Shower Pump issues - help needed

Hi

I have installed a single impeller shower pump to a shower bar mixer. Our hot water pressure is very low so I installed this to up the pressure.

The problem is that the cold water comes straight from the main as opposed to a header tank, so the pressure coming into the bathroom is very high. When I turn the shower mixer bar to open the cold water over powers the hot water stopping any from flowing resulting in the pump not turning on.

I can over ride this by opening the hot water tap on the sink then quickly closing it, this creates a shock wave triggering the pump to start pumping. Obviously not ideal.

Any ideas on how to over come this problem? I have fitted a pressure reducing valve to the cold water and set it to the lowest setting but the problem still remains. I'm thinking the next thing to do is change the mixer bar for a separately operated hot and cold shower mixer rather then the thermostatic bar mixer that I have, so the cold won't have the chance to over power the hot???

Any thoughts welcome.

Andy

You've fitted the wrong type of pump by the sounds of things...I'm guessing that you've fitted a Positive Head type when you should have fitted a Universal type. Solution is to buy a different pump

replumb your shower properly twin pump with feeds taken from the hot and cold stored water cylinder/tank, shower are designed to have balanced pressure supplies.

Ok, so do you think if I fitted a header tank for the cold water and plumbed it into a twin impeller pump with the hot running from its own hot water cylinder my problems would be solved?

Or shall I leave the cold water as mains pressure and get a different pump for the hot water?

Or is there an easier way of controlling the cold water pressure to equal it out to the hot?

Andy.

Your problem is the thermostat in the shower as it will naturally feed both hot and cold from the start. Unless you can start the shower so it only feeds from the hot side 1st then you'll probably never overcome the imbalance to allow the hot to flow enough to start the shower, without re-plumbing the supplies to balance them up.

A remote switch for the pump may allow you to bump start the pump each time.
With the pump switched off at it's power outlet, try turning on the shower then go and turn the pump on, if it keeps running and the shower then works, then you can set up a remote switch (pull cord in the bathroom) which will allow you to remote start the pump each time.

If that works then you can balance the cold pressure with the PRV to the output pressure of the pump to equalise the supplies.

It's one way you can also use a positive pump in a negative head situation. Much cheapness compared to a universal pump

andyvaillant said:

Ok, so do you think if I fitted a header tank for the cold water and plumbed it into a twin impeller pump with the hot running from its own hot water cylinder my problems would be solved?.

Click to expand...

That is the usual way. For the cold water you can probably use the same tank that feeds the hot water cylinder.

Mains pressure cold and a different pump will not help - the problem is the pressure difference between the mains cold and pumped hot. They will never be the same.

You know what I didn't even think about spurring off the hot water header thank in the lift that feeds the cylinder. Do you think it could be as simple as finding the pipe before it enters the tank and spurring off from there?

If so that sounds like the easier option as the cylinder sits behind the shower. That would give me the gravity fed cold water in after with minimal re-plumbing.

If your shower backs onto your airing cupboard then a twin pump and a new cold feed from your loft are definitely the best option

No, if you are thinking about changing the pipework and then changing the pump to a twin impeller then you need to have separate feeds from the cold water cistern to the pump and the cylinder. Do not feed the pump's cold supply from the supply pipe for the hot water cylinder.

You also need to check the size of the cistern to ensure you have a large enough tank to feed both.