Jandy Gas Heater- burning but not heating

[ladfromaus]

Hi, I apologise for the length of this post but I wanted to give as much detail as possible to solicit help.

Up front I will say I was not on the ball and did not do much to prep my saltwater pool at the end of last season. I do run the pump on a much reduced schedule during the winter, so I don't really close the pool. The problem I have now is, I have a Jandy JXI260N heater and the water will not heat. The burner will come on just fine and I can feel the heat in the exhaust, but the water will not heat. Pump is circulating water through the pool, but I don't know if it going through the heater, or is just being diverted at the manifold and back out without going through the tubes.

I took the cover off near the inlet/outlet and removed and "checked" the Thermal Regulator Valve (no I didn't heat it up to see if it opened fully, but I think that's the opposite of the problem I have). To me it looks like a slightly beefed up car engine thermostat and appears built the same way. It is in the closed position at rest, and I can push open the valve slightly against the spring with my thumbs. I've felt that same feeling with car thermostats before and it feels normal.

My next guess is it could be the "bypass valve", but I can't find any information on how this works to begin trouble shooting. I have a few other random ideas such as airlock in the tubes causing water to bypass, scale built up preventing flow, debris blocking somewhere inside there, but these are thoughts without really knowing how it all works and flows inside there.

My next action would be to take the manifold off and see what's in there and check the bypass valve and around that area. Anyone have any thoughts on what I could try or target or if there is a known issue like this?
Many Thanks

 

[ajw22]

Your signature does not show how many gallons in your pool.

What makes you think your heater is not heating the water? If the burners are on the heat has to go someplace. If the heat is not going into the water the heater will over temp and shutdown.

Post pics of your equipment and valves.

 

[ladfromaus]

Sig fixed, thanks for that tip!

I base my comment on the outlet pipe not being any warmer than the inlet after an hour or so, which it has been previously when running. Also, historically the pool temp did come up a little after running for a couple hours, which it now does not. I could try to let it run longer than a few hours, but I'm like you in thinking that the heat has to go somewhere and if (seemingly) not the water, is it going to cause damage to components, so I haven't persisted with long runs yet. It has not shut itself down yet, and it doesn't seem overly warm, except for the exhaust, which is toasty.

I'll have to resize the pics I just took. Will post them in a bit.

 

[ladfromaus]

Equipment

• ladfromaus
• Mar 20, 2020
• 6

Pictures of equipment as it stands.

 

[ajw22]

Your 260K BTU heater will raise your pool about 1 degree an hour. This time of year the pipes are cold, the ground is cold, the air temperature is cool, and you lose a lot of that heat before it gets into the pool.

You could also have a scaled up heat exchanger reducing the efficiency of the heater. You have to open it up and take a look inside.

 

[ladfromaus]

Your 260K BTU heater will raise your pool about 1 degree an hour. This time of year the pipes are cold, the ground is cold, the air temperature is cool, and you lose a lot of that heat before it gets into the pool.

You could also have a scaled up heat exchanger reducing the efficiency of the heater. You have to open it up and take a look inside.

That's what I figured would be the answer. I was hoping someone may have been able to point me to something specific. Thanks.

 

[sktn77a]

If the heat isn't getting to the water, then that 260,000 BTU is heating up the components inside the heater - not good!

I have a 200,000 BTU gas heater in a 15,000 gal pool and you can definitely feel the difference in temperature between the pool water and the water coming back in through the returns.

 

[ladfromaus]

3 cheers for @ajw22 , you called it Allen. It's been running 6 hours now and I can feel the temp difference in the inlet/outlet. Pool temp is coming up and the return to the pool is warmer than the pool water. Hopefully this scare will motivate me to take better care of my gear going forward. Thanks for the input guys.

 

[ajw22]

3 cheers for @ajw22 , you called it Allen. It's been running 6 hours now and I can feel the temp difference in the inlet/outlet. Pool temp is coming up and the return to the pool is warmer than the pool water. Hopefully this scare will motivate me to take better care of my gear going forward. Thanks for the input guys.

What I have found happens when heating my pool early in the season is the ground around the pool and pipes is a big thermal sink. For a while the surrounding ground absorbs the heat before it gets into the water. Once the surrounding ground is warmed and the heat flows into the water the ground then acts to keep the water warm otehr then the lost through surface evaporation. Basically you are heating more then just the water when the ground is cold.

 

[JamesW]

The flow rate makes a difference in how much the water temperature rises from inlet to outlet.

What is the pump speed?

 

[ladfromaus]

Sorry James, didn't get notified of your comment. I'm not sure of the speed. I'm pretty sure I have a variable speed pump, but not quite sure how to check or adjust the speed. I'll have to do my homework on that, both to find out what the current speed is and how and more importantly why/when to adjust it.