Yes, Bunny, that's what they say. But user's experience seems to be different.
I would always fit a pump over run as it reduces thermal stress and theoretically slightly increases the efficiency.
Hi I will tell you now that you must wire pump at boiler , I know it says not required but I fitted a glowworm energy which is the same heat ex and design, didn't wire pump to boiler which meant it overheated regularly. engineer came out and said run pump wire to boiler to sort as soon as i did, issue solved. Don't make the same mistake I made.
Good luck
I would always fit a pump over run as it reduces thermal stress and theoretically slightly increases the efficiency.