cold shower when the heating is on

[tomcord71]

Hi, brought an old house which is going to be fully renovated, but am struggling with the shower until I rip it out. There is a boiler in the kitchen feeding the central heating and the hot water. Not a combi. There is also a hot water tank in the bathroom cupboard upstairs and an economy 7 switch for this in the same cupboard. I assume there is a hot and cold water tank in the attic I need to check, not sure how the hot water gets into the attic, but the hot and cold feed for the shower come from above. I changed a very old thermostatic mixer shower for a basic B and Q mixer valve when we moved in. After that the shower has been ok, not great, but good enough. Now we have started using the central heating, the shower is rubbish. Can anyone advise why?. In my mind the heating and hot water are on separate circuits. The boiler heats the hot water on demand, but there is also the immersion heater in the tank in the airing cupboard for extra. Does the shower run just from the boiler or from the hot water tank as well? The hot water from the bathroom taps is still ok. Can anyone advise what I should be checking for. I don't really want to have to fit a electric shower when it will all get ripped out soon when we put up an extension.

Thanks

tom

 

[Azzer1704]

Do you have a pic of your airing cupboard? You say the boiler heats water on demand but that it's not a combi. Are you sure thats correct. Perhaps its a thermal store??

 

[Last Plumber]

When you say the shower is rubbish, do you mean poor flow, low temperature or something else ?
Bit more info if poss please, then we may be able to help you a bit more

 

[tomcord71]

ok, do did bit more digging around in the airing cupboard and attic last night, am in the process of putting together a diagram with all the pipes but in summary.

Three cold water tanks in the attic. Two joined together with a pipe to basically make a bigger tank. One small one that is full of crud, am guessing this is an expansion overflow tank?

Boiler is a gloworm 15HXI, so it s a combi, looks around 5-6 years old.

There is a copper tank in the airing cupboard, with a pump with 3 speed controls on it, a valve, which I guess is a flow diversion valve? A switch for hot water only or Economy 7, a thermocouple clipped to the outside of the tank and lots of pipes.

So I guess the hot for the shower is fed from the hot water tank, with the pressure supplied from a cold inflow to the bottom of the tank coming in from the attic tank? The cold for the shower comes straight from the attic tank. The water is plenty hot enough, jus the flow is rubbish. The hot water taps on the bathroom sink and bath are hot and flow well. The shower just does not have much flow when hot. But, if you drop the shower head to bath level and let if flow for a bit it seems better. It was all much better before we turned the central heating on. Someone has suggested maybe an airlock? I will sketch out the pipework and post the picture when I have ten mins spare.

 

[Stoney Ground]

That boiler is not a combi, and all hot water will be fed from cylinder.

If cylinder temp is not getting high enough as heating is on, this could be due to shower valve using more hot than cold and pressure on hot supply is lower as it goes through cylinder.

Try turning hot water on an hour earlier than heating to allow cylinder to heat up first.