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A gas powered instant water heat–experimenting with jet sizes

December 29, 2013 by Mike 14 Comments

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In this post I got over how I fixed this boiler up to work in my van. The gas wasn’t burning properly and was quite unsafe. This is to heat the water for the shower–see shower post

I knew nothing about water heaters or boilers before taking this apart and had a lot of questions to which a lot of my answers were along the lines of ‘if your asking that then you shouldn’t be messing about with it’. But messing about with it is EXACTLY what I need to do. Now I know this works and I can use it safely how I want.

bester-water-heater
This is a cheapo Chinese Ebay water heater.
lpg?
The label on the unit says it runs on LPG but upon testing, It was clear the flame was not burning properly.
carbon-monoxide-yellow-flame
Running on propane at 37mbar. The carbon monoxide monitor alarmed almost right away and gave a reading of 900ppm which is ridiculous since it was being tested outside! scrap or investigate?
inside-boiler
I had a look inside. There is nothing to these things – A water flow lever hits a microswitch which sparks the electronic piezo ignition and operates the incoming gas solenoid after a couple of seconds. The gas then comes in through a thermostat control (gas flow control) and enters the 6 jet assembly where it mixes with air and enters the 3 rows of gas diffusers to heat the water via the heat exchanger directly above. Water flow can also be controlled – less flow = hotter.
natural-gas-jets
I removed the gas diffuser to access the jets (middle jet removed in this picture). I compared these hole sizes with the ones in the hob. They seemed larger which would confirm my suspicion of this heater being for natural gas which requires about 2.5 less oxygen than propane to burn.
diy-gas-jets
Learning time. I wrapped masking tape around all of the jets and found a pin with the exact size of the jet in the hob and used it to create a new hole in the masking tape. Note, this is not a fix and certainly not a permanent solution! I am just trying to establish whether the factory fitted jet sizes are too large for propane
water-heater-blue-flame
We cautiously fired the boiler up with the modified jets. Check out those nice blue flame! the monoxide monitor did not even alarm and the flames burnt smooth as anything with no orange flames in sight. The conclusion is that the jets are the wrong type for the quoted gas type on the label. I will be installing brand new LPG jets

Update: I contacted all the suppliers of this boiler I could find and none could help me find some replacement LPG jets so went for the next option – upgrade the masking tape for aluminium tape.

gas-heater-jet
Here is the brass gas jet. I will wrap these in foil tape and puncture a new hole
changing-gas-jet-size-foil
I found a needle that perfectly fits an LPG jet (from the cooker) and used it to pierce a new hole in the foil. I was able to get a really clean hole with no tears in the foil
modified-lpg-jets
Tests were successful – after burning for about 15 minutes but I’ll see how the foil holds up after a few months.

Conclusion – should I use this heater?

These heaters work really well. The water heats up in seconds and the boiler only operates when the tap is open. No storing of water and waiting 20 minutes for water to heat up just so you can wash your hands. This is a neat and convenient little heater but should only be used for intermittent use (washing etc).

Potential safety risks with this type of boiler:

  • open flue–uses oxygen from room and may also vent CO if the flames do not burn properly
  • when used with a self priming pump, a leak after the output of the heater may be enough to engage the flow switch and turn the boiler on inadvertently
  • outer housing can get rather warm due to its very compact size–they’ve squeezed it all in.
  • has to burn a lot of gas to quickly get the water hot

The heater will only be used for a minute or 2 at a time–fill sink with hot water or wash hands. The amount of oxygen in the room it uses up will not be significant in that amount of time. A 12v extractor fan is also fitted to the roof for air ventilation and gases are vented through a fixed flue in the roof.

People seem to get very upset about these types of water heaters in vans but I think it all depends on how it is used. Let’s not forget about the gas hob–the flames are not contained, is used for longer periods and a lot easier to leave switched on. That’s more dangerous in my opinion.

I’m going to see how I get on with this water heater and if I find my self using a lot more hot water then I’ll look at other options.

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Filed Under: Converting my van Tagged With: uk, van conversion

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Comments

  1. László says

    June 10, 2015 at 8:17 pm

    Thank you Mike! This is incredibly useful information. I’m wondering how the tape held up?

    And since it’s my first comment: thank you for having taken the time not only to do the research but then also to document all your conversion steps. I find your blog to be very inspiring and informational; it’s been keeping me dreaming and planning for months now. Kudos!

    Reply
    • Mike @vandogtraveller.com says

      August 23, 2017 at 3:42 pm

      The tape held up very well, and still is! I always check the flames to see how they are burning – they’re always blue and powerful which is perfect. I wouldn’t actively recommend modifying the jets with foil tape though, and just because it has worked great for me doesn’t mean it will for everyone else. I’m also really cautious and careful with this kind of stuff. So if you can, find the right replacement jets if that’s the problem you’re looking at.

      Anyway, thanks for following the blog and commenting. You’re welcome

      Reply
  2. Steve says

    July 10, 2015 at 1:00 am

    Mike, what you are saying above is perfectly correct.
    The different nozzle/jet sizes for LPG & NG are clearly evident to the naked eye.
    A clear blue flame would indicate you have the gas flow correct.
    Any “yellow” in the flame says either: Insufficient air (oxygen) or a blocked flue.
    (No air flow…low oxygen.)…or…as you say: Wrong jets.

    It would be interesting to know where you bought this wrongly-jetted heater?
    (In the UK?…Theoretically…that should not be possible.)

    But I must say, your diagnosis & clarity will help many.

    I work on many LPG water heaters here….some of the sights I have seen:
    You simply would not believe.
    They are all of a “muchness”….
    But I will say this: If the flue is blocked: The thermo-electric cut-outs are too slow acting to be any sort of protection….
    They work on the water in the coils being overheated……flames can ensue before that point is reached. I know: I’ve seen it.

    But as you say: Be aware, watch what you are doing & ensure things are working correctly.

    Do Not Assume. It is, after all….common sense.

    Cheers.

    ps…How DID the tape hold up?…Ther would little or no heat down there…I guess it was quite resiliant…..a month or better?

    Reply
  3. Gary says

    February 2, 2016 at 9:52 pm

    What kind of system would you recommend now for an instant hot water shower in a van?

    Reply
    • Mike @vandogtraveller.com says

      August 23, 2017 at 3:38 pm

      I’d still go this. It’s still working great and it’s just really practical to have instant hot water

      Reply
  4. Neill says

    October 13, 2016 at 11:59 pm

    Hi there – From my investigations of gas water heaters the problem is gas is different pressures in different parts of the world and its not possible to buy adjustable regulators down at the mbar levels to suite different countries. I bought a cheap american one thinking I’d find a converter but sadly didn’t. There may be a way but I couldn’t find one! Luckily I got all my money back including postage back to US as I said they shouldn’t be selling to the UK if they don’t work in the UK.

    As I’m going to just be using it sadly in the UK I’ve opted for a Kampa Geyser Hot Water System. It exhausts into the room but I’ll be using it for a shower outside in the elements similar to your pal Phil so no biggie. I was very excited about making my shower as hadn’t seen any others like it then saw yer pal phils… there are very few new ideas out there!

    I’m going to have a wood burning stove in my van so I’ll probably buy one of those wee coils of metal to pre-heat the water before it goes into the Kampa system.

    Great website – keep up the great work!

    Cheers,
    Neill

    Reply
  5. Matt Hubbert says

    January 10, 2017 at 4:58 pm

    Hi Mike. I’ve been doing a little research on these types of heaters in preperation for my future build, since you can still buy these brand new on ebay. I noticed most of them are rated for a gas pressure of 28mbar like yours. I also noticed you’re using a 37mbar regulator. Could this have been the cause of the problem? 28mbar regulators are readily available, do you think it might have been as simple as downsizing your regulator?

    I find the gas stuff quite confusing, it seems 28mbar is the typical pressure for pure butane, and 37mbar is for propane, yet LPG is a mix that differs between countries. How is one supposed to choose the appropriate regulator without knowing whats in their LPG at any one time? And also, how does one supply their different appliances with the correct pressure (eg 28mbar for a boiler, 37mbar for a hob) with one regulator? What are your thoughts?

    Reply
  6. Bledwyn says

    May 3, 2017 at 4:53 pm

    Hi Mike
    How did this heater work out in the long run? Still got it, performance ok?
    Do you run it off the batteries or have you managed to feed it off your electrical system? Cheers mate
    Justin

    Reply
    • Mike @vandogtraveller.com says

      August 23, 2017 at 3:45 pm

      Hey, yeah it’s actually ran perfect and never had a problem since I installed it.

      Also, it runs off gas, not electricity. Although it does use an electronic piezo ignition for which is takes a few D-cell batteries for – I’ve never had to replace them though and they last years.

      Reply
  7. Jeremy Le Vine says

    August 4, 2017 at 2:34 pm

    Hi Mike – what a very practical guy you are! I have the identical heater and want to convert it to LPG- silly question, but how do the wretched knobs pull off without breaking them?

    Reply
    • Mike @vandogtraveller.com says

      August 23, 2017 at 3:44 pm

      Hey, they just pull off. If it’s difficult with the hands you can get a flat rule and slide it under the knob and sort of twist it to push the knob off the spindle. I did it several times and they didn’t break so you should be fine. Good luck!

      Reply
      • Jeremy Le Vine says

        August 23, 2017 at 5:45 pm

        Thanks, that’s great…..very worried about breaking them with the unlikeliness(?) of a replacement from China. More power to your elbow!!
        Kind regards, Jeremy.

        Reply
  8. Tony Baker says

    October 16, 2017 at 9:03 pm

    re the jets, I would drill out the originals and tap a thread into the jet that takes standard jets, that way you can change jets easily to suit what type of gas is available.

    Reply
  9. Glen Scott says

    December 2, 2018 at 3:48 pm

    Is there anyway of seeing your fixed flue and extractor fan set up cheers

    Reply

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