Sillychuckie

Hi. I need to purchase a hot-water expansion vessel for my system, and understand I need to size it, based on "10% of the system volume" (based on a Google). I'll be fitting a sealed system with under floor heating. Can someone clarify which of these items would contribute towards the system volume? - All Radiators (total volume). [I'm assuming 'YES'] : 72 litres. - UFH Manifold 1 & Loops. [I'm assuming 'YES'] : 43 litres - UFH Manifold 2 & Loops: [I'm assuming 'YES'] : 72 litres - Hot Water Cylinder: [I'm thinking NO, as the cylinder contents isn't actually part of the 'sealed' system?] : 180 litres. A website also suggested adding another 10 litres for good measure for the boiler, and perhaps another 10 for the pipe runs. My total of the above is coming in at around 386 litres, so I was going to purchase a 35 litre expansion vessel. Then again, if this vessel is needed to take up expansion as I heat up the hot water cylinder, maybe it is actually *ONLY* the hot water cylinder volume that matters (180litres), and the rest is handled by the expansion vessel in the boiler? Can someone provide a little advice here so I'm as well prepared for when the plumber comes? Its one of the sealed red things (wall mounted) he needs. I know I could ask him, but for reasons I wont go into, its not so easy for me to reach him until he comes on Thursday to do the work (so I'm trying to get in as much of the stuff he will need ready for him in advance). I'm just trying to figure out which of the things above 'matter'. Perhaps there are 2 different sorts (one of the sealed system items like Rads & UFH), and then another for the cylinder (if not 'built in'). If thats the case, then I don't understand why system volume matters at all here. Surely it would directly based on the volume of your cylinder only. Thanks. SC.

(so in case anyone else finds this on Google years later, I can confirm that the side of the mixer & pump can be moved from left to right, without any form of compromise. i.e. The blending valve can be brought to the front also). Whoever did it in the original image above, clearly couldn't read any instructions. (bizarre given they hadn't even fitted the flow and returns yet). As the earlier poster said... 'RTFM' (though in my case, I wanted to verify 100%, prior to purchasing). In the end I just bought one, and as the previous poster said, it is in the instructions.

Hello. I appreciate this topic is old (not sure if you'll receive a notification of my reply, or if others will see it has had a new reply). I'm facing the same issue, and, based on the image above, would appear to have the same manifold. @CotswoldDoltUpper. Can I confirm? Were you able to reverse it (as in the image above), yet also manage to keep the mixing valve facing the correct direction? Would you be able to send an image of what yours looks like now? Is it possible to swap the pump to the right hand side, without any other negative/disadvantage? Thanks. SC