low hot water flow from combi boiler

[bcoleman]

Hi,

I've got a FER FALCON combi boiler and while it seems to produce a good DHW flow to my kitchen taps, the hot water flow upstairs is pretty feeble.

The main problem with this is it makes it very difficult to get the mixer shower (manual one from a set of mixer taps) to produce a nice even temp and the shower seems to either be too hot or freezing cold - or even cycling between the two even when the position of the taps is not moved!

Any ideas what might be causing this? I've made sure that I'm not running any other water at the same time so this shouldn't be the reason.

Thanks for any ideas you can offer.
Ben

 

[Agile]

What you think the flow rate and what it actually is may be different.

You need to measure it with a container and stopwatch.

Then tell us and we can comment.

When was the boiler last competently serviced?

Tony

 

[bcoleman]

Thanks Tony,

You were right - just measured it and am currently getting around 7 l/m of hot water on the downstairs tap and exactly the same upstairs. It juts looked different to the naked eye!

Anyway, I measured the flow from the cold tap as well and it's around 12 l/m.

Are these levels to be expected? Should I be able to get a nice even temp on the mixer shower with these hot and cold flows? If not, is there any easy way to even the flows up?

Not suer when it was last serviced as have only recently moved in - probably not for a while though.

Thanks again.

 

[Happyplumber]

You will find it very difficult to control temperature on shower with manual controls,a thermostatic shower unit which is suitablle for combination boiler needs to be installed


Something like the one below and cheap as chips

http://www.screwfix.com/prods/47639...r/Triton-Altair-Thermostatic-Bar-Mixer-Shower

 

[bcoleman]

Thanks but is that the only option? can't i do anything to increase the flow to the hot tap or decrease the cold one?

Have only just put the standard mixers on and don;t really want to have to chnage them!!

 

[Agile]

Can I suggest an alternative?

Firstly the boiler if in good order should be able to heat 7 li/min to about 45° at this time of year, thats too hot to keep your hand in for long.

Secondly, use hot water only at the shower and adjust the boiler DHW temp until thats comfortable ( or just a little too hot and then add just a trickle of cold, best setting the cold on its own before turning on the hot ).

Of course that assumes your boiler actually has a hot water temp knob! its a very basic model and some dont!

If it doesnt then you will have to do the best you can setting the cold flow but it will be a VERY sensitive adjustment.

Tony

 

[bcoleman]

Thanks Tony.

It has got a dial on the front for adjusting the hot water temp so I'll give that a try tonight.

Othwerwise, could I fit some sort of valve into the feed to the cold tap to reduce the flow to something more like that of the hot tap? Would one of these do the job, or are they 'all or nothing'??

http://www.screwfix.com/prods/16505/Plumbing/Brassware/Isolating-Valve-With-Handle-15mm

 

[Agile]

You can adjust the cold tap to any flow rate you choose so I dont see any point in restricting it at the supply pipe.

Tony