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Mixer tap fluctuating temperature

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brightncheerful
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Mixer tap fluctuating temperature

#140374

Postby brightncheerful » May 21st, 2018, 3:21 pm

The mixer tap on my shower isn't temperature-specific controlled. There are two taps: one for the water flow, the other the temperature. The hot water pipe comes from the central heating boiler, so too the cold presumably?

What I don't understand is why after I've turned on the water flow and turned the temperature tap to enable a comfortable temperature during showering and then turning off the water flow tap to stop the shower, the next time i turn on the water flow tap, the temperature of the hot water is hotter than I'd left it so I have to adjust the temperature tap each time i use the shower.

any suggestions, please?

tia

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Re: Mixer tap fluctuating temperature

#140379

Postby PinkDalek » May 21st, 2018, 3:29 pm

brightncheerful wrote:The mixer tap on my shower isn't temperature-specific controlled. There are two taps: one for the water flow, the other the temperature. The hot water pipe comes from the central heating boiler, so too the cold presumably? ...



Depending on the type of system, I'd guess there is a separate feed for the cold and the hot comes from a hot water cylinder. If that's the case, wouldn't using your previous setting depend on how hot the water in the hot water cylinder is, when you next come to use it?

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Re: Mixer tap fluctuating temperature

#140388

Postby Meatyfool » May 21st, 2018, 4:08 pm

My grohe shower started playing up - it turned out that the thermostatic mixer used a wax based cartridge which over time starts to fail to mix and maintain temperature . Don't recall if the symptoms were the same as yours, but replacements can be found on t'Net, and you don't need specialist plumbing knowledge to replace them.

Though in my case I did need to acquire a 35mm spanner.

Meatyfool..

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Re: Mixer tap fluctuating temperature

#140389

Postby csearle » May 21st, 2018, 4:14 pm

brightncheerful wrote:What I don't understand is why after I've turned on the water flow and turned the temperature tap to enable a comfortable temperature during showering and then turning off the water flow tap to stop the shower, the next time i turn on the water flow tap, the temperature of the hot water is hotter than I'd left it so I have to adjust the temperature tap each time i use the shower.
What I'm wondering is if maybe it takes a while to stabilise the temperature but that you're super keen to get in there quick! Or, maybe you adjust it once your long-suffering body has acclimatised to the heat and get a shock next time when you thrust your cold self into the hot deluge? C. :)

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Re: Mixer tap fluctuating temperature

#140390

Postby Slarti » May 21st, 2018, 4:16 pm

Every cold tap in my house is fed directly from the mains.

At least 2 of them run alongside the hot pipe as the cold water can run very warm, if the hot has been run first. EG Wash hands and face, then wash teeth.


Since my recent boiler incident, for the shower, the mixer tap now has to be set at a different, cooler, position to get water at the temperature I want. So I assume that the hot water in the tank is now hotter.

If it is not a thermostatic mixer, then given varying temperatures of hot and cold water, why would the same position always give the same temp?

Also, if you are turning the temp down, each time, won't it soon be off? Or do you have to turn it up during your shower?
Or is someone else using it who likes it hotter?

Slarti

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Re: Mixer tap fluctuating temperature

#140392

Postby Maylix » May 21st, 2018, 4:34 pm

The cold supply also will come either from the cold mains or some sort of header tank in the house. Either way, the cold water is not at a constant temperature; the temp of it will depend on several factors including the ambient temperature, so on a hot day will be slightly warmer....etc.
HTH
Maylix

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Re: Mixer tap fluctuating temperature

#140397

Postby brightncheerful » May 21st, 2018, 5:15 pm

Combi boiler, no tank.
No one else uses the shower or runs hot tap(s) elsewhere in the house at the same time.

Ambient temperature I understand - I have a window open all weathers. Perhaps the boiler heats the water to a higher temperature when i turn on the water flow tap at the start and doesn't maintain the consistency throughout and/or once the water flow tap is turned off. The inconsistency might be caused by the boiler having to also heat the central heating radiators, one of which is underneath the open window.

I don't change the comfortable temperature at the end of the shower so needing to acclimatise my initial cooler body temperature to the shower's hotter level makes sense. Albeit doesn't explain why as I have to lower the temperature whenever I use the shower the starting temperature should be cooler, unless my body is colder than i think.

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Re: Mixer tap fluctuating temperature

#140400

Postby jfgw » May 21st, 2018, 5:55 pm

brightncheerful wrote:Combi boiler, no tank.

Thank you for clarifying. I guessed that from your original post.

Has the shower always done this or was it ok in the past? Has it slowly gotten worse?

What sort of shower is it? Do you know if it is manual or thermostatic? Do you know the names (Manufacturer and model)? How old is it?

I have known this sort of issue to be cured by descaling the cartridge of a thermostatic shower.

Julian F. G. W.

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Re: Mixer tap fluctuating temperature

#140422

Postby tjh290633 » May 21st, 2018, 6:49 pm

It strikes me that this may be down to differing pressures in the cold and hot supply. Unless they both come from the same source, there can be differences in the pressure, and the route that they have to take will affect it.

My daughter has a combi boiler and I always use the shower at the maximum temperature, as the boiler setting for hot water seems to be suitable. The temperature at the sink hot tap seems to be lower, which may be down to a longer route causing higher heat loss.

Could it be that the problem lies in your boiler controls?

TJH

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Re: Mixer tap fluctuating temperature

#140488

Postby stewamax » May 22nd, 2018, 10:28 am

the next time i turn on the water flow tap, the temperature of the hot water is hotter than I'd left it

Q: But does it stay at that (hotter) temperature or gradually over a minute or two settle down to a colder temperature?
It is normal for shower cartridges to have a short delay in responding. When you turn the shower on, water at the shower head is initially cold (brrr...), then get hot, probably overshoots the desired temperature setting, and finally settles back to the desired set-point. if your cartridge is ageing or the mechanism attached to it that controls the flow of hot water is scaled up, the response time might be minutes - or it might not even ramp down until you turn the temperature knob/lever to kick the mechanism into life.
The combi boiler itself might be the cause, with an intermittently sticking diverter valve, but the shower cartridge sounds like the culprit.

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Re: Mixer tap fluctuating temperature

#140733

Postby brightncheerful » May 23rd, 2018, 11:42 am

jfgw wrote:
brightncheerful wrote:Combi boiler, no tank.

Has the shower always done this or was it ok in the past? Has it slowly gotten worse?
What sort of shower is it? Do you know if it is manual or thermostatic? Do you know the names (Manufacturer and model)? How old is it?
Julian F. G. W.


Always done this. installed new approx 10 years ago.

I don't know what sort of shower it is - manual i think. No overt sign of manufacturer or model: we chose the style etc from brochure provided, supplied and fitted by the bathroom installer. I could probably get details from them.

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Re: Mixer tap fluctuating temperature

#140735

Postby brightncheerful » May 23rd, 2018, 11:48 am

tjh290633 wrote:It strikes me that this may be down to differing pressures in the cold and hot supply. Unless they both come from the same source, there can be differences in the pressure, and the route that they have to take will affect it. My daughter has a combi boiler and I always use the shower at the maximum temperature, as the boiler setting for hot water seems to be suitable. The temperature at the sink hot tap seems to be lower, which may be down to a longer route causing higher heat loss. Could it be that the problem lies in your boiler controls? TJH


The boiler has two controls for temp: one for water from taps, the other for radiators. I have tap temp 57, rad temp 60. Neither at maximum, more likely 75% max.

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Re: Mixer tap fluctuating temperature

#140736

Postby brightncheerful » May 23rd, 2018, 11:51 am

stewamax wrote:
the next time i turn on the water flow tap, the temperature of the hot water is hotter than I'd left it

Q: But does it stay at that (hotter) temperature or gradually over a minute or two settle down to a colder temperature?


I don't know. I haven't (yet) given it a chance to settle before I turn the temperature down a bit. I shower daily: tomorrow I'll attempt to withstand the experience.

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Re: Mixer tap fluctuating temperature

#140774

Postby jfgw » May 23rd, 2018, 1:38 pm

brightncheerful wrote:I don't know what sort of shower it is - manual i think.


You could try adjusting the hot water temperature at the boiler. A thermostatic shower valve should adjust automatically but a manual one will have to be set to a significantly different position.

Do you have any other mixer taps such as on a basin or sink? What happens if you set a comfortable temperature and hold your hand under for a couple of minutes?

If it is a manual shower, the problem is almost certainly elsewhere.

Julian F. G. W.

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Re: Mixer tap fluctuating temperature

#140919

Postby brightncheerful » May 24th, 2018, 10:27 am

This morning, I turned on the shower as usual but instead of immediately adjusting the temperature to suit, I withstood its starting temperature. I wasn't aware of any change in the starting temperature throughout the experience and gradually I got used to it.

Which rather confirms as someone has suggested that my body temperature (and the ambient temperature) before going into the shower are the determining factors.


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