Calcium deposits in heater
- Thread starter glennx99
- Start date
I suspect that the heater is not getting enough flow. Possibly a system design or configuration issue.
What exact pump do you have?
What is the filter pressure (lowest/highest)?
Can you post a picture of the pump/filter/heater?
What exact pump do you have?
What is the filter pressure (lowest/highest)?
Can you post a picture of the pump/filter/heater?
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- - - Updated - - -
See other post.
I should say that we have a number of people in Bloomington trying to figure this out, and you are not the first person to mention low flow so that is definitely on the table for a possible cause. I see possible causes as being (perhaps a combination of)
1. High phosphates contributing to calcium phosphate scale forming inside heater (before drain an refill phosphates read 44,000ppb; now 1,000 ppb; city water 400 ppb).
2. Heater not cooling down before pump shuts off
3. Low flow
Your input is welcome!!!
GDA
Your pump is on the lower end in power. It should be ok as long as the system is designed properly. However, there's not much room for error. Just a little bit of excess resistance and your flow rate will be too low.
If the heater is below the water level, you need to add a real flow switch. The heater uses a pressure switch, which can be triggered by the weight of water resulting in the heater running with little or no flow.
I would definitely recommend making sure that the heater has a cool down period before the pump shuts off.
Can you post a picture of the plumbing between the pump and filter?
What is your filter pressure?
If the heater is below the water level, you need to add a real flow switch. The heater uses a pressure switch, which can be triggered by the weight of water resulting in the heater running with little or no flow.
I would definitely recommend making sure that the heater has a cool down period before the pump shuts off.
Can you post a picture of the plumbing between the pump and filter?
What is your filter pressure?
Definitely way too much pressure for that pump. Your flow will be too low.
Also, the equipment looks like it's below the pool. If it is, it'spossible for the heater to run with no flow at all, which can quickly destroy the heater.
I think that low flow is the problem. If there is scale in the heater, the primary cause is probably overheated water from low flow.
Also, the equipment looks like it's below the pool. If it is, it'spossible for the heater to run with no flow at all, which can quickly destroy the heater.
I think that low flow is the problem. If there is scale in the heater, the primary cause is probably overheated water from low flow.
Thanks for your feedback. Now that you mention it the heater was cycling of and on without the pump running. It would only go on briefly then shut itself off. I brought this to the attention of our local serviceman and he adjusted the pressure switch I think.
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Today's update. The heater was rebuilt as follows:
New heat exchanger
New pressure switch
New (we didn't have these before) sensors so that if the heat exchanger overheats the system will shut down (in the past the heat exchanger would get so hot the side plastic panels would melt).
Switch that will allow cool down before pump shuts off
As mentioned previously, pool was drained to reduce 45,000ppb phosphate levels, now under 1,000ppb.
Still working on finding a lab to confirm that the scale in the heat exchanger was phosphate.
Tentatively what I think I've learned: Phosphates are probably under-assessed. Often thought of as algae-food, they are potentially a contributor to scale and should be considered if there is, in our case, a heater failure but also SWG issues. Other things need to be ruled out as well including flow and cool-down time.
My plan is to have our man back here in a month or two to check for scale buildup in the heat exchanger.
Thank you, thank you, thank you, to all who contributed thoughts about my situation. I'll post more down the road.
G
New heat exchanger
New pressure switch
New (we didn't have these before) sensors so that if the heat exchanger overheats the system will shut down (in the past the heat exchanger would get so hot the side plastic panels would melt).
Switch that will allow cool down before pump shuts off
As mentioned previously, pool was drained to reduce 45,000ppb phosphate levels, now under 1,000ppb.
Still working on finding a lab to confirm that the scale in the heat exchanger was phosphate.
Tentatively what I think I've learned: Phosphates are probably under-assessed. Often thought of as algae-food, they are potentially a contributor to scale and should be considered if there is, in our case, a heater failure but also SWG issues. Other things need to be ruled out as well including flow and cool-down time.
My plan is to have our man back here in a month or two to check for scale buildup in the heat exchanger.
Thank you, thank you, thank you, to all who contributed thoughts about my situation. I'll post more down the road.
G
I would suggest adding a flow meter to monitor flow rates. They’re relatively inexpensive.
I would also add a flow switch to the heater safety circuit set to the minimum GPM for that heater.
I would also add a flow switch to the heater safety circuit set to the minimum GPM for that heater.
+1 Glenn for the followup.i believe many may benefit from info in this emerging topic.
A year and a half later there have been no problems with the heater. My opinion is the main problem was very high levels of phosphates resulting from breakdown of phosphonic acid-based sequestrant. Under high heat in the heat exchanger I believe this caused scale to form, reducing water flow and causing the heater to overheat. It also cause cloudiness when liquid chlorine was added to the pool resulting in local pH changes.