Which shower to buy?

[mike_DIY]

Hi.

I'm trying to get some help and advice on showers. BTW, I'm not a plumber in case you hadn't guessed We recently bought a house and had a new combi boiler installed (Its a Halstead CBX24). The boiler works great and gets the water nice and hot...

However we also had a new shower fitted (Bristan Artisan Thermostatic Bar Shower) which for the first 2-3 months worked pretty well. However its recently started to get colder and colder. Now it wont warm up at all. I spoke to Bristan about this and they said its because the cartridge has failed, probably caused by unbalanced water pressure between hot and cold outlets. I see now from doing a little more research that this is a general problem with thermostatic showers on unbalanced water pressures. We've gone and tiled up the pipework in our bathroom now so there's little chance of the pipework changing now, so I assume that only leaves us with the option of getting a different shower.

So I really wanted to find out what our option are with regards to showers. I had planned on just getting a manual mixer (This is the one we like) but I want to be sure this will work on our system before I go splashing out more money.

If anyone here is able to offer some advice on this I'd really appreciate it.

Mike

 

[secret squirrel]

You can just replace the cartridge, they all fail at some point, depends how old they are and use etc.

If you can't get to the pipework make sure what ever shower you buy fits! otherwise you'll be chopping out tiles anyway.

If the problem has been caused by unbalanced water pressures, this would show up normally on install but (I think) doesn't normally happen on combi systems. Unless theres quite a difference in pressure.

If the pressure is significantly different, then all your doing is just curing the symptom not the problem. Then, sooner or later have the same problem again, which will cost you another shower! To cure this you need to test the water pressure of the hot and cold then possibly fit a PRV.

 

[WHPES]

You don't want to get a manual mixer for a combi system! Must be thermostatic.

There are some makes of mixer which are able to work with unbalanced pressures but I would advise you get a PRV fitted to the cold supply to the bathroom.

Is your existing mixer a standard bar with 1/2" BSP connections at 150mm apart? If so any standard bar mixer will go in its place.

 

[mike_DIY]

Hi. Cheers for the replies.

What exactly is the reason you can't install a manual shower on a combi system? (Sorry if I'm being ignorant, I just like to understand the reasons for things). I would have thought a manual mixer was just a twin tap with a single outlet...therefore giving you control over how the water is mixed?

The existing shower has a technical data sheet on the Bristan Website [DLMURL="http://www.bristan.com/WebRoot/BristanDB/Shops/Bristan/Products/WEB_DATA-1059876-D1.PDF"]which you can see here[/DLMURL]. The thing is it actually states: "Suitable for all plumbing systems, preferably balanced". I'd just worry that getting another thermo shower would result in the same issue.

I don't think we can fit a PRV because the entire room has been tiled up and we really don't want to pull any of the times off...and if we fitted it to the pipe going into the room, we'd get reduced pressure at the sink and toilet as well...not sure if thats such a good idea.

Cheers again for any replies.

 

[Plumbstar Tom]

The PRV can go any where on the cold supply or even on the incoming mains

If you fit the correct flow limiters to the shower as well you should be okay with a single thermostatic shower on a combi

You buy Pressure balancing Shower vales for combis and these manually showers adjust and compensate for different pressures

 

[WHPES]

You shouldn't have manual mixers as the showers don't have a dedicated supply from a hot water source such as a cylinder (so if someone runs cold water, dishwasher runs etc. you get scalded, and vice versa for the hot).

Flow limiters can go into the outlets from the wall. They are simple little discs which throttle back the flow.

 

[WaterTight]

I thought combis produced mains pressure hot and cold at outlets?

Is unequal pressure common then?

 

[WHPES]

Depends on the rating of the combi. If demand for hot exceeds available supply the (dynamic) pressure will be lower than the cold as the combi won't be able to supply as much hot water as you are aksing for. Static pressures (with no demand) will of course be the same.

Just suppose your combi can supply 9 litres per minute of hot water and your shower requires 8 l per minute combined flow, mixing on average 70% hot to 30% cold. If a PRV is fitted ans someone runs a cold tap on full taking 8l per minute, the showe mixer is going to be starved. A thermostatic mixer reduces the hot flow to compensate. A manual will send out water at full temperature (getting close to 65 degrees C)

A reduced water flow shower head will help with your initial demand problem, but you still need a PRV.

 

[WaterTight]

thanks for that, very interesting, and makes sense

could you also buy a shower valve that is designed to mix mains pressure cold and low-pressure (be it gravity fed or low-rated combi) hot to solve the prob? presumably this is more expensive than fitting a prv ...

 

[LoraSt]

I don't know much about Mira or Triton.....But you can draw your attention at Gainsborough showers...My Stanza Black 8.5kw from electric showers 8.5 kw is working 3 years without any repairs. But I think you needed more powerful shower...9.5 or 10kw for example. What type of boiler do you have?