Help with propane to natural gas heater swap

dorn4ever

Member
Aug 25, 2016
14
Oshkosh, Wisconsin
Hi everyone great site lots of info! So here it goes.... I have an old lasts lite heater with electronic ignition and natural gas house has natural gas. The heat exchanger and most things are rotted out. I got a old but ten years newer in way better condition laars lite 2 for real cheap it's basically the same heater except this new one is propane and has push button ignition and a pilot. I can swap everything like the block and the U shaped pipe with orifices for the burn tray part no problem but my question is what to swap or use for the ignition since the old one was electronic and the newer one has the push button and pilot? There's no pilot setting on the gas valve that I have to use so I would have to swap the electronics and the heating element and just remove the button and pilot light? Sorry if that's hard to follow just trying to make this work! Any questions or help is appreciated!
 

flyweed

Bronze Supporter
Aug 3, 2009
525
SW Wisconsin
it's sounds to me like a big problem waiting to happen. Do yourself, your family and anyone that lives close to you a favor, and don't try swapping parts out from one heater to another. Unless you are a licensed Hvac or gas Tech, you'd be best off leaving it to the pro's to come in and tell you if it's even feasible, or possible to do. But it sounds like you are wanting to convert the standing pilot unit to the electronic ignition of the old one..and that is practically impossible.
 

ps0303

TFP Expert
In The Industry
Jul 6, 2011
4,185
FL
Sure you could frankenstein the new unit from the old. You would need to put all of the electronics, gas valve, etc from the old to the new older unit. It's a bit of work and could run into maybe an issue or two. I have never done it and probably wouldn't.
 

dorn4ever

Member
Aug 25, 2016
14
Oshkosh, Wisconsin
Thanks for replies and sorry for the late response I was expecting emails when my thread got replies. Anyway, to simplify explaining my original post all I did was use the "body" including the manifold, header, burner tray etc. And a couple sensors. Basically all of that was so far deteriorated on the older unit. I swapped everything else from the whole gas block with u pipe and correct orifices as a whole and the electronic ignition module and the on/off and thermostat panel (not using the push button ignitor and pilot) I did have someone come and do the gas connections. Brand new hot surface ignitor because I ended up breaking it when I took it out. Everything went fine they are essentially the exact same model just one is ten years newer. Went to fire it up and the ignitor wouldn't glow. Tested with a voltmeter and got voltage up until the ign terminal on the fenwal ignition module. Where do I go from there? Does that mean the ignition module is junk? Gas doesn't flow through the valve until there is power and heat from the hot surface ignitor correct or am I missing something else that could be wrong first before I get a new electronic ignition module? Is there constant power up until that point and the on/ off switch is just bad?
 

dorn4ever

Member
Aug 25, 2016
14
Oshkosh, Wisconsin
Thank you for the reply! I'm following a flow chart but I'm not sure if these tests should be performed with everything on like I'm trying to fire it up, gas valve on, switch on, water flowing through? I have the water going through but switch and gas off. On the flow chart I got to the black wire on the pressure switch and it was at about 15 vac. I turned off the pool pump and "backwashed" and now I'm getting 26 vac which I think I did the right thing there?? Next step in one of the flow charts I'm looking at is black/yellow wire at the IND location on the ignition module which same location and wire color is the TH spot on my module and that goes up to the temp control board. This wire is where I get no voltage. Another flow chart next step after the pressure sensor is to check voltage at the IGN location on the ignition module which is one of the wires from the hot surface ignitor and I get no voltage there either. Where do I go from there?? Thanks so much
 
Thread Status
Hello , This is an inactive thread. Any new postings here are unlikely to be seen or responded to by other members. You will get much more visibility by Starting A New Thread