Sludge in heat exchanger

[Lakermac]

Hi all,
Before i start my hearing season here in md. I decided to do some maintenence work on my heat exchanger. It's a home made tube in shell design that worked quite well for me last season but i had some issues that need addressed. When i took it apart i noticed a couple spots of slimy gunk on my tubes and a few on the shell walls. The attached picture is one looking down the shell with the white stuff on top of the pipe. Just wondering if anyone has seen something like this before or if i need to change something about my water treatment scheme.
Thanks,
L.

 

[warno]

It looks like the same stuff that was caked all over heat exchanger in my boiler. I believe I was told is from minerals in the water (calcium, I think it was) building up on the surface.

I've only ran one year so far and this year I canned so much stuff including running soft water in my boiler so I don't know if it will fix it or not but it might be something to look into.

Did you check your water hardness before running last winter?

 

[Lakermac]

It looks like the same stuff that was caked all over heat exchanger in my boiler. I believe I was told is from minerals in the water (calcium, I think it was) building up on the surface.

I've only ran one year so far and this year I canned so much stuff including running soft water in my boiler so I don't know if it will fix it or not but it might be something to look into.

Did you check your water hardness before running last winter?

I filled it with a city water supply, not sure of the hardness but i wouldn't assume it is very hard. I put boiler treatment in it when i filled. I have also only ran one season which is what concerns me about what might happen in the future as it gets more use on it

 

[warno]

I was the same way with mine. City water and treatment.

Here's the thread I started when I found it in mine boiler

https://www.hearth.com/talk/threads/white-scum-inside-water-jacket.152963/#post-2073298

 

[Handsonautotech]

Hi all,
Before i start my hearing season here in md. I decided to do some maintenence work on my heat exchanger. It's a home made tube in shell design that worked quite well for me last season but i had some issues that need addressed. When i took it apart i noticed a couple spots of slimy gunk on my tubes and a few on the shell walls. The attached picture is one looking down the shell with the white stuff on top of the pipe. Just wondering if anyone has seen something like this before or if i need to change something about my water treatment scheme.
Thanks,
L.

To me it looks like deposits from minerals in water. Only way to get arpund that is to use distilled water after doing a good flush of the system. Probably not needed as long as you have no tinymports for the water to travel through.

 

[peakbagger]

If you are worried about it sulfamic acid usually works well to remove it. Generally the theory with closed loop systems with minimal makeup is the junk in the water drops out of suspension and forms sludge then pretty much wont do it anymore and folks live with it. If the system has a leak and water is being made up frequently it could be more an issue.

 

[Bob Rohr]

Looks like hard water deposits, and a very thin layer will reduce the heat transfer. A hydronic cleaner or mild acid will clean it out. Hercules Sizzle has worked for me, follow dilution instructions.

Deionized water is what you want if your fill water is hard. Some simple soap tests will tell, google hard water tests.

Some minerals will become more soluble as the water warms, sodium chloride for example. Other minerals become less soluble as temperature increases.

So some will coat out the surfaces, others form the chunks you see at the bottom of water heaters. You want ALL of them stripped from your fill water.

Typical water softeners will strip some of the minerals out, not all and they will leave the water with high conductivity due to the ion exchange process, you really don't that that either as it leads to corrosion.

DI water is by far the best choice if you have hard or high TDS water.

 

[mustash29]

Bob,

Would you also recommend DI for an open system that is treated with sodium nitrite / sodium nitrate? The system will contain mild steel, stainless steel, copper & brass.

I tried asking my water treatment rep at work but he seemed to think that DI water would be too "hungry" and tend to suck ions out of all the metals. I also have the option of using RO effluent (reverse osmosis) before it gets polished with the demin bed.