Heaters all have a bypass?

[Bperry]

I have a 20 year old larrs lite heater I’ve been limping along the past year. I had it working at the end of last winter but when I went to turn it on again today it was not working due to a blown fuse. After replacing the fuse, it fired right up and I thought, great we can get some more pool use for a couple months.

Then I hear some clanging around in the pipes and see the pipes bouncing around with what’s sounds like rocks being pushed through the filter and see chunks of rusted metal in my salt cell so I powered off the pump and heater, removed and rinsed out the cell and all appears to be ok, except the heater.

obviously the heat exchanger went kaput and the heater is done for, but I’m wondering if there is usually some kind of bypass internally that lets the water avoid going through the heat exchanger? I’m wondering if I can leave the heater plumbing hooked up and off without worrying about more metal chunks breaking loose and getting into the plumbing. It stopped making the horrible noise when I turned the heater switch off so I suspect there’s something like a bypass.

 

[JoyfulNoise]

The old teledyne Laars heaters were not know for their sophistication. I don’t believe the header block has a high flow bypass with a thermal regulator like more modern gas heaters. Either way, if the heat exchanger is compromised (leaking) then you need to take the heater out of service and bypass the plumbing manually or else it will continue to lose water. Even in modern heaters there’s always a small flow of water through the heat exchanger. Do it now while the weather is still nice so you’re not losing sleep in the winter when freezes hit think the leak will get worse. Cutting and gluing on PVC takes 30mins at most. Just make sure you kill the power and the gas to the heater.

 

[Bperry]

The old teledyne Laars heaters were not know for their sophistication. I don’t believe the header block has a high flow bypass with a thermal regulator like more modern gas heaters. Either way, if the heat exchanger is compromised (leaking) then you need to take the heater out of service and bypass the plumbing manually or else it will continue to lose water. Even in modern heaters there’s always a small flow of water through the heat exchanger. Do it now while the weather is still nice so you’re not losing sleep in the winter when freezes hit think the leak will get worse. Cutting and gluing on PVC takes 30mins at most. Just make sure you kill the power and the gas to the heater.

What’s strange is that it doesn’t appear to be leaking water, only metal! Ha.

 

[wireform]

That's right when there's no more metal the water will take over.

 

[MSchutzer]

If your heater is a Laars LX or LT then there is a high flow spring based bypass in the polymer input / output heater. There’s no thermal regulator like in modern heaters, the pressure based bypass gets adjusted for a certain range of temperature rise through heat exchanger.

If you have a LX or LT heater the bypass spring components may have broken and that may be the metal pieces you are seeing.

I have a LX400 that I installed in 2002 and it’s still working fine and is in good shape. I’ve only had to replace the pressure sensing switch once and clean some cobwebs out of the gas orifices a couple of times. The nice thing with these heaters is that all the burners and the burner tray parts are stainless so they don’t rust away.

 

[Bperry]

If your heater is a Laars LX or LT then there is a high flow spring based bypass in the polymer input / output heater. There’s no thermal regulator like in modern heaters, the pressure based bypass gets adjusted for a certain range of temperature rise through heat exchanger.

If you have a LX or LT heater the bypass spring components may have broken and that may be the metal pieces you are seeing.

I have a LX400 that I installed in 2002 and it’s still working fine and is in good shape. I’ve only had to replace the pressure sensing switch once and clean some cobwebs out of the gas orifices a couple of times. The nice thing with these heaters is that all the burners and the burner tray parts are stainless so they don’t rust away.

I don’t think mine is an LX or LT. It has a cast iron input and the burner tray is rusted out so probably older than those models. strange that the big chunks of metal stopped coming out when I turned the switch off. Maybe was just coincidence. Now I’m curious to take it and find out.