Heating Help

Buderus H-X cleaning

Hello. I am wondering what is the best thing to clean a cast aluminum heat exchanger. The condensation deposit build up is quite hard! I was told Mineral oil would work but doesn't seem to help at all. So what's working?
Thanks in advance.

I do not know about Buderus, ...

... but Weil McLain are insistent that you not use mineral oil on their (aluminum) heat exchangers in their Ultra series boilers. They give very explicit cleaning methods in their installation manual. I imagine Buderus also have instructions for cleaning their aluminum heat exchangers.

Cleaning the water side and the fire side of the H-X are probably different in any case. So, as they say in the computer busingess, Read The Fine Manual. ;-)

Cleaning the Fireside

I found plain water shot from a pressure washer will dissolve that white-green buildup between the fins and rinse it clean and shiny. Take care not to soak the electrics, obviously.

Heat X/C cleaning

If it's that bad you might try disassembling the exchanger and take it down to the car wash. Then you can get the benefit of high pressure without soaking the electronics and mechanical room.

How do you know...

... what's in the stuff they use at a car wash? If cleaning a cast aluminum heat exchanger is to be done, you want to be really sure there is no trisodium phosphate being  used as it is very bad on aluminum, especially if a bit of the undissolved stuff remains stuck to the heat exchanger It removes the protective oxide coating and without it, aluminum wastes away.

Weil-McLain recommend vacuum cleaning the heating surfaces, and not to use any solvent. If that is not enough, wash it in clean warm water. If even that does not work, they have a special tool to mechanically clean it. A piece of 20-gauge or liter sheet metal 3/4" wide by about 18' long may be used to loosen the deposits.

Heating & Plumbing Contractor

I wont plug any names (viessmann) but if you use a wall hung Mod. Cond. boiler with stainless heat exchanger you wont ever have these problems. (VIESSMANN!)

personally

I don't care much for that part of the Buderus. The rest of it is fine. My personal new favorite is Triangle Tube. SS heat exchanger. None of this cast clean up bs.

Mineral Oil

Here is the procedure Buderus recommends.  We have used this process this season with good results.   It is a little lengthy, IMHO

1. Shut down power to boiler, shut off gas supply, remove cover.
2. Remove burner/fan assy.  Disconnect gas valve plug, fan power plug, an tachyometer plug.  Unscrew gas flex connector from gas valve. This should be hand tight.
3.  Unclip burner hood & remove assy, burner diffuser, and ceramic burner.  Handle with care & set aside.  Inspect gasket for damage.
4.  Remove & empty/wash out condensate trap.
5  Remove lower HX condensate plate.  (4 spring clips)  Clean off plate & re-install. Check gasket for damage.  Re-install condensate trap.  *** Don't forget this step***
6.  Loosen any buildup on upper HX with a nylon brush or old credit card.  Do not use a metal brush.
7.  Wash out HX with water.   Spray down HX with mineral oil, and be sure to soak it thoroughly.  You should have mineral oil in the trap when you are done.
8.  Re-install burner plate, diffuser, hood, & fan assy.  Re-connect control plugs and gas flex.  Do not tighten gas with a wrench, hand tighten firmly.
9.  Restore power & gas, press & hold chimney sweep button until decimal appears in display.
10. Fire boiler for 10-15 minutes.  It will smoke alot outside. 
11.  Repeat steps 1-3, and wash out HX.  Remove any stubborn buildup with a card or nylon brush. 
12.  Check Ionization rod, and clean off with a rag.  If heavy buildup is present, use brass wool or a small brass wire brush.  DO NOT USE SANDPAPER OR A FILE! 
13.  Repeat steps 8-10, and check combustion.  CO should be under 440ppm on high fire.
14.  Check differential gas pressure, according to service procedure.  This is done in low fire.  The reading should be -.02" WC.
15.  Press chimney sweep button to exit service mode, check gas line for leaks, and replace cover. 
Do not use TSP on this boiler, you will damage the HX.
I have used this procedure, with fair results.  Those HXrs are hard to clean that's for sure.   Hope this helps!
Peace,
Radman

For the water side, ...

... but is it safe for the fire side?