms below.
I understand your anology of two accelerators on one carberator. If any or both of the two thermostats signal for heat both the apartment and the two rooms will be heated. If both are satisfied then no heating occurs. This can result in an uneconomical overheating operation I agree, however is there a technical reason why this wouldn't work or would it cause signal equipment damage of some sort?
The Thermostats are simply a closed switch with no feedback signal that could somehow damage the relay or the other thermostat is that correct?
Again thanks for your time and attention in this matter.

walshmp53:
The problem you will have connecting two low voltage thermostats in parallel is with the anticipator circuits. Low voltage stats have a very fine heating element inside them to stabilize the control operation. This element tricks the sensing element into bringing on the heat sooner, to allow for more even room temps. The impedance is adjustable so that the thermostat can be matched to different heating systems. If two low voltage thermostats were connected in parallel, this anticipator system would be messed up, causing eratic control. This would create more problems than you may have now. I don't have a catalogue handy to gve you some examples, but there are electronic controls available that use a remote sensors and can be set to control one device from an average reading of several sensors.
They are nice.......but expensive.

Thanks for your input. I'll leave it at one thermostat and concentrate on the second furnance. I really appreciate your help.

Ok with the themorstats what ur trying to do is be able to turn on or off one hvac unit fron two places in your home. If thats not what your are trying to do let me know. I'm going to tell you thaT this can be done. This is not unhurd of .I have done this befor. But you can't do it with two themorstats and thats it. What you need are things called relays inorder to do it. If you think about it what your really trying to do is hook up two 3 way themorstats .I dont think your going to beable to find that i don think there is a such things as 3 way themorstats.And if there isnt im telling you it can be done with a relay. Ill be more then happy to show you how But i need you to tell me what its is your relly trying to do....
thank you joe

to heat other area is a seperate circ. pump.You said you have forced hot water.Install a manifold,2nd circ. pump,cut piping to other area and repipe for a seperate 2nd loop with its own tstat.PDF