Flomaster inlet control set discharging slowly

TheWombat · May 5, 2015

I'm not well up on Flowmaster unvented cylinders, but I have one that's dripping fast. A couple of months ago it was dripping occasionally, apparently only when it was being heated but I'm now sure this was really the case. At that time I assumed the T+P, as the expansion was well below pressure and the drip wouldn't do it while I was watching, so I recharged and left it. But now it's dripping all the time, and it's obviously cold.

Can anyone tell me what's the likely fault with these? It's less than three years old. Does it mean changing the whole control set (part number 076-388-0001 according to the fine manual) or can you just change/service the expansion relief valve, which seems to be opening at just 3 bar (in other words I don't think it's the pressure reducing valve). The book of words talks about a replaceable cartridge but doesn't list it as an available spare. Can check with not-so-local supplier when they re-open, but any practical advice much appreciated.

The thermostat on the immersion was completely out-of-whack causing it to over-heat when it was a few of months old (as I remember it), but it's indirect most of the time and on the lowest setting it's was sensible. Are these Flomasters flaky or is this one just having bad luck?

MSM · May 5, 2015

I would check the pressure reducing valve. If its discharging cold water perhaps its letting more than it should. Don't know the exact spec for the expansion valve but 3bar may be the correct discharge setting. Is the water coming out from the expansion tank when you press on the pip?

Unregistered · May 5, 2015

@MSM - The pressure reducer is 3 bar on these and that's what I appear to be getting. The Expansion Relief must obviously be higher than the nominal inlet pressure - in this case specified at 6bar, with the cylinder T+P higher still at 7 bar (and 90C FWIW). I can't find anything >3Bar beyond the pressure reducer valve, which is why I suspect it's the expansion relief valve at fault.

This is why I hoping someone will be familiar with this setup, as the expansion relief appears to detach from the Inlet Control Set, although in the spares diagram it's one (expensive) unit and a PITA to change.

But, yes, I am wondering if the pressure reducer itself may have gone as Idea B. However, if it had gone and I was somehow getting >6bar in to the tank I'd expect to see more evidence.