...another shower

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I have read many of the shower postings but find I need to ask advice.

I have a gravity fed open-vented system in a flat & would like to install a shower. As there is only a ceiling lighting circuit in the bathroom, I was steering away from electric installations.

Cold water pressure is 2.2bar from a loft tank but the hot water head to the shower fitting is zero. I fitted a Croydex H2O venturi shower, hoping that the cold water pressure would improve the hot. The shower does not work, except on cold.

Alternatively, I have been looking at the Trevi Boost but am reluctant to invest more in a venturi system. Although they claim to work with negative head, £250 is an expensive way to find out.

Also, I have been looking at the Stuart Turner Showermate 1.2 Bar Single pump. This I would install at the hot tank, in the kitchen, & I would assume, requires its own 22mm pipe to the shower with a surrey flange to the tank. The hot tank is an Albion Superduty with 45 litre capacity, which may not be sufficient to pump.

I would appreciate any relevant comment on either option.

 

[ChrisR]

Cold water pressure is 2.2bar from a loft tank

You may have got that wrong? It will only be true if your loft tank is 22metres above the shower. 7 floors?
The venturi showers would normally only be fitted to CW mains.

 

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As I am not allowed access to the storage tanks in the flat block loft, I can't comment on the arrangement up there. I have been told that it is a storage tank system. Measuring pressure with a gauge at the bath tap reads 2 to 2.2 bar.

Literature with both the Croydex & the Trevi Boost suggest 2bar CW as ideal.

 

[ChrisR]

Does 22 metres sound about right - some gauges...
What are the tap H and C max flow rates ?

Sounds like soething is blocking the path of the HW in the shower. CHeck for a non return walve, which will be in the HW side. What pressure do Croydex say will be enough on the HW side?
Some tiny non return (check) valves take a lot of opening. I'd be tempted to hoike it out and put a larger one (22mm say) in the HW supply pipe. I doaresay Croydex wouldn't approve.

Chat to Croydex looming I think.

 

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Thanks Chris.

The Croydex H20 has a non return valve built-in which seems OK but I will check it out. The real culprit may be a second valve that is opened by cold water pressure to let the hot through. This shuts off the hot supply when the cold is turned off. Being spring operated, I thought the spring may be too heavy for the cold water to open. I tried removing the spring & the shower did not improve.

Croydex do stipulate a min. 30cm head. Can you get non-return valves for low pressure?

May try digging out the tiled in pipes to see if there are any valves in there.

HW rate of flow.... 17litres/min
CW rate of flow.... 39litres/min

 

[ChrisR]

HW rate of flow.... 17litres/min
CW rate of flow.... 39litres/min
Both very good!

What's the highest point in thte pipework relative to the HW level, in the HW pipe's run?

 

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Not quite sure what you mean.

Base of HW supply tank 183cm, pipes run down to floor level (through the cylinder) then back up to shower head at 180cm.

The shower head could be lowered.

 

[kevplumb]

where does the cold feed to the cylinder come from

 

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where does the cold feed to the cylinder come from

...thats what I meant by the HW supply tank. CW comes from the same source as the CW supply, into the storage tank above the Albion Superduty cylinder.

 

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Have just measured the HW rate of flow through the 15mm non-return valve as 5.2 litres/min, down from 17litres/min.

Removing the valve gives 5.8 litres/min, suggesting it is the 15mm pipe restricting the flow as the bath tap is fed by a 22mm pipe. The Croydex H20 does not seem to accommodate a larger pipe.