Hot water query

[denis567]

We have only lived in this property a few months, and we are in the middle of some extension building work. The plumber informs us that the central heating system (oil fired) has been connected up so that it is not possible to have hot water, in the summer, without the full system being switched on. He informs us that it would be a very expensive job to have the system altered.
We have an electric immersion heater, but it would be very expensive to use that through the summer, so I wonder if it would be possible to have the central heating system working, but to physically turn off all the radiators, so that we still have hot water.

[buildersmate]

The best person to ask about this is going to be the plumber who has inspected it and understands exactly how it has been plumbed. However what he will probably tell you is the following:
Water circulates around the primary circuit, moving between the boiler (where it gets heated) to the rads and a coil that runs through the hot water tank. When hot water runs through the HW tank the heat in the coil transfers into the secondary water of the tank to heat it - this water eventually gets drawn off to supply your HW needs.
Any one of these devices (rads / HW coil) can usually be turned off individually. This is effected by connecting them in parallel - not in a long string. In other words, the primary water runs through one device before being returned back to the boiler to be reheated.

Having understood the above, you should be able to appreciate that you can turn off all the devices except one - the HW coil (which in your set-up is probably not possible to turn off) and the HW will still work.

The way a conventional set-up works (which you don't appear to have) is using a diverter valve which forces the primary water into either the HW coil or a pipe leading to all the rads (which splits individually to them further down the pipe), or both. This enables quick and easy diversion of water into either HW, CH or both parts of the system.

[denis567]

Thanks buildersmate, will certainly have a word with the plumber when he gives us a quote for the cost of rectifying the problem
Denis

[maclarencat]

I dont know if this helps but at our last house we never altered our boiler in the winter or turned the radiators off we simply turned the central heating room thermostat down to 5% and that meant the heating never kicked in but the hot water still worked.