I have a hayward 400d heaterthat is rattling then cutting off...what could cause this?

this is caused by an obstruction in the water flow. check for blockages in both the supply and return piping

motor is overheating the thermo is shutting it off for safety need a new motor or pump sometimes the whole pump is cheaper than fixing the old one

Thank you for posting your question here on Fixya.com.

The Hayward H100 has a diverter plate welded into the header that helps direct some of the water flowing thru into the heat exchanger to heat the water. If the weld fails the diverter can interfere with that flow and cause overheating or poor flow thru the heater which in turn can lead to the problems you describe.

Remove the inlet side hose once you have blocked the flow of water from the pool and you should see the diverter in the inlet. If you can move it then it is broken and needs to be fixed back in place or the whole heat exchanger needs to be replaced.

If the diverter is not moving then your issue is likely an overall water flow one and the next place to look is the filter. Poor overall system flow may be enough to close the pressure switch telling the heater the pump is on but not enough to keep the water in the exchanger from getting too hot, again causing the symptoms you describe.

If this answer does not fix your problem, please comment with additional details prior to rating the answer. You may also contact me thru our website at www.arrowpools.net. Positive feedback is appreciated once your problem is solved!

John

cooked the motor. sounds like low oil level caused the rattle u might be up for a n ew motor....

water to slow for the heater or the by pass valve is bad

That plate should not move at all. If it is moving is is damaged. In the past that meant replacing the heat exchanger but I recently had someone tell me they took theirs to a radiator shop that tach welded the plate in place and it works fine now. Either way, the rattle is from water boiling in the unit due to poor flow through the heat excahnger. The plate we are talking about is what controls that flow.

Actually, the clicking is likely causing the shaking. Inside the manifold of a H100 is a stainless steel diverter plate that send some of the passing water into the heat exchanger and lets the rest past and back to the pool. When it breaks, you will hear a 'clicking' noise at it rattles in the water path. When it breaks, the flow to the heat exchanger is intermittent and you will begin to boil the water, causing the shaking. This situation is dangerous, especially without a pressure relief in the heater or pipe. As long as your water chemistry is sound, Hayward will usually cover this under warranty even if the unit is over a year old. Contact them to get a factory authorized repair rep out at: http://www.haywardnet.com/locator/

the cutter has that bushing attached to act as a tire as it travels across the scan axis, these infrequently wear out and cause the carriage to basically drag the blade behind causing your uneven cut pattern, the cutter must be replaced. If you need direction on how to do so please contact me