I've seen a few old posts about this but i've not found any that mention the exact cause and solution.
I've got a Baxi combi 80 eco that's going through venturis (melting them) at the rate of one every 3 weeks. My friend is a corgi registered engineer and even he's stumped by what the cause is.
We thought the fault was being caused by dry firing as the boiler did seem to loose pressure over a prolonged period of time. After the last venturi change i made a point of checking the pressure regularly and topping up if necessary, it pretty much never needed topping up.
Last night when i came home the house was like an oven, i checked the boiler and it seemed the radiators were running at max temp although the thermostat was turned half way down. When i switched the timer to off the pressure gauge went crazy jumping up and down, the boiler started making some scary noises and it wouldn't go off. When i flicked the main switch to off the heating did switch off but when i switched it to hot water only the radiators/CH would come on full again, the pressure switch would go crazy and again the scary noises.
In fear of the boiler exploding i switched it all off and left it. When i later tried turning it on for some essential hot water the boiler wouldn't fire up at all. Surprise, surprise the venturi had melted again, i've replaced it along with the thermistor and the boiler seems to be working fine again ( no jumping pressure gauge or noise and the hot water switch only gives hot water). My friend thought the problems sounded like a jammed diaphragm or switch but surely that couldn't have been the problem if it's all fine now?
Anyone got any similar experience or diagnosis as i'm getting to the point of just ripping the thing out and replacing it?
I've got a Baxi combi 80 eco that's going through venturis (melting them) at the rate of one every 3 weeks. My friend is a corgi registered engineer and even he's stumped by what the cause is.
We thought the fault was being caused by dry firing as the boiler did seem to loose pressure over a prolonged period of time. After the last venturi change i made a point of checking the pressure regularly and topping up if necessary, it pretty much never needed topping up.
Last night when i came home the house was like an oven, i checked the boiler and it seemed the radiators were running at max temp although the thermostat was turned half way down. When i switched the timer to off the pressure gauge went crazy jumping up and down, the boiler started making some scary noises and it wouldn't go off. When i flicked the main switch to off the heating did switch off but when i switched it to hot water only the radiators/CH would come on full again, the pressure switch would go crazy and again the scary noises.
In fear of the boiler exploding i switched it all off and left it. When i later tried turning it on for some essential hot water the boiler wouldn't fire up at all. Surprise, surprise the venturi had melted again, i've replaced it along with the thermistor and the boiler seems to be working fine again ( no jumping pressure gauge or noise and the hot water switch only gives hot water). My friend thought the problems sounded like a jammed diaphragm or switch but surely that couldn't have been the problem if it's all fine now?
Anyone got any similar experience or diagnosis as i'm getting to the point of just ripping the thing out and replacing it?