Author Topic: Just picked up a Reznor RA235 with a junk heat exchanger... build a boiler?  (Read 2828 times)


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Hey guys...    new to the forum but not to waste oil.

Ive been processing waste motor oil into fuel for our trucks for years...    and with our stockpile continuing to grow (nearly 2k gallons on hand), figured I might as well get some other use out of it too.

So I scored a complete Reznor RA235 with external pump for $200.  Went and picked it up...  guy said it worked when he pulled it down but he removed it because he was upgrading (unit is 15+ years old) and the heat exchanger had some burn holes in it.

Got it home and pulled it apart.  The burn chamber itself is in good shape...  but the oval tubes under the chamber are rough.  All 3 tubes have holes on the fan side of the unit.

Now...  I'm planning for this season, to just patch it up and get it running to make sure everything works...     however the unit is WAY too big for my shop.  After doing some math...  it would be plenty to heat both my shop..  and supplement my home.

To do that...  I'm thinking boiler.  I'll have to rebuild the heat exchanger completely next year for sure...   so why not pull the working parts off the unit and either tracking down a used boiler unit or building one from scratch and converting it to be waste oil fired.  A simple system with a single large heat exchanger in the main air handler in the house...   and another heat exchanger in the shop.

Basically, build an outdoor waste oil fired boiler similar to the add-on wood fired boilers.

Does this sound plausible?

I'm curious what direction I should go to heat the water tank if I do this...     either build a burn chamber with a water jacket (roughly 200-250g tank) or a stainless coil inside the burn chamber heating a remote (heavily insulated) 250 gallon tank.  Which would be more efficient?

The burner will be controlled via a water temp thermostat.

In my mind..  it seems like a simple system/idea.  The shop and house are roughly 50' from each other..   I figure build a small outbuilding in between to house the boiler and water tank, pumps, etc..

Am I crazy?


Thanks guys


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I'm a little slow at putting my plans into action. I have been building my waste oil boiler in my head for a couple of years now. I do have some parts just not a boiler yet.I bacically want to do the same as your plans but probably not heat my shop unless I find a really big BTU boiler. Good luck on your build. Keep us posted on your build and pics or videos really make adifference!


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This is exactly what I'm doing, except I'm putting the boiler in my garage (not a separate building). I've already installed a heat exchanger in my ductwork for the furnace in the house, and ran the 1" insulated PEX lines underground to the garage. Just have to hook up the boiler in the next few weeks. I'll be using a hydronic shop heater to heat the garage itself (the hanging type with fan).

I was going to purchase a used standard oil boiler and convert the burner using the CK kit, however I just picked up a Triad vertical boiler with a Clean Burn burner off of craigslist. So I'll be using that now to save the headache of converting a standard burner.

In the house, I'm adding a second thermostat and will have the fan only wired to it with a "strap on" aqua stat wire in series to the fan. So, when the thermostat "calls for heat" it will just turn the fan on, unless the supply line isn't hot enough, then nothing will happen until it gets cold enough for the regular thermostat to turn on the furnace normally. I also may wire in an alarm to the aquastat to alert me if the boiler gets below temp...

I'll be getting this project finished up in the next few weeks and will be posting some pics of the setup.

« Last Edit: November 25, 2017, 07:08:33 am by acarter »