new mixer shower, plus pump=weak/no cold water! Help please!

[alp078]

hi, i wonder if someone could offer some advice.

We have recently had a new thermostatic mixer shower installed, along with a twin pump. The cold is direct from the the tank in the loft above.

Hot to the shower runs just fine, but cold is pretty much just a dribble. It flows for a while and then cuts out, leaving us running the risk of scalding. The problem seems to come and go somewhat and may be explained by other work we have done in the bathroom; new basin, new bath??

The reason for the pump in the first instance was poor hot pressure with the old shower... we now have the opposite!

My thanks in advance for your thoughts. If any more info or even images would assist then i will gladly do my best!

Andrew

 

[seco services]

show us some pics.

 

[alp078]

happy to. What would it be useful to see in particular?

 

[seco services]

as you say its the cold that is the issue.
if you can explain the pipe run from the tank to the shower and is their any isolation valves etc.

 

[alp078]

ok, here goes... (hope these come out ok)

pic 1 Shows cold feed to shower from loft (in old set-up this was taken direct from the tank, now from tank, to pump, back up to loft to join this pipe. Hot comes up from h/w tank via pump

pic 2 Cold from tank in loft down to pump in airing cupboard (with tap in pic). Cold returned from pump in adjacent pipe seen exiting pic on left (where it then travels to down pipe in pic 1)

pic 3 Pipework as described above (mounted). Lower pipe into pump, upper returning. Pipe seen behind with tap at bottom of pic supplies h/w to basin and bath

pic 4 Pipework to pump

All valves / taps are at full open position

Any ideas gratefully received. Please let me know if i can supply anything else.

Andrew

 

[alp078]

to elaborate a little on the problem...

If turning the shower on full cold we get nothing but a dribble. If we turn it on 'cool' we get a short flow of good pressure before teh water warms slightly as the cold flow reduces and then cuts out completely (cutting the shower and pump off). The only way to get a sustained flow of good pressure is to run at hot only... which is, frankly, too hot.

Hope that helps.

 

[seco services]

i would say you have airlock in one of the horizontal pipes.and it can't escape.

 

[alp078]

ok, how would i identify this and how would i remove it?

 

[seco services]

does the hot from pump not go up to the loft and down to shower ?
does the hot when turned on at shower kick the pump in ?
does the cold when turned on at shower kick the pump in ?

 

[alp078]

1) No, from tank to pump, pump, down under floor to shower (shown up from floor in pic 1 above).

2) Yes, with good pressure

3) No, not when turned full on cold. Short flow (as described above) when turned on 'cool' (part hot, part cold) then cuts out cutting out pump.

Uploading a photo now of hot from h/w tank...

 

[alp078]

hot to and from pump (horizontal pipes). Right of pic shows pipe dropping down below floor (from pump) to shower

 

[seco services]

can you not run your cold from pump to shower same route as hot and not up to the loft.
looking at your pic you haven't go enough static head. at you loft tank.
what pump is it and model ?
looks like a salamander or stuart turner

 

[alp078]

salamander ct50.

Can you explain 'not enough static head'?

Would be difficult to change now as shower fully tiled and enclosure installed.

 

[seco services]

have you the instruction book that came with the pump?

 

[alp078]

sure, right here http://www.salamanderpumps.co.uk/Download/instructions.pdf

sorry, thanks for your patience