new combi boiler, now have cold shower :-(

[Sneaks]

Ok, I'm not very technical but will try my best.

We've just had an old back boiler, hot & cold tanks taken out and replaced with a worcester bosch boiler - its quite a big one as we have potentially 3 showers across 3 different floors so the plumber got us one that would cope IF we needed all 3 showers on (we only really use 1 shower).

Everything is fine, heating etc. but the showers are luke warm and have to be put on their hottest setting and its still luke warm.

The bathroom taps come out really hot so don't think its just because the showers are 'higher' in the house

The pressure of the shower is a lot better than we had before, almost power shower quality.

The plumber said he could increase the temp of the water but he said a) that would increase scale (and our hot taps are spitting out white water at the mo), and b) the water is actually fine from the taps.

I have 2 theories

1) the pressure is too high - the boiler can't keep up with heating the water. What do I do if this is the case?

2) they are mixer showers (I have no idea if this is true!) and perhaps we need thermostatic showers - but from what I understand, they are used to stop FLUCTUATING temp, they don't increase the temp as such.

PLEASE HELP ME!

 

[Agile]

This is a common problem!

I dont know why your boiler installer is not answering your questions but many dont know much about showers and some dont communicate very well.

Thermostatic showers mix a proportion of cold water all the time with the hot. This seems to increase as they get older and perhaps if internal seals are failing.

I dont deal with showers because they are too problematic. One simple solution is to restrict the cold flow into the shower with the isolating valve but these are rarely fitted. Another is to take the shower apart and clean and descale it but this needs skill. Last is to replace it with a new one and hope it will be a bit better.

The problem is that shower makers love pictures of ladies using their showers but fail to give all the technical info we would need. Thats another reason I dont deal with showers.

You must have a VERY big boiler to run three showers together or perhaps they dont have a very good flow rate.

Tony

 

[Sneaks]

I would imagine that if we did run all three boilers together it would be a stretch. It was originially a student house, with 2 ensuites and a bathroom, but we kicked all our mates out, bought the house and now me and my hubby live here along (with dog and cats), so we only usually have 1 shower on at a time. But we wanted to have the option of having 3 in case we ran out of money and had to get lodgers in.

 

[Sneaks]

the boiler says 'greenstar 30 CDi' on it if that helps?

would a thermostatic shower be the best replacement?

How do I know if it is already a thermostatic shower, or whether its just a mixer?

 

[sidepipe]

If it's just a mixer shower, then normally it will have a hot and cold tap and so you could just adjust them until the flow rate is slow enough. A thermostatic mixer will generally have some way of adjusting the temperature, whether in combination with flow or as a separate control.

The "white water" out of your hot tap may just be tiny air bubbles... does it get whiter as it gets hotter? Fill a glass and see if it clears. We have a Worcester Greenstar 37Cdi and it does the same, and we live in a soft water area!

I would have thought that a 30kW boiler would be enough ( just ) to give you a warm shower at a reasonable flow rate, but if it is a mixer where you can not control the flow and temperature separately, then it could just be that the flow is too high - see if there is a valve/tap on the cold inlet to the boiler and try turning it down a bit - if the shower gets hot then its the flow rate, if not, its the shower valve.

Thermostatic mixers are extremely simple devices, but sometimes they can stick. Take it apart and give it a bit of a clean ( you really won't believe how simple it is! )

 

[Sneaks]

Thank you!

The shower has a silver torpedo shape kind of bar, on the left end there is a dial you turn for more/less water to come out (with little dots on it), on the right end there is a hot-cold dial, (with increasingly bigger red/blue dots on).

I assume this is a thermostatic one?

if the shower was working perfectly fine with the old boiler system, and the plumbers did nothing to the shower, do I assume its the pressure in - as you say the little tap near the boiler?

I'm scared to touch anything in case I blow up the house with gas!

 

[Sneaks]

oh and pretty sure its limescale. I filled up a black cereal bowl with hot water from the kitchen tap and it was like someone had dissolved a piece of chalk in it - you couldn't even see the bottom of the bowl, even after waiting a few mins.

 

[sidepipe]

Well, its probably the flow rate - there are a million posts asking questions about combis and flow rates on here ( including one from me ) and so it is really a common problem.

HOWEVER... if you have a flow rate adjuster on the shower itself, then in theory turning the flow down should help. If it is indeed thermostatic then it should adjust to the slower rate and the hot water should be hotter. If this doesn't happen, then I would suspect the shower valve - it could be that some dirt entered the pipe whilst the boiler was being fitted and is making it stick ( though it sounds unlikely... )

Slowing the cold water flow in to the boiler will fix the issue if the problem is that the boiler can't cope. Another thing that you can try is put the hot bath tap on full blast and see how warm the water is ( not conclusive because the shower may not be the same rate, but an indication at least. )