shower pump

ok, quick update. tried lowering the temp on HWC but still same result of pump runs for about 6 mins and then starts scavenging. Does the thermostat on the HWC operate the immersion heater cut off? because i generally heat my HWC up using my boiler.
Gunna try the scenario of emptying all the hot water from the HWC and the gunna try running the shower with the mixer valve turned to hot and see what happens.
any other thoughts would be greatly appreciated.
 
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have you tried running the shower without any power to the pump for a few seconds? and then switching it on, doing this a few times
 
wonderb0y said:
have you tried running the shower without any power to the pump for a few seconds? and then switching it on, doing this a few times
yes wonder boy, this does help purge any air in the system, but when the pump is switched on after this the same scenario happens whereby after 6 mins or so, the pump starts to struggle and the hot pressure drops
 
UPDATE:
shower pump runs ok when there is no hot water in the HWC , so i guess when the cold water enters the HWC and mixes with the hot water, this must cause the air to be entrained into the flange and into the pump?

will try the suggestion of capping the vent pipe for a short period to see what happens
 
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ChrisR wrote

but these soon go through the pump, and don't form after a few minutes.

I doubt that. Here is what New Team have to say.


The reality of the situation is that the majority of centrifugal pumps do not work at thier best installed in certain installations where low static heads or high hot water temperatures are combined together. In these environments the pump can suffer from a condition known as "cavitation" which can dramatically affect the performance and life of the pump.

To briefly explain cavitation we must first advise that all water contained within the domestic plumbing system is to some varying degree aerated, and it is this air that contributes heavily towards the problems. When the water is heated in the storage cylinder the concentration of air reaches a saturation point where some of it has to be released. Generally the air will collect around the wall of the cylinder and gradually work its way upward towards the open vent to escape naturally and once any outlet is opened in our case the shower. During this action a certain amount of the air will be drawn along the supply pipe with the flow. As the water is drawn towards the pump the resistance of fittings, pipework and valves etc., will add resistance to create a pressure drop at the inlet to the pump.

The normal boiling point of water is taken to be 100°C at atmospheric pressure but as the pressure of the water is lowered the boiling point is also lowered pro rata, in many cases as low as 60°C. In some cases as the water reaches the pump there is a sufficient pressure drop at the entry point to release the remaining air in the water reducing the overall volume and causing the water to boil. It is the vapour or steam that is created from this reaction that prevents the full flow of hot water from entering the pump and can sometimes cause the shower to run erratic or the shower cold. The other side affect from this is to cause the ceramic seal on the hot side of the pump to bind, which will after time spin on the shaft and contribute to the damage to the shaft seals. Now imagine, instead of the stored water in the cylinder being 60°C it was at 70°C. This would then dramatically increase the instances of cavitation on low head, high resistance installation.

In your own installation to affect a long-term solution to this situation it may be necessary to ensure that the water temperature is in line with British Standards (6700) the Plumbing Codes of Practice (342) at 60° to 65°C maximum. To achieve this the cylinder thermostat (if fitted) should be set at around 50C.
 
Does the thermostat on the HWC operate the immersion heater cut off? because i generally heat my HWC up using my boiler.

can somebody answer this for me please
 
nabby68 said:
Does the thermostat on the HWC operate the immersion heater cut off? because i generally heat my HWC up using my boiler.
Jesus H. Christ. :rolleyes:

No. The cylinder thermostat doesn't operate the immersion heater. Ever.

FFS. Do the f***ing stop end thing before there's a nuclear strike and the forum explodes and everyone is deprived of knowing the outcome of the simplest bleeding test you could possibly have been asked to do. :rolleyes:
 
Softus said:
nabby68 said:
Does the thermostat on the HWC operate the immersion heater cut off? because i generally heat my HWC up using my boiler.
Jesus H. Christ. :rolleyes:

No. The cylinder thermostat doesn't operate the immersion heater. Ever.

FFS. Do the f***ing stop end thing before there's a nuclear strike and the forum explodes and everyone is deprived of knowing the outcome of the simplest bleeding test you could possibly have been asked to do. :rolleyes:
ok, so when i do the f***ing stop end thing whats the f***ing solution if it works, as chris r rightly says, this is only a temporary measure. would prefer to know the solution to the problem so i dont have to go backwards and forwards to this forum explaining every step i have done.
watch your blood pressure softus!!
 
nabby68 said:
ok, so when i do the f***ing stop end thing
Now. Do it now. Anytime now, as long as it's now.

whats the f***ing solution if it works
Do the test and post the result of the test here. It doesn't matter what the solution is, since you'll have to remove the stop end after the test anyway. If you ever actually get around to doing it of course, because if you never do it then you'll never have to remove the stop end, because it won't be there.

as chris r rightly says, this is only a temporary measure.
No, it's not a temporary measure, it's a test.

would prefer to know the solution to the problem so i dont have to go backwards and forwards to this forum explaining every step i have done.
I'm sure that your preference has been noted. So has the fact that you've said many times that you would do the test, and yet you still haven't done it.
 
If the stop end test proves what ChrisR states then the OP has a second set of problems which don't solve the first. :(
 
Tell you what - don't do the test.

Balenza has spoken. Balenza will solve your problems, and I wish him luck in solving them entirely without your cooperation in performing the tiniest little bit of investigation that he requests.
 

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