Home Automation Domotica Forum Europe, Bwired Forum

Hello,

can I power off the OTGW now in summer - an Intergas similar boiler connected by opentherm connection and a Lyric T6R thermostat?
Will the boiler work - as I have an DHW indirect tank besides the boiler - for DHW heating?

Thank you.

I powered off the OTGW and the thermostat too and it seems that the DHW heating works.

When powered down, the boiler interface of the OTGW will present a high level on the opentherm line. A boiler should interpret that the same as no thermostat, or an on/off thermostat in off state. So, the boiler should not start heating.

What happens to DHW depends on the boiler settings. There are normally three options:

• Comfort mode, where the boiler always keeps a tank of water heated.
• Eco mode, when water is only heated on demand (by running a tap).
• Smart mode, where the thermostat controls when an amount of water is heated in anticipation of need.

Obviously that last mode won't work correctly when you power down the OTGW. But you should still get hot water (after a while) when you open the tap. But I suspect, with an indirect DHW tank, you need to have it set to comfort mode. Heating the tank on demand would take much too long.

But why do you want to power off the OTGW in summer? It only uses 1 or 2 Watts, which is peanuts compared to the energy consumed by an indirect DHW tank. Unless you are remodeling your house and don't want to install the thermostat and OTGW in a temporary location, I wouldn't bother to try and save about 5kWh over the whole of summer.

Thank you!
Well I just powered off to prolong the OTGW lifetime not to save energy... if it doesn't work, the lifetime will be longer.

That is something I never even considered. So I did some research. During normal use, the PIC will not write to EEPROM, So we don't have to worry about the 1,000,000 typical erase/write cycles. Aside from that I found estimates that the PIC should last at least 30 years. And more likely 50 to 200 years. When it fails, it will usually be due to deteriorating solder joints, ESD, or cosmic rays, combined with changes in temperature. The PIC doesn't get hot when running, because it only operates at 4MHz, while it is rated for up to 20MHz. So, the most likely causes for eventual failure of the device are actually unrelated to whether the OTGW is working or not.

But I'm honored that you seem to consider the OTGW a family heirloom that you want to be able to pass down the generations

There are other parts not just the PIC on the board, and everything get older by power on usage: electrolytic capacitors the most!