Power shower and a single Grundfos Booster Pump

[GeoPlumbing]

Hello
I am a plumber and I have come across a problem that I need confirmation form someone out there that I am giving the right advice. Firstly I'm no newbie I've been doing plumbing for a very long time, but the good thing about the domestic plumbing is that you always come across something new to learn.
So here's the Problem:
A Vented Hot water cylinder with a cold water storage tank above it inside a cupboard of a one bedroom flat... all new.
The previous plumbers installed a 22mm single Grundfos Home Booster pump (PC: 1048) on the hot water services for the whole flat, on outlet of the hot water cylinder,approx 300mm away from the cylinder. This pump should be 2 meter after the cold water tank outlet and installed before the hot water cylinder.

Also there is an Aquastream power shower (has a built-in Pump) in the bathroom, connect to the same hot water services as the booster pump... therefore when you turn the power shower on, the booster pump also comes on.... therefore you have two pumps working simultaneously.

This is the tricky part... non of the other taps will allow hot water through unless you go to the bathroom and open the hot water on the Bath tap and there is always air in the system.

I think it is due to:

• Two pumps on the same system causing conflict with each other
• The booster pump being installed in the wrong place
• The Plumber did no install a AA vent in the hot water services

My suggestion are simple:

1. To replace the Home booster with a twin Negative booster pump (for hot and cold) and remove the power shower and install a Therm Shower mixer.
2. Remove the booster pump... not sure if the kitchen tap will receive hot water with gravity feed.
3. Remove all of it and install an Unvented cylinder or combi boiler- Not Gonna happen! :cry_smile:

May thanks in advance for reading this... Any Help is good help

Leigh

 

[jam1979]

fitting the double impellar pump to the hot and cold for the shower and putting a thermostatic valve in seems most plausable

 

[BLOD]

Sounds like it could be a piping issue.
Keep the aqua stream as its a good shower IMO but make sure it's piped up right with its own feeds from hwc and cwst and keep the grunfos booster just to supply the other hot outlets, it might mean some repiping work.
Pif you cam post a photo of the set up it would be helpful

 

[PlumbBobBob]

how big is the cwst? oh and welcome to the forums leigh

 

[GeoPlumbing]

Sounds like it could be a piping issue.
Keep the aqua stream as its a good shower IMO but make sure it's piped up right with its own feeds from hwc and cwst and keep the grunfos booster just to supply the other hot outlets, it might mean some repiping work.
Pif you cam post a photo of the set up it would be helpful

The pipe go beneath the floor boards... so yea I did think of that although this would be very costly. thank you for agreeing that having 2 pumps on the same system is wrong.

 

[GeoPlumbing]

how big is the cwst? oh and welcome to the forums leigh

Hello
Firstly thank you
Both services are 22mm " The previous plumbers installed a 22mm single Grundfos Home Booster pump (PC: 1048) on the hot water services for the whole flat"