Salamander Negative Pump Pulsing issue

[budedwards]

Recently had a Negative pump fitted that was sourced used to keep costs low. The pump has followed all the tests provided by Salamander support and runs perfectly. However when hooked up to the Thermostatic valve it pulses. 6 seconds on, half second off, 6 seconds on and so on.

If i remove the shower hose from the thermostatic valve this increases the pulse time to around 20 seconds on and half second off.

I have purchased the widest bore shower hose i could find 12mm but this has made little difference.

I am not convinced i needed a negative pump..

anyone ever come across this issue?

The CWT is in the loft and the shower is on the floor below the other side of the hot water tank.

 

[ShaunCorbs]

Where is the pump fitted ?

 

[budedwards]

Where is the pump fitted ?

Hi Shaun,

The pump is fitted in the cupboard next to the Hot Water Cylinder.

 

[ShaunCorbs]

Did you check the vessel charge on top when empty ?

Also you haven’t plumbed it in to spec eg s flange ?

 

[budedwards]

Did you check the vessel charge on top when empty ?

Also you haven’t plumbed it in to spec eg s flange ?

I did check and top up the vessel post install following Salamander how to video mate

The plumber installed it mate not me, would you mind elaborating what you mean by flange?

 

[ShaunCorbs]

Should be like this as the way you have it can lead to air coming in via the vent and stopping the pump

 

[budedwards]

Should be like this as the way you have it can lead to air coming in via the vent and stopping the pump

View attachment 76823

wow ok, thanks for that.

I'll speak to the plumber and see if he can rectify

 

[SimonG]

Problems are it's a salamander, it's been installed by a half wit, it looks like it tees off of the cylinder cold feed and hot same as above.

 

[budedwards]

Problems are it's a salamander, it's been installed by a half wit, it looks like it tees off of the cylinder cold feed and hot same as above.

so which problem is causing the pulsing?

Here is the pipework consideration.

I'll happily get in a different plumber if the issue is the setup

Also i was trying to determine if it was a negative pump i needed all along but no-one has mentioned that as a potential issue.

 

[ShaunCorbs]

Plumber is the issue and negative head wouldn’t effect / cause the pulsing

 

[SimonG]

That's not a plumbers work, maybe handyman or diy.

Not enough info on if a negative head shower is required.

How did you keep costs low on the negative head pump?

 

[ShaunCorbs]

That's not a plumbers work, maybe handyman or diy.

Not enough info on if a negative head shower is required.

How did you keep costs low on the negative head pump?

Second hand pump

 

[budedwards]

Plumber is the issue and negative head wouldn’t effect / cause the pulsing

I've asked another plumber to quote.

watching plumbers youtube channels they do seem to fit the pumps in the same way so this is a common issue/mistake i'm guessing.

They say the rule of thumb is use a negative head pump if you are getting less than 1Ltr per minute flow, i am getting around 3 Ltr per minute so on that basis i could of gone for a positive head.

 

[SimonG]

Flow rate has nothing to do with positive or negative head pumps.

 

[budedwards]

Flow rate has nothing to do with positive or negative head pumps.

What is the method to decide if you need negative or positive?

 

[ShaunCorbs]

Any links to these channels ?


Height of shower and the type of shower is the deciding factor eg pos vs neg

Also neg / universal can be used in both types/ situations

 

[budedwards]

Any links to these channels ?


Height of shower and the type of shower is the deciding factor eg pos vs neg

Also neg / universal can be used in both types/ situations

View attachment 76830

Thanks Shaun you've been most helpful.

I'll let you guys know what the alternate plumber does to resolve but rest assured i will let him know your thoughts/recommendations

 

[budedwards]

so took it upon myself to swap the Negative pump for a positive one as i wasnt convinced the Negative pump was required or wasnt causing the issue.

Now have a positive pump in place and working perfectly.

Looks like (hopefully) i can avoid the fitting of flanges and expensive plumber refits.

 

[Ben-gee]

Up to you, but if it’s drawing air down the vent your new pump won’t last long….