Old Home Heat Only Control

I am in the process of smarting up my home. It is over 100 yrs old which has caused some bumps. My current bump has to do primarily with my heating. I do not have a typical HVAC system. I have two mini-splits for AC purposes and I have steam heat (think big cast iron radiators) driven by a boiler. I would like to have a smart thermostat to control the heat this winter. However most of the ones I find seem more suitable for central air systems as they control both heat and AC. I have found several UK products which are designed for heat only systems (probably the abundance of older homes over there), but I am wary to buy something not supported in the US. I was wondering if anyone else has either had experience setting up one of the popular smart thermostats(ecobee, nest, etc.) for a heat only system, used one of the UK products here in the US, or have figured out any other solution for this type of issue. Thanks

Hi there @sablejack,
I have a 100 year old smart home with split thermostats for heat and AC. My heat is also steam with radiators.

First, the Nest and ecobee3 should work fine in theses types of setups. As long as they are wired correctly there should be no issues in just handling a heat only setup. One big consideration in older homes is the presence of a C wire, which theses smart thermostats need for power. My house did not have these at the wall.

I ended up going with CT 100 zwave thermostats and use ST for all of the programming and remote control. These are considerably cheaper and are highly reliable. They can also run on batteries without a C wire which let me avoid having to run wires through the walls. (Just need to change the batteries once a year).

Definitely not as smart as the others, but meets my needs. Hope that helps.

Yep, it’s doable. Our home has hydronic heated floors for heating. I installed Nest thermostats a few years ago and it manages the heat much better now as it has learned to turn off the heat before the set point without it going way over. Anyway, it was a little tricky getting the wiring sorted out. For out setup we have a relay module that manages all of the zones. It was critical to make sure the C (common) wire was connected to provide suitable power (24 VAC). Our Nest thermostats have worked flawlessly for years. If you only have two wires going to your thermostat, it gets more challenging. Depending on heat usage the power available on the wires it’s hit or miss if it works. In that case you may have to arrange to get 24 VAC to that thermostat for it to work right.

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I second the 2gig CT100. About the most versatile smart thermostat out there for attaching to an existing system. I started using mine directly on a millivolt system (gas stove) and later added the 24vdc and relay so the thermostat would be line powered rather than battery. I love the versatility the thermostat gives us over the old timer style.
If the outside door is open, it shuts off. If the lights are out and the bedroom door is closed, it turns down. If nobody is home, it turns down.

Oh yeah, it’s also about the cheapest one out there.

@ultrazero @Ac7ss Thanks for the recommendation on the 2gig thermostat. I will definitely check it out. While I like the idea of adaptive control for the most part I could probably come up a logic structure using CoRE pistons which would do what I need after a little tinkering.

@snowboardjoe I am glad to hear that things like Nest work with heat only although I am pretty sure I don’t have the line to power the unit (I can’t remember ATM). Only a few areas in the house (kitchen, master bath, laundry room) have had the electrical work updated. I ran into that problem when trying to install a z-wave light switch.

Exactly what I have done. There are a couple of apps out there already for controls. (Such as the one for the doors being open.) I use a piston for my particular heating needs.