Vado DX thermostatic shower

Goldenyears

We have an intermittent problem with  our Vado DX thermostatic pumped shower.  It was installed a year ago as part of a total main bathroom makeover by a small independent builder recommended by our architect (we had another ensuite bathroom that needed drawings and Building Control sign off).  The builders had installed many bathrooms/showers before. They were not specialists but they had access to qualified electricians and plumbers.  This may or may not be relevant.

Because the temperature seemed erratic and up to 43 deg for no reason I started to take regular measurements once a day with a digital max/min thermometer.  When the hot water supply temp varied over 57-62 deg the shower temp also varied 37-43 without touching the control handle.  Apparently my thermostatic valve was not thermostatic. Then I turned the temp down and for the next few weeks it entered a new phase of astonishing stability.  With the supply temp varying 57-62 deg as before, the shower temp was 35.1 plus or minus 0.2 deg every day.  It didn’t last. For one day only the temp was 44 deg, then  back to stability for 10 days then 44 deg for one day and so on.  Moving the temp control handle colder has absolutely no effect on days when it does this.  Any suggestions on what causes this?

ThisIsWeird

What type of water system do you have - combi boiler, for instance?

And exact model of shower - could you post a pic?

I'd be astonished if it wasn't thermostatic. Or do you mean that it is thermo, but doesn't behave like one?

And, stupid Q - the HandC were connected the right way around? When you feel the supply pipe as it enters the valve, which side becomes hot?

Did it ever work correctly?

Goldenyears

We have an electrically heated immersion tank. The hot is pumped.  The cold is gravity fed from loft cistern to the pump.

The Vado model number is CON-BV048D/3-BR  (and the faceplate/handle style is LIFE but not relevant)
The workings are behind the faceplate on a false wall so not accessible without removing handles and faceplate.  I may leave that to a local bathroom specialist to investigate and re-commission because the handle grub screws are behind a chrome button that doesn't come off without using a blade maybe (and then bounces down the drain).  
Did it ever work correctly ?  A good question. It may be that it didn't but I have only doing temperature checks for the last 3 months.

ThisIsWeird

Goldenyears said:

We have an electrically heated immersion tank. The hot is pumped.  The cold is gravity fed from loft cistern to the pump.
The Vado model number is CON-BV048D/3-BR  (and the faceplate/handle style is LIFE but not relevant)
The workings are behind the faceplate on a false wall so not accessible without removing handles and faceplate.  I may leave that to a local bathroom specialist to investigate and re-commission because the handle grub screws are behind a chrome button that doesn't come off without using a blade maybe (and then bounces down the drain).  
Did it ever work correctly ?  A good question. It may be that it didn't but I have only doing temperature checks for the last 3 months.

That's good info :-)

So, the supplies are from stored 'gravity' sources, boosted by a dedicated shower pump. You say the 'hot is pumped', and that the cold from the CWS tank goes 'to the pump'. By this, I presume you mean that this is a 'twin' pump, and that both the H and C are boosted by the same pump at the same time? Cool.

Your hot is from a hot cylinder, so that eliminates a possible cause - that the hot supply fluctuates, as it possibly could from a faulty combi.

Did the shower installers also fit this pump? Good - that means they are responsible for it all :-)

So, what's the cause? If the actual 'flow' from the shower is good - ie the pump fires up reliably, does its business, and pumps both sides effectively, then it ain't the pump. Can you hear it running during a shower? If so, does it sound 'even' at all times? Or does it sometimes make funny sounds?

I'm going to guess that it's either a faulty thermostat (the shower I fitted had a faulty thermo from the day of installation, but it was only when it completely stopped working 10 years later that I realised just how bad it was. I'd assumed, until then, that it was my combi not delivering the goods, but a new thermo cartridge made it work perfectly for the first time...), or the other possible cause could be that the hot cylinder requires a 'flange' to be fitted in its outlet, as - without it - it draws air from the expansion pipe. Silly Q - do you know if they fitted a 'Surrey', 'Essex' or other Home County flange in the top of your cylinder? Or, just about possibly, it could be that the gate valve supplying the hot cylinder is partially closed, but that would have involved a plumbing doofus, and they don't exist.

Anyhoo, at only a year old, the solution is to call them out :-)

Please report back.

ThisIsWeird

Another test - with the shower full on, how does the water flow change when you go from max hot to max cold? Are the flow rates similar?

Goldenyears

The flow does not change when you move the temperature control handle.  Both hot and cold are boosted by the pump which always sounds OK.  It was a new pump and cost an arm and a leg. I don't have any concerns about the pump.  My thoughts are that it is an intermittent problem with the cartridge.  Maybe the installer didn't flush out the pipes enough and some particles have got in.  The one thing we don't have to worry about is hard water. Our water is very very soft.  Vado have instruction videos on-line on how to dismantle and clean the cartridge. I have seen these, but I am not confident and will have to get someone in.