Heat store and new boiler settings

[SmogLee]

Hi, I've got a large heat store and underfloor heating.

The boiler is controlled (switched) by a cylinder thermostat.

I've just got a new condensing boiler and I'm just trying to sort out best settings.

The cylinder recommends the cylinder stat is set between 65 and 70 degrees. Which is what I've done.. however, it does seem to over read as a setting of 60 degrees was giving return temperatures to boiler in excess of 65 degrees.

I've turned it down a little further so that return temp is 67 degrees before boiler switches off. So, that's a tank of hot water between 65 and 70 degrees by my reckoning.

Now, the boiler is a condensing type as you might imagine with modulation.

I need the boiler temp to be higher than the cylinder stat so that the cylinder control works (or the boiler would just keep clicking in trying to reach a temp it can't), but how much higher?

I've currently got the boiler set at 75 degrees, but given that the tank only needs to be say 70 max, is this too high? Can I lower it? Is it worth doing?

Thanks

Lee

 

[SmogLee]

Any advice guys?

 

[gasmarc]

i would have thought the the stat on the cylinder is set at 55 or 60 degrees would be fine , the stat will cut of when it reaches temperature on the cylinder