Rejetting HW System: Nat Gas -> LPG?

[Skew ChiDAMN!!]

A friend of mine recently built his house in a rural area and had the plumber fit an external "insta-heat" type Dux brand hot water service that he'd bought at a clearance sale.

It worked well at first, but after a couple of weeks only gave a few mins worth of hot-water before cutting out. On eye-balling it, there's a big sticker on the outside proclaiming "Natural Gas" and he's running from LPG bottles. I'd have thought the plumber would've picked up on that subtle clue, but...

My advice? Fit the right jets. Simple enough, eh? So I'd thought.

On his first call to the Dux service centre, he was told that's illegal. :eek: Huh? I assured him it's not and to try again. Second call, and he was told it's not a problem, that all Dux units use interchangeable jets and that he wants part #'s such'n'such. The price on both parts? Just under $600! :eek::mad:

What gives? Is this a realistic price or is there some idiot oin the service line who's yanking his chain?

From memory, LPG requires larger air ports than Natural Gas, so would it be feasible (assuming one knew the correct specs) to simply redrill the existing jets? I'm not asking whether it's legal, just whether it's feasible.

'Cos if it is just a metter of redrilling, where do those mongrels get off asking such a ridiculously exorbitant price? Are these things made from brass or solid titanium alloy?

[DJ’s Timber]

Something is certainly amiss here, sounds like they are yanking his chain.

If he can remove the original jet, I would take it to a trusted plumbing supply store or a gas specialist and explain the situation and maybe they might have a matching jet with the correct sized hole.

[savage]

Hey Skew,
You are correct as far as I can tell, in my other place the old fella next door was an old school plumber. He told me a few times that he had come across just this situation and had to modify the jet in the field all he did was redrill to the correct size for that heater. The trick is getting your hands on the right size drill bit as they are very fine and they break sooo easy.

[Gas Man]

Hi Skew,
<O</O

Generally speaking the conversion that you are attempting is relatively easy, however with that said I strongly recommend that a qualified person undertake the process.
<O</O

Usually a number of items need to be replaced for this conversion:

1. Most natural gas appliances are fitted with an appliance regulator in addition to any other line regulator. This reduces the working pressure of the gas to its correct value – in the case of natural gas this is 1kpa (LPG is 2.75kpa) so your appliance is starving for gas thus not working properly. The appliance regulator is usually removed and replaced with a test point fitting.
2. The line regulator must be capable of delivering gas to the appliance at a working pressure of 2.75kpa.
3. The pilot spud will need replacing and no it cannot be drilled out for this conversion. LPG has a higher working pressure therefore needs a smaller orifice.
4. The burner injectors also need to be replaced and as above they cannot be re-drilled, but need replacing to a smaller size.
5. In some instances the burner unit itself needs to be replaced – this is because of the different burning characteristics between Natural and LPG.

Apart from the legal aspects this work carries a safety risk that needs to be addressed. Again I would recommend qualified people to do the work.

Cheers
Jeff.

[Iain]

NOt hot water but when we put in our gas hotplates the plumber just switched jets, which appeared to be a standard size.
Only took him about two minutes and charged $10, plus took the other jets with him.

[savage]

As I said above it is easy to redrill the jets given you have the right size drill bit, and given that you have to go up, not down!...the rest of what Jeff say's sounds right enough too. The old fella next door to me was only talking about re-jetting, we where not talking about a full conversion in the conversations, actually we where talking about carbys and such, when the subject came about redrilling jets. So I'd think about what Jeff has to say, sounds like good info.

[Skew ChiDAMN!!]

Generally speaking the conversion that you are attempting is relatively easy, however with that said I strongly recommend that a qualified person undertake the process.

Thanks for the info, Jeff. Believe me, I've no intention of doing it myself; water I've no qualms about installing, but gas? No thanks.

'Tis just that the info we've received from those who should know (ie. the Dux service line) is so... whacked. (To put it politely. ) The Service line quoted $540- (I think that's what my mate said), for just the pilot spud and burner jet. I find that hard to accept, we could replace the whole unit for that!

So, the jets need to be smaller dia, eh? That rules the easy option out. I think I'll advise him to do the phone-book stroll and get some quotes from plumber/gas-fitters. Hopefully the prices will be more realistic... [fingers Xed]

[b1ueshift]

I bought a converted Bosch LPG water heater (converted from LPG) from a second had gas appliance shop in Moorabin recently. They owner told me the conversion process costs about $250 for a Bosch.

I'm guessing your supplier doesn't really want to deal with the public (probably because consumer protection laws mean that he might have to give you a refund, for any number of reasons if you want to return it or he's afraid of damages that he may be held responsible for any damages his product does, but the laws that are desinged to protect you, end up hurting you but that's another topic).

Anyway, I reckon the quoted price is way too high. A repair shop would probably get the parts at trade price which is probably much lower. I'd let a technician do it, it shouldn't be that expensive.