Replaced shower, no cold water.

[Stuart Grimshaw]

I recently swapped out an old Mira Event XS shower, with a new one of the same model, I had to drain the hot water cylinder because I couldn’t work out which tap turned off the feed and 2 of them were seized.

After fitting the new shower, hot water works fine but there’s no cold coming out, I’ve left it running a good while and nothing.

All the taps work as expected and there’s no water leaking from the shower, what should I be checking?

 

[Exedon]

Not a gate valve on shower cold feed by any chance?

 

[terryplumb]

Are the cold taps that work fed directly from the mains ? Did you drain the cold water loft tank ?

 

[Stuart Grimshaw]

Not a gate valve on shower cold feed by any chance?

No, or at least if there is, I didn't switch it off, I had to turn the water off at the mains.

Are the cold taps that work fed directly from the mains ? Did you drain the cold water loft tank ?

We do have a cold water header though I don't think it drained, after I'd shut off the main valve the cold water stopped all over the house.

 

[terryplumb]

You told us that you drained the hot water cylinder,how did you do that without draining the loft tank that supplies water to it ?

 

[Johntheo5]

No, or at least if there is, I didn't switch it off, I had to turn the water off at the mains.


We do have a cold water header though I don't think it drained, after I'd shut off the main valve the cold water stopped all over the house.

That shower has gravity fed hot and cold, so if you have hot water coming from the shower then the CWST must be full (but check it) as it supplies the HW cylinder so looks like a air lock in the cold supply to the shower, can you slacken back the cold pipe that attaches to the shower and vent/bleed it, (shower off).
Does the CWST supply cold water elsewhere and is it flowing there?

 

[Stuart Grimshaw]

I’ve loosened the bung at the bottom of the shower and cold water comes out so I don’t think it’s air locked.

Also, the motor has started to whistle a bit, I don’t want to damage it running it too much with no load.

 

[Deluks]

Did the hot water control dial in the right place, in relation to the knob that it attaches to?

 

[Johntheo5]

When you slacken that combined filter back do you get HW bleeding out as well.

 

[Johntheo5]

Have you tried running it with the shower head on the floor or remove the shower head and hold the hose on the floor while starting it.

 

[Stuart Grimshaw]

Have you tried running it with the shower head on the floor or remove the shower head and hold the hose on the floor while starting it.

Yeah, I removed the shower head and tried but still the same result.

I’m just going to replace it and try again.

 

[Johntheo5]

You have hot and cold water right up to the shower as proven by slackening the filter(s) housing, the shower pump is running because you can get a hot shower but not cool?/cold so points to the thermostatic cartridge, unit should be under warranty.

 

[Stuart Grimshaw]

I’m going to return my current unit. What’s the difference between thermostatic and non thermostatic? It looks like the previous model was non-thermostatic and the replacement IS thermostatic… could that be causing the issue?

 

[Johntheo5]

Thermostatic control gives very tight control of the set temperature required even if the supply of hot and/or cold water changes due to being drawn off somewhere else or the temperature in the HW cylinder starts falling, the vast majority of showers are thermostatic and are safer than non thermostatic, thermostic shouldnt cause the slightest problem.
Are you sure the hot and cold pipes are installed properly and not swapped?.

 

[Stuart Grimshaw]

The pipes are solid copper right into the shower and the previous one was the same model, and the cold worked OK then. I'm sure the pipes are not the other way round.

My replacement for the replacement should be here tomorrow, lets see how that goes.