On Feb 1, 4:32 pm, grouch wrote:
Lately our hot water has been taken over by the heating system which
is inconvenient when not
requiring the radiators to be on. It means we have to have house
heating on to get hot water,
not a happy situation in summer.

Not really so, normally. Boilers I've seen that provide heat
for radiators and domestic hot water simply rely on what's
called an "aquastat" to control the burner, keeping the boiler's
water jacket at/near set temp.

Resulting in firing up a BIG (for the purpose) burner to heat
a couple of gallons in the part of the jacket for domestic hot
water, and maintaining temp in lots of stuff you don't want
heated in summer.

House heating is only on when heating t-stat says so,
powering circ pump.

What sort of coup resulted in this "take over"? Why don't
you simply install separate water heater? It'll cost more
up front, and likely save lots long-term.

John