H100ID1 Clunking or popping

If you have a Hayward H100ID1 pool heater and it is shaking, popping, clunking or banging and only gives faint pulses of heat, TURN IT OFF.

 The lack of comprehensive safeties is giving ample warning of a problem.  Much better than some cryptic error code too.

The good news is that you can fix it quickly, easily and without having anyone scam you about faulty "water chemistry" or other fantasies.  The first one I fixed ran perfectly over a decade with NO issues until the pool was removed as the kids had aged out of it.

Some will tell you the manufacturer is at not at fault, this is an out an out lie.  To save cost, a very good design was ruined by the lack of a simple bracket.  The popping and shaking is water basically exploding within the heat exchager because there is insufficent flow through it and the water boils.  There are safeties to prevent overheating and lack of flow into the header but no safety on actual flow through the heat exchanger pipes themselves.  This is the first flaw.  Below is a schematic of the heat exchanger and header.

The reason the water boils inside the heat exchanger tubes is the poor design of the header baffle attachments or complete lack of baffle attachment on the downstream end.  This lack allows the baffle to raise and permit the inlet water to run straight through the header to the exit, bypassing the heat exchanger all together.  This causes the water in the heat exchanger to flow too slowly and boil creating the popping and shaking of the unit.

As shown below, the fix is to remove the exit piping of the heat exchanger header (heater outlet) and jam a 3/8" or so stainless bolt or rod that is a few inches or more long between the heat exchanger exit tubes and the top of the baffle plate.  This should hold the plate DOWN and force water flow through the heat exchanger properly.  For extra security, glue (thickened epoxy, or JB weld) the baffle brace in place.

 Opinions are mine, use at your own risk etc etc.

The first one of these I fixed cold, not knowing what was wrong, in less than 30 minutes, from popping through diagnosis to quiet heat.  This was with dealers and service people wanting $100.00 just to lick it and always blaming the customer and their poor pool chemistry which was analy maintained.  The gall of hayward was they replaced or fixed the same unit a year after it was installed for exactly the same problem.  I did it for a beer, 'cause I am like that.

Sometimes the best advice is given freely, but if this warms you and your heart, consider donating via paypal to nospamevereh@gmail.com  beer is the fuel of not much of value actually but truth in advertizing still survives.

It has been a number of years since I published this.  The fix works, is just as easy and is free if you have a chunk of stainless that is 3/8" thick, beer has gone up.  Naturally advice is still free and one gentleman (Mr Anderson in fact)  was helped and recognized the travesty that is the inflation of beer pricing.  As Morphius would say, many thanks Mr. Anderson, I drink to your health!

 Last updated may 2025.