Bristan shower mixer-unit, wax controller, gone cold!

[Eddy009]

We would rather like to start taking showers again, now that the worst of the winter is over!

A professional plumber installed a Bristan shower mixer-unit here a year ago and at first it worked fine - although the water was never as hot as we would have liked it.

I understand from the instruction booklet that the mixing of the hot and cold water coming into the unit is controlled by some kind of expanding/contracting wax mechanism.

Slowly the maximum temperature began to decrease until last autumn the unit just wouldn't put out water that was warm enough for a shower. The maximum temperature was lukewarm or less!

Since then we've been happily having baths! But now that the "summer" is here, I'ld like to fix this problem.

I have detached the unit to see if the filter was blocked where the hot water enters the unit. It isn't.

If I switch the unit on, the hot-water inlet pipe becomes very hot with the water inside it, proving that hot-water is reaching and entering the unit from the Combi boiler downstairs. But the reasonable mixing of hot and cold that we had when the unit was fitted just doesn't happen any more. Only a LITTLE of that hot water is being taken by the unit, being mixed with cold, and being put out as tepid.

Have been in touch with Bristan and the so-and-so's have said they will send an engineer and possibly replace but ONLY if I first provide credit card details! I can see the possibility of a Bristan engineer turning up, fitting a new unit, but finding some way of relieving Bristan of the blame and thus charging my credit card!

Has anybody any advice?

We saw this problem coming before we got the new bathroom put in and we asked the fitter to install a manual unit with two taps, hot and cold. He convinced us this would make life a misery for people taking showers - with people having to rapidly adjust the taps if someone flushed a loo or ran a tap somewhere else in the house while the shower was being used. But we wish now we had stuck to our guns. How reliable are these units that rely on a blob of wax behaving itself year-in and year-out?

Thanks.

Eddy.

 

[tripty]

In general, Bristan thermostatic showers are very reliable (if fitted according their instructions) and stop the chance of being scalded in the shower; which can be quite likely with certain combi installs. Bristan are quite a good company to deal with and isn't your shower still under guarantee?

What sort of mixer is it? A bar one like this

Have you cleaned the non-return valves also? Try taking out the cartridge and clean it, smear some silicon grease on any rubber rings when putting it back together.

 

[Eddy009]

Thanks very much, Tripty. Yes, my unit looks very much like the one in your pic.

When you say I ought to try cleaning "the non-return valves", are these the two filters - where the hot comes in and where the cold comes in, from the pipes in the wall?

When you say I should try taking out the cartridge and cleaning it, is this "cartridge" just inside the right-end of the unit (as shown in the pic)? If I take off the temperature-setting case at the right-end, there is then a brass body that appears to be screwed into the main part of the unit - it has a typical tap-type head coming out of it for regulation of the temperature. Is this brass unit what you mean? It looks like it can be unscrewed out of the main casing with the right wrench.

When you say "smear some silicon grease on any rubber rings when putting it back together", is this just to make sure I can open the thing up again at some point in the future?

Sorry for asking the above questions, but am rather nervous about handling this unit, given that Bristan are being so touchy.

Thanks,
Eddy.

 

[tripty]

Have you got the original bristan instructions? If not see this pdf for an example:

http://www.bristan.com/WebRoot/BristanDB/Shops/Bristan/Products/INSTRUC. PDF-1032384-D2.PDF

Take a look at pages 3 which explains how to service the mixer and page 4 shows how it fits together - *but* it may *not* be exactly the same as yours. If you know the name of your mixer shower try and find the instructions for it on the bristan website if you haven't got the original or ask Bristan to send you a copy.

In answer to your questions:

1. the non-return valves are just after the filters.
2. yep, you got it the cartrigde and/or a retaining nut should just unscrew.
3. yeh, the grease protects the rubber seals, helps prevent them being pinched etc. You don't want to put it back together and find it leaks

 

[Eddy009]

Tripty, many thanks for your help, above. Have just spent an hour doing as much of a check as possible.

1. Both the hot and cold filter-nets were clean. I even held a towel over both outlet pipes and then switched the water back on hard, to flush out any heavy grit that may have sunk down the pipes inside the wall, but no grit was thrown up.

2. Pressed both non-return valves downwards and then turned the unit over so that water drained from inside both non-return valves: and again, no sign of any grit or debris.

3. Tried to wrench, anti-clockwise, the brass cartridge at the right-end (cold-water end) of the unit but it just will not give! Struck the end of the wrench hard, half a dozen times, with a hammer, but still no give! It just won't unscrew. Visibly looks like a very tight fit.

4. Tried to wrench, anti-clockwise, the brass housing of the "ceramic disc valve" at the left-end of the unit, the hot-water end, but it too just will not budge! So couldn't check with there is very fine debris in there. Maybe both these brass units, right and left, have become stuck somehow during the six months or so of good use we got from the unit?

So there's a problem inside the unit and I can't get at it. And it really annoys the hell out of me, to feel the left-end of the unit feeling very hot, proving the hot water gets into it, but then this piece of Bristan kit has simply given up properly mixing hot with cold.

Have been on to our local Trading Standards Office and they've redirected me to "Consumer Direct" to get advice as to how handle Bristan's demand that they won't do a thing to help with this faulty device of their's unless I supply my credit card details first!

So, we'll see.

But am strongly inclined to just go out and buy an old-fashioned manual mixer-unit with two taps on it, so that it's us wot does the mixing from now on!

Cheers.
Eddy.

 

[tripty]

Calm down, are you sure your trying to unscrew the correct part? I've done that before - attacked a mixer with a spanner only to find I've been trying to unscrew the wrong bit.

Could you take a pic of the mixer with and without the end caps off?

Did you try WD-40?

Did you register your shower with Bristan? Have you got proof of purchase?

 

[Eddy009]

Hi Tripty,

Here's a copy of my Instruction Booklet. See page 6 for an image of the two cartridges at either end.

http://www.tradeplumbing.co.uk/assets/images/bristan/INSTRUC.PDF-1044824-D1.pdf

Meanwhile, have found the following interesting page:

http://www.howtomendit.com/answers.php?id=109710

I can't quite work the discussion out. Some of the guys above talk about the cartridge just dropping out, and others talk about having to place the unit in a vice on a bench in order to wrench it loose!

Mine looks like this:

Temperature Control End: take off the knob and expose the spindle, typical tap-spindle with teeth, in brass. It has a little clip just after it. Obviously this spindle turns within the body of the brass unit. From the clip onwards the brass is all one solid mass, culminating in a nut arrangement at the very end. The nut suggests the whole brass unit has been screwed into the outer chrome casing. But can I turn it? No. Maybe in a vice, I could. Anyway, have just looked at the instruction booklet and it shows the whole cartridge, including spindle, as being one item that fits inside the chrome outer casing.

Flow-Control End: take off the knob and there's another small spindle, clip, and then a bigger and more easily managed nut than at the temperature end, suggesting this cartridge too has been screwed into place. Will it turn? No. Again, maybe a vice would help.

It seems to me these things are ridiculously complicated! I mean, how would granny cope with something like this going on the blink every six months? Even if one of my neighbours has a vice, and I can get the two cartridges out, what then!?

I sent the registration card off to Bristan. Hopefully they received it and have it filed.

 

[tripty]

Yeh, the cartridge should unscrew. How big is your spanner? Might be scale sticking it in place so you could try some kettle descaler, white vinegar. But you've got a 5 year parts & labour guarantee, as you sent the reg off, so I'd try getting them round.

 

[firstalertplumbing]

You should fit a pressure equalisation valve as per manufacturers instructions.
The rate at which the combi runs will differ from the rate of the shower slowing the flow through the combi thus heating the water more which in turn will confuse the thermostatic mixing valve on the shower as it trys to compensate for the heat rise, shutting the hot off altogether. A equalisation valve will have to be fitted within a certain distance from the shower itself (usually 1 meter) so re-tilling often ensues. Hope this helps :)

 

[Phil1960]

We are on our third thermostic cartridge. The things seem to last two to three years at the most. Must be a design fault.