Cold Thermostatic Shower but Hot Water from Taps (Combi)

[Julia30]

Hiya,

I moved into a Victorian terrace-house 18 months ago. It has a Vaillant combi boiler with dials rather than digital controls. The manual says "TURBOmax VUW 242/1 E, 282/1 E."

This story may be unrelated, BUT I had a new bathroom fitted in October. I used to have a Mira shower that seemed to work fine. However, the guy I hired was a total cowboy who installed a new thermostatic shower valve upside down, which stopped the shower mixing. The shower's manufacturer flipped the cartridge, which seemed to solve the problem. This could be irrelevent though.

The shower worked okay for a few weeks, although two separate plumbers commented that the water wasn't very hot (despite the water dial on the boiler being set to maximum - 9). The water seems to have gotten gradually cooler since then. Now the shower is icy cold. It seems worse when the washing machine is running, but it's hard to tell.

Turning on the cold bath-tap used to help the shower temperature (probably by restricting the water flow). Similarly, the hot water taps in the house don't get very hot. They run cold when you run them at max flow. They warm up if you run them very slow.

I live in a REALLY hard water area. Could that be a factor? I've tried to do some research online, and I've come accross "blocked heat exchange plates" but that might as well be in Chinese to me! I've booked somebody to come and take a look, but I'm really nervous about being ripped off by another coboy. Does anybody have ideas about what this might be and how it could be fixed (and how much I should pay), just so I can be prepared when the next plumber/gasman turns up?

Many thanks in advance, Julia xxxx

 

[hazetimesfive]

so the water to all the taps is not as hot as it used to be?

 

[Julia30]

Hi hazetimesfive,

The taps are lukewarm if you put them on full flow, but I'm not sure if they're colder than they used to be. If you turn them right down (restricting the flow) they do get hot but even then they *only just* get too hot to touch. This applies to all the hot taps in the house (tested just now on the kitchen tap).

Xxxx

 

[Hugh Jaleak]

I know exactly what the water is like, and it's a fair bet the boiler has scaled up inside. Your boiler heats the water as you use it, with a constant flow of fresh water through various parts, then can (and do) scale up. By turning on cold taps and slowing down the flow of water through the boiler, it gets a greater chance to heat up.

 

[joe-90]

You have to remember that the water going into the boiler is much colder than it was in Novemeber.

How did the bathroom fitter get the cartridge wrong? It comes ready to fit out of the box. Sounds like it was wrong when you got it.

 

[Julia30]

Hugh Jaleak - it does seem like the water is going to the shower too fast, and not getting a chance to heat up. Our old method of slowing it down with the cold-water tap doesn't work any more though.

Joe-90 - the bathroom fitter installed the valve upside down. He denied that was the problem made us order a replacement cartridge. He "installed" that, and it (obviously) had no effect. He then refused to complete the work and we had to pay the shower's manufacturer to send an engineer to fix it. The engineer took one look at the valve, laughed, and then put the cartridge in upside down to match the valve. Luckily all the parts have rotational symmetry and it did cause the shower to mix properly for a few weeks. The water gradually started to feel colder though. I know the weather is a factor, but this is icy-cold - like it's not even *trying* to heat up. Annoyingly, the water out of the hot bath tap is fine (as long as you don't run it at full flow).

 

[picasso]

Can you isolate the feeds to the shower ? could be a stuck/missing non return valve passing cold water into the hot supply.

 

[Julia30]

Picasso - I don't know what that means! The hot and the cold do come from two different pipes.

This is the monster -

http://www.bathstore.com/products/trinity-victorian-exposed-thermostatic-shower-valve-315.html

 

[debaj]

Have you tried turning the thermostatic control on the shower all the way round in one direction and then the other to determine which way increases the temperature. Sometimes the pipes in older houses are fitted the oppsosite way and so the original installer may have installed the cartridge upside down to compensate for this, without installing the actual unit upside down. So where you might be intending to increase the temp it might actually be turning the mix more to the cold supply. Also do you know if the installer put a flow regulator in. As this shower is designed for low pressure systems, if your system has quite good pressure, as it sounds it does, the flow rate might be too great to supply hot enough water, as joe90 mentioned the supply water is colder and as Huge Jaleak mentions the boiler can only warm the water so much dependent on the speed at which it passes through it.

 

[Julia30]

Now I'm so confused! I thought I was doing the right thing by booking a boiler guy, but now everyone's talking about the shower itself!

The shower *has* worked correctly in the recent past (despite its initial problems) though. Also, the water coming out of the shower is icy cold, regardless of the temperature dial (in either direction). It's not lukewarm - it's freezing, so it looks like the boiler has just stopped trying to heat the water all together.

 

[Julia30]

Debaj - the bathroom fitter definitely won't have put any kind of flow regulator in. He was a total cowboy and not very bright. Do you think it's something I should do in addition to getting the system power-flushed and/or the heat exchange plate (??) replaced?

 

[debaj]

Do you still have HW from other taps. Try only turning them on so the flow rate is slow and see if you get hotter water. If you have "hot" water from other taps but cold from the shower (even with the flow turned down) then there is a separate problem with the shower. I think it sounds like Hugh Jaleak is right though about the heat exchanger being scaled. I would definitley get an engineer in to diagnose if you have no "hot" water at all.

 

[debaj]

Sorry Julia, just saw your other post. I would wait and see if you can rectify any problem with your boiler first. If there is no hot water getting to the shower at all then there is another issue. The flow regulator is just a small valve that should have come with the shower that goes on the back of the mixer cartridge. Whether it needs one would be based on the output of your combi.

 

[Julia30]

Just wanted to let you know - we fixed the shower. A plumber fitted a pressure regulator to the main water supply (into the house). He also moved the hot and cold pipes (so they were on the right sides) and installed a new replacement cartridge (the correct way up). Everything is fine now. Xxx