I have 2 boilers in my house. 1 is for the main house and the other one is for the annex which is built a few feet away from the main house. My 1st boiler is connected to Nest thermostat. Can I connect my 2nd boiler to the same Nest thermostat?
Use 1 Nest Thermostat with 2 boilers
boilernestthermostat
Related Solutions
Yes, it is easy to control a swamp cooler with any thermostat. The problem is that in order to use a swamp cooler effectively, you need strategic openings (typically open windows) to let the air out. This is the part which is hard to automate. The best way to use a swamp cooler is to open windows in the rooms that need the cooling the most. You want as much windowspace opened as possible without any outdoor air coming back in through the windows. There are some automated devices I've seen (such as UP-DUX that vent into the attic but they cause additional resistance so they are much less effective.
Your drawing has a couple of problems...
- You need to use the Rc terminal
- The coil on your R8222B1062 needs to connect to the Y2 and the C (not the R)
- I don't think you want to connect to the C terminal on the nest because your heating system is already providing the C to power the thermostat.
- I think you're right about this one but I wouldn't rely on the thermostat powering Y1 and Y2 simultaneously when it called for high. I would rather to design it so that if the Y1 is not powered but the Y2 was, it would still run on high. This gives you a little more redundancy in case of a relay or wire failure.
Below is a drawing that would fix these problems but it is much more generic, the only specific part is that Packard contact delay because I am unfamiliar with a generic part name for that. If you fix 1 - 3, your design should work flawlessly. Again, the exhaust ventilation is your biggest problem.
I would put a nice 24v DPDT relay and a nice 24v 3PDT relay on the appropriate mounting sockets and mount them to a DIN rail. This will make it easy and clean. Put it all in a box with the transformer and the Packard and voila.
I fixed it myself. In the manual (page 18) there is the following image.
As shown on the photo in the question:
From left to right: The red "bridge cable" is meant to close the circuit in order for the next two (bus +/-) to work. But the bus connectors only work with with an eBus system. Which is not compatible with the Nest Heatlink.
The two wires that are used to connect the boiler to the heat link (the left brown/blue wires) should be connected to the 4/3 connectors instead. So after removing the red bridge cable and connecting the heat link to 4/3 of the boiler, it worked fine.
Disclaimer for those with the same problem: I'm not a electrician, although I did check the solution with one. Try this at your own risk.
Best Answer
If the tstats get power from the boilers, the OP would have to be sure than only one of the boilers is supplying power to the Nest tstat. If the transformers were out of phase, you'd have a direct short. A dry contact relay for the 2nd boiler control would be safer, triggered by the call for heat on the first boiler.
But clearly the OP has 2 zones and 2 tstats are called for...best and safest approach. Like Freeman said, unless the heating performance and heat loss of the two spaces are identical, one space will be either over-heated or under-heated compared to the other.
BTW, what is currently controlling the 2nd boiler? A tstat in the outbuilding? An old fashioned manual one? If so, I really think the best solution would be to replace it. It doesn't need to be a super expensive Nest type...programmable tstats for heating only shouldn't cost much more that $50-$60. Probably the best and least expensive solution.