Balancing a CH system containing a bypass rad?

30 Nov 2011
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United Kingdom
Our CH system has TRVs on all but two of the rads (hallway w. the thermostat and a towel rail in the bathroom) which act as bypasses for the pump. The boiler (a Windhager pellet boiler) does not incorporate any form of bypass circuit so, as I understand it, we need one or more rads without TRVs to protect the pump.

Given that some of the rads are heating up a lot slower than others (esp. the lounge which sits at the system end furthest away from the boiler) and I know all the lockshields are currently fully open, I thought I'd balance the system and see whether I could improve the performance of the slow-to-warm-up rads.

Unfortunately, two out of the three nearest rads to the boiler are the two permanently open rads. Therefore, I would expect these to need the greatest flow reduction when balancing the system.

Is it OK to balance a system in which the bypass rads are so close to the boiler? Will the flow rate post-balancing still be sufficient for them to serve their purpose of protecting the CH pump?

Apologies is this question has been asked before. I've had a good search around but couldn't find an answer to this specific question.


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I would just close the lockshields and then open say 1 and a half rotations. That way they won't hog all the hot water but is definately anough for the water to flow around to cool a bit. Then just balance all the other radiators as normal, on the 3rd rad starting with 1 3/4 turns open then the 4th 2 turns etc.....

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