Motison CyberStat CY1201 WiFi thermostat installation & review

[MN Renovator]

Thanks for the measurements and screenshots. Tiny and reasonably powerful.

[Servicetech]

Does the thermostat use mechanical relays for switching the outputs? Do you heat a click from the thermostat when the system comes on?

[Servicetech]

Originally Posted by NiHaoMike

An oversized heat exchanger would be more efficient in steady state operation, but blanking off one of the burners will not give you an oversized heat exchanger since you'll only be using part of it. What would is downsizing the burner nozzles (or otherwise reducing the fuel flow) and then somehow adjusting the airflow to maintain the correct mixture. (I think you would then have to slow down the air handler to avoid condensation and corrosion, but I'm not sure.)

That's the whole kicker on a natural draft furnace like the OP has, no easy way to do this.
I've tried downsizing orfices, delta T across the plenum drops faster than BTU input. Dropping input in 1/2 drops Delta T by about 2/3. 80K to 40k would take Delta T from 50f to 20f. Excess air in the combustion chamber accounts for a large portion of the efficiency loss.

I ended up just finding a good buy on a smaller furnace on Craislist. Easier to replace the whole furnace than experiment with different downsizing strategies. Bought a 2004 44,000BTU 90% furance still new in the box for $250, sold the 1999 88,000BTU 80% furnace for $175. Deals are out there, just have to look for them.

[Daox]

Originally Posted by Servicetech

Does the thermostat use mechanical relays for switching the outputs? Do you heat a click from the thermostat when the system comes on?

I checked this out today. There are no clicking noises from the thermostat that I can hear when the heat kicks on/off. That isn't to say its not using a real small relay though. I think the spec sheet says that each pin can only carry 400mA.

[Servicetech]

Sounds to me like some sort of transistor/optocoupler/triac doign the switching. Could cause compatibility issues with some systems. The 400ma rating is marginal for some AC contactors, especially when inrush current is considered. A typical contactor reads 10-20 ohms coil resistance. With 24VAC applied the 400ma will be exceeded until the contactor pulls in.

[Daox]

Just a quick update on this. The thermostat has been working flawlessly. I love it and have taken a few opportunities to use it to turn the heat up (before getting home early) and also to turn it down when I'm going to be away when the program would normally turn the heat up.

[Servicetech]

If a manual override is done at the thermostat, does it do a temporary or permanent hold?
Are cycle times/tempature swing adjustable?

I just noticed that they included a test lamp to verify good common, well done on thier part. Obviously they are focusing on DIY installer who may not own a meter.

For an $80 price point his looks like a nice wifi stat.

[Daox]

You can do a temporary or permanent hold via the physical thermostat controls. You can also adjust the temperature swing as well. I never did get to writing that part of it up. I'll have to get some pictures and do it later.

Their focus is the DIY crowd.