"nickd" wrote in message
oups.com...

Sorry, I didn't make it very clear. I think
I can get the F&E tank higher than all
the rads now, so I could easily have the
whole system OV.

In this case, I don't need the heat exchanger
and can connect it exactly as it is at the moment
(with a larger boiler) or I could take
the CH off the Boilermate and feed it seperately
(which would give me the whole store for DHW).

Which do you think would be best?

The larger boiler should be adequate to re-heat fast enough and solve any
problems. Take the CH off the Boilermate as that is how it is currently and
this eliminates inefficient boiler cycling. If there are problems even with
a larger boiler, you can make the system a DHW priority system by inserting
a flow switch on the cold main just before it enters the store, and have
this, via a cheap relay from Maplins (about £5) cut out the CH pump. So when
DHW is called the CH is not extracting heat. Of course, get the DHW take
off coil cleaned out. This will entail pouring chemicals into the coile.
Best done when you have the thermal store out.




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