Bosch Boiler Controls

Chester

Homeowner question:

Does anyone here have any experience with the relatively new Bosch t-stat/boiler controllers? One is a fancy-looking Wi-Fi-connected product that connects directly to the boiler and the other one is a t-stat device that connects to the boiler through a proprietary zone controller. They use indoor temps rather than outdoor reset to modulate the boiler (although the fancy one appears to have some outdoor reset compensation based on internet data). Bosch says they keep the boiler operating at the lowest possible fire needed to maintain indoor temps. They replace the FW200 ODR controller.

I like the idea of having a t-stat that actually manages the boiler instead of just being an on/off device, at least theoretically. I was reluctant to try these when I had my new boiler installed last year because they had just hit the market.

Thanks in advance!

Here are some links to the brochures.

http://www.bosch-climate.us/files/75H995143-Bosch_Control-Smart-Tstat-brochure-7-24-15-web_US.pdf

http://www.bosch-climate.us/files/75H99513_nsc-v3_4-2015_US.pdf

GW

Must be brand new, I'll have to inquire, looks nice. I've been curious when boiler manufacturers would bring a wifi to the market. Hvac manufacturers are years ahead.

Chester

Looks like the wifi one was released in Europe first and then in the U.S. late last year. The other system hit the market last spring.

Captain

I've had a GB142 installed in my house for the past 9 years. It came with the Buderus RC10 thermostat. It maintains the lowest possible supply water temp to satisfy the room temp setpoint. It works great (I think the quit supplying the RC10 with the GB in North America because everyone over here liked using outdoor rest). I ordered the wifi enabled thermostat that controls the same way as the RC10 a couple weeks ago. It has a lot of cool features my old stat didn't and uses the same base plate (no wiring involved). The one thing it doesn't do is send me an alarm message if there is and error or it can't maintain temp for some reason. Isn't that one of the main reasons you get a wifi enabled thermostat? Seems weird to me. With all the other features built into it, you'd think it would be an easy thing to add.

Chester

Thanks Captain. How many zones do you have? I'm wondering how you'd integrate that thermostat in a multi-zone system.

Aaron_in_Maine

I went to Bosch for a training last fall on the Greenstar boiler. And the trainer showed us this control system at the end of the day. I believe he said the Internet thermostat could only be used on one zone. If that is the case I would put it on the main zone and use the other indoor reset thermostats on the your other zones.

Chester

Thanks Aaron. Do you have an opinion on the merits of indoor vs outdoor reset? Would you recommend it to a customer?

Aaron_in_Maine

The way they explain it is it helps the boiler with cycling quite a bit because of instead of a straight on or off signal from a regular thermostat. The boiler knows what is going on in the building and can react accordingly. The way he explained it is it reacts to the exact heat loss of the building not just a guess on a sheet of paper. I am debating using it in my house I am building about a year from now.

Captain

I have three zones. The Bosch thermostat tries to keep the water circulating constantly and just varies the supply water temp, so my basement zone has a three way diverting valve connected to a on/off thermostat. I over sized the basement radiators so it has no trouble maintaining its temperature setpoint. The third zone is the floor heat in my garage slab. It takes the return water from the two other zones and sends it through a thermostatic mixing valve to bring the supply water temp down. Its controlled using an on/off tstat that enables a pump.

Chester

You guys have convinced me to give it a try. Thx.

Chester

Captain said:

I have three zones. The Bosch thermostat tries to keep the water circulating constantly and just varies the supply water temp, so my basement zone has a three way diverting valve connected to a on/off thermostat. I over sized the basement radiators so it has no trouble maintaining its temperature setpoint. The third zone is the floor heat in my garage slab. It takes the return water from the two other zones and sends it through a thermostatic mixing valve to bring the supply water temp down. Its controlled using an on/off tstat that enables a pump.

So you have two zones that are presumably wired to a zone controller with the Bosch t-stat wired right into the boiler? I'm still confused how this works in a multi-zone system since the Bosch t-stat doesn't connect directly with the zone controller.

Captain

The Bosch t'stat varies the supply water temperature to maintain the space temp on the main floor. My basement (zone 2) has a three way diverting valve connected to a on/off thermostat. If the basement has a call for heat the three way valve diverts water through the basement rads. The third zone is floor heat in my garage slab. It takes the return water from the two other zones and sends it through a thermostatic mixing valve to bring the supply water temp down. Zone 3 space temp is controlled using an on/off t'stat that enables a pump. I drew a quick schematic without showing every last accessory. See the attached document.

Chester

Thanks for the nice drawing! Sorry to keep bugging you with additional questions...

What happens if the basement zone calls for heat when your main zone isn't calling for heat? Does the Bosch still control the water temp to the zone?

Captain

There can be a bit of a delay when there is a call for heat in the basement. But this rarely happens because the Bosch tstat tries to keep the circulator running at all times and varies the supply water temperature. I like to call it Indoor reset/constant circ mode. I over sized the basement radiators so it does not have trouble maintaining the space temperature even when the Bosch tstat reduces the supply water temp.

GW

We've done this a bunches of times, install the sensor in the zone you want "warmest". Get rid of old thermostat in that room

I've just about seen it all. I was at a guys house two or three months ago. Original installer installed buderus BFU. He got confused. He went back and installed traditional thermostat right next to the BFU. Some plumber heater dudes just shouldn't be allowed to touch controls.

Gary

Solid_Fuel_Man

GW said:

Some plumber heater dudes just shouldn't be allowed to touch controls.



Gary

Trust me, I couldn't agree more!

SFM

kentw

I have a G124X with 2107 and room sensor. Can I replace the room sensor with the CT-100? I would love the remote WiFi access.

GW

May need to call Bosch on that one, good question