My daughter just purchased a house with a pool that has a Sta-Rite SR200NA natural gas heater.. Initially the blower and burner would not turn on and the Service Unit light would come on when we tried to fire it up.. I Checked the LED lights on the back of the control panel and got the blower and burner to come on.. Now, however.. about 15 - 20 seconds after the burner ignites, there is a knocking sound coming from the manifold and the temp gauge shows the temp shooting up rapidly..It sounds like a spring or something has let loose in the manifold.. Is it possible that the manifold bypass valve spring has let go..? Bad Bypass valve? or is it more likely that the spring on the thermal regulator ( thermostat ) is the culprit.. When the unit is not running, there is no knocking or water restriction to the pool.. It happens so quickly that I turned off the heater to prevent damage to the coils in case it was not getting water and did not check to see if the water flow back to the pool was restricted.. Anyone have this problem before?? Any suggestions?
Sta-rite sr200na heater knocking when burner turns on
- Thread starter PAULIEB1
- Start date
Pool Clown
In The Industry
I would expect to hear this complaint from someone that just installed the heater because this sounds like the heater is plumbed in backwards. Confirm that the inlet pipe to the heater is coming from the filter and the outlet is going back to the pool (pipe disappears into the ground). If you didn't have the rapid temp increase, i would say yes, look towards one or both of the by-passes.
The short cycling, noisy, shaking, popping or banging are all indications of the by-pass(s) malfunctioning.
The short cycling, noisy, shaking, popping or banging are all indications of the by-pass(s) malfunctioning.
The heater is plumbed correctly.. What I find interesting is that this does not happen until the unit ignites.. If I understand the operation correctly.. neither the thermal regulator nor the bypass valve are connected electrically so why would this only occur when the burner/blower is turned on.. ? I would seem that the problem would occur the minute you turn on the pump and put the heater under pressure. Am I missing something?
Pool Clown
In The Industry
The noise you are hearing is the water reacting to the higher than normal temps. Water is beginning to boil. When you have a broken by-pass valve, it's broke in the wide open position allowing most of the water to by-pass the exchanger. the water that does happen to travel through the exchanger travels too slowly, absorbs too much heat, and begins to boil. When the heater is off there is no heat acting on the water and it flows quietly.
When you go to remove the thermal by-pass, pay close attention to how easily the by-pass (thermostat) comes out. If it doesn't come out easily, feels like its hung up on something, that may be the flow by-pass that is broken. In that case, that would be your problem. Stop, and begin to remove the header/flange. Referring to the manual will give you an idea on what the part looks like.
When you go to remove the thermal by-pass, pay close attention to how easily the by-pass (thermostat) comes out. If it doesn't come out easily, feels like its hung up on something, that may be the flow by-pass that is broken. In that case, that would be your problem. Stop, and begin to remove the header/flange. Referring to the manual will give you an idea on what the part looks like.
That's kind of what I came up with, but confirmation is always appreciated.. I'll be ordering both the regulator and bypass valve to make sure I have the correct part..While I'm at it, I will replace the o-rings also.. Thanks for the info.. I'll let you know how I make out when I get into it..