Shower pump head

[acmedone]

When fitting a positive head pump, the recommendation is that the pump should be fitted at least 600mm below the bottom of the tank.

Fair enough specifying a minimum pressure but why from the bottom of the tank? - the pressure seen by the pump is from the top of the water.

So does the spec mean that it needs 600mm head and that it is a recommendation to maintain that height below the tank so that it should continue to work if the tank is down to the last dregs?

Any other considerations?

 

[Richard C]

That’s really only a rough guide to insure sufficient flow which also applies to any pipe work or the shower head as this will also affect the available static head. What’s’ more important is a minimum flow rate of 1 litre/min; this is required to trigger the flow switches & start a positive head pump; a flow of less than 1 litre/min will require a negative head pump. You also need to design pipe routes carefully if you want to avoid problems with air locking.

Salamander show 600mm below the CWS tank & is designed to ensure a safety margin; ST for example require a minimum suction flooded head of 500mm from the top of normal water level. They amount to the same thing really & you may be able to pinch a bit off the 600mm but you will most likely need a negative head pump. You should never install any type of pump above the bottom of the tank, even a negative head pump must still be installed below the base of the tank or it probably won’t work & if it does will have shortened life.

Once the pump is running it will continue to do so but if there is any danger of running the CWS tank dry, you must fit a cut out float switch; if you let the pump run dry, you’ll most likely kill it. You should also bear in mind that failure to follow manufacturer’s installation instructions will invalidate the pump warranty.

 

[acmedone]

That’s really only a rough guide to insure sufficient flow which also applies to any pipe work or the shower head as this will also affect the available static head. What’s’ more important is a minimum flow rate of 1 litre/min; this is required to trigger the flow switches & start a positive head pump;

Thanks. Confirms my thoughts.

You should also bear in mind that failure to follow manufacturer’s installation instructions will invalidate the pump warranty.

This is nonsense (if they try to wriggle out, not an insult to you). Failure due to incorrect installation would be easy to distinguish from faulty manufacture.

 

[Richard C]

This is nonsense (if they try to wriggle out, not an insult to you). Failure due to incorrect installation would be easy to distinguish from faulty manufacture.

Believe me it’s not; a bit like insurance companies, give them the slightest excuse & they won’t pay out & in such a case they would be justified. Some also limit their usual 3 year warranty to two or even one year if you don’t seek guidance from their technical dept. on DIY installations.

 

[acmedone]

This is nonsense (if they try to wriggle out, not an insult to you). Failure due to incorrect installation would be easy to distinguish from faulty manufacture.

Believe me it’s not; a bit like insurance companies, give them the slightest excuse & they won’t pay out

Oh, I certainly believe you. Doesn't make it right if there is a manufacturing fault and failure would have happened no matter how installed. I expect they rely on few customers going to the trouble of having the thing expertly examined.

 

[Richard C]

I expect they rely on few customers going to the trouble of having the thing expertly examined.

Your views seem to be a little jaded perhaps you’ve had a bad experience . You don’t have to have your intended installation expertly examined but if it fails under warranty it might be. It's not rocket science but you need to understand what you are doing & follow the basic rules & principles imposed by the manufacturer to get the best cover from their product warranty.

If you /use any product outside the manufacturer’s recommendations, do you honestly expect them to honour the warranty? All products are designed & built to a certain specification dictated by price against life expectancy. The higher the price the better the spec, the more abuse they will take & the longer they will last. If any product fails in a situation outside use specifications, it could almost certainly be proved it was due to exceeding said product specification; it would be virtually impossible to prove a manufacturing fault even if one may have existed.

 

[acmedone]

I expect they rely on few customers going to the trouble of having the thing expertly examined.

Your views seem to be a little jaded perhaps you’ve had a bad experience . You don’t have to have your intended installation expertly examined but if it fails under warranty it might be.

No bad experience but we seem to be at cross purposes.