Atag Boiler with weather compensation

[Jem16]

Jen,

They are referring to the difference between your flow and return temperatures - the delta should be higher. At the moment you still have too low a flow temperature to make any reasonable judgements in how well the system is balanced.

Ah ok - I'm with you now. What are you saying it should be then?

I would now wait for the weather to get much colder and then see how your system really performs.

Weather compensation is not at it’s best when you move into Autumn or out of Spring.

Ok I shall continue to monitor it.

 

[richard978]

I had a new Atag 35+ Economiser fitted in May with an outdoor weather sensor and using the Atag Zone controller with it.

So far it's been doing what I expect and reducing the flow and return so that the boiler is condensing.

Now we're getting colder weather, I can't seem to get the house to be warm enough in the evenings so need some help please.

So far I have it set up to come on at 8am till 10am at 20 degrees ( controller is in the Hall so set lower so that main living room doesn't overheat) then 12 degrees from 10am till 4pm where it goes back to 20 degrees till 10pm then back down to 12 degrees till 8am. During the "off" times, the temperature will drop around 3 or 4 degrees at the moment.

What I've noticed so far is that the Atag Zone controller won't even reach 20 degrees - usually reaches around 19 degrees. Main living room has a temperature of around 20.5 degrees which is just a little too cool in the evening.

So how can I improve this? Am I doing something wrong, settings wise? The sensor is hard wired to the boiler but I also have Weather Compensation mode set on the Atag Zone controller - maybe this is wrong?

Those boilers are hard work to set up, they have some sort of heating curve which sort of makes the room stat pointless.

Some Viessman boilers have the same system, but it's very technical and designed for homes that have multiple zones and different forms of heating.

I worked on a home in Derbyshire which had limecrete flooring with underfloor heating in one wing and radiants on the upper floors. The system was set up with a particular curve and weather compensation..... traditional room stats were not present.

 

[Brambles]

Richard,

I think that you are confused. They have two very different functions.

The curve determines the flow temperature, not the room or zone temperature. It is within the control logic if the boiler ( or with Open Therm the controller).

Without a room or zone thermostat there would be no control to either call for heat or vice verse to the boiler.

There will almost certainly have been a thermostat (s) for the system you worked on.

 

[richard978]

Richard,

I think that you are confused. They have two very different functions.

The curve determines the flow temperature, not the room or zone temperature. It is within the control logic if the boiler ( or with Open Therm the controller).

Without a room or zone thermostat there would be no control to either call for heat or vice verse to the boiler.

There will almost certainly have been a thermostat (s) for the system you worked on.

Yes there is always a stat but because of weather compensation and the settings being used the boiler may not act in the way you would expect.

If there settings are wrong then you will find parts of the house very cold even though the boiler is on.

Its all down to how the boiler is set up, and that boiler is a very sophisticated bit of kit.

 

[Brambles]

There is nothing overly complex with an Atag boiler - in fairness to Atag, they even publish the control logic - which it makes it very straight forward to trouble shoot unexpected behaviour. A few other boiler manufacturers could learn a lot from Atag.