2

Where should the expansion tank be installed? On the primary side or on the secondary side? Both sides perhaps?

  • x1 ?
  • x2 ?
  • x3 ?
  • or x4 ?

enter image description here

servant0
  • 417
  • 9
  • As I understand expansion tanks, they are for hot water tank pressure expansion, so close/on the tank. Your #1. – crip659 Feb 10 '23 at 00:54
  • @crip659 My understanding is that they buffer back-pressure on the cold water input to the heater, so would go in position 4; that also prevents accelerated failure of the rubber membrane inside the expansion tank due to direct hot water exposure. – Armand Feb 10 '23 at 02:37
  • 2
    Two different applications, though in point of fact the one crip659 is thinking of is also better served by having it on the cold side of the (domestic out of the taps) water heater tank (so long as there's no valve between the water heater and the expansion tank.) – Ecnerwal Feb 10 '23 at 03:20

1 Answers1

2

If this somewhat confusing due to local terminology not disambiguated question is about a circulating heating loop, the expansion tank goes as close to the inlet of the (unseen) circulating pump as is practical. That makes the risk of cavitation less, and cavitation is Not Good for pumps.

Assuming the circulating pump is contained in the white and black unlabeled thing that's presumably a boiler with streamlined housing, because that's a terribly useful thing for a boiler to have, as they often travel at speeds of 100 kilometers an hour while sitting in your house, x4

Ecnerwal
  • 174,759
  • 9
  • 212
  • 440
  • yes, you are right. black&white box contains a pump inside located after **x4** point. the box also contains an expansion tank (also after **x4** point and before the pump) but this expansion tank is small/insufficient (based on the calculation) so that's why I need an additional one - just wasn't sure where to put it – servant0 Feb 10 '23 at 01:21