.flv player? Can't find anything.

Is that 'external air'? In UK - ASHP - 'air source'.

Wot owlman said above +1.

Apart from that modern machines use very little water and depending upon your pipe sizes and distance from the DHW source to the machine you could find that the machine has reached its water level before the pipe has heated up and can deliver hot water to the machine in sufficient quantity to make any difference. The machine then does its cycle pumps out and fills again,by which time the water in the pipe and the pipe has cooled down. IMO the probability of marginal benefit is high. If you have a tap close to the relevant machines run the hot tap and see how many litres of water flow before usable hot water emerges and then compare this to the amount of water per machine fill to level.

Posted By: Peter_in_HungaryWot owlman said above +1.

Apart from that modern machines use very little water and depending upon your pipe sizes and distance from the DHW source to the machine you could find that the machine has reached its water level before the pipe has heated up and can deliver hot water to the machine in sufficient quantity to make any difference. The machine then does its cycle pumps out and fills again,by which time the water in the pipe and the pipe has cooled down. IMO the probability of marginal benefit is high. If you have a tap close to the relevant machines run the hot tap and see how many litres of water flow before usable hot water emerges and then compare this to the amount of water per machine fill to level.

That’s a really good point; I think your suggestion may be the reality; that the water isn’t warm by the time its filled the machine; I shall test as you suggest :)

Posted By: passivhausfanIn North America, where they do connect to the hot, the advice is to run the tap hot first before you switch them on.

Somehow in the land of extravagance I am not surprised. Many years ago I saw a documentary about water. Therein contained a piece on the amount of water taken out of the Colorado and the amount of water lost out of Arizona swimming pools in its hot climate. I forget the numbers. There was a comparison of the American extravagance to that of those in much of underdeveloped world, it changed my approach to the use of water and how much energy I use to heat it.

i have solar thermal so a lot of hot water in summer i add the hot water through the front tray of washing machine at the beginning of the cycle i use couple of 2 litre plastic milk bottles as i have a sink next to washing machine

I assumed dathi meant via the pull out detergent dispenser tray. Probably the simplest and most energy efficient of all, provided you don't have to run off loads of water to get the hot stuff.

When installing a new kitchen some 7 years ago I decided to plumb in the dishwasher with the hot water to benefit from solar hot water, like the OP.
Reading through the manual of our Bosch dishwasher, it is specified to take in water at any temperature between 5 and 50 C (going against what the sales people tried to tell us)
The dishwasher measures the temperature of the incoming water and then decides how much post heating is needed, contrary to older machines which would heat for a set amount of time.
I measured the consumption: a cold feed ECO cycle takes 1.5 kWh, a hot feed ECO cycle less than 0.5 kWh. For an automatic cycle, the consumption is higher and the savings bigger, depending on the state and quantity of the dishes.
Since modern machines fill up their internal reservoir and recycle the water in there for the wash, and then again the rinse cycles to be more economic, pipe lag is less of an issue.
Hope this helps.

Also worth using the 'delay start' button on ours - electric is much cheaper outside peak times and usually greener too.