Best flow/return temperatures Band B boiler

[cdbe]

We finally have enough radiators in our house (after extension/renovation relying on just a few in the wrong places running at full tilt to keep the house fairly warm) to maintain a nice temperature.

What should the boiler be set at? We have a megaflo so I presume there's a minimum (flow temperature) for this, and the boiler has a recuperator so does condense a bit so presumably a maximum return temperature would be good to aim for - although I can't see how much control I have over this with a low (potentially just one radiator as we have some smart TRVs) heating demand.

 

[Gasguru]

I'd run it close to maximum...you don't want it condensing much given its age and parts availability.
It's nearly 20 years old, unlikely to have ever had a proper service (and it's impossible to fully clean the recuperator due to the design and it could be very corroded by now)
The sump gasket (almost certainly required for servicing) appears to be obsolete (along with many other parts).
For the minimal gas savings keep the flow temp high.
Others with experience of this model may have a different opinion.

 

[Razor900]

I agree with GG. The last thing you want is that boiler doing any condensing in the primary hex. Wait until it needs replacement and go for a priority hot water setup so you can have different flow temps for heating and DHW reheat.

Once up to temp the return won't be a lot cooler than the flow but I would go for a flow temp of 70 degrees. You can get a roomstat that will only allow it to come on a few times an hour which will maximise efficiency by not cycling as much