Hayward h300 pool heater parts

lapurple

Active member
Jun 9, 2018
43
Baldwin, Florida
I can't seem to find the answer I'm looking for so I'm hoping someone here could help. Hubby's got to replace the front header gaskets because we have a major leak. The header bolts are pretty rusty so we're probably going to have to change them. I need to know the size of the bolts so he can stop and get some on his way home today, probably at Home Depot or something.

Would appreciate any information. Thanks!
 

JamesW

TFP Expert
Mar 2, 2011
20,783
The bolts are part of the heat exchanger.

The header slips on the bolts and gets secured by the nuts, which I think are 5/16-18 flange nuts.

 

JamesW

TFP Expert
Mar 2, 2011
20,783
If you have a leak, I suspect that it's probably in the heat exchanger.

Can you see where the water is leaking from?
 

JamesW

TFP Expert
Mar 2, 2011
20,783
It's unusual for the seal to fail. I suspect that the heat exchanger is bad, but it's probably worth replacing the seal to see if that works.

I'm only about 95% sure on the size for the nuts. You can remove one to take to the hardware store to be sure.

I think that the nuts require a 1/2" socket to remove. (A 5/16" bolt should take a 1/2" socket).

Get stainless as regular nuts will corrode quickly.
 
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