Quatt support

[garykrige]

Great project!

I have a quatt heatpump system which works in combination with my Remeha Ace 39C to provide heat to underfloor heating + 12 radiators. So my system is a bit complex. I am having trouble getting good control of the quatt system because it is a man in the middle on opentherm and I am not able to communicate directly with the boiler. I do have a second otgw which I've considered installing between the quatt and the boiler.

I've noticed while using SAT that there is a lot of gas usage and it doesnt seem to understand how to maximise electricity usage based on a COP value.

I wonder if this is something that will fundamentally change the way that SAT tries to optimise things, or if this is a simple update. As far as I understand things, with a heatpump you are able to set a much lower minimal setpoint and so the overshoot duty cycle aspect of SAT can be avoided.

[sergeantd83]

I do have a second otgw which I've considered installing between the quatt and the boiler.

You can install a new OTGW between your heat pump and your gas boiler. This will serve as an indicator that your heat pump has instructed the gas boiler to start heating. We can use the hvac_action of the OTGW thermostat that is connected between your heat pump and boiler. However, we would need to develop such a feature.

I've noticed while using SAT that there is a lot of gas usage and it doesnt seem to understand how to maximise electricity usage based on a COP value.

This is true. SAT doesn’t monitor the COP; it only uses internal weather compensation and embedded PID algorithms. The only way to achieve this would be by smoothing the PID algorithm, but this would result in a longer time to reach the desired temperature.

I wonder if this is something that will fundamentally change the way that SAT tries to optimise things, or if this is a simple update. As far as I understand things, with a heatpump you are able to set a much lower minimal setpoint and so the overshoot duty cycle aspect of SAT can be avoided.

Exactly. Your system will almost never need to operate in Low-Load control. Moreover, SAT aims to use the least amount of energy necessary to maintain the thermostat’s setpoint.

[garykrige]

Thanks for confirming my suspicions. Winter feels like its almost over in my area, so I'm not finding a lot of chance to test this setup, and the iterations are a bit slow with heating, but my approach is:

• set Heating Curve Coefficient to 1.4 (to lower the setpoint that is requested by SAT).
• set Minimum Consumption to zero so that SAT knows that I can run with 0 gas usage (I havent looked into the code yet, so I dont know if this is helpful or not)
• activated Dynamic Minimum Setpoint.

I think I'm changing too many variable at once, but lets see if this stabalises things.

I didn't manage to find docs on what minimum_setpoint_adjustment_factor does? Will this config help here?

[sergeantd83]

set Heating Curve Coefficient to 1.4 (to lower the setpoint that is requested by SAT).

In order to understand better how SAT calculates the heating curve follow the Heating Curve Version hyperlinks.

set Minimum Consumption to zero so that SAT knows that I can run with 0 gas usage (I havent looked into the code yet, so I dont know if this is helpful or not)

No, it is not helpful at all. We use this sensor to track the instant gas consumption.

activated Dynamic Minimum Setpoint.

This setting is useful mostly to gas boilers or installations equipped with TRVs.

I didn't manage to find docs on what minimum_setpoint_adjustment_factor does? Will this config help here?

@Alexwijn could explain better than me for this feature 🙃.