Pool Heater Making Strange Sound

[PhilB]

Anyone have an opinion on this.

I have a Hayward H100 pool heater. We use it quite a bit. I've noticed that starting last week, when the water runs through it but the unit is not operating, it is quiet. However, once I turn on the heater and the unit fires up, after about half a minute it sounds like there's a rock or something banging around inside the unit. Turn off the gas, sound stops. Turn the heat back on, the clanking sound starts again.

Any ideas? Is this a dangerous situation? I have about 3 weeks left of the season here in NYC, once the kids head back to school pool usage essentially stops, so I can take the unit apart then and see what I can tell. But I'm just wondering if I should stop using it.

Any help is appreciated.

Thanks,
Phil

[mas985]

Pool heaters, including water heaters, make a sort of poping sound if there is enough sediment build up in the heat exchanger. How long have you had the heater and have you ever had the heat exchanger cleaned? Also, does your pool tend to have high calcium hardness?

[PhilB]

Pool heaters, including water heaters, make a sort of poping sound if there is enough sediment build up in the heat exchanger. How long have you had the heater and have you ever had the heat exchanger cleaned? Also, does your pool tend to have high calcium hardness?

We've recently gone through a period where I had a hard time stabilizing alkalinity and PH. I use a cartridge filter and even the cartridge was clogged with "plaque", I had to soak the cartridge in muriatic acid and water to dissolve the build up. When rinsed afterward, a stream of milky white water flowed off the cartridge. This certainly restored the filter performance and flow as well.

This is only the 2nd season with the heater, and even though it's been HOT temperature wise, my kids and wife love and use the heater almost daily, especially at night. So it has gotten considerable use this season.

We've never had the heat exchanger cleaned. I did rinse the unit out when I closed down last season for the winter, and then let it dry, and stored the heater inside throughout the winter. If cleaning the heat exchanger means rinsing it, I can certainly remove the plumbing and clean it out with the garden hose.

Thanks,
Phil

[mas985]

Given your problems with the filter, it is probably a good bet you have the same issue with the heater. So I suspect there is probably some calcium buildup in the exchanger and it just needs to be cleaned out. However, you may need to do a bit more than a simple hose off. Check your manual for instructions but mine suggests using a long cylindrical metal brush to clean out the sediment.

[Pool Clown]

You guys are probably right.

But in another circumstance, there is the possibility that one of the by-passes, the flow, or the thermal, that could be the cause of the boiling. This will usually cause the heater to short cycle.

My money is on the calcium.

I post this for others that may have a similar issue without the water chemistry problem.

"Just a clown talking, ignore him. "

[PhilB]

You guys are probably right.

But in another circumstance, there is the possibility that one of the by-passes, the flow, or the thermal, that could be the cause of the boiling. This will usually cause the heater to short cycle.

My money is on the calcium.

I post this for others that may have a similar issue without the water chemistry problem.

"Just a clown talking, ignore him. "

It's not short cycling....I ran it Saturday all day and it ran fine, over 8 hours it raised the water temp probably 10 degrees (about 10000 gallons). It started right up and I checked it everyone so often, the fan and burner stayed on and ran with no issues. It just sounded like an old boiler, making these knocking sounds like a rock or something is in a pipe.

The season here in NYC is almost over - that is, 2/3s of the kids are back (away) at school already and my 3rd starts in a couple weeks. So once I close up in the next couple of weekends, I'll take the heater into my workshop and take it apart and report back on my findings.

Thanks again,
Phil