Thermal store question

[Robert Tyrrell]

Ive got to take a second look at a thermal store this afternoon that's connected to a gas boiler and the problem is that the heating won't come one unless the water is on as well, when the heating reaches temperature the water heating isn't working - or so I've been told They can't get enough hot water to have two showers in a row.
I've tried changing the old Potterton EP2002 programmer for a new Drayton LP722, which should cause the HW to run independently of the CH but it isn't.
I know that theres a 2 port on the heating side but no other valves sooooo.... does anyone have a wiring diagramme that I could use to help diagnose this?

Cheers

 

[deg]

Are you sure it's a thermal store? That's not how they work.

 

[leesparkykent]

The water in the thermal store circulates around the radiators which is normally controlled by a room thermostat and pump. The hot water is mains pressure and heated through a heat exchanger/coil by the water in the thermal store.....So the thermal store needs to be up to temperature to provide hot water. IMO its best to maintain the thermal store temperature so always got hot water and can draw when required for heating.

 

[zzzjim]

.......So the thermal store needs to be up to temperature to provide hot water. ....

As Lee explains. One stored source of heat , If you budget is limited the only way to get more Hot water out is to demand less of your heating !

Or have controls set to keep thermal store up to heat , at a higher cost .

 

[zzzjim]

...

 

[Robert Tyrrell]

Cheers guys but not much help really - I understand the principal of it all but not how to wire it all and that's why I was asking for the diagramme

 

[Robert Tyrrell]

I think that what's happened with the wiring is that the installer has wired it all to the heating and that means that as soon as the timer says no more heating is required, the boiler is switched out and stops heating the stored water resulting in a lack of temperature in the thermal store so that there is no hot water for the shower.
This is why I need the diagramme - so that I can work it all out without having to squash myself into a small, dark space with my torch, multimeter and screwdriver

 

[Last Plumber]

http://www.jouleuk.co.uk/wp-content/uploads/2015/09/Thermalstore-Installation-Manual.pdf


Have a look at this there's a few different ideas on here.

i don't come across them often, there aren't many in my part of the world but are they not supposed to be permanently hot ?

 

[Robert Tyrrell]

i don't come across them often, there aren't many in my part of the world but are they not supposed to be permanently hot ?

Yep I think that they are - this is the first one I've found around here as well. Mostly UVDHWC around here.
Thanks for the link btw - I'll take a look

 

[Robert Tyrrell]

OK - I've had a look at the wiring diagramme in the pdf that Last Plumber supplied the link to and I've altered it to suit what I know is there at the moment so if anyone can see a problem please let me know

 

[Last Plumber]

I would wire it so that the boiler is on the Hot water channel of the prog to keep the tank hot during the day at least. Via the tank stat and HLS

Wire the CH zone valve from the prog CH Channel via room stat.