Hot Water Priority Feature Request

[harvybob]

Hi, Some boilers have an option for hot water priority - where the boiler will increase the heat output to heat up a hot water tank quickly - at a higher temprature then the radiators would normally take.

for this, the boiler has an additional set of controls.

Is there a way for PiHome to be programmed such that if Hot Water demand is on, Close off all zone valves for non hot water if the following two criteria is met: there is a demand for hot water from the tank +the scheduled window for hot water is active?

[pihome-shc]

@harvybob
is there any interface on boiler that can be checked? or how we know if boiler does this feature? and how to check if there is hotwater demand? this can be implemented.

[harvybob]

Apologies missed this, how is hot water demand managed at the moment? Alternatively all tanks will have a thermostat so would need to detect using a gpio pin on the pi - a simple is the circuit open or closed. The thermostat is usually 0v so shouldn't be a problem?

Most boilers have the feature however usually undocumented, if the boiler has a feature it would be in the installation manual, internally wiring would have contacts for the room stat, and a second pair for dhw.

[dvdcut]

recently i had new boiler installed and it has this feature but when i asked the installer about this feature he dismissed me by saying i don't have pipe work for this and i can not use it :( but currently hot water goes to my manifold and then based on which zone calling for heat that hot water circulated in that zone (either heating or hot water) i think this is how most of the houses have it setup. may be yours is different and you do have pipe work for hot water

[harvybob]

Hi dvdcut, There are generally two ways to use HotWater Priority - first and the easiest is using a three port valve - which requires plumbing to be setup as such.

The other way (and the way that alot of plumbers dont know/want to know) is by using the correct actuators on the port valves (assuming you use these!) and/or using relays.

My setup is the second - i have three port valves, one for hot water, one for UFH and the third for rads. The same will apply if you have two port valves. The Hot water actuator has been changed to a 6 wire version - this allows the actuator to send both open and closed signals which is what is needed for my boiler to know if hot water is needed or radiator. If you want to use the existing 5 wire actuactor, you need in include a relay to flip the signal from open to closed and vice versa... Plumbers usually dont want to get involved in the electric side so dont want to do it.

Your setup may be different from this again, but will still be doable in some way! do you use an UFH manifold or are you using port valves?