Thursday, 3 January 2013


There are bound to be things that I either forgot to mention in the manual or just didn’t have the time and space to talk about in any detail. As I spot them I’ll mention them here in this single blog posting. 

If you find any yourself feel free to write a comment here or email me and I’ll write up something to cover that topic.

Page 19 “Unvented hot-water cylinder”

The combination valve
I talk here about finding the tap that turns off just your high pressure hot water. What I didn’t mention is that this tap often turns off some or all your cold water as well.

Why would it do that? Well mixer showers, for example, work best if the hot and cold water enter the shower valve at exactly the same pressure. In a high pressure system this is usually the case anyway but it isn’t guaranteed. For example, the maximum pressure of the hot water is restricted - usually to 3 bar – whilst the cold water is left to roam wide and free to hit whatever pressure it feels like. It's unlikely that your cold water would routinely be over 3 bar, but it’s not unheard of and in this situation your mixer showers would start to act up as they try to deal with hot and cold water at different pressures.

To prevent this happening the cold water for all the showers is often taken off from the combination valve attached to your hot water cylinder. This valve is where the pressure reduction of the hot water takes place and as such now ensures that both hot and cold water are at exactly the same pressure.

From a homeowners point of view this is no big deal but the fact that I didn’t mention this might cause some confusion.

Page 76 "Replacing the washer on the stop tap"
In step 5 you need to be supporting the stop tap with either a set of pump pliers or an adjustable spanner before you start trying to loosen off the head otherwise you risk damaging the pipework entering and leaving the tap. I guess this is common sense really, but worth while mentioning just in case common sense isn't all that common after all :)

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