Non Return Valve Questions

Comer1

Hi, I have an oil stove and solid fuel stove on my central heating system with two pumps and non return valves so that one pump wont pull water through the other boiler. My problem is that one seems to be sticking as hot water is now being pulled through the oil stove by the solid fuel pump. I really don't want to drain the system to change this relatively new valve as getting air out that last time took weeks. My first question is what is the nut for on the non return valve (first picture below) and does it have anything to do with the valve sticking. Secondly, as the oil is only used about 5 times a year, I've closed the valve beside the pump as a solution. Is this a bad idea?

Thanks

Comer1

Anybody?

Sparkpea

that nut is an airvent to bleed the nrv, its not really a good idea to turn the pump valve off incase anyone lights that stove but its a temporary fix

Comer1

Thanks, is it unusual for a new non return valve to be sticking like this. If I turn on/off the pumps a few times, it can close it.

That pump is for the oil boiler so I don't think any harm can come of someone turning on the boiler it's thermostat will keep it from overheating.

I suppose the danger is if I get hit by a truck or something, it might take someone quite a while to cop why the oil boiler system isn't working.

Sparkpea

its usual for old ones to stick now and again yes, many systems dont even have them on it so isn't doing any harm heating the oil boiler except loosing a bit of heat