New Vitodens 100-W (B1HE) Model 120 installed replacing 22 year old Vitodens 200 - Questions...

rosco

Adapting to the new boiler and the contractor did a quality install. I did have some configuration issues that will be addressed soon. I was raking my brain trying to figure out where the DHW only/DHW+Heat/Off switch or setting was on the new controller only to understand that it's not there by default and the summer changeover happens based on calendar dates. Given we use a heat pump down to around 35F and that will absolutely be sufficient during the shoulder seasons and even many winter daytime hours it seemed out of sync with our setup to be using expensive natural gas (NStar-MA rates) keeping the heating circuit energized at whatever boiler temp is called for by the outdoor reset when there is no call for AUX heat. That can vary - sometimes 100% on boiler during very cold days; sometimes night time hours only and sometimes not at all for many warmer days. So I've discussed this with the contractor and the plan is to install relays on the air handlers that connect to plug 96 in the Vitodens to only get the boiler going when basically AUX heat is called for (our boiler is our AUX - no resistive heating strips in the air handlers).

My questions. Will this create any ill effects on the boiler long term as I assume they are designed more for continuous operation. Will it heat up pretty fast so I'm not blowing colder air for very long?

Some added background… The system follows the design shown in the manual for Layout 2. Vitocell DHW on one side and a LLH on the other side. Two air handlers with hydro-coils and circulators sit on the other side of the LLH. No Viessmann room control. Basically the thermostats call for AUX when the heat pump lockout temp is reached and gets the circulators moving and with this set of relays will energize the heating side of the Vitodens.

EBEBRATT-Ed

You could put a temp sensor on the AHY return line to hold the blower off until the water is warm if you want.