Hot water shenanigans

[Prezza]

Ok folks, need some advice here. My father-in-law has a cold water storage tank in the attic which feeds the cold bathroom taps - the kitchen cold is direct from the mains. There is no traditional boiler - combi or otherwise - as hot water comes from a timed immersion heater in the ground floor airing cupboard and is pumped directly into the hot water cylinder - also in the airing cupboard. However, since a new immersion heater was installed, warm water is coming out of the bathroom's cold taps and also making its way into the cold water storage tank. Can anyone tell me why?
Cheers folks.

 

[cross thread]

Check the thermostat setting on the new immersion,set to 50-55 degrees

 

[CBW]

Are you sure it’s a separate immersion heater - a setup I’ve not heard of or seen before. Has any work carried out other than that? Perhaps a mixer tap became faulty when the immersion failed?

Edit: just looked up online - is it a Willis external one?

 

[Prezza]

Yeah, the system has a separate small water heater next to the hot water storage tank. As far as I can tell, this heater (perhaps immersion is the wrong name for it) is on a timer to come on twice a day and sends the heated water to the tank. I just tried the cold bathroom tap a moment ago and it's producing warm water. The bathroom's cold taps are drawing water from the CWST in the attic, so the system must be forcing the hot water back up there.

 

[Prezza]

I suppose if too much hot water is being produced the pressure in the HWST could force it back from where it came, but I assumed the immersion heater would have some sort of non-return valve to prevent this.

 

[Nige F]

Are you sure it’s a separate immersion heater - it a setup I’ve heard of or seen before. Has any work carried out other than that? Perhaps a mixer tap became faulty when the immersion failed?

Edit: just looked up online - is it a Willis external one?

I just looked too - and saw that they need to be correctly orientated - The immersion @ the bottom ! Otherwise the created air pocket can mess up the heat setting.

 

[Prezza]

Just looked at one online and I think you're right, it looks like a Willis external immersion. Apparently NIE (Northern Ireland Electric) have timed control of the immersion because it's on Economy 7, and they're activating it for about six hours each day, which seems an awful lot considering only two people live in the house and the shower is electric. I think the excess is finding it's way back to the CWST through expansion. Thanks for the replies, you've all been really helpful.

 

[CBW]

Just check it’s not the cold water storage cistern that’s being heated up with the weather, is there insulation on the cistern?

 

[Prezza]

It's an old metal cold water cistern with no insulation, but it's never been a problem before. I think it's just a case of too much hot water being produced.

 

[Johntheo5]

Just looked at one online and I think you're right, it looks like a Willis external immersion. Apparently NIE (Northern Ireland Electric) have timed control of the immersion because it's on Economy 7, and they're activating it for about six hours each day, which seems an awful lot considering only two people live in the house and the shower is electric. I think the excess is finding it's way back to the CWST through expansion. Thanks for the replies, you've all been really helpful.

As above, the immersion "top" must be on the bottom, these type of immersions suffer from very high outlet temperatures requiring the thermostat setting very low, not easily done with the thermostat in the bottom, the stats also fail, yours my have failed "on", a more permanent cure is to install a pipe stat on the outlet pipe from the immersion and wire it in series with the immersion stat(s), you then control the temperature with this stat and use the immersion stat as a o/temp stat.

 

[Prezza]

Cheers. That's good info.