vaillant eco tec plus - internal pump running

[tan8856]

hi

the previous owner of this house told us something along the lines of the boiler heats the main rads on one curcuit and the towel rads + ufh on another curcuit.

what im noticing is that the towel rads + ufh are on more often than the main rads and that they are on when the boiler display is not showing a rad (either on or flashing) or a flame. i know they are on because i can hear water running through them. what IS showing though is a circle with a triangle in it which the book says means 'internal pump is running'.

does that sound normal to you? what does the internal pump do thats different to the main rads pump? we do have a separate thermostat for the towel rads. i assumed the internal pump would just be doing something with the water inside the combi?

thanks

 

[Agile]

It could well be correct.

You should have another pump circulating the UFH.

If you want a lecture on how it works you should call a local competent engineer to examine it and explain it to you.

Otherwise if its working properly then thats all you actually ned to know.

There should be seperate ( longer ) times set for the UFH as it has a long thermal time constant.

Tony

 

[tan8856]

It could well be correct.

There should be seperate ( longer ) times set for the UFH as it has a long thermal time constant.

Tony

The UFH just has a thermostat and no timer. Is that normal or sensible?

 

[Agile]

The boiler will normally supply the heating circuit at about 70°C flow temperature.

UFH should only be supplied at a maximum of 50°C. |Otherwise the floor could get too hot to walk on! The tube is not designed for operation in UFH use above 50°.

That is achieved by another pump circulating water round the UFH loop. This loop is supplied from the heating circuit by a blending valve which mixes a small amount of heating water to keep the UFH at the target 50°.

It sounds as if your system has not been properly installed or configured.

Tony