Thanks Zein, really thumb's up for BUILDER'S HARDWARE, great after sales service. never expected to get a call...really appreciate it 
I will go up to the roof and check if the installation is correct as suggested by you and will revert...once again..thank you for the call.....

My pumber just installed the CM3-5PT from Builders Hardware. Even he was impressed with the quitness of teh pump. Thanks Zheilanwane and Builders Hardware. You guys were the cheapest out there. It was worth driving down from Shah Alam to buy in Kepong )

My Grundfos water pump at roof top is very noisy. Model is CM 5-4 PC. Anyone having the same problem?

Hi all, I also want to ask if water pumps are water proof or not?
I ask because my water tank is located on roof concrete slab, so obviously it will be expose to rain.

Will check whether there is a mat or not.
But the loud sound is not knocking sound, it is more like a low motor roaring sound.

Your pump inlet need to be bigger pipe, all the same thickness from water tank to the pump.inlet. from the blur picture you too it look like is using small pipe and only at the inlet a converter is use.

May I know what is the yearly maintenance that you mention?
Changing oil?

Hi,

I stay in a Condo ( 10 - 15 years old). It uses steel pipes, which have become rusted.
Water pressure is low when 2 pipes are open.
When 3 pipes are on (2 showers & flush toilet), 1 shower can't use.

Will adding a water pump solve this?