Combi boiler & Shower problem

[badboilerz]

Morning everyone,

Just wondering if I could get some input on a problem we've been having with the Shower/Combi boiler for quite some time now..

We have a Mira mixer shower running of the combi boiler, it will run warm when you turn the temperature from cold to hot. All ready and good, you jump into the shower then suddenly it'll decide to go cold, luke warm or hot in random order

It will do this 80-90% of the time whenever someone goes for a shower (this month it seems to be moving permanently to luke warm shower/cold).

I've noticed the hot water pipe feeding the shower body gets cold before it actually feeds into the shower body itself...
Therefore making me think that the issue is not the shower unit itself, but more on the boiler side?

A trick which has been working (but less now, over time), is to turn the bathroom sink/bath cold water on which will help sometimes and balance the cold water? the shower will then be a little warmer. If this still doesn't do the trick then the warm water tap will be tried along with the cold, but at a lower/slower flow than the cold tap...

As you can see it's very annoying, but it is also causing alot of water wastage... One shower will need two taps running and the shower..

any help is much appreciated

 

[picasso]

what boiler do you have ?

 

[badboilerz]

Hi,

It's a Sarigas F20A i think

 

[picasso]

How old is that ? its probably got a diaphragm and microswitch for the hot water so on the information you have given worn diaphragm,


(jesus I am starting to sound like our resident cell 84 terrorist)

 

[badboilerz]

Its ~10 years old. I'm going to have a look in the manual and see the wherabouts of the part you metioned..

Is the part serviceable at all? Or only to be replaced

Thanks

 

[gigz]

If you open a hot tap does that go hot and cold as well ?

 

[picasso]

I just looked at the instructions and can honestly say that they are worse than ferrolis, the diaphragm is normally a cheap part to replace but your boiler is not exactly run of the mill.

 

[Tipper]

It's probably the shower-only flow being to low for the combi to deal with hence it turns off and on (= cycling) and so gives alternate hot and cold water to the shower.

It could be the shower head is scaled up or indeed just a low flow type requiring too low a flow for the combi. Try removing the head from the hose, does it do it then?

I would suggest a new shower head and/or hose as that may also be restricted. Make sure you get one for a mixer shower and not one for an electric shower as they usually have smaller jets and a lower flow.

 

[badboilerz]

If you open a hot tap does that go hot and cold as well ?

Hi,

yes the kitchen tap water is normally hot, it is however luke warm when the pressure or flow is full tap open. In between flow it usually stay hot/very hot..

 

[badboilerz]

I just looked at the instructions and can honestly say that they are worse than ferrolis, the diaphragm is normally a cheap part to replace but your boiler is not exactly run of the mill.

Thanks picasso. I've never liked the boiler myself, just waiting for the right time to get a new one, too much on at the moment..

I've had a look in the manual the only thing that I can make out as the diaphragm is the divertor unit within the pump unit itself, is this the part you are referring to? If it is, then it shouldn't be too much of an issue, as I've had that out in the past...

 

[Charnwood]

The further you open a hot tap fed by a combi the cooler the water coming out of the tap will be.
Combis are the work of the devil!
Try filling a bath from one.