what will dissolve coffee grounds?

Nom_Deplume

Hi...I am trying to clean an HTP Elite FT. I vacuum out the coffee grounds every year, but over time some of them have gotten stuck in the vertical tubes. I tried poking at them with a wire but couldn't move them. CLR does absolutely nothing to them. I am not able to vacuum them out or blow them downwards with a wet/dry vac.

I am aware that there is a cleaner called "Axitherm Clean F Steel". But while I do have black stains on the stainless steel, I believe those stains do not affect how the boiler works. The coffee grounds don't prevent water draining through the tubes as of now, but ultimately they will, so that's more important to fix.

All suggestions appreciated. (PS I am a homeowner with some but not much experience.)

hot_rod

You got it, vacuum first, then use a spray cleaner, get a nylon brush. In some cases you need to use an old credit card to dislodge debris between the tubes. Most all the manufacturers have You Tube videos showing how to clean those coils.
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JUGHNE

I remove the back target wall and then I just vacuum and rinse.
Then use a credit card, used a sheet metal notcher to cut "teeth" in one side. I have at least 2 of them, one to cut with and one to mark where I stopped for a break. Use it to saw the grounds out while rinsing away down the drain. I use a garden hose with pistol spray.
I used to use some chemicals but found them ineffective.

On most of these water tubes there are stainless steel support rods on the back side that you can not see. You will feel them as you cut your way around, they are evenly spaced, maybe 9 or 12 of them. Don't try to cut them with your card, you can't, but know they are there as you hit them and realize they are a permanent part of the HEX.

With the garden hose use you have also flushed the drain system rather well. Connected to the bottom of the water heater, you also flush the WH tank.

Nom_Deplume

I'm sorry, but I think you are both talking about Munchkin-type stainless water-carrying coils. Credit cards are not useful in my case.

The Elite FT is a "fire tube" boiler. The vertical tubes I am talking about are not on the water side. They are on the fire side. They are used to pull hot air down vertically from the burner on top. Condensate also drips through them.

So the coffee grounds are collecting on top of the SS block that has the vertical tubes in them, and some of the coffee grounds have worked their way into the tubes and are stuck there.

Tinman

I used a thin nylon brush and it worked well. 

JUGHNE

I thought that the "fire tube" design was supposed to not have the "coffee ground" problem.
The vertical design would seem to promote wash down with condensate....... or not??

JUGHNE

I did notice that the coffee grounds can be picked up by a magnet.....strange that the magnet will not stick to the SS HEX BTW.
That might work (extension pick up tool) to pull some of it out of the tubes.

mattmia2

Some formulations of stainless steel are ferromagnetic, others are not.

PerryHolzman

The problem is that the common chemicals that will dissolve the carbon deposit "coffee grounds" will also damage the SS tubes and heat exchanger (perhaps not instantly - but, unrepairable failure likely within a year or two.

I'm aware of some chemicals that will dissolve these deposits without damaging the heat exchanger metals; but, they are hazardous to use and require neutralization to dispose. Certainly not something a common residential technician or company can deal with (whereas a Power Plant with a fully staffed chemistry department with 10's of thousands of dollars of safety equipment and supplies at their disposal, along with existing high 6 to 7 figure annual contracts for waste disposal, can do it).

So cleaning them with a soft brush before they set up, or a mechanical scrapper after they set up is the only methods.

hot_rod

I think most of the 400 series stainless are magnetic, I believe the Elite is 439. If the particles you are cleaning out stick to a magnet, would that be part of the metal breakdown?
Either the air they breathe or the fuel they consume are the other byproducts of combustion.

JUGHNE

IIRC, the Munchkin and Lochinvar I see are non magnetic SS tubes. So I wondered how the coffee grounds are able to attract to the magnet.

Nom_Deplume

JUGHNE said:

I thought that the "fire tube" design was supposed to not have the "coffee ground" problem.
The vertical design would seem to promote wash down with condensate....... or not??

We don't have a big coffee-ground problem...not like our previous boiler, a Munchkin, which was a POS. But there are some grains on top of the HX every year, and some in the condensate trap. Those I can easily clean out, of course, but now I am finding some grains stuck inside the tubes.

I will try harder to push them out with a thin brush...

flat_twin

https://www.grainger.com/product/TOUGH-GUY-36-in-Nylon-Pipe-Brush-2RVD9
How dimpled are the tubes on the HTP. Could a brush of this size be used?

I've never tried to look directly down the tubes. I'd have to use a mirror or try to capture a photo with my phone. Will try that next time I open it up. I usually just vacuum the fire side and flush it down with water then clean the trap. No chemicals of any kind per mfg.

mattmia2

If i recall the UFT has something like extruded fins in the tubes. I think i have a picture somewhere.

mattmia2

flat_twin

In that case maybe some long heavy zip ties could be used to dislodge any stuck coffee grounds.

mattmia2

So there is actually something to clean in other models? I have never seen the inside of any of these other than mine. This probably explains my confusion with the manual.

flat_twin

The WM manual says nothing about servicing the down tubes other than to flush them with water. Solid_fuel_man posted this pic of the bottom of the Eco HX a couple years ago. Not the same design as the HTP photo obviously and maybe not prone to have an issue with coffee grounds.

Nom_Deplume

OP here. The HX in our HTP Elite FT looks a lot like the picture above, although it is inside a cylindrical SS enclosure.

Following advice above, I tried to clean inside the holes with a narrow brush. Unexpectedly, I can work my way in with the brush on one side of each elongated slot (marked "yes" in my photo) but not on the other side (marked "no"). Almost every slot is like that, although a few are open on both sides.

Is this normal?

flat_twin

To promote heat transfer the tubes are dimpled in a staggered pattern, creating more surface area. Your cleaning brush is running into the dimples.

Is it possible the "stuck coffee grounds" are actually the dimples in the tubes? Just a wild guess...

Nom_Deplume

Excellent point. But there are times when the brush seems to hit a hard place (under the 'no' in the image), and there are places where the brush seems to grind against some stuff and ultimately it goes through (under the 'yes' in the image). The white nylon bristles end up a light rust color, which you wouldn't think stainless would do.

Also the 1/4" wide brushes I happened to have are only 7" long, so they didn't go through to the bottom, just their length. I need to get longer brushes.

Solid_Fuel_Man

Ever tried using a water pick? The dental cleaning kind? 

Use hot water to rinse as well. 

HVACNUT

How about an air compressor?
On a side note, what are the combustion numbers? 
Isn't reoccurring coffee grounds sometimes indicative of cross contamination? The exhaust is not being drawn back in at the vent termination, and no leaking gaskets anywhere?

Nom_Deplume

Exhaust an intake are well separated. I cannot guarantee no leaking gaskets, but I don't see any evidence of such.

Regarding Water Pik, I did run a garden hose from the utility tub, and used the single-jet mode of the garden sprayer to hit each hole. There is not, and has never been, any observable difficulty in water draining.

Thanks to everyone for the helpful comments and suggestions!