Atag Efficiency

[lockett]

I had an Atag ic Economiser 27Plus boiler fitted in October, despite this being the most expensive boiler offered by my local installer I'm less than impressed by its performance. It takes ages to heat my house, despite turning on the heating at 8:30am the radiators only reach full temperature by lunchtime. I checked the boiler operation it was showing “pump overrun”, this seam to happen a lot. I have looked on the forums at what this means, but still a bit confused. As far as I can tell this function is to release excess heat stored in the boiler. The confusing part is the boiler outlet pipe is bearly warm as are the radiators, why is there a build-up of heat in the boiler, why isn't it putting this heat into the heating system?
The thermostat is calling for heat, flame icon and green light at the boiler.
I have set the flow temperature to 60deg as suggested by the government campaign, this does not make sense to me, how can you lower the boiler temperature and still achieved the same level of comfort.

The Boiler has the option to have the pump run in continuous mode (why) could this help the situation?

Any advice will be much appreciated

 

[terryplumb]

You should take the matter up with the installers. Has anything changed since fitted in October ,or has it been this way since day one ?

 

[lockett]

It's hard to say, I think as the weather has turned colder it's became more noticeable. This is my first winter in the house so I don't have an idea of what is normal.

 

[JonathanM]

It might be helpful to check just a couple of basic things. If you go to page 50 of the manual below you can see how to get more detailed information about the boiler status. The next time you are waiting for the system to heat up you could check the flow and return temperatures which are 8.3.1. and 8.3.2. and see how they vary over time.

I checked the boiler operation it was showing “pump overrun”, this seam to happen a lot.

Is that happening after you've run the hot water?

The thermostat is calling for heat, flame icon and green light at the boiler.

What thermostat do you have? What temperature is it set to? And whilst the system is heating up, what is the room temperature that the thermostat is reading?

Manual:

https://www.atagheating.co.uk/hubfs...n and Service Instructions from July 2022.pdf

 

[lockett]

I have a EPH thermostat, set to 22deg, actually temperature shows 20.3 Deg flame icon on.
Thank you for pointing out the boiler status function, what a useful feature, I will monitor the readings.
Hot water does not appear to have any effect on the heating operation.

 

[lockett]

What temperature differential would you expect between temperature out and temperature into the boiler.

 

[JonathanM]

It might be a thermostat issue rather than a boiler issue. As far as I know, pump overrun would normally happen every time the thermostat turns the boiler off. After the boiler turns off it runs for a period of time to get rid of any excess heat in the heat exchanger. By default on your boiler it seems to be set to run for 1 minute. Most modern thermostats use an algorithm called TPI to control the temperature. Once you get close-ish to the set room temperature, they do a series of short burns, several times an hour. After each burn the boiler will turn off and the pump presumably will overrun. This can happen 6 times, or sometimes even 12 times, per hour. So that might explain why you are seeing the pump overrun a lot. The pump may also overrun after you have run the hot water.

But it doesn't really explain why it takes so long to get up to temperature in the first place.

Although it can be a pain, the only way to find out what is happening might be to monitor the thermostat and boiler for a good length of time, starting when it comes on in the morning. See what the room temperature is, how long the burner symbol on the thermostat comes on for, and what the flow and return temperatures are on the boiler and how they increase over time.

 

[JonathanM]

What temperature differential would you expect between temperature out and temperature into the boiler.

It depends on your system. It's meant to be about 20 degrees on modern set ups, but it can be much lower, or a bit higher. Is the flow temperature getting up to 60+?

 

[JonathanM]

Do you know if this is your thermostat?

 

[lockett]

The thermostat boiler icon is showing most of the time.
The flow is 59deg and return 48drg.
It is now 2:00pm and the radiators are finally hot, so I will have to wait until tomorrow morning and do your checks when the system is starting up.

 

[JonathanM]

At the same time you should also check how long the burner on the boiler itself comes on for at a time. Is it coming on for just a few seconds, or less than a minute, or for a good few minutes at a time. Hopefully doing all this might help work out if there is an obvious simple answer, or whether you need to get the installer back to investigate. If the system is working properly, the boiler should only cut out if the flow temperature gets up to 60+ (with your current setting) or if the thermostat turns it off. And keep an eye on when the pump is on overrun.

 

[lockett]

Thank you I will follow your suggestions

 

[wibbit]

This probably isn't the issue, but one thing I noticed about my ATAG, it has a water flow sensor, and if you do not have enough flow through your system, then the boiler will turn off, even if the water is still cool.

I can't remember off the top of my head what the message was when that happened, I was seeing that with my underfloor heating, where the amount of water from the boiler being "added" to the underfloor loop via the mixin valve, was not enough to generate sufficient flow through the boiler to keep the boiler running, as such the whole system effectively "stopped" till the underfloor heating loop cooled sufficiently to cause the amount of water being mixed it to result in the boiler being able tor run.

Just offering an alternate data point.

 

[JonathanM]

This probably isn't the issue, but one thing I noticed about my ATAG, it has a water flow sensor, and if you do not have enough flow through your system, then the boiler will turn off, even if the water is still cool.

I can't remember off the top of my head what the message was when that happened, I was seeing that with my underfloor heating, where the amount of water from the boiler being "added" to the underfloor loop via the mixin valve, was not enough to generate sufficient flow through the boiler to keep the boiler running, as such the whole system effectively "stopped" till the underfloor heating loop cooled sufficiently to cause the amount of water being mixed it to result in the boiler being able tor run.

Just offering an alternate data point.

I think there's a good chance it will come down to insufficient flow, one way or the other. The manual for this boiler says one of the common fault codes is "104 - Flow Check Failed". Does that ring a bell?

 

[lockett]

I don't get any fault codes not 104 or anything.
Thank you for the input, but in my case I have a radiator system, and I have good water pressure.