Bathroom refurb combi/shower query ( long-ish)

[jhiker]

I've got a Baxi 105e combi boiler heating a 3-bed semi and I'm generally very pleased with it. It's mounted in the airing cupboard next to the bathroom where the immersion heater used to be. The water pressure is good. There are no other tanks of any kind. The boiler on/off times are controlled by an external programmable timer and the boiler itself has a rotary switch to enable one of three settings, which are hot water only, hot water and central heating, and central heating only - I think. The central heating timed to come on in the mornings and in the evenings during the cooler months. The hot water, of course, on demand from the taps. Anyway, my point is this - during the warmer months the central heating is switched off at the timer so it never activates. The hot water continues to come on 'on demand'. The switch on the boiler is set to both central heating and hot water. When you put the tap on either upstairs or downstairs it takes a good while for hot water to come through - you can run off half a sink before it gets fairly warm. Would it be better to leave the electronic timer on it's morning/evening program all year round and set the boiler switch to 'hot water only' during the summer months. If it's set like this would it fire up now & again to keep the reservoir of water hot so it reaches the taps quickly? Which is the 'correct' way to do it? On a separate note - the boiler was installed with the intention of adding a shower later to replace the existing electric shower when the bathroom was refurbished. Hot and cold feeds were led to the back of the shower wall and capped. The time has come to have a shower fitted and I would like a bit of advice. I've read hundreds of threads on here and I think I've distilled them down to a few pearls of wisdom.. I reckon I need a thermostatic mixer shower but should I look for one with a pressure balancing valve. Indeed is there any way to tell whether I need a separate pressure balancing valve fitted before the shower without actually switching on and trying it? Bearing that in mind should I be looking for something like the Mira

415 - I want something reasonable but I don't want to spend a fortune. Lastly, what would you recommend for a durable, easily fitted surface for the floor - currently floorboards with hardboard on top of that. I want to paint the top part of the walls above the tiling but bathroom compatible paints aren't that inspiring - are there any suitable textured finishes or mock panelling boards that look OK once they're on the wall? I'd be grateful for any pointers.

[Ian Stirling]

The hot water and heating circuits are seperate. The problem is that your pipes contain half a sinkfull of water - this has to be run off before any hot can get out. There is no way round this - other than perhaps replumbing in 15mm pipe, which will trade off flow for waste volume, or adding some sort of system to circulate hot water back through a return pipe to the boiler, so there is no water going cold. Either of these is going to be quite major. But nothing you can set the controller to will help (it's possible that the central heating pipes run next to the hot water pipes, and warm them in the winter, so you don't have to run off so much.

[John Rumm]

I am not familier with this particular boiler, and hence don't know if it applies, but: some boilers contain a very small reserve of water that they keep "tempered" so that when you turn on a tap the water that comes out of the boiler is already at full temp (so called "instant" hot water). This helps minimise this problem.

If your boiler is one that does *not* have this capability then you have the added problem that you have a heat exchanger full of cold water to empty *plus* any additional water drawn through the boiler while it is lighting and proving the flame etc.