Shower cold pressure too low

[aharrisreid]

Hi there,

I have a mixer-shower fed via. a double-impeller pump receiving hot water from a cylinder (open-vented) and cold water from a feeder tank which also feeds the cylinder. The pump is level with the bottom of the cylinder, about 3m below the feeder tank. The pump was installed because the shower head is only 1m. below the feeder tank.

Now the problem. When the mixer is set to max. cold, the water is medium-hot (just bearable for a shower). When set to max. hot, the water is scalding - far to hot for anyone to stand under.

First I thought cold water was not being drawn through the pump, but the above suggests to me that cold water is reaching the shower, just not enough of it

My next test was to block the hot feed to the pump, then turn on the shower. The pump did not activate, suggesting the cold pressure was not enough to activate the pump, but how come the hot pressure is enough to activate the pump, when they originate from the same tank? Is it possible the microswitch on the cold side is not working properly (I assume it expects roughly the same pressure as the hot side to activate the pump).

I have considered using a pressure-equalising-valve, but as the cold pressure is so low, the hot pressure would become unacceptable. Could I use cold feed from the mains instead, and pass it through a PEV before it reaches the pump? For the record, the pump is a Newteam Duraspeed.

Any ideas would be appreciated.

Alan

 

[seco services]

you checked the pump filters ?

 

[aharrisreid]

Seco Services - thanks for the reply.

Good idea - where do I find the filters, on the inlet connections to the pump?

Regards,
Alan

 

[seco services]

You got it. pump end.
You can disconnect the flexis from pump and run them into a bucket make sure your getting good flow from each.

make sure you isolate the supplies before disconnecting and have an old towel around pump stop any water soaking it.

 

[aharrisreid]

I have now disconnected the hot and cold feeds to the pump and checked the filters - they were crystal clear! I turned on the cold via. the isolator valve and water shot out at a good pressure, so I can't work-out why the pump is drawing such a small amount of cold compared to the hot.

Any ideas what I should try next?

TIA,
Alan

 

[alan999]

Hi
Can you swap the hot and cold feeds over at the pump and see if you get the same problem except too cold rather than too hot. Would then indicate a blocked pipe or blocked feed at the shower. Best check with the MI of the shower first.

 

[aharrisreid]

alan999 - thanks for the reply.

MI? Not familiar with the terminology. Mixer Input? Please confirm (or not).

Regards,
Alan

 

[Charnwood]

MI = Manufacturers Instructions.

 

[gasservice85]

When was the pump installed?
Did you do it?
Is it a thermostatic valve?
Make of pump and valve ?

 

[aharrisreid]

Hi gasservice85

I've been at the house for 6 years, and the pump/shower system was already installed - I guess between 10 and 15 years ago.

The pump is a Newteam Duraspeed (twin impeller). The mixer is a Bramham brass 'antique style'. I don't know the model, but the nearest I can find to it is the
Sirrus Mayfair Antique Dual Control (http://www.showerdoc.com/shower-spares/mixer-showers/sirrus-by-gummers/GUM-PARENT-21-Sirrus-Mayfair-Antique-Dual-Control?pg=5)

Regarding the mixer - I don't think it is a thermostatic valve, because there is an outer lever controlling the flow amount, and an inner 'tap' controlling the temperature. The tap has approximately 3/4 turn from max.hot to max.cold.

Hope this gives some clues.

Regards, Alan