Hey Scotch,
probably a different thermostat cartridge in your mates laddomat or similar loading valve.. You can swap it out for a higher temp one..yours could be a 78 degree unit?

It won't be the Laddomat. That just controls the temperature that the store loads at. Once the whole store is at that temperature, the store temperature will continue to rise as long as the boiler is dumping energy into it.

I would look for a boiler thermostat of some sort. My Atmos has a fan thermostat and an air intake thermostat.

Look at page 10 section 4.2 of http://vigasboilers.com/wp-content/themes/vigasboilers/pdfs/Vigas%20Manual%20Feb%202010.pdf. That tells you how to change the boiler water temperature of a Vigas with AK3000 controleer.

Well that seems to have worked, the store now gets to 90 degrees and I am getting an extra day between burns.

Cheers
Scotch

Posted By: tonySadly also maximising your heat losses

But unless I'm misunderstanding that's just more rapid heat loss on heat he wasn't previously able to store (i.e. previously lost). The same amount of wood has been burnt in both cases hasn't it? When the store gets down to 80 degrees he's back to the heat loss situation he had before, but he's gained whatever time that has taken since the burn. So that's a win isn't it?

Maybe we're just looking at the same thing from glass half full & glass half empty points of view?

Tony, I assume you have a traditional DHW tank rather than a TS type setup?

Just had a long meeting with our plumber and this issue came up. He is advising the vented route with our TS and smaller DHW tank and use of flat plate heat exchanger on smaller tank to provide mains pressure DHW but my concern is that the tank would need high 60s-70s to get nice hot water for showers. Will only be the smaller tank rather than the 1000l TS but still seems higher than you could get away with if we were using the water directly rather than through a heat exchanger. So many options!

This is a hard one.

Tony's point about heat loss is correct but is only part of the picture (unless you were to use an immersion heater).

Running less frequently there are less transient inefficiencies starting up the boiler and less instances of hot water left in the pipes.

There is also another downside as the boiler efficiency is probably lower for the last part of the burn when heating the water to 90 rather than 80.

I think it go either way depending on the distance boiler characteristics and distance from boiler to thermal store.

If you really want to tie yourself in knots try considering if a bigger thermal store at a lower temperature is 'better' (even this doesn't have a simple answer).