Recent content by Woodreeve

That's all right - I don't do drastic!

I suppose in some installations, for example where all rads have TRVs and there is no MV, the ABV will come into play while the boiler is still running. In that case a higher flow rate would be required than is the case when it is just used in over-run mode (e.g. with MVs and an S plan). This...

That's very helpful. But if domestic installations require overrun flows of only about 0.1 m3/h, I'm puzzled why the flow operating range for the Honeywell valve runs up to 1500 kg/h (1.5 m3/h). Chart attached. One reason why the "minimum flow rate" quoted by Vaillant seemed a reasonable...

Apologies - my hallucination That's interesting. My previous boiler (Vaillant Ecotec plus 418, 2015 vintage) specified, in the Installation Instructions, a minimum flow rate of 12.9 L/min (0.77 m3/h). The current one (Vaillant EcoFit Pure 418) has no minimum flow rate in the instructions, but...

Yes, that's another can of worms. In their instructions, Honeywell specify aiming for the "minimum boiler flow" when setting up the ABV. My understanding however is that when boiler manufacturers use this term, they mean the minimum flow that the boiler requires in order to fire. For my 18 kW...

I've also been wrestling with this for years - partly because I have found that professionals tend to screw the valve down a long way so as to minimise flow during normal running, apparently without realising that this is accompanied by inadequate flow during over-run. I've attached the...

Anyone up for a(nother) discussion) on ABVs? 1. ABVs open in response to the increased upstream pressure that results from closure of MVs (or TRVs). 2. This mechanism will only operate effectively if the performance characteristics of the pump concerned include a pressure increase large enough...