broken shower pump - pressure problem but which solution?

[pinchy]

the pump for my shower is broken and 3 plumbers have all agreed this was due to pressure - the cold water storage tank that the pump draws from is too high up in relation to the pump

the problem I am having is that each plumber has come up with a different solution and they all have varying degrees of complication and cost

solution 1: The most complicated and expensive solution offered was to install a secondary smaller tank that draws off the main cold water storage tank before the water reaches the pump, thereby reducing the pressure

solution 2: The pipes that fork off from the cold water storage tank pipe (one goes directly to the pump as the cold water supply and one goes through the hot water tank before reaching the pump) should be a different width and therefore will reduce the pressure before the pump

solution 3: simply to fit a pressure reducing valve

By the time I was offered the 3rd solution I was completely confused as to why the other 2 were ever offered, particularly because the person who suggested solution 1 didn't stand to actually do the work or make any money out of it (he was actually someone from the company that makes the pump so he was just avoiding saying the pump was at fault)


I would be really grateful if someone can tell me whether solution 3 is as good as anything else

thanks

 

[Softus]

solution 1: The most complicated and expensive solution offered was to install a secondary smaller tank that draws off the main cold water storage tank before the water reaches the pump, thereby reducing the pressure

I've never known this to be a solution to a problem.

solution 2: The pipes that fork off from the cold water storage tank pipe (one goes directly to the pump as the cold water supply and one goes through the hot water tank before reaching the pump) should be a different width and therefore will reduce the pressure before the pump

Pipe gauge won't change the pressure. Not one bit.

solution 3: simply to fit a pressure reducing valve

I still don't know why someone thinks that the pressure is too high.

This ought to be very simple.

1. What do the pump manufacturer's instructions give as the maximum head (or pressure) for the inlet to the pump?

2. What is the existing head?

 

[pinchy]

the instructions say:

"maximum static head - 10 metres"

it is quite possible that the cold water storage tank is higher than that because we have another 2 floor flat above us and the tank is in the roof above that

is that what you mean?

 

[Softus]

Yup - that's exactly what I meant.

In which case solution #3 is the one for you - cheap, easy, quick and effective.

 

[TicklyT]

Or, if you have to replace the pump anyway, look for a pump that is suitable for the inlet pressure you have. Some pump manufacturers quote max. inlet pressures of 1.4 Bar. That's about a 45' head.

 

[pinchy]

I think I initially underestimated the importance of one major factor in all of this - because we have a flat above us, they are drawing off the same pipe from the coldwater storage tank as we are. In all the pump manufacturers instructions it suggests that it must be a dedicated feed from the cold water storage tank to the pump. I think that is why the person from the original pump company suggested the secondary tank.

this is doing my head in!

 

[Fluffster]

Out of interest why are you pumping it when the pressure is already so high?
You can always install a single line pump if the hot needs to be pumped.
Pete

 

[pinchy]

Out of interest why are you pumping it when the pressure is already so high?
You can always install a single line pump if the hot needs to be pumped.
Pete

unfortunately it has to travel quite a bit before it reaches the shower and the shower is one of those big shower columns that needs a lot of pressure. by the time the water reaches the shower the pressure isn't that high

now I'm looking into running cold water from the mains supply direct to the shower and just pumping hot water (with a single line pump as you suggest)