I was wondering if Combination Boilers have a return because if the water was just left in 'dead legs' obviously the water would eventually get stagnant, is their any sort of re-circulation pump or return valve ? Or does it just stay in the pipes until next use ?Also does the cold water mains go straight from the mains to the Kitchen Sink, then to the other appliances, or does it go from the combination boiler and then to the rest of the appliances ?
There has to be a flowing loop, so there is a return.
I think tinman has his pipes crossed.There is obviously a return on the heating circuit as otherwise it would not work but there is no return on the domestic water side. The cold water is connected to the various points of use as required and the cold feed to the boiler will be one of those connections. The hot water does stay as you say in the pipes just as it would with almost all domestic installations until you turn on the tap next time. A return hot water system such as you suggest is normally only found in large dwellings, hotels and similar large commercial applications.The water would need to be in the pipe for a considerable time to stagnate.
