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Plumbing

Bypass is before 3PU rather than after 3PV on HTG circuit

Anonymous user 03/03/2024 - 3.24 PM

Hi We have bought a new house, the heating was not in good shape so we got Daikin out to look at it because it was their kit. The plumber responsible claimed there was nothing wrong despite us not getting heat during the timer settings. Daikin were great, found a number of problems and fixed them except one and this is the reason for my question. In their notes they say, and I apologise for any typos as its handwritten and I'm not sure if 3PU or 3PV: "Bypass is before 3PU rather than after 3PV on HTG circuit" How bad is this? We have heating now and I haven't seen any other issues but I'm loathe to have the plumber who caused this, then denied any problems come back out to touch it but if it needs done then it needs done. They also mention that "Bypass found fully open. This needs commissioned. IV at Cylinder found almost closed"

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1 Answer

Anonymous user

Pretty Bad, the bypass needs to be after the Pump. If say for example you have TRV's on all your radiators as they turn down it will place stress on your pump…unless you have a bypass which allows the flow of water to continue to circulate even when the radiators are open minimally or closed. If you have the set up you're referring to your pump will struggle. Furthermore, you can get air problems in your system which is could lead to the air pressure release valve opening and a drop in pressure in your system which means the boiler going off or overheating potentially. On the end points of your question, the Bypass should be open but not fully as you don’t want the water flowing quickly round, this can not give the radiators the correct heat they need. IV should also be open.

Answered13 September 2019