Shower Pump Water seems to surge

[disslee]

Need help please, I have recently added a shower pump to my bathroom.
the shower is 2.4 bat with 22mm inlets and outlets.
The pump has a dedicated hot from the cylinder and the cold is a dedicated feed 22mm to the cold tank
the hot is less than 1m from the pump and is connected using a flange
When i turn on the show the water comes ovt very fast thenslows down for a bit then goes fast again then slow again approx 6 second fast then 6 seconds slow. Does anyone know what this might be I am not sure it is air as the flange has a copper pipe going down into teh cylinder to stop air.
[i]I thought it could be the cold water that feeds the tank may be lagging, ie a bit of a vacum in the tank.[/i]
What do you reckon??? Many thanks in advance

[peter the plumber]

My gut feeling is that it’s a faulty pump unit.

Ring the makers help line and ask them about it.

[disslee]

The Pump is brand new I will speak to the sellers, I am thinking that it may be getting air from some where, I can check by disconnecting the pump outlets and putting some pipe on it into a bucket under water and I should not see any bubbles right if there is then this Surrey flange I have must be letting air in. My next step if there is air is to fit an Deleted Flange, dedicated 22mm for pump.
I think this because some sites I have seen say that there is a build up some times of air at the impellers.

Link deleted. We do not allow links to external sites unless approved.

The nearer the pump is to the supplies, the better it will operate (and obviously a two-chamber pump can be put nearer to the supply). This is because a pump may be capable of producing a very high pressure, but can only "suck" at one atmosphere before a vacuum is created and performance will not increase. Even before this, "cavitation" (tiny vacuum or dissolved air bubbles) will start at the impeller blades, and this is very bad for the pump. Water from the rising main contains dissolved air, and heating it up encourages it to liberate this. It is therefore a good idea to connect a shower pump to a hot water cylinder with a "Surrey flange" or an "Deleted flange""

[peter the plumber]

I am sure you are over “thinking “ this problem.

If a pump fails or cause problems within the first 72 hours, it’s a manufacturing error.

Not an installing error.

It doesn’t happen that often, but it does happen.

I have done the same myself a few times, spent hours trying to find a fault, which was never there.

Shower pumps are not that complicated to install and I feel you would be better off take this one off and getting a replacement.

Or get a plumber in to check it.

[disslee]

Many thanks I will speak to the pump people.
You know Deleted is like mind ticking over to get it fixed

Thanks for yor help I will let you know the conclusion