Odd heating / hot water system

[ArtfulBodger]

Hi

Have to go and replace a couple of 11" heaters in central London tomorrow evening. The owner has sent me some photos of his setup. We have successfully established over the phone that he has voltage to both heaters and both are open circuit.

It appears to be a thermal store system running both HW and CH, via the two pumps.

If you look at the header tank you will see that there is no valve fitted nor an overflow!

Obviously both heaters are 3kW, so 6kW in total for CH? this doesn't sound like much to me. I'm assuming that the hot water is supplied via a heating coil and that the CH is run via the water in the thermal store.

So, can I drain down below the heater level just by opening the drain off in the picture or would the CH be via another heating coil?

Any advice appreciated, plus, anyone know just how good this sort of system is?

Ta

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[ArtfulBodger]

Come on! some of you brainboxes must be able to help!

 

[ollski]

one pump will flow the water round the main flow and return to heat the main body of water (the one you need to drain), the other pump fires up to circulate this water around the heating circuit, sometimes in a coil and sometimes not. The water flows round its coil under mains pressure.
I changed a pump on one today, give it a couple of hours to drain and over an hour to fill on thehttp://rangecylinders.co.uk/products/flowmax/models/electric7/index.html job cost.