Forum Discussion

bcole66's avatar
bcole66
Explorer
Aug 13, 2015

Voltage to gas valve?

I recently (last night) installed a brand new 10 gallon Suburban hot water heater in a park model in the campground where I am currently staying. (For a friends park model, not my travel trailer) The problem is there is no 12V available in a park model, and the new hot water heater is DSI ignition and requires 12v. I had purchased an inexpensive 120v/12v step down transformer from Grainger and mounted in in the compartment right next to the heater. The heater fires, but the solenoid valve rattles like crazy and the flame is erratic. I initially thought I had a faulty gas valve but then I noticed the output of the transformer is 12VAC and the gas valve is 12VDC! Any thoughts or comments on how I can provide 12VDC to my hot water heater?
  • YC_1's avatar
    YC_1
    Nomad
    Aug 13, 2015
    Just spend the $50 or less for a pre-built power supply. It will get very techie here with ripple, diodes, capacitors, and lots of geek stuff.

    Yeah, I'm a geek but you need a solution that is solid, simple, and effective without worry. Add diodes and capacitors improperly and the next thing you know you will have reverse voltage.

    Not throwing my geek buddies under the bus, just want you to make it work safely without any geekdom.
  • hohenwald48's avatar
    hohenwald48
    Explorer
    Aug 13, 2015
    Old Biscuit is right about that AC ripple. It can be a problem.

    A lot of those little wall cube power supplies provide surprisingly stable DC outputs. It mostly depends on what it was originally designed to power.
  • Old-Biscuit's avatar
    Old-Biscuit
    Explorer III
    Aug 13, 2015
    Whichever means you decide on for supplying the 12V DC Voltage..........measure the AC Ripple that is occurring.

    Measure the DC Voltage using the AC Scale on voltmeter.
    Anything over 1V AC will cause damage to circuit board, DC set of t-stats and eventually gas valve solenoids.
    Acceptable AC Ripple is .5 or less volt AC
  • hohenwald48's avatar
    hohenwald48
    Explorer
    Aug 13, 2015
    If you really want to do this cheap, go to the local Goodwill store. They always have boxes of the wall cube power supplies. Find one with a 12VDC output (the cubes are marked) and your good to go for about fifty cents.
  • budwich's avatar
    budwich
    Explorer
    Aug 13, 2015
    You can test things out using a car battery charger... or even a power supply used by one of those portable electric cooler (cooltron? or equivalent) that put out 5-6 amps of "nice DC power".
  • WyoTraveler's avatar
    WyoTraveler
    Explorer
    Aug 13, 2015
    bcole66 wrote:
    I didn't realize they had such inexpensive power supplies available. Thank you.


    One diode and a capacitor to ground for a couple of bucks. You already have the transformer. That is just about all that is in that $23 box.
  • bcole66's avatar
    bcole66
    Explorer
    Aug 13, 2015
    I didn't realize they had such inexpensive power supplies available. Thank you.
  • Boband4's avatar
    Boband4
    Explorer
    Aug 13, 2015
    Just to confirm - since it is a park model that means it only has a 110 household referigerator? I was thinking if it has a 2 way refrigerator you might be able to pull a 12 VDC wire pair from there? How about the furnace, they usually have a 12VDC control board too.

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