Grundfos UPS3 proportional pressure + automatic bypass

[Deleted member 281264]

I have a UPS3 controlling the radiator circuit on a hydraulically seperated system with closed couple tees

The manual and videos on UPS3 say you shouldn't use the proportional pressure setting when there is an automatic bypass, but on any other setting other then PP the pipes make a clattering noise

Why do they say not to use PP mode when there is an automatic bypass in the system? Does anyone know if the ecotec 630 has an automatic bypass

 

[Johntheo5]

Because in PP mode the head decreases as the flow demand decreases. If you have the (UPS3) on setting PP2, and assuming you require a minimum flow of 0.4m3/hr you set the ABV to a bit less than index 0.2 (2M) and PP2 will maintain this flow at a 2M head, if the heating demand then requires say 1.6m3/hr then the pump head will increase to 3M and the ABV will increase its flowrate considerably more than having say a manual bypass where it would increase to 0.49m3/hr, 0.4xsq.root(3/2).

 

[Deleted member 281264]

Does this mean I have to adjust the ABV in the boiler? (if there is one) I don't have one outside of the boiler as far as I can see

I have two seperate pumps outside of the boiler, one for UFH other for rads which is the UPS

Setting PP2 is the only pump setting that stops the pipework from being noisy in the rad zone, I had only discovered PP settings yesterday. I just want to make sure I do not do any damage to the system

 

[Johntheo5]

The CCTs act similar to a LLH I think so the primary (boiler} circuit shouldn't be affected in bypass mode at least, if the boiler has a internal by pass then it will be preset and you may see its setting in the installation guide.

 

[Deleted member 281264]

Thanks, yes CCT's provide the same function as a LLH but just in a much cheaper way.

I thought it wouldn't be affected since anything after the closed couple tees has it's own independant flows, I just wanted to check. Cheers for your replies