And poof, he was gone.
Navien Combi Boilers
- Thread starter hard-work
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I don’t think that follows. Mine is an “ordinary” boiler, fan-assisted. But the fan does not suck the gas out of the pipe. The gas pressure, with the gas solenoid valve open, is set at 8.6mbar. The pressure downstream of the jet will be a little below atmospheric, due to the fan, so the jet sees a slightly higher differential, but if the upstream pressure were below 8.6mbar the gas flow would be insufficient (and if the design were changed, using a fan producing lower differential, the inlet pressure could be raised to compensate).
A negative pressure gas valve, as I understand it uses a valve which only opens when there is negative pressure downstream. I assume (somebody correct me if I’m wrong) the pressure upstream of the valve is still regulated, to give the correct flow when fan vacuum is applied. I would guess a higher fan differential than on a traditional system is needed. I suppose it gives additional safety as if the fan fails, gas flow stops, it doesn’t rely on a pressure switch opening, and closing the solenoid valve.
Vacuum chlorinators in water treatment have used a similar system for many years. A vacuum regulator is installed close to the pressurised chlorine store, so everything downstream is under negative pressure, avoiding the risk of escape of poisonous gas. The vacuum is produced by a water-operated ejector, the water also dissolving the chlorine for feeding to the process stream.
That's not a condensing boiler though.
Edit.
Sorry, I should have said, that's not a zero ratio gas valved boiler though.
Amazing this one thinks he can lecture me on gas controls.
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You are correct. Yes, additional safety as if the fan fails, gas flow stops. They tend to use venturis inside the valve.
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Negative pressure gas valves are not new. They have been in commercial use for a long time. The valves you are prattling about on the boilers you see, cannot allow 24 foot of 15mm pipe on a 200,000 BTU/Hr boiler. Struth!!!
What isn't, a boiler with a traditional valve, or with a negative pressure type? And what is a zero ratio gas valved boiler?
BTW I don't claim specific expertise, just making general points, and always keen to learn.
I see Maintap is avoiding direct questions again.
Fixit, what boiler mod are you talking about?
Fixit, what boiler mod are you talking about?
The only one prattling is you.
Are you going to answer or once again deflect the questions??
What boiler manufacturer quotes this? Interested.
I've been watching this for a while and see a few of the more respected chaps are on here,but I'd like to know were hard work s going with this.Are you a sales rep or something or have you technical knowledge in the gas field or are you just having a pop at the forum or just a pop at the good people on this forum because you've dropped a few clangers in your posts which makes you seem a bit silly and hard to follow at times.
He's the current incarnation of Big Burner and Water Systems, Dr Drivel etc.
He pops up every year or so spouting the same old nonsense.
He pops up every year or so spouting the same old nonsense.
I had a bit of a flood today...
View from my holiday cottage in Devon
There's now a pint of San Miguel on that table BTW
View from my holiday cottage in Devon
There's now a pint of San Miguel on that table BTW
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