BartW Posted October 14, 2023 Share Posted October 14, 2023 Hi all, a bit of a call for help. I have finally started the installation of vIllant unitower plus with Heat Pump. Many months ago when discussing this in relation to primary / secondary pumps and ways to connect the buffer it was said no need to have an additional pump as the one in the heat pump will pump the water in the circuit, and then individual manifold pumps will do the rest. well… when following the installation guide today, I cam across “connect the pump”. Wait a minute. I have not got one, I thought it was built into the unitower right? I am assuming that whatever pump the external unit comes with is part of a completely separate sealed circuit. So do I actually need another pump to push the water out of unitower and around the heating pipes? Many thanks! bart Link to comment Share on other sites More sharing options...
joth Posted October 14, 2023 Share Posted October 14, 2023 Just to confirm you're looking at page 36 of this manual? https://www.vaillant.co.uk/downloads/aproducts/renewables-1/arotherm-plus/unitower-operating-installation-and-maintenance-instructions-1799370.pdf That section is very ambiguous what pump that actually is, but skimming the rest of that document for "circulation pump" it seems to use that phrase exclusively for a DHW secondary return pump ("for legionella function"), not for the heating primary circuit. I'm really surprised there's no plumbing schematic to clarify this . Link to comment Share on other sites More sharing options...
JohnMo Posted October 14, 2023 Share Posted October 14, 2023 Several ways to connect a buffer. The normal 4 port, so BOTH supply and return pipes connected and the flow AND return go through the buffer. Piped this way you have hydraulic sepereration and you need a pump either side of the buffer. The other way is a two port, where EITHER the flow OR return pass through the buffer. This can be either / or flow or return pipes not both. There is no hydraulic sepereration so only pump is required. The other question is do you need a buffer? Link to comment Share on other sites More sharing options...
BartW Posted October 15, 2023 Author Share Posted October 15, 2023 8 hours ago, joth said: Just to confirm you're looking at page 36 of this manual? https://www.vaillant.co.uk/downloads/aproducts/renewables-1/arotherm-plus/unitower-operating-installation-and-maintenance-instructions-1799370.pdf That section is very ambiguous what pump that actually is, but skimming the rest of that document for "circulation pump" it seems to use that phrase exclusively for a DHW secondary return pump ("for legionella function"), not for the heating primary circuit. I'm really surprised there's no plumbing schematic to clarify this . Yes exactly my point and yes I read the exact same page. And it does mention circulation pump, but which one. as for the buffer, yes we have three floors of UFH. I just still don’t know if there is a pump in the tower already… Link to comment Share on other sites More sharing options...
joth Posted October 15, 2023 Share Posted October 15, 2023 4 hours ago, BartW said: Yes exactly my point and yes I read the exact same page. And it does mention circulation pump, but which one. The circulation pump described on page 36 is definitely the DHW secondary return pump, as it describes connecting it to connector X11 which elsewhere in the manual is listed as being for domestic hot water circulation Link to comment Share on other sites More sharing options...
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