Thks for this. Pumps can be smaller capacity if judiciously connected to needed outlets that require the desired flow rate.

This can also be achieved during renovation, where the plumbing for WC inlet refill are separated in each bathroom from cold supply to each bathroom. A separate dedicated distribution pipe of sufficient diameter and slope and an appropriate reducing (e.g. 1" or 3/4" to 0.5") outlet to each WC should offset the pressure loss and yet achieve satisfactory refill time though not as fast as the pumped assisted rate. This also avoid water hammer issues or leaking toilet refill valves overwhelmed by persistent and eventual wear from pump pressure. The inlet point at the wall will of course terminate at a higher distance from the toilet floor eg 12-24" vs the usual 6-12" which is shared with the cold plumbing line to basin or bath/ shower depending on bath layout. It also avoid the nightmarish scenario of a leaky flush valve that will empty the tangki in minutes and causing the pump to run dry but some models will have dry run protection.

Combine this with low flow rate but high pressure wash basin aerators and shower head e.g. Takagi Kimochii or the 200 holes Korean fine spray type, the required overall flow rate can be reduced somewhat thus allowing a smaller pump with that flow rate to be used.

This post has been edited by halcyon27: Jul 18 2020, 07:07 PM

I read some said the air could get caught in cm3-5pm1 then need to climb up to reset. If I use on off switch below the ceiling, anything happen then just switch off then on back. Will it back to normal ?

This post has been edited by skyvampire: Jul 19 2020, 11:32 PM

Quick comment on WC water inlet - It seems there is a type of WC mechanism that is build for "high pressure" WC water inlet. I accidentally bought this type for my normal house, subsequently got it changed to the "normal/low pressure" type.

Just a sharing that it might solve the problem of high pressure WC inlet causing leak...anyone can comment?

@zheilwane sifu: I am considering to replace my existing pump with Grundfos Scala 2 as my current pump does not work well (too less pressure) at the 3rd floor. Reason for considering Scala 2 is becoz this model has variable speed as i am worried about too strong pressure and the strain on my piping which seemed to be problem in my neighborhood (pipe bursting at the joints just next to tangki, due to piping design fault).

After checking the internet, i read there was a design flaw in earlier versions of Scala 2 prior to batch 1901 (i.e. any unit made prior to week 1, 2019): Grundfos Bulletin Number: SC-19-08-03.

My questions are: (1) Whether the Scala 2 is suitable for my environment (5 baths, 3 storey with rain shower but max only 2 baths are used simultaneously), and taking into consideration the piping design fault?
(2) Whether the newly re-engineered Scala 2 (batch 1902 onward) managed to resolve the design flaw issue which caused leakages and breakdown after sometime?

TQ for ur input!

Is it advisable to use copper pipe with brass compression fittings for CM5-4PM1 outlet to supply to bathrooms? Can the compression fittings take the pump pressure? Is it suitable if the pipe runs exposed on the outside wall? I don't see this being done in Malaysia. I'm forced to run the pipe on the outside wall exposed to sun and rain and I wanted something that can withstand the sun, rain and pump pressure.

scala2 pump not suitable for 5 bathrooms, u wan something better and variable speed get UNI E CM5-4pm1, u get good flowrate and can control pressure

Hi, I recently purchased a Grundfos CM3-5PM1 pump from online store, successfully install it..its working..
but produce quite loud sound and vibration (even louder than my previous 1HP Tsunami pump).
The pump was installed inside the roof, on top of plywood platform layered with rubber pad (free gift) in between.

Currently Im in the process of registering the ewarranty at www.grundfos-ewarranty.com.my
but havent completed yet due to missing invoice.

1. Am I correct to assume the pump is genuine if the warranty registration is accepted?
2. Is there any other way I could verified that my pump is genuine not an imitation?

not from authorized dealer, grundfos wont layan warranty. Need invoice from authorized seller. My ex-staff stole my pumps and sold online, they cant produce receipt, the pump is memang genuine grundfos, but no warranty also.

Could be stolen goods, could be parallel import and etc etc, thatz y they nd both warranty card and invoice

This post has been edited by zheilwane: Aug 10 2020, 10:14 PM

Just to provide an update, i did manage to get copy of invoice from the online store
and the e-warranty registration is successful. So I guess its a genuine product.

Now, I just need to figure out what is causing the loud vibration.
My suspect.. it could be because of my attic wooden frame structure causing
the vibration from the pump to be amplified.

Does anyone have suggestion, how to improve the setup?


Turn On the sound:

Hallo to the sifus,

I have question to ask - if my Grundfos pump running causes the water to turn hot (not just shower water, but tap water also become hot) - what does that mean? is it pump got problem need to replace?

(i know it's the pump because when i switch off the pump from the main switchboard, the water becomes cool)

If want to replace, the CM3-5PM1 pump can be installed on the roof (open air) or not?

U nd to snap video to show, jus audio is not enough, nd to show the piping and etc etc. u can also ask the seller for support i bliv they reply faster than waiting forumers to check your posting. If u have video of the pump now, stand 3 - 5 feet away, snap a video of the surrounding

pump running non stop causing water to be hot. either due to faulty pressure controller or pipe leak

New to this. May I know if it is necessary to install water pump for condo unit? If I need to decide only when I feel the water pressure is too low?

I just installed scala2 in my new house with bypass as well.The pressure now with bypass quite good already without turning on the pump.

Also, the pump sometimes on and off on and off.. the installer said might have some small leaking somewhere. So is it ok if i just turn my water pump on when only i want to use it?

Btw my area still not many people, probably thats why the main pressure still strong.

i dont see the problem. u may switch it on during the day and switch it off at night to save bill.
u can even install a switch near your bathroom so u can switch on and off when required.

If it's me I will try to find the source of the leak n fix it if possible. Might turn out to be an easy fix

If I may comment:
From pump to the piping, maybe it is better to use flexible hose, long term vibrations from the pump might cause the rigid pipe to stress and break.

can show picture of flexible hose?
can stand pump pressure? how to specify when buying?
how long must hose be from the pump to join to say pvc pipe to reduce vibration?
use what sort of clips to join? gotta use adaptor at pump outlet & also at pvc pipe?
hose easily available from usual hardware shop?

Just google expansion joint or flexible joint for pump and you can see the picture. All industrial pumps are installed with this kind of joint to reduce the fatigue from pump vibration.

I think it should be something that can be easily sourced since pump installation should be connected with flexible joints.

This post has been edited by blanket84: Aug 29 2020, 12:17 AM

I just installed the CM3-5PM1 water pump for my upstairs water tank bcos pressure too low for handheld heated shower. But this pump is making a lot of vibration noises. It’s probably installed on a wooden beam in my roof. Shouldn’t a plumber install it on a rubber block or something that can absorb the vibration?