Hot and cold showers

[Emma1999]

I live in a flat in London in a converted three floor house. I recently had a combi boiler fitted but whenever I run the shower it goes hot and then cold. I have been told this is because combi boilers were not built to run showers and there is a backlog of water being heated causing the thermostat to cut out and therefore causing the cold periods. Other people in the other flats are probably using the water as well and this will be lowering the water pressure compounding the problem. Is this true and also is my only option an electric shower? Any help would be great. Thanks.

 

[Bahco]

Combi boilers were not built to run showers

Not true as you can get a lovely shower from them via a mixer shower.

Fluctuating water pressure DOES affect performance though on a combi shower but it will affect an electric shower too

 

[gas4you]

Are you on the top floor by any cahance as water pressure will be worse up there.

Could be other problems like the combi going to overheat and shutting off, then coming back on when temp drops. You need to see what boiler is doing when shower is running. Do your hot taps work ok?

As Bahco says, you have been told a load of old c**p about combis and mixer showers.

 

[Emma1999]

Yeah the hot taps do work and am on the first floor. Was told that because the hot taps use more water the through flow of the boiler is constant which means no backlog and therefore the themostat does not switch off. Whereas the shower uses a quarter of the water and causes this backlog which overheats and causes the thermostat to switch off. Is this to a load of c**p? If it is the boiler going to overheat and switching off is there any thing that can be done?

 

[Bahco]

The shower uses a quarter of the water and causes this backlog which overheats and causes the thermostat to switch off. Is this to a load of c**p?

Not an expert but given as my combi shower works lovely, it probably IS a load of crap

Is your shower ok to be fitted to a combi.

Check the make and ask the manufacturer.[/b]

 

[gas4you]

Lets get back to basics here. You have been told a pile of poo.

What combi boiler do you have? What shower do you have?

 

[Emma1999]

Just checked, the boiler is 'Glow-worm 24cxi' and the shower is a concealed 3/4" thermostatic shower value. Its apparently suitable for high pressure between 0.5-4.0 bar and is suitable for gravity fed, modulating combi boliers, pumped unvented and main pressure systems.
Is that enough info?

 

[Agile]

Providing the boiler is set up correctly then it should be possible to achieve a proper shower performance.

First thing to do is turn the hot water temperature at the boiler to half way and see what effect that has. Do NOT run on maximum!

Getting a proper shower can depend on setting the boiler and the shower to work in harmony.

Tony

 

[gas4you]

Have you checked that your shower head is not scaled up? I gather London is a hard water area.

Next get a bucket and measure a level of 10 ltres in it. Then see how long it takes to fill it. Try it will cold only, then hot only. Your combi should take about 1 min to fill this with hot water. If it takes longer then could be an inlet blockage or scaled up plate heat exchanger.

 

[ChrisR]

How recently fitted, Em?

 

[fitz1]

hasnt the cxi a pre heat.