Stuart Turner Monsoon Pump - Different Hot And Cold Presure

[JackK]

I had a £600 stuart turner monsson 3 bar pump installed - The cold water is fed from the loft tank and the hot water from a side flange on the cylinder (Like it should be I imagine)

What is weird is that the pressure from the hot is not the same as the pressure from the cold - How can that be? Both sides should pump at 3 bar and so have the same litres per minute..

Its annoying when I use my tap when the cold water comes out super fast but the hot does not and trickles.

I have tried in a few taps as the whole house is running off this pump now and there is definitely less hot water then cold even though both on the same pump! All isoltaion valves are open as well!

 

[Johntheo5]

Are the cold feed to the Pump and the cold feed to the HW cylinder on two separate pipes coming from the loft tank and what size vent is on the HW cylinder?.

 

[JackK]

There are two pipes from the cold water storage - One for cold water to ST pump and one for cold water to the hot water cylinder - Both open full.

The cylinder I have is this one

https://www.gledhill.net/products/vented-cylinders/envirofoam-stainless/

It has 28mm feed from tank to the hot water cylinder and 28mm vent at top

The flange on side is 22mm -

The ST pump has 22mm cold

 

[Johntheo5]

Is this a new installed pump or has it been there for some time/.
There may be filter/strainers on the pump inlets that can be cleaned.
If you switched off the pump is the gravity flow through both the same?

 

[JackK]

This is a new pump! If I switch off pump then hot water is non existent and cold water is good !

Do you really think the strainer is blocked up - Not easy to drain down hot water and inspect the pipes!

 

[Johntheo5]

There should certainly be some gravity flow through the hot, should be practically the same as the cold. Are there any "penny slotted" type valves where the flexible hoses are connected to the pump? You should certainly determine the reason for no flow.

 

[JackK]

There are no penny slots - There are turn knobs for isolation which have been fully opened !

 

[Johntheo5]

 

[Johntheo5]

There are no penny slots - There are turn knobs for isolation which have been fully opened

On both inlet and outlet?, 4 in all.

 

[JackK]

On both inlet and outlet?, 4 in all.

The new pumps have turn knobs for isolation. They are fully open!

 

[Johntheo5]

So you can check your strainers without drain down.

 

[polesapart]

If I switch off pump then hot water is non existent and cold water is good

With the pump off, can you easily block the flow at a cold tap with a thumb over the spout?
And is the kitchen cold tap different?
With pump on, does is activate when a toilet is flushed?

 

[JackK]

With the pump off, can you easily block the flow at a cold tap with a thumb over the spout?
And is the kitchen cold tap different?
With pump on, does is activate when a toilet is flushed?

When pump is off I can block hot water easily and cold water with some force

The kitchen cold tap is main fed and very powerful

With pump on pump activated when toilet is flushed as all house is now plumbed to run off pump - In hindsight I wish I had an unvented cylinder and got away with all this crap - (Hot water cylinder, cold water tank, ST pump which is damn noisy) - I replaced all of it and its still messed up

 

[polesapart]

Then I can only suggest, like the others above, a blocked filter on the pump hot inlet or some other restriction on the hot supply to the pump.

Whilst you've got the pump inlets undone you could open the hot and cold isolation valves and check (bucket+measuring cup) that the flow rates to the pump under gravity are roughly equal.

 

[oldbuffer]

What is the exact model number of the pump you have?