Cavitation when my heater starts

Jump to latest Follow Reply
Time for an update on the cavitating heater.

For an update on my water chemistry, view this thread.

Ever since I got my TA down to 110 I have been able to get my Ph down below 8.0 I had continued to dump muriatic acid into my pool, till I eventually got the TA down to 90 and have been able to maintain a Ph of 7.6 all day yesterday and this morning.

With these conditions, I have been seeing little white chips (scales really) floating in my water. I was hoping this was the scalling in my heater breaking up and being discharged into my pool. Today, I decided to take the filter apart, clean it, and treat my heater with a more concentrated batch of muriatic acid.

I took some pictures. This is my pool. While I wouldn't call it sparkly it isn't cloudy either.
D100796.jpg

D100797.jpg

It was very windy today & I couldn't wait for it to stop blowing, so this is all I got.
D100798.jpg
 
With the heater on its end, I poured my muriatic concoction into the heat exchanger. I filled an empty muriatic acid container (gallon jug) with tap water about 3/4s of the way. I filled the rest of the container with muriatic acid (20^ Baume 31.45%).
You can see it working.
D100807.jpg


After the muriatic acid stopped reacting, I let it sit for a while, then flushed the heat exchanger with a garden hose until scale & foam stopped coming out of the tubes. I repeated this seven times. On the sixth & seventh time, there was no reaction at all so I believe I got it all out.
 
I put everything back together & brushed the pool. Everything is up and running. I am pretty sure my TA will go down a bit, so will my Ph as there is bound to be some residual muriatic acid in the heater.

My plan is to let it circulate for the rest of the week, I'll check my filter again Friday. If there is no scale I'll fire up the heater (& more importantly the hot tub) if there is a lot of scale, I'll clean everything again and give it another week.
 
By-the-by, 4:00 pm test numbers are.

FC: 2.0 (I added 182 ounces of 6%)
CC: 0.2
TA: 70
PH: 7.0
CH: 310

The sample was taken right after I got everything back in service, so I still expect something to happen with the TA & PH if there was some residual acid in the heater. I believe I got it all out, but you never know.
 
I filled an empty muriatic acid container (gallon jug) with tap water about 3/4s of the way. I filled the rest of the container with muriatic acid (20^ Baume 31.45%).
Click to expand...
And then you dumped it into the heater.
:shock: :shock: :shock: :shock: :shock: :shock: :shock: :shock: :shock: :shock:

Thankyou, I can die now knowing I have seen it all.

So you had a heater that was under warranty..............................

You had someone come out and tell you it is scaled and that is why this is happening................................
Did they ever check the internal bypass?
I have never witnessed a heater scaling that fast, and enough to limit flow and overheat, I honestly dont know if it would be possible.
 
Just-a-PB said:
I filled an empty muriatic acid container (gallon jug) with tap water about 3/4s of the way. I filled the rest of the container with muriatic acid (20^ Baume 31.45%).
Click to expand...
And then you dumped it into the heater.
:shock: :shock: :shock: :shock: :shock: :shock: :shock: :shock: :shock: :shock:

Thankyou, I can die now knowing I have seen it all.
Click to expand...

At least you'll die happy.

Just-a-PB said:
So you had a heater that was under warranty..............................

You had someone come out and tell you it is scaled and that is why this is happening................................
Did they ever check the internal bypass?
I have never witnessed a heater scaling that fast, and enough to limit flow and overheat, I honestly dont know if it would be possible.
Click to expand...

The heater manufacturer wasn't going to cover scaling under the warranty. There is nothing they could have done wrong to cause scaling. My pool builder was hee-hawing over paying to replace the heater, or even just the heat exhanger ($1500). We were going to get into a never ending argument about me not following his instructions to a tee. Even though I believe I did. Other than using liquid bleach instead of the Tri-chlor tabs he told me to use.

& yes, he checked the internal bypass.. it was working fine. Which stands to reason since it wasn't an issue until the burners came on. Otherwise, water flowed freely through the heater.

& there was definitely a lot of scaling going on.

Unless you don't think that is calcium scale in the picture of my filter. There was also a white coating on the heater tubing, especially on the exit side.
 

Enjoying this content?

Support TFP with a donation.

Give Support
Just-a-PB said:
I have never witnessed a heater scaling that fast, and enough to limit flow and overheat, I honestly dont know if it would be possible.
Click to expand...
It's definitely possible. Based on the reported information, I am not at all surprised that the heater was scaled.

New plaster gives off calcium hydroxide, which raises the pH and creates a lot of calcium carbonate (aka plaster dust). The higher temperatures in the exchanger further raise the CSI. Once a base of scale is created, the scaling speeds up because the initial scale layer catalyzes further precipitation and this slows the water flow, which causes it to heat up even more, further increasing the CSI.
 
We dont sell standard plasters, so I have never had any issues like this.
I can now see how that could happen, where it is basically baking on. Still seems like you need the perfect storm to make this happen that fast.

I feel for you.
New heater $1700, 1800. New exchanger is $750 if you can tackle it yourself. I would go with the new exchanger.
The builder should be able to get you one at cost, or below if he has any relationship with the local rep. Just a couple of new seals and your in business.
 
Just-a-PB said:
I feel for you.
New heater $1700, 1800. New exchanger is $750 if you can tackle it yourself. I would go with the new exchanger.
The builder should be able to get you one at cost, or below if he has any relationship with the local rep. Just a couple of new seals and your in business.
Click to expand...

definitely an option we already discussed. Him supplying the core & me doing the work. Since that is an option, I figured what's the worse I could do?

The only thing is if I change out the heat exchanger, I'd be tempted to start the heater up right away. This way, I'm forcing myself to wait a week.

But after the cleaning, the core looked very clean. I was surprised at how much of the scaling was removed.
 
JamesW said:
Just-a-PB said:
I have never witnessed a heater scaling that fast, and enough to limit flow and overheat, I honestly dont know if it would be possible.
Click to expand...
It's definitely possible. Based on the reported information, I am not at all surprised that the heater was scaled.

New plaster gives off calcium hydroxide, which raises the pH and creates a lot of calcium carbonate (aka plaster dust). The higher temperatures in the exchanger further raise the CSI. Once a base of scale is created, the scaling speeds up because the initial scale layer catalyzes further precipitation and this slows the water flow, which causes it to heat up even more, further increasing the CSI.
Click to expand...

If this is the case, & the calcium dust is getting past my filter, how am I going to get it out of my pool?
 
JamesW said:
Just keep your CSI slightly negative for a while and the calcium carbonate will not precipitate.
Click to expand...

Precipitate?

pre·cip·i·tate
[v., pri-sip-i-teyt; adj., -tit; n., -tit]
- verb (used with object)-tated-tating 1. to hasten the occurrence of 2. to separate (a solid) from a solution 3. to fling down - verb (used without object)-tated-tating 4. to condense from vapor and fall to the earth's surface as rain, snow, etc. 5. to separate from a solution as a precipitate
Click to expand...

So it will not separate from the water.

Ever?
 
Just keep the CSI slightly negative for a while and you should be fine. For the next 30 days, I recommend that you target about -0.15. After you feel that any scaling issues have been resolved, you can raise your target CSI to closer to 0.0 to +0.1.
 
You must log in or register to reply here.
Thread Status
Hello , This thread has been inactive for over 60 days. New postings here are unlikely to be seen or responded to by other members. For better visibility, consider Starting A New Thread.
Top Bottom
Back
Jump to latest Follow Reply